Benzocaine; butamben; tetracaine is a combination of topical anesthetics, available in gel, spray, and liquid formulations, for application to accessible mucous membrane except the eyes. These products are used for topical anesthesia and mild pain control, including use during procedures such as endoscopy, surgery, or dental procedures. It can be used for gag reflex suppression as well. The onset of anesthesia is less than 1 minute and effects last 30 to 60 minutes. Benzocaine and tetracaine are more likely than other local anesthetics to cause contact sensitization. The potential for sensitization increases with the duration of contact, and can be avoided with appropriate application technique. Cases of methemoglobinemia have been reported from improper use of topical benzocaine-containing anesthetic sprays; benzocaine; butamben; tetracaine products should never be delivered in excess of 2-second sprays. These products are not intended for prolonged application time or use.
General Administration Information
For storage information, see the specific product information within the How Supplied section.
Route-Specific Administration
Oral Administration
Other Oral Formulations
Liquid Clinical Kit (Cetacaine) for subgingival application:
-Remove and discard the shipping cap, replacing it with the Luer-lock dispensing cap. Do not remove the dispensing cap after it is in place.
-Remove the small cap from the Luer-lock port, retaining it for replacement after use. Lock a delivery syringe into the port. Invert the bottle and slowly draw liquid into the syringe. Do not draw more then 0.4 mL liquid into the syringe.-Application in excess of 0.4 mL (i.e., 400 mg) per patient visit/appointment is contraindicated.
-If air is drawn into the syringe, push the liquid back into the bottle and slowly redraw liquid into the syringe.
-Turn the bottle upright and remove the syringe from the port. Replace the port cap.
-Attach a Microcapillary Tip to the syringe. The tip may be bent to improve access.
-Tissue does not need to be dried prior to application.
-Place the tip subgingivally and apply the liquid by slightly depressing the plunger while following the geography of the pocket. Discard the syringe and the tip after use.
-Wait approximately 30 seconds before beginning the procedure. When used as directed, the site should remain anesthetized for 30 to 60 minutes.
Topical Administration
-Apply directly to the site where pain control is required.
-Tissue does not need to be dried prior to application.
Other Topical Formulations
Aerosolized Spray (Cetacaine):
-Insert the Jetco cannula (J-4) firmly onto the protruding plastic stem on the bottle and press the cannula forward to actuate the spray valve.
-Spray the site for approximately 1 second or less (i.e., 200 mg). Spray in excess of 2 seconds (i.e., 400 mg) is contraindicated.
-The cannula may be removed and reinserted as many times as required for cleaning or sterilization, and is autoclavable.
Metered Spray (Exactacain):
-Insert the applicator firmly into the spray nozzle.
-Apply 3 metered sprays to the site. Application in excess of 6 metered sprays is contraindicated.
-The applicators are disposable and indicated for single use only; discard the applicator after each patient use.
Liquid:
-Apply 0.2 mL (i.e., 200 mg) with a cotton applicator or directly to the site until desired anesthesia is achieved. If a cotton applicator is used, do not allow it to remain in position for an extended period of time; local reactions are related to the duration of the application time.
-Application in excess of 0.4 mL (i.e., 400 mg) is contraindicated.
Liquid Clinical Kit (Cetacaine) for topical application:
-Remove and discard the shipping cap, replacing it with the Luer-lock dispensing cap. Do not remove the dispensing cap after it is in place.
-Remove the small cap from the Luer-lock port, retaining it for replacement after use.
-The Luer-lock port allows for a single dip of an appropriate applicator (e.g., a microbrush).
-Dip the applicator into the liquid by inserting it through the Luer-lock port, and gently remove it. Replace the port cap.
-Use the applicator to apply the liquid to accessible mucous membranes. Discard the applicator after use. Do NOT re-insert the applicator through the Luer-lock port, as cross-contamination of the liquid would likely result.
-Wait approximately 30 seconds before beginning the procedure. When used as directed, the site should remain anesthetized for 30 to 60 minutes.
Gel:
-Gently depress the pump to dispense a bead of gel approximately 0.25 to 0.5 inches long (i.e., 200 mg).
-Use a cotton swab for application, spreading thinly and evenly over the desired area. Discard the cotton swab after use.
-Application of a bead of gel in excess of approximately 1 inch long (i.e., 400 mg) is contraindicated.
Adverse reactions are minimal with appropriate use of benzocaine; butamben; tetracaine products (i.e., as a single dose applied topically to mucosal tissue by a healthcare practitioner).
Adverse reactions caused by local anesthetics are more likely to occur in patients following prolonged self-medication (which is contraindicated), and present as a contact dermatitis characterized by erythema and pruritus which may progress to vesiculation and oozing. Localized allergic reactions may occur after prolonged or repeated use of any aminobenzoate anesthetic. Prolonged or occluded contact of the anesthetic to any site is not recommended as it increases the possibility of a serious allergic reaction, dehydration of the epithelium, or an escharotic effect. If manifestations of an allergic reaction such as rash (unspecified), urticaria, or edema occur, the drug should be discontinued. Unpredictable adverse reactions such as hypersensitivity or anaphylactoid reactions are extremely rare.
