Natamycin is an ophthalmic antifungal suspension used to treat fungal blepharitis, conjunctivitis, and keratitis. It has in vitro activity against Candida, Aspergillus, Fusarium, Acremonium (previously known as Cephalosporium), and Penicillium species. Natamycin works by altering membrane permeability, depleting essential cellular constituents. Because natamycin does not penetrate the cornea, conjunctiva, or other mucosal surfaces, topical application does not produce effective levels in the deep stroma or the anterior chamber. This drug was approved by the FDA in October 1978.
General Administration Information
For storage information, see the specific product information within the How Supplied section.
Route-Specific Administration
Ophthalmic Administration
-Natamycin is for topical administration to the eyes only; do NOT inject parenterally.
-Instruct patient on proper instillation of eye suspension (see Patient Information).
-Instruct patient not to wear contact lenses if signs or symptoms of an ocular infection are present.
-To prevent contamination, do not touch the tip of the dropper to the eye, fingertips, or other surface.
-Shake well before using.
-Wash hands before and after use.
-Tilt the head back slightly and pull the lower eyelid down with the index finger to form a pouch. Squeeze the prescribed number of drops into the pouch. Close eyes to spread drops.
-To avoid contamination or the spread of infection, do not use dropper for more than one person.
The following events have been identified during post-marketing use of natamycin in clinical practice. Because they are reported voluntarily from a population of unknown size, estimates of frequency cannot be made, but most are expected to be infrequent to rare. Adverse reactions reported during post-marketing use of natamycin that are localized to the eyes include changes in vision (e.g., temporary blurred vision), corneal opacification, eye discomfort (ocular irritation and ocular pain), ocular edema, eye hyperemia, foreign body sensation, and tearing or increased lacrimation.
Systemic absorption of natamycin is not expected after topical administration to the eye; however, systemic adverse effects have been reported rarely following post-marketing use of natamycin. These systemic adverse reactions include allergic reactions, chest pain (unspecified), dyspnea, and paresthesias.
A superinfection may occur rarely during treatment with natamycin. Natamycin possess no antiviral nor antibacterial activity; thus, a viral or bacterial ocular infection may develop with prolonged or repeated natamycin therapy. Consider the possible presence of a non-susceptible microorganism in ocular infections that fail to improve after 7-10 days of treatment.
Use is contraindicated in patients with a known hypersensitivity to natamycin or any other component in the formulation. Some patients with allergies to cheeses may have sensitivity to natamycin, which is used commonly as a preservative food additive in cheeses. Natamycin is classified as a polyene antifungal; thus, administer natamycin with caution in patients with hypersensitivities to other polyene antifungals. Consider discontinuation of therapy in patients developing an allergic reaction during natamycin treatment.
Natamycin is only indicated for topical administration to the eyes. Take measures to prevent intramuscular administration and intravenous administration of the aqueous suspension.
Natamycin is only indicated for the treatment of ocular fungal infections including fungal blepharitis, conjunctivitis, and keratitis. This product is ineffective in patients with an ocular viral infection such as herpes simplex virus epithelial keratitis, vaccinia, and varicella. In addition, avoid natamycin administration to patients with an ocular bacterial or mycobacterial infection as natamycin exhibits no in vitro antibacterial activity.
Instruct patients to avoid wearing contact lenses during treatment with natamycin if signs and symptoms of fungal blepharitis, conjunctivitis, or keratitis are present.
Safety and efficacy of natamycin have not been established in neonates, infants, or children.
No data are available to determine whether the use of natamycin during pregnancy can cause fetal harm or affect reproduction capacity; however, systemic absorption is not expected following topical ophthalmic administration. Administer natamycin during pregnancy only if clearly needed.
According to the manufacturer, it is not known if natamycin is excreted in human milk; however, systemic absorption is not expected following topical ophthalmic administration. Caution is advised when administering natamycin to a nursing woman. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to maternally administered natamycin, health care providers are encouraged to report the adverse effect to the FDA.
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: Acremonium sp., Aspergillus sp., Candida sp., Fusarium solani, Fusarium sp., Penicillium sp.
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 fungal keratitis:
Ophthalmic dosage:
Adults and Geriatric: Initially instill 1 drop topically into the conjunctival sac every 1-2 hours. Application frequency may be reduced to 1 drop topically every 3-4 hours after the first 3-4 days of treatment; however in some cases, application frequency should be gradually reduced at 4-7 day intervals to ensure treatment success. Duration of therapy is 14-21 days or until resolution of active fungal keratitis. Reevaluate patient if improvement is not evident after 7-10 days of treatment.
Neonates, Infants, Children, and Adolescents: Safety and efficacy have not been established.
For the treatment of fungal blepharitis and fungal conjunctivitis:
Ophthalmic dosage:
Adults and Geriatric: Instill 1 drop topically into conjunctival sac every 4-6 hours. Duration of therapy should be based on clinical reevaluation and additional laboratory results.
Neonates, Infants, Children, and Adolescents: Safety and efficacy have not been established.
Maximum Dosage Limits:
-Adults
24 drops/day per affected eye.
-Geriatric
24 drops/day per affected eye.
-Adolescents
Safety and efficacy have not been established.
-Children
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
No dosage adjustments are needed.
Patients with Renal Impairment Dosing
No dosage adjustments are needed.
*non-FDA-approved indication
There are no drug interactions associated with Natamycin products.
Natamycin binds to ergosterol, a sterol essential for the stability of fungal cell membranes. As a result of this binding, cell membrane integrity is impaired, causing loss of intracellular potassium and other cellular contents. Natamycin possess dose-related fungicidal activity against a variety of yeast and filamentous fungi. The in vitro antifungal activity of natamycin includes Candida, Aspergillus, Fusarium, Acremonium (previously known as Cephalosporium), and Penicillium species.
Natamycin is administered topically to the eyes. Systemic absorption is not expected following topical administration of natamycin.
-Route-Specific Pharmacokinetics
Oral Route
Natamycin is not indicated for oral administration; however if accidentally ingested, absorption of natamycin from the gastrointestinal tract is limited.
Other Route(s)
Ophthalmic Route
Following topical administration to the eyes, natamycin produces therapeutic concentrations within the corneal stoma; however, absorption into the intraocular fluid is limited. In animal studies involving rabbits, natamycin concentrations in the aqueous humor and sera were not measurable (sensitivity of no greater than 2 mg/ml). Furthermore, topically administered natamycin is not expected to be absorbed systemically.