Cantharidin is a topical solution indicated for the treatment of molluscum contagiosum in adults and pediatric patients 2 years and older. It should only be administered by healthcare providers who have undergone training on the preparation and administration process. Ensure the drug is applied only to the molluscum contagiosum lesions, as accidental exposure of the surrounding healthy skin may cause localized skin reactions (vesiculation, pruritus, pain, skin discoloration, erythema). Additionally, avoid administering the drug via the oral, mucosal, or ophthalmic routes. Life-threatening and fatal toxicities can occur if cantharidin is ingested and ocular toxicities can occur with ophthalmic exposure.
General Administration Information
For storage information, see the specific product information within the How Supplied section.
Route-Specific Administration
Topical Administration
-All healthcare providers should receive instructions and training prior to preparation and administration.
-Use nitrile or vinyl gloves and eye protection during preparation and administration.
-Cartons contain single-use applicators and break tools.
-The single-use applicators are intended for a single treatment session only. Use no more than 2 applicators per treatment session.
-Do not attempt to use a clogged applicator.
-Do not cut or modify the applicator in any way; doing so could reduce dispensing control.
Other Topical Formulations
Topical solution
Preparation
-Put on personal protective equipment (i.e., gloves and eye protection).
-Remove the applicator from the outer protective tube by removing the purple end cap from the white outer protective tube and sliding the applicator out of the tube. DO NOT remove the applicator cap.
-Completely remove the white paperboard sleeve, so the glass ampule is visible. DO NOT remove the applicator cap prior to breaking the glass ampule.
-Inspect the applicator and break tool for damage prior to use. If damage or leaks are observed, discard in a sharps container and handle in accordance with accepted medical practice and applicable law.
-Break the ampule using the break tool:-Set the break tool on a horizontal surface.
-Ensure the applicator cap is in place. Then set the applicator in the break tool with the cap pointing toward the hinge.
-Press down firmly on the break tool until a snap is heard.
-Open the break tool and remove the applicator. Discard if any leaks are observed.
-Gently tap the capped end of the applicator on a horizontal surface for approximately 10 seconds or until the solution has collected at the bottom of the applicator tube.
-To confirm the applicator is working properly, remove the cap and gently squeeze the tube to apply a droplet to a paper towel or gauze.
Administration
-Apply a small droplet of the solution onto a lesion. Then use the applicator tip to spread the solution to cover the entire lesion. Repeat the application until all lesions have been treated or up to 2 applicators have been used. To avoid transference, allow the solution to completely dry (up to 5 minutes) before contacting healthy skin. Do not cover any treated lesions with bandages.
-Avoid contact with surrounding healthy skin. If unintended contact occurs, immediately remove by wiping with a cotton swab or gauze.
-Avoid oral, mucosal, or ophthalmic administration. Life-threatening or fatal toxicities can occur if administered orally. Ocular toxicity can occur after contact with the eyes; do not apply near the eyes.
-Allow the dried solution to remain on the lesions for 24 hours, and then remove with soap and water. If severe blistering, severe pain, or other severe adverse reactions occur, remove the solution with soap and water prior to 24 hours after treatment.
-Avoid fire, flame, or smoking near lesions during treatment. The solution is flammable, even after drying.
-Avoid use of other topical products on the treated lesions until 24 hours after treatment or until washing.
-DO NOT reuse the applicator. Discard the applicator in a sharps container and handle in accordance with accepted medical practice and applicable law.
-Wipe the surface of the break tool with 70% isopropyl alcohol after each use. After 12 uses or if any damage is observed, the break tool should be managed as solid waste and placed in plastic recycling containers or the general trash.
During clinical trials, no serious adverse reactions were reported; however, 2.3% of patients treated with cantharidin discontinued therapy due to an adverse reaction. Additionally, 35% of drug recipients had the solution removed prior to the 24-hour time point due to treatment-emergent adverse reactions. Local skin reactions at the application site were observed in 97% of patients. These localized reactions included skin vesicles (60% mild, 32% moderate, 4% severe), pain or skin irritation (41% mild, 20% moderate, 2% severe), pruritus (47% mild, 8% moderate, 1% severe), scab (39% mild, 9% moderate), erythema (24% mild, 21% moderate, less than 1% severe), skin discoloration (28% mild, 4% moderate, less than 1% severe), xerosis (19% mild, 2% moderate), edema (7% mild, 3% moderate), skin erosion (6% mild, 1% moderate), and contact dermatitis (1% moderate).