Use of benzocaine-containing products can result in methemoglobinemia, which is a rare but serious condition where too much of the hemoglobin in red blood cells becomes unable to bind and carry oxygen. Severe cases of methemoglobinemia can result in death. If a patient receiving benzocaine; butamben; tetracaine becomes cyanotic or if elevated methemoglobin concentrations are suspected, immediately institute treatment to counteract methemoglobinemia (such as administration of methylene blue) as oxygen delivery is ineffective throughout the body until the condition is reversed. Signs and symptoms of methemoglobinemia may appear within minutes to 1 to 2 hours after benzocaine exposure and may occur with initial and/or subsequent use. Advise patients to seek immediate medical attention for discoloration (pale, gray, or blue-colored) of skin, lips, or nail beds; shortness of breath; fatigue; confusion; headache; lightheadedness; or rapid heart rate. Chocolate-brown rather than red blood is characteristic and may indicate methemoglobinemia, but this change is a late sign. Health care professionals using local anesthetics during medical procedures should monitor patients closely for methemoglobinemia, use co-oximetry when possible, and have resuscitation equipment and medications readily available, including methylene blue. Use benzocaine products in the smallest amount possible in order to relieve pain. Over-the-counter (OTC) oral drug products containing benzocaine should not be used to treat infants and children younger than 2 years. More than 400 cases of benzocaine-associated methemoglobinemia have been reported to the FDA or published in the medical literature since 1971. Of the 119 cases recently evaluated, most were serious and required treatment. Twenty-two cases (18%) occurred in pediatric patients; 11 of these were in children younger than 2 years. Four of the 119 cases (3%) resulted in death, including 1 infant and 3 adults. Thirty-six cases (30%) had a reported methemoglobinemia concentration of 30% to 55% (normal concentration is 1% to 2%). Seventeen cases (14%) had a reported methemoglobinemia concentration of 55% or more, which is considered life-threatening.
Do not use benzocaine; butamben; tetracaine products 72 hours before having pancreatic function tests with bentiromide, as the benzocaine component could interfere with results.
Benzocaine; butamben; tetracaine contains ester anesthetics, which are metabolized to para-aminobenzoic acid (PABA), and thus should not be used in anyone with ester local anesthetic hypersensitivity or para-aminobenzoic acid, PABA hypersensitivity.
Benzocaine; butamben; tetracaine products are intended only for topical administration to mucous membranes, excluding the eye. Ophthalmic administration and any type of parenteral administration, such as subcutaneous administration, intramuscular administration, and intravenous administration, are contraindicated.
Benzocaine; butamben; tetracaine products are intended only for topical administration to mucous membranes, excluding the eye. Ocular exposure is contraindicated.
Application of benzocaine; butamben; tetracaine to large areas of denuded or inflamed tissue (e.g., mucous or skin abrasion, mucous or skin atrophy, burns) is contraindicated as excessive absorption can occur, possibly increasing the risk of systemic toxicity. These products are intended only for short term topical administration to relatively healthy, small areas of mucous membranes, excluding the eye.
Do not cover the site of benzocaine; butamben; tetracaine application. Covering the site of application with items such as dentures or cotton rolls is contraindicated (they essentially act as an occlusive dressing), as this allows for retention of the active ingredients directly on the mucous membrane which could cause an escharotic effect. Additionally, increased systemic absorption can occur, increasing the risk of systemic toxicity.
Benzocaine; butamben; tetracaine products are contraindicated for use in patients with cholinesterase deficiencies, including pseudocholinesterase deficiency.
Benzocaine use can result in methemoglobinemia. Patients with reduced oxygenation status may have signs and symptoms of methemoglobinemia at lower serum methemoglobin concentrations than healthy individuals. Patients with breathing problems such as those with asthma, bronchitis, emphysema, chronic obstructive pulmonary disease (COPD), or cardiac disease, tobacco smoking patients, and geriatric patients are at greater risk for complications related to methemoglobinemia. Patients with certain hereditary defects including G6PD deficiency, hemoglobin-M disease, methemoglobin reductase deficiency, and pyruvate-kinase deficiency may also be at greater risk for developing methemoglobinemia. Signs and symptoms of methemoglobinemia may appear within minutes to 1 to 2 hours after benzocaine exposure and may occur with initial and/or subsequent use. Advise patients to seek immediate medical attention for discoloration (pale, gray, or blue-colored) of skin, lips, or nail beds; shortness of breath; fatigue; confusion; headache; lightheadedness; or rapid heart rate. Health care professionals using local anesthetics during medical procedures should monitor patients closely for methemoglobinemia, use co-oximetry when possible (methemoglobinemia can cause unreliable readings on standard two-wavelength pulse oximeters), and have resuscitation equipment and medications readily available, including methylene blue. Several factors influence the amount of benzocaine contained in a single spray including manufacturer differences, varying concentrations, length of time actuator is depressed, residual container volume, and orientation of the spray. Use care to assure the maximum dose of benzocaine; butamben; tetracaine is not exceeded during a procedure or an appointment. If a patient becomes cyanotic or if elevated methemoglobin concentrations are suspected, immediately institute treatment to counteract methemoglobinemia (such as administration of methylene blue) as oxygen delivery is ineffective throughout the body until the condition is reversed.
An appropriate dose of benzocaine; butamben; tetracaine products has not been established in pediatric patients. Over-the-counter (OTC) oromucosal drug products containing benzocaine are contraindicated in neonates, infants, and children younger than 2 years due to the risk of life-threatening and fatal methemoglobinemia. Benzocaine products should be used sparingly and only as needed in older children and adolescents; do not apply more frequently than directed. Signs and symptoms of methemoglobinemia may appear within minutes to 1 to 2 hours after benzocaine exposure and may occur with initial and/or subsequent use. Advise patients to seek immediate medical attention for discoloration (pale, gray, or blue-colored) of skin, lips, or nail beds; shortness of breath; fatigue; confusion; headache; lightheadedness; or rapid heart rate. Health care professionals using local anesthetics during medical procedures should monitor patients closely for methemoglobinemia, use co-oximetry when possible (methemoglobinemia can cause unreliable readings on standard two-wavelength pulse oximeters), and have resuscitation equipment and medications readily available, including methylene blue. Several factors influence the amount of benzocaine contained in a single spray including manufacturer differences, varying concentrations, length of time actuator is depressed, residual container volume, and orientation of the spray.
