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Natacyn (Natamycin): Side Effects, Uses, Dosage, Interactions, Warnings

Natacyn

Medical Editor: John P. Cunha, DO, FACOEP Last updated on RxList: 2/22/2023

Drug Summary

What Is Natacyn?

Natacyn (natamycin ophthalmic suspension) is an antifungal medication used to treat fungal infections of the eyes.

What Are Side Effects of Natacyn?

Natacyn may cause serious side effects including:

  • hives,
  • difficulty breathing,
  • swelling of your face, lips, tongue, or throat,
  • vision changes,
  • eye redness or irritation,
  • swelling of the eye,
  • eye pain or numbness, and
  • chest pain

Get medical help right away, if you have any of the symptoms listed above.

Common side effects of Natacyn include:

  •  mild eye irritation or discomfort (redness stinging or burning)
  • allergic reaction
  • change in vision
  • chest pain
  • corneal opacity
  • shortness of breath
  • eye swelling
  • eye pain
  • feeling like something is in the eye
  • weakness, and
  • tearing

Seek medical care or call 911 at once if you have the following serious side effects:

  • Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
  • Serious heart symptoms such as fast, irregular, or pounding heartbeats; fluttering in your chest; shortness of breath; and sudden dizziness, lightheadedness, or passing out;
  • Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors.

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.

Dosage for Natacyn

The preferred initial dosage in fungal keratitis is one drop of Natacyn 5% instilled in the conjunctival sac at hourly or two-hourly intervals. The frequency of application can usually be reduced to one drop 6 to 8 times daily after the first 3 to 4 days. Therapy should generally be continued for 14 to 21 days or until there is resolution of active fungal keratitis.

What Drugs, Substances, or Supplements Interact with Natacyn?

Do not use other eye medications with Natacyn unless your doctor approves. Tell your doctor all medications and supplements you use.

Natacyn During Pregnancy or Breastfeeding

During pregnancy, Natacyn ophthalmic should be used only if prescribed. It is unknown if this drug passes into breast milk. Consult your doctor before breastfeeding.

Additional Information

Our Natacyn (natamycin ophthalmic suspension) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

Description for Natacyn

NATACYN® (natamycin ophthalmic suspension) 5% is a sterile, antifungal drug for topical ophthalmic administration. Each mL of the suspension contains: Active: natamycin 5% (50mg). Preservative: benzalkonium chloride 0.02%. Inactive: sodium hydroxide and/or hydrochloric acid (neutralized to adjust the pH), purified water. The active ingredient is represented by the chemical structure: Established name: Natamycin

Chemical Structure

Molecular Formula: C33H47NO13
Molecular Weight: 665.73

Chemical name: Stereoisomer of 22-[(3-amino-3,6-dideoxy- β-D-mannopyranosyl)oxy]-1,3,26­trihydroxy-12- methyl-10-oxo-6,11,28-trioxatricyclo[22.3.1.05,7] octacosa-8,14,16,18,20-pentaene-25-carboxylic acid.

Other: Pimaricin
The pH range is 5.0 - 7.5.

Uses for Natacyn

NATACYN® (natamycin ophthalmic suspension) 5% is indicated for the treatment of fungal blepharitis, conjunctivitis, and keratitis caused by susceptible organisms including Fusarium solani keratitis. As in other forms of suppurative keratitis, initial and sustained therapy of fungal keratitis should be determined by the clinical diagnosis, laboratory diagnosis by smear and culture of corneal scrapings and drug response. Whenever possible the in vitro activity of natamycin against the responsible fungus should be determined. The effectiveness of natamycin as a single agent in fungal endophthalmitis has not been established.

Dosage for Natacyn

SHAKE WELL BEFORE USING. The preferred initial dosage in fungal keratitis is one drop of NATACYN® (natamycin ophthalmic suspension) 5% instilled in the conjunctival sac at hourly or two-hourly intervals. The frequency of application can usually be reduced to one drop 6 to 8 times daily after the first 3 to 4 days. Therapy should generally be continued for 14 to 21 days or until there is resolution of active fungal keratitis. In many cases, it may be helpful to reduce the dosage gradually at 4 to 7 day intervals to assure that the replicating organism has been eliminated. Less frequent initial dosage (4 to 6 daily applications) may be sufficient in fungal blepharitis and conjunctivitis.

