ATACYN EYE DROPS (Each bottle contains Natamycin 5% w/v)

Indications

• Fungal keratitis
• Superficial ocular fungal infections

Dosage

Children: Refer to the BNF for Children for specific paediatric dosing recommendations.

Adults: Refer to the BNF for specific dosing guidelines.

Mechanism of action

Natamycin inhibits fungal growth by binding to sterols, specifically ergosterol, in the plasma membrane. This binding prevents ergosterol-dependent fusion of vacuoles, as well as membrane fusion and fission. This mechanism is distinct from that of most other polyene antibiotics, which primarily alter fungal membrane permeability.

Pharmacodynamics

Natamycin is an antifungal drug for topical ophthalmic administration, exhibiting in vitro activity against a range of fungi. Its activity is dose-related, and it is classified as predominantly fungicidal. However, natamycin does not show efficacy against gram-positive or gram-negative bacteria. When administered topically, it achieves effective concentrations within the corneal stroma, although it does not significantly penetrate into intraocular fluid.

Pharmacokinetics

The pharmacokinetics of natamycin indicate that after topical application, it is absorbed at the site of infection. However, systemic absorption is minimal, and the drug primarily exerts its effects locally in the eye. Due to its topical application, the distribution is limited to the ocular tissues, and metabolism or elimination details are not well-characterized.

Adverse effects

• Ocular irritation
• Burning sensation
• Stinging
• Redness
• Swelling

Precautions

• Use with caution in patients with a history of hypersensitivity to natamycin or other polyene antibiotics.
• Avoid contact with the eyes other than for topical ophthalmic use.

Pregnancy

Natamycin is classified as a Category C drug. Adequate and well-controlled studies in pregnant women are lacking. Use during pregnancy only if clearly needed.

Breast-feeding

Natamycin is excreted in breast milk. Caution should be exercised when administered to a nursing woman.

Storage

Store at room temperature, away from light and moisture. Keep out of reach of children.

Formulations

• Natamycin 5% ophthalmic suspension

Mechanism of action

Like other polyene antibiotics, Natamycin inhibits fungal growth by binding to sterols. Specifically, Natamycin binds to ergosterol in the plasma membrane, preventing ergosterol-dependent fusion of vacuoles, as well as membrane fusion and fission. This differs from the mechanism of most other polyene antibiotics, which tend to work by altering fungal membrane permeability instead.

Pharmacodynamics

Natamycin is an antifungal drug for topical ophthalmic administration. It is a tetraene polyene antibiotic derived from <i>Streptomyces natalensis</i>. It possesses in vitro activity against a variety of yeast and filamentous fungi, including <i>Candida</i>, <i>Aspergillus</i>, <i>Cephalosporium</i>, <i>Fusarium</i> and <i>Penicillium</i>. Although the activity against fungi is dose-related, natamycin is predominantly fungicidal. Natamycin is not effective in vitro against gram-positive or gram-negative bacteria. Topical administration appears to produce effective concentrations of natamycin within the corneal stroma but not in intraocular fluid.