There are no data available on benzocaine; butamben; tetracaine use during human pregnancy to inform a drug-associated risk of adverse developmental outcomes. These products should not be used during early pregnancy unless the healthcare provider judges the potential benefits outweigh the unknown hazards; routine precaution for the use of any topical anesthetic should be observed. A study by the American Dental Association provides some evidence that, when needed, the use of dental local or topical anesthetics at 13 weeks to 21 weeks of pregnancy or later is likely safe and does not raise incidences of adverse pregnancy outcomes or other adverse events; the study analyzed data from the Obstetrics and Periodontal Therapy (OPT) trial, a multicenter study of over 800 pregnant patients in the early to mid second trimester who received required dental procedures.
There are no data on the presence of benzocaine; butamben; tetracaine in human milk, the effects of the drug on the breast-fed infant, or the effects on milk production. However, when used appropriately, as a single dose applied topically to mucosal tissue, systemic absorption is expected to be minimal and unlikely to affect the nursing infant. In order to avoid infant ingestion, benzocaine; butamben; tetracaine should never be applied on or near the breast or nipple of a woman who is breast-feeding. Infant ingestion should be avoided because the benzocaine component has been associated with life threatening cases of methemoglobinemia in infants and children 2 years of age or less. This drug combination was evaluated by the American Academy of Pediatrics (AAP). However, lidocaine is classified as usually compatible with breast-feeding if an alternative is needed. Consider the developmental and health benefits of breast-feeding along with the mother's clinical need for benzocaine; butamben; tetracaine and any potential adverse effects on the breast-fed infant from benzocaine; butamben; tetracaine or the underlying maternal condition.
For topical anesthesia of all accessible mucous membranes, except the eyes; for the control of mild pain and for mucosal anesthesia during procedures (such as endoscopy or surgery) at sites including the ear, nose, mouth, pharynx, larynx, trachea, bronchi, esophagus, vagina when feasible, or rectum when feasible; for dental anesthesia, including anesthesia to subgingival tissue; and for use to control gagging:
Topical dosage (Cetacaine spray):
The average expulsion rate of residue from a one second spray at normal temperatures is 200 mg.
Adults: Apply 200 mg directly to the site or tissue to be anesthetized by spraying for 1 second or less. Do not administer more than 400 mg or spray in excess of 2 seconds. Reduce dosage in acutely ill patients and in debilitated elderly patients.
Topical dosage (Exactacain spray):
Adults: Apply 3 metered sprays directly to the site or tissue to be anesthetized, for normal anesthesia. Do not apply in excess of 6 metered sprays. Reduce dosage in acutely ill patients and in debilitated elderly patients.
Topical dosage (gel):
Adults: Apply 200 mg to the desired area by thinly and evenly spreading the gel with a cotton swab. A 200 mg dose of gel is equivalent to a bead approximately 0.25 to 0.5 inches long. Do not apply in excess of 400 mg of gel (a bead approximately 1 inch long). Reduce dosage in acutely ill patients and in debilitated elderly patients.
Topical dosage (Liquid):
Adults: Apply 200 mg, approximately 0.2 mL, directly to the tissue using an applicator such as a microbrush or a cotton applicator. If a cotton applicator is used, do not allow it to stay in position as local reactions could occur. Do not apply more than 400 mg, approximately 0.4 mL. Reduce dosage in acutely ill patients and in debilitated elderly patients.
Subgingival dosage (Cetacaine Liquid):
Adults: Using a syringe fitted with a microcapillary tip, apply 200 mg of solution, approximately 0.2 mL, subgingivally by following the geography of the pocket. Do not apply in excess of 400 mg, approximately 0.4 mL, per dental visit. Reduce dosage in acutely ill patients and in debilitated elderly patients.
Maximum Dosage Limits:
-Adults
400 mg per procedure. For Exactacain metered spray, 6 metered sprays per procedure.
-Geriatric
400 mg per procedure. For Exactacain metered spray, an appropriate dosage has not been established.
-Adolescents
Safety and efficacy have not been established.
-Children
Safety and efficacy have not been established.
Patients with Hepatic Impairment Dosing
Specific guidelines for dosage adjustments in hepatic impairment are not available; it appears that no dosage adjustments are needed.
Patients with Renal Impairment Dosing
Specific guidelines for dosage adjustments in renal impairment are not available; it appears that no dosage adjustments are needed.
*non-FDA-approved indication
Adapalene; Benzoyl Peroxide: (Moderate) Concurrent use of benzoyl peroxide and topical anesthetics may decrease the efficacy of the anesthetic. In a clinical study, an estimated 75% increase in patient-reported, prick-induced pain was noted in areas treated with both 5% benzoyl peroxide and 6% benzocaine cream as compared to areas treated with 6% benzocaine cream alone. Investigators attributed the decreased anesthetic effect to a breakdown of the benzocaine molecule by either or both benzoyl peroxide or benzoyl peroxide-derived free radicals. It is recommended that the skin area that is to be topically anesthetized have no previous treatment with benzoyl peroxide or that the skin is thoroughly washed prior to the application of the anesthetic.