Cantharidin topical solution is a vesicant that causes local skin reactions (vesiculation, pruritus, pain, discoloration, erythema) at the application site. If a patient experiences severe blistering, severe pain, or other severe adverse reactions, immediately remove the solution with soap and water. Cantharidin is intended for use only on molluscum contagiosum lesions; avoid accidental exposure on surrounding healthy skin. If contact with healthy skin occurs, immediately remove the solution by wiping with a cotton swab or gauze. Avoid use of other topical products (e.g., creams, lotions, sunscreen) on treated areas until 24 hours after cantharidin treatment or until drug removal, as the application of other topical products could spread cantharidin and cause blistering to healthy skin.
Cantharidin is intended for topical use only; avoid oral, mucosal, or ocular exposure. Advise patients to seek immediate medical attention if cantharidin is accidently ingested, as life-threatening or fatal toxicities (renal failure, blistering or severe damage to gastrointestinal tract, coagulopathy, seizures, flaccid paralysis) can occur. Do not apply cantharidin near the eyes, as ocular toxicity can occur if it gets into the eyes. If cantharidin comes in contact with the eyes, flush eyes with water for at least 15 minutes and seek immediate medical attention.
Cantharidin is a flammable liquid, even after drying. Avoid fire, flame, or tobacco smoking near the treated lesions until cantharidin has been removed with soap and water.
No data are available regarding the use of cantharidin during pregnancy to evaluate for a drug-associated risk of major birth defects, miscarriages, or adverse maternal or fetal outcomes. However, due to the low systemic drug exposure after topical administration, maternal use is not expected to result in fetal exposure.
Avoid application of cantharidin to areas with increased risk for potential ingestion by or ocular exposure to the breast-feeding infant. There are no data on the presence of cantharidin in breast milk, or the effects on the breast-fed infant or milk production. However, due to the low systemic absorption of cantharidin after maternal topical administration, breast-feeding is not expected to result in exposure of the infant to the drug. Consider the developmental and health benefits of breast-feeding along with the mother's clinical need for cantharidin and any potential adverse effects on the breast-fed infant from the drug or the underlying maternal condition.
Per the manufacturer, this drug has been shown to be active against most strains of the following microorganisms either in vitro and/or in clinical infections: molluscum contagiosum virus (MCV)
NOTE: The safety and effectiveness in treating clinical infections due to organisms with in vitro data only have not been established in adequate and well-controlled clinical trials.
For the treatment of molluscum contagiosum:
Topical dosage:
Adults: Apply topically to each lesion as a single application. Ensure a sufficient amount of solution is applied to cover each lesion; however, use no more than 2 applicators during a single treatment session. Allow the solution to remain on the lesions for 24 hours, and then remove with soap and water. Repeat the treatment every 3 weeks as needed. During clinical trials, patients received up to 4 applications (Days 1, 21, 42, and 63).
Children and Adolescents 2 to 17 years: Apply topically to each lesion as a single application. Ensure a sufficient amount of solution is applied to cover each lesion; however, use no more than 2 applicators during a single treatment session. Allow the solution to remain on the lesions for 24 hours, and then remove with soap and water. Repeat the treatment every 3 weeks as needed. During clinical trials, patients received up to 4 applications (Days 1, 21, 42, and 63).
Maximum Dosage Limits:
-Adults
2 applicators per treatment session.
-Geriatric
2 applicators per treatment session.
-Adolescents
2 applicators per treatment session.
-Children
2 to 12 years: 2 applicators per treatment session.
1 year: Safety and efficacy have not been established.
-Infants
Safety and efficacy have not been established.
-Neonates
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
There are no drug interactions associated with Cantharidin products.
Cantharidin is a vesicant produced by beetles in the order of Coleoptera (blister beetles or Spanish fly). When applied topically, cantharidin is absorbed by the lipid layers of epidermal cell membranes and causes activation or release of neutral serine proteases. These neutral serine proteases ultimately cause acantholysis (loss of coherence between epidermal cells) and nonspecific lysis of skin. For the treatment of molluscum contagiosum, the exact mechanism is not fully known.
Cantharidin is administered topically. Pharmacokinetic data are limited.
-Route-Specific Pharmacokinetics
Topical Route
The pharmacokinetics of cantharidin were assessed in 16 patients 2 years and older with at least 21 molluscum contagiosum lesions at baseline. The patients were administered a single, topical application of solution to each lesion (average and median number of treated lesions were 47.4 and 35, respectively). Of the 16 patients, only 1 patient had a detectable cantharidin plasma concentration (3.391 ng/mL at 2 hours post-dose).