HOW SUPPLIED

NATACYN® (natamycin ophthalmic suspension 5%) is a 15mL fill packaged in a 15 mL amber glass bottle with a black phenolic closure. A flint glass dropper with a red plastic closure and a black rubber bulb are packaged separately in a clear plastic blister with Tyvek backing.

NDC 0065-0645-15

STORAGE: Store between 2-24°C (36-75°F).Do not freeze. Avoid exposure to light and excessive heat.

Revised: May 2008. ALCON LABORATORIES, INC., Fort Worth, Texas 76134, USA. FDA revision date: 07/18/08

Side Effects for Natacyn

The following events have been identified during post-marketing use of NATACYN® (natamycin) in clinical practice. Because they are reported voluntarily from a population of unknown size, estimates of frequency cannot be made. The events, which have been chosen for inclusion due to their seriousness, frequency of reporting, possible causal connection to NATACYN® (natamycin) , or a combination of these factors include: allergic reaction, change in vision, chest pain, corneal opacity, dyspnea, eye discomfort, eye edema, eye hyperemia, eye irritation, eye pain, foreign body sensation, paresthesia, and tearing.

Drug Interactions for Natacyn

No information provided.

Warnings for Natacyn

No information provided.

Precautions for Natacyn

General

FOR TOPICAL OPHTHALMIC USE ONLY - NOT FOR INJECTION. Failure of improvement of keratitis following 7-10 days of administration of the drug suggests that the infection may be caused by a microorganism not susceptible to natamycin.

Continuation of therapy should be based on clinical re-evaluation and additional laboratory studies.

Adherence of the suspension to areas of epithelial ulceration or retention of the suspension in the fornices occurs regularly.

Use only if the container is undamaged.

Carcinogenesis, Mutagenesis, Impairment of Fertility: There have been no long term studies done using natamycin in animals to evaluate carcinogenesis, mutagenesis, or impairment of fertility.

Pregnancy: Pregnancy Category C. Animal reproduction studies have not been conducted with natamycin. It is also not known whether natamycin can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. NATACYN® (natamycin ophthalmic suspension) 5% should be given to a pregnant woman only if clearly needed.

Nursing Mothers: It is not known whether these drugs are excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when natamycin is administered to a nursing woman.

Pediatric Use: Safety and effectiveness in pediatric patients have not been established.

Geriatric Use: No overall differences in safety or effectiveness have been observed between elderly and younger patients.

Overdose Information for Natacyn

No information provided.

Contraindications for Natacyn

NATACYN® (natamycin ophthalmic susp ension) 5% is contraindicated in individuals with a history of hypersensitivity to any of its components.

Clinical Pharmacology for Natacyn

Natamycin is a tetraene polyene antibiotic derived from Streptomyces natalensis. It possesses in vitro activity against a variety of yeast and filamentous fungi, including Candida, Aspergillus, Cephalosporium, Fusarium and Penicillium. The mechanism of action appears to be through binding of the molecule to the sterol moiety of the fungal cell membrane. The polyenesterol complex alters the permeability of the membrane to produce depletion of essential cellular constituents. 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. Systemic absorption should not be expected following topical administration of NATACYN® (natamycin ophthalm ic suspension) 5%. As with other polyene antibiotics, absorption from the gastrointestinal tract is very poor. Studies in rabbits receiving topical natamycin revealed no measurable compound in the aqueous humor or sera, but the sensitivity of the measurement was no greater than 2 mg/mL.

Patient Information for Natacyn

Do not touch dropper tip to any surface, as this may contaminate the suspension. Patients should be advised not to wear contact lenses if they have signs and symptoms of fungal blepharitis, conjunctivitis, and keratitis.

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Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.