Articaine; Epinephrine: (Moderate) Use articaine and benzocaine together with caution. Monitor cardiovascular and respiratory vital signs, as well as the patient's state of consciousness if used concurrently due to potential for additive CNS and/or cardiovascular toxic effects. Manifestations of toxicity may include CNS excitation and/or depression, cardiac conduction depression, or peripheral vasodilation. Additionally, coadministration may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue local anesthetic use. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Benzoyl Peroxide: (Moderate) Concurrent use of benzoyl peroxide and topical anesthetics may decrease the efficacy of the anesthetic. In a clinical study, an estimated 75% increase in patient-reported, prick-induced pain was noted in areas treated with both 5% benzoyl peroxide and 6% benzocaine cream as compared to areas treated with 6% benzocaine cream alone. Investigators attributed the decreased anesthetic effect to a breakdown of the benzocaine molecule by either or both benzoyl peroxide or benzoyl peroxide-derived free radicals. It is recommended that the skin area that is to be topically anesthetized have no previous treatment with benzoyl peroxide or that the skin is thoroughly washed prior to the application of the anesthetic.
Benzoyl Peroxide; Clindamycin: (Moderate) Concurrent use of benzoyl peroxide and topical anesthetics may decrease the efficacy of the anesthetic. In a clinical study, an estimated 75% increase in patient-reported, prick-induced pain was noted in areas treated with both 5% benzoyl peroxide and 6% benzocaine cream as compared to areas treated with 6% benzocaine cream alone. Investigators attributed the decreased anesthetic effect to a breakdown of the benzocaine molecule by either or both benzoyl peroxide or benzoyl peroxide-derived free radicals. It is recommended that the skin area that is to be topically anesthetized have no previous treatment with benzoyl peroxide or that the skin is thoroughly washed prior to the application of the anesthetic.
Benzoyl Peroxide; Erythromycin: (Moderate) Concurrent use of benzoyl peroxide and topical anesthetics may decrease the efficacy of the anesthetic. In a clinical study, an estimated 75% increase in patient-reported, prick-induced pain was noted in areas treated with both 5% benzoyl peroxide and 6% benzocaine cream as compared to areas treated with 6% benzocaine cream alone. Investigators attributed the decreased anesthetic effect to a breakdown of the benzocaine molecule by either or both benzoyl peroxide or benzoyl peroxide-derived free radicals. It is recommended that the skin area that is to be topically anesthetized have no previous treatment with benzoyl peroxide or that the skin is thoroughly washed prior to the application of the anesthetic.
Benzoyl Peroxide; Sulfur: (Moderate) Concurrent use of benzoyl peroxide and topical anesthetics may decrease the efficacy of the anesthetic. In a clinical study, an estimated 75% increase in patient-reported, prick-induced pain was noted in areas treated with both 5% benzoyl peroxide and 6% benzocaine cream as compared to areas treated with 6% benzocaine cream alone. Investigators attributed the decreased anesthetic effect to a breakdown of the benzocaine molecule by either or both benzoyl peroxide or benzoyl peroxide-derived free radicals. It is recommended that the skin area that is to be topically anesthetized have no previous treatment with benzoyl peroxide or that the skin is thoroughly washed prior to the application of the anesthetic.
Bupivacaine Liposomal: (Major) Avoid use of other local anesthetics for 96 hours after liposomal bupivacaine administration. Use benzocaine and other formulations of bupivacaine together with caution. Monitor cardiovascular and respiratory vital signs, as well as the patient's state of consciousness if used concurrently due to potential for additive CNS and/or cardiovascular toxic effects. Manifestations of toxicity may include CNS excitation and/or depression, cardiac conduction depression, or peripheral vasodilation. Additionally, coadministration may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue local anesthetic use. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Bupivacaine: (Major) Avoid use of other local anesthetics for 96 hours after liposomal bupivacaine administration. Use benzocaine and other formulations of bupivacaine together with caution. Monitor cardiovascular and respiratory vital signs, as well as the patient's state of consciousness if used concurrently due to potential for additive CNS and/or cardiovascular toxic effects. Manifestations of toxicity may include CNS excitation and/or depression, cardiac conduction depression, or peripheral vasodilation. Additionally, coadministration may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue local anesthetic use. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Bupivacaine; Epinephrine: (Major) Avoid use of other local anesthetics for 96 hours after liposomal bupivacaine administration. Use benzocaine and other formulations of bupivacaine together with caution. Monitor cardiovascular and respiratory vital signs, as well as the patient's state of consciousness if used concurrently due to potential for additive CNS and/or cardiovascular toxic effects. Manifestations of toxicity may include CNS excitation and/or depression, cardiac conduction depression, or peripheral vasodilation. Additionally, coadministration may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue local anesthetic use. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Bupivacaine; Lidocaine: (Major) Avoid use of other local anesthetics for 96 hours after liposomal bupivacaine administration. Use benzocaine and other formulations of bupivacaine together with caution. Monitor cardiovascular and respiratory vital signs, as well as the patient's state of consciousness if used concurrently due to potential for additive CNS and/or cardiovascular toxic effects. Manifestations of toxicity may include CNS excitation and/or depression, cardiac conduction depression, or peripheral vasodilation. Additionally, coadministration may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue local anesthetic use. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen. (Moderate) Use lidocaine and benzocaine together with caution. Monitor cardiovascular and respiratory vital signs, as well as the patient's state of consciousness if used concurrently due to potential for additive CNS and/or cardiovascular toxic effects. Manifestations of toxicity may include CNS excitation and/or depression, cardiac conduction depression, or peripheral vasodilation. Additionally, coadministration may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue local anesthetic use. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Bupivacaine; Meloxicam: (Major) Avoid use of other local anesthetics for 96 hours after liposomal bupivacaine administration. Use benzocaine and other formulations of bupivacaine together with caution. Monitor cardiovascular and respiratory vital signs, as well as the patient's state of consciousness if used concurrently due to potential for additive CNS and/or cardiovascular toxic effects. Manifestations of toxicity may include CNS excitation and/or depression, cardiac conduction depression, or peripheral vasodilation. Additionally, coadministration may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue local anesthetic use. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Calamine; Pramoxine: (Moderate) Caution is advised if combining local anesthetics. The toxic effects of local anesthetics are additive. A major cause of adverse reactions appears to be excessive plasma concentrations, which may be due to accidental intravascular administration, slow metabolic degradation, or overdosage. In addition to additive toxic effects, rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine-containing products. Clinicians should closely monitor patients for the development of methemoglobinemia when a combination local anesthetic is used during a procedure. If a patient becomes cyanotic or if elevated methemoglobin concentrations are suspected, immediately institute treatment to counteract methemoglobinemia (such as administration of methylene blue) as oxygen delivery is ineffective throughout the body until the condition is reversed. Patients who are receiving other drugs that can cause methemoglobin formation, such as prilocaine, are at greater risk for developing methemoglobinemia. (Moderate) Caution is advised if combining topical local anesthetics. The toxic effects of local anesthetics are additive. In addition, rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine-containing products. Clinicians should closely monitor patients for the development of methemoglobinemia when a combination local anesthetic is used during a procedure. If a patient becomes cyanotic or if elevated methemoglobin concentrations are suspected, immediately institute treatment to counteract methemoglobinemia (such as administration of methylene blue) as oxygen delivery is ineffective throughout the body until the condition is reversed.
Ceftriaxone: (Moderate) Caution is advised if combining topical local anesthetics. The toxic effects of local anesthetics are additive. In addition, rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine-containing products. Clinicians should closely monitor patients for the development of methemoglobinemia when a combination local anesthetic is used during a procedure. If a patient becomes cyanotic or if elevated methemoglobin concentrations are suspected, immediately institute treatment to counteract methemoglobinemia (such as administration of methylene blue) as oxygen delivery is ineffective throughout the body until the condition is reversed.
Chloroprocaine: (Moderate) Use chloroprocaine and benzocaine together with caution. Monitor cardiovascular and respiratory vital signs, as well as the patient's state of consciousness if used concurrently due to potential for additive CNS and/or cardiovascular toxic effects. Manifestations of toxicity may include CNS excitation and/or depression, cardiac conduction depression, or peripheral vasodilation. Additionally, coadministration may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue local anesthetic use. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Clindamycin; Adapalene; Benzoyl Peroxide: (Moderate) Concurrent use of benzoyl peroxide and topical anesthetics may decrease the efficacy of the anesthetic. In a clinical study, an estimated 75% increase in patient-reported, prick-induced pain was noted in areas treated with both 5% benzoyl peroxide and 6% benzocaine cream as compared to areas treated with 6% benzocaine cream alone. Investigators attributed the decreased anesthetic effect to a breakdown of the benzocaine molecule by either or both benzoyl peroxide or benzoyl peroxide-derived free radicals. It is recommended that the skin area that is to be topically anesthetized have no previous treatment with benzoyl peroxide or that the skin is thoroughly washed prior to the application of the anesthetic.
Dapsone: (Moderate) Coadministration of dapsone with benzocaine may increase the risk of developing methemoglobinemia. Advise patients to discontinue treatment and seek immediate medical attention with any signs or symptoms of methemoglobinemia.
Dibucaine: (Moderate) Caution is advised if combining local anesthetics. The toxic effects of local anesthetics are additive. A major cause of adverse reactions appears to be excessive plasma concentrations, which may be due to accidental intravascular administration, slow metabolic degradation, or overdosage. In addition to additive toxic effects, rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine-containing products. Clinicians should closely monitor patients for the development of methemoglobinemia when a combination local anesthetic is used during a procedure. If a patient becomes cyanotic or if elevated methemoglobin concentrations are suspected, immediately institute treatment to counteract methemoglobinemia (such as administration of methylene blue) as oxygen delivery is ineffective throughout the body until the condition is reversed. Patients who are receiving other drugs that can cause methemoglobin formation, such as prilocaine, are at greater risk for developing methemoglobinemia. (Moderate) Caution is advised if combining topical local anesthetics. The toxic effects of local anesthetics are additive. In addition, rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine-containing products. Clinicians should closely monitor patients for the development of methemoglobinemia when a combination local anesthetic is used during a procedure. If a patient becomes cyanotic or if elevated methemoglobin concentrations are suspected, immediately institute treatment to counteract methemoglobinemia (such as administration of methylene blue) as oxygen delivery is ineffective throughout the body until the condition is reversed.
Ethyl Chloride: (Moderate) Caution is advised if combining local anesthetics. The toxic effects of local anesthetics are additive. A major cause of adverse reactions appears to be excessive plasma concentrations, which may be due to accidental intravascular administration, slow metabolic degradation, or overdosage. In addition to additive toxic effects, rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine-containing products. Clinicians should closely monitor patients for the development of methemoglobinemia when a combination local anesthetic is used during a procedure. If a patient becomes cyanotic or if elevated methemoglobin concentrations are suspected, immediately institute treatment to counteract methemoglobinemia (such as administration of methylene blue) as oxygen delivery is ineffective throughout the body until the condition is reversed. Patients who are receiving other drugs that can cause methemoglobin formation, such as prilocaine, are at greater risk for developing methemoglobinemia. (Moderate) Caution is advised if combining topical local anesthetics. The toxic effects of local anesthetics are additive. In addition, rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine-containing products. Clinicians should closely monitor patients for the development of methemoglobinemia when a combination local anesthetic is used during a procedure. If a patient becomes cyanotic or if elevated methemoglobin concentrations are suspected, immediately institute treatment to counteract methemoglobinemia (such as administration of methylene blue) as oxygen delivery is ineffective throughout the body until the condition is reversed.
Hydralazine; Isosorbide Dinitrate, ISDN: (Moderate) Rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine products. Nitrates may also induce methemoglobin formation that will be additive to that formed by benzocaine products. Therefore, caution is warranted when combining nitrate medications with topical or oromucosal benzocaine products. Patients using OTC benzocaine gels and liquids should be advised to seek immediate medical attention if signs or symptoms of methemoglobinemia develop. In addition, clinicians should closely monitor patients for the development of methemoglobinemia when benzocaine sprays are used during a procedure.
Hydrocortisone; Pramoxine: (Moderate) Caution is advised if combining local anesthetics. The toxic effects of local anesthetics are additive. A major cause of adverse reactions appears to be excessive plasma concentrations, which may be due to accidental intravascular administration, slow metabolic degradation, or overdosage. In addition to additive toxic effects, rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine-containing products. Clinicians should closely monitor patients for the development of methemoglobinemia when a combination local anesthetic is used during a procedure. If a patient becomes cyanotic or if elevated methemoglobin concentrations are suspected, immediately institute treatment to counteract methemoglobinemia (such as administration of methylene blue) as oxygen delivery is ineffective throughout the body until the condition is reversed. Patients who are receiving other drugs that can cause methemoglobin formation, such as prilocaine, are at greater risk for developing methemoglobinemia. (Moderate) Caution is advised if combining topical local anesthetics. The toxic effects of local anesthetics are additive. In addition, rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine-containing products. Clinicians should closely monitor patients for the development of methemoglobinemia when a combination local anesthetic is used during a procedure. If a patient becomes cyanotic or if elevated methemoglobin concentrations are suspected, immediately institute treatment to counteract methemoglobinemia (such as administration of methylene blue) as oxygen delivery is ineffective throughout the body until the condition is reversed.
Isosorbide Dinitrate, ISDN: (Moderate) Rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine products. Nitrates may also induce methemoglobin formation that will be additive to that formed by benzocaine products. Therefore, caution is warranted when combining nitrate medications with topical or oromucosal benzocaine products. Patients using OTC benzocaine gels and liquids should be advised to seek immediate medical attention if signs or symptoms of methemoglobinemia develop. In addition, clinicians should closely monitor patients for the development of methemoglobinemia when benzocaine sprays are used during a procedure.
Isosorbide Mononitrate: (Moderate) Rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine products. Nitrates may also induce methemoglobin formation that will be additive to that formed by benzocaine products. Therefore, caution is warranted when combining nitrate medications with topical or oromucosal benzocaine products. Patients using OTC benzocaine gels and liquids should be advised to seek immediate medical attention if signs or symptoms of methemoglobinemia develop. In addition, clinicians should closely monitor patients for the development of methemoglobinemia when benzocaine sprays are used during a procedure.
Lamotrigine: (Moderate) Consider ECG monitoring before and during concomitant use of lamotrigine with other sodium channel blockers known to impair atrioventricular and/or intraventricular cardiac conduction, such as benzocaine. Concomitant use of benzocaine with lamotrigine may increase the risk of proarrhythmia, especially in patients with clinically important structural or functional heart disease. In vitro testing showed that lamotrigine exhibits class IB antiarrhythmic activity at therapeutically relevant concentrations.
Lidocaine: (Moderate) Use lidocaine and benzocaine together with caution. Monitor cardiovascular and respiratory vital signs, as well as the patient's state of consciousness if used concurrently due to potential for additive CNS and/or cardiovascular toxic effects. Manifestations of toxicity may include CNS excitation and/or depression, cardiac conduction depression, or peripheral vasodilation. Additionally, coadministration may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue local anesthetic use. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Lidocaine; Epinephrine: (Moderate) Use lidocaine and benzocaine together with caution. Monitor cardiovascular and respiratory vital signs, as well as the patient's state of consciousness if used concurrently due to potential for additive CNS and/or cardiovascular toxic effects. Manifestations of toxicity may include CNS excitation and/or depression, cardiac conduction depression, or peripheral vasodilation. Additionally, coadministration may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue local anesthetic use. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Lidocaine; Prilocaine: (Moderate) Caution is advised if combining topical local anesthetics. The toxic effects of local anesthetics are additive. In addition, rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine-containing products. Clinicians should closely monitor patients for the development of methemoglobinemia when a combination local anesthetic is used during a procedure. If a patient becomes cyanotic or if elevated methemoglobin concentrations are suspected, immediately institute treatment to counteract methemoglobinemia (such as administration of methylene blue) as oxygen delivery is ineffective throughout the body until the condition is reversed. (Moderate) Use lidocaine and benzocaine together with caution. Monitor cardiovascular and respiratory vital signs, as well as the patient's state of consciousness if used concurrently due to potential for additive CNS and/or cardiovascular toxic effects. Manifestations of toxicity may include CNS excitation and/or depression, cardiac conduction depression, or peripheral vasodilation. Additionally, coadministration may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue local anesthetic use. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Lidocaine; Tetracaine: (Moderate) Use tetracaine and benzocaine together with caution. Monitor cardiovascular and respiratory vital signs, as well as the patient's state of consciousness if used concurrently due to potential for additive CNS and/or cardiovascular toxic effects. Manifestations of toxicity may include CNS excitation and/or depression, cardiac conduction depression, or peripheral vasodilation. Additionally, coadministration may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue local anesthetic use. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Mafenide: (Moderate) Rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine products. Examples of other drugs that can cause methemoglobinemia include the sulfonamides. Therefore, caution is warranted when combining such medications with topical or oromucosal benzocaine products. Patients using OTC benzocaine gels and liquids should be advised to seek immediate medical attention if signs or symptoms of methemoglobinemia develop. In addition, clinicians should closely monitor patients for the development of methemoglobinemia when benzocaine sprays are used during a procedure.
Menthol; Pramoxine: (Moderate) Caution is advised if combining local anesthetics. The toxic effects of local anesthetics are additive. A major cause of adverse reactions appears to be excessive plasma concentrations, which may be due to accidental intravascular administration, slow metabolic degradation, or overdosage. In addition to additive toxic effects, rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine-containing products. Clinicians should closely monitor patients for the development of methemoglobinemia when a combination local anesthetic is used during a procedure. If a patient becomes cyanotic or if elevated methemoglobin concentrations are suspected, immediately institute treatment to counteract methemoglobinemia (such as administration of methylene blue) as oxygen delivery is ineffective throughout the body until the condition is reversed. Patients who are receiving other drugs that can cause methemoglobin formation, such as prilocaine, are at greater risk for developing methemoglobinemia. (Moderate) Caution is advised if combining topical local anesthetics. The toxic effects of local anesthetics are additive. In addition, rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine-containing products. Clinicians should closely monitor patients for the development of methemoglobinemia when a combination local anesthetic is used during a procedure. If a patient becomes cyanotic or if elevated methemoglobin concentrations are suspected, immediately institute treatment to counteract methemoglobinemia (such as administration of methylene blue) as oxygen delivery is ineffective throughout the body until the condition is reversed.
Mepivacaine: (Moderate) Use mepivacaine and benzocaine together with caution. Monitor cardiovascular and respiratory vital signs, as well as the patient's state of consciousness if used concurrently due to potential for additive CNS and/or cardiovascular toxic effects. Manifestations of toxicity may include CNS excitation and/or depression, cardiac conduction depression, or peripheral vasodilation. Additionally, coadministration may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue local anesthetic use. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Nitrates: (Moderate) Rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine products. Nitrates may also induce methemoglobin formation that will be additive to that formed by benzocaine products. Therefore, caution is warranted when combining nitrate medications with topical or oromucosal benzocaine products. Patients using OTC benzocaine gels and liquids should be advised to seek immediate medical attention if signs or symptoms of methemoglobinemia develop. In addition, clinicians should closely monitor patients for the development of methemoglobinemia when benzocaine sprays are used during a procedure.
Nitroglycerin: (Moderate) Rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine products. Nitrates may also induce methemoglobin formation that will be additive to that formed by benzocaine products. Therefore, caution is warranted when combining nitrate medications with topical or oromucosal benzocaine products. Patients using OTC benzocaine gels and liquids should be advised to seek immediate medical attention if signs or symptoms of methemoglobinemia develop. In addition, clinicians should closely monitor patients for the development of methemoglobinemia when benzocaine sprays are used during a procedure.
Penicillin G Benzathine; Penicillin G Procaine: (Moderate) Coadministration of penicillin G procaine with other local anesthetics, such as benzocaine, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue penicillin G procaine and any other local anesthetic. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Penicillin G Procaine: (Moderate) Coadministration of penicillin G procaine with other local anesthetics, such as benzocaine, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue penicillin G procaine and any other local anesthetic. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Pramoxine: (Moderate) Caution is advised if combining local anesthetics. The toxic effects of local anesthetics are additive. A major cause of adverse reactions appears to be excessive plasma concentrations, which may be due to accidental intravascular administration, slow metabolic degradation, or overdosage. In addition to additive toxic effects, rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine-containing products. Clinicians should closely monitor patients for the development of methemoglobinemia when a combination local anesthetic is used during a procedure. If a patient becomes cyanotic or if elevated methemoglobin concentrations are suspected, immediately institute treatment to counteract methemoglobinemia (such as administration of methylene blue) as oxygen delivery is ineffective throughout the body until the condition is reversed. Patients who are receiving other drugs that can cause methemoglobin formation, such as prilocaine, are at greater risk for developing methemoglobinemia. (Moderate) Caution is advised if combining topical local anesthetics. The toxic effects of local anesthetics are additive. In addition, rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine-containing products. Clinicians should closely monitor patients for the development of methemoglobinemia when a combination local anesthetic is used during a procedure. If a patient becomes cyanotic or if elevated methemoglobin concentrations are suspected, immediately institute treatment to counteract methemoglobinemia (such as administration of methylene blue) as oxygen delivery is ineffective throughout the body until the condition is reversed.
Pramoxine; Zinc Acetate: (Moderate) Caution is advised if combining local anesthetics. The toxic effects of local anesthetics are additive. A major cause of adverse reactions appears to be excessive plasma concentrations, which may be due to accidental intravascular administration, slow metabolic degradation, or overdosage. In addition to additive toxic effects, rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine-containing products. Clinicians should closely monitor patients for the development of methemoglobinemia when a combination local anesthetic is used during a procedure. If a patient becomes cyanotic or if elevated methemoglobin concentrations are suspected, immediately institute treatment to counteract methemoglobinemia (such as administration of methylene blue) as oxygen delivery is ineffective throughout the body until the condition is reversed. Patients who are receiving other drugs that can cause methemoglobin formation, such as prilocaine, are at greater risk for developing methemoglobinemia. (Moderate) Caution is advised if combining topical local anesthetics. The toxic effects of local anesthetics are additive. In addition, rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine-containing products. Clinicians should closely monitor patients for the development of methemoglobinemia when a combination local anesthetic is used during a procedure. If a patient becomes cyanotic or if elevated methemoglobin concentrations are suspected, immediately institute treatment to counteract methemoglobinemia (such as administration of methylene blue) as oxygen delivery is ineffective throughout the body until the condition is reversed.
Ropivacaine: (Moderate) Use ropivacaine and benzocaine together with caution. Monitor cardiovascular and respiratory vital signs, as well as the patient's state of consciousness if used concurrently due to potential for additive CNS and/or cardiovascular toxic effects. Manifestations of toxicity may include CNS excitation and/or depression, cardiac conduction depression, or peripheral vasodilation. Additionally, coadministration may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue local anesthetic use. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Sulfadiazine: (Moderate) Rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine products. Examples of other drugs that can cause methemoglobinemia include the sulfonamides. Therefore, caution is warranted when combining such medications with topical or oromucosal benzocaine products. Patients using OTC benzocaine gels and liquids should be advised to seek immediate medical attention if signs or symptoms of methemoglobinemia develop. In addition, clinicians should closely monitor patients for the development of methemoglobinemia when benzocaine sprays are used during a procedure.
Sulfamethoxazole; Trimethoprim, SMX-TMP, Cotrimoxazole: (Moderate) Rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine products. Examples of other drugs that can cause methemoglobinemia include the sulfonamides. Therefore, caution is warranted when combining such medications with topical or oromucosal benzocaine products. Patients using OTC benzocaine gels and liquids should be advised to seek immediate medical attention if signs or symptoms of methemoglobinemia develop. In addition, clinicians should closely monitor patients for the development of methemoglobinemia when benzocaine sprays are used during a procedure.
Sulfasalazine: (Moderate) Rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine products. Examples of other drugs that can cause methemoglobinemia include the sulfonamides. Therefore, caution is warranted when combining such medications with topical or oromucosal benzocaine products. Patients using OTC benzocaine gels and liquids should be advised to seek immediate medical attention if signs or symptoms of methemoglobinemia develop. In addition, clinicians should closely monitor patients for the development of methemoglobinemia when benzocaine sprays are used during a procedure.
Sulfonamides: (Moderate) Rare and sometimes fatal cases of methemoglobinemia have been reported with the use of topical or oromucosal benzocaine products. Examples of other drugs that can cause methemoglobinemia include the sulfonamides. Therefore, caution is warranted when combining such medications with topical or oromucosal benzocaine products. Patients using OTC benzocaine gels and liquids should be advised to seek immediate medical attention if signs or symptoms of methemoglobinemia develop. In addition, clinicians should closely monitor patients for the development of methemoglobinemia when benzocaine sprays are used during a procedure.
Tetracaine: (Moderate) Use tetracaine and benzocaine together with caution. Monitor cardiovascular and respiratory vital signs, as well as the patient's state of consciousness if used concurrently due to potential for additive CNS and/or cardiovascular toxic effects. Manifestations of toxicity may include CNS excitation and/or depression, cardiac conduction depression, or peripheral vasodilation. Additionally, coadministration may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue local anesthetic use. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Tretinoin; Benzoyl Peroxide: (Moderate) Concurrent use of benzoyl peroxide and topical anesthetics may decrease the efficacy of the anesthetic. In a clinical study, an estimated 75% increase in patient-reported, prick-induced pain was noted in areas treated with both 5% benzoyl peroxide and 6% benzocaine cream as compared to areas treated with 6% benzocaine cream alone. Investigators attributed the decreased anesthetic effect to a breakdown of the benzocaine molecule by either or both benzoyl peroxide or benzoyl peroxide-derived free radicals. It is recommended that the skin area that is to be topically anesthetized have no previous treatment with benzoyl peroxide or that the skin is thoroughly washed prior to the application of the anesthetic.
Benzocaine, butamben, and tetracaine are local anesthetics that cause a reversible blockade of nerve conduction by decreasing nerve membrane permeability to sodium. This decreases the rate of membrane depolarization, thereby increasing the threshold for electrical excitability. The blockade affects all nerve fibers in the following sequence: autonomic, sensory, and motor, with effects diminishing in reverse order. Clinically, loss of function occurs as follows: pain, temperature, touch, proprioception, and skeletal muscle tone. Direct nerve membrane penetration is necessary for effective anesthesia, which is achieved by applying the anesthetic topically to the area to be anesthetized. While systemic absorption of local anesthetics can produce effects on the central nervous and cardiovascular systems, systemic absorption of benzocaine; butamben; tetracaine is expected to be minimal with appropriate use.
Benzocaine; butamben; tetracaine is administered topically to mucosal tissue.
-Benzocaine: Metabolism occurs in the liver and metabolites are excreted renally.
-Butamben: Metabolism occurs primarily by plasma cholinesterases to inert metabolites which are excreted in the urine.
-Tetracaine: Systemic absorption is dependant upon the dose administered, tissue vascularity, and degree of vasodilatation. Tetracaine is hydrolyzed to para-aminobenzoic acid by plasma pseudocholinesterases. It has the slowest rate of hydrolysis of the ester type local anesthetics and its metabolites are primarily renally excreted.
-Route-Specific Pharmacokinetics
Topical Route
Topical application of benzocaine; butamben; tetracaine to mucosal tissue produces anesthesia in approximately 30 seconds and the duration of action is 30 to 60 minutes.
-Benzocaine: Following topical administration, absorption is minimal. Systemic absorption is favored by broken skin or mucosa. Onset of action is rapid with initial effects obtained in about 1 minute and action lasting about 15 to 20 minutes.
-Butamben: The onset and duration of action following topical administration are both described as intermediate between benzocaine and tetracaine.
-Tetracaine: Systemic absorption from topical preparations is minimal, but application to broken or bruised skin greatly increases absorption. The onset of action is 3 to 10 minutes and the duration of action is 30 to 60 minutes.