Professional Drug Information > Natacyn

Natamycin (Ophthalmic)

VA CLASSIFICATION
Primary: OP202

Commonly used brand name(s): Natacyn.

Another commonly used name is
pimaricin . ^{04}
Note: For a listing of dosage forms and brand names by country availability, see Dosage Forms section(s).

^†Not commercially available in Canada.

Category:


Antifungal (ophthalmic)—

Indications

Accepted

Blepharitis, fungal (treatment) or
Conjunctivitis, fungal (treatment)—Ophthalmic natamycin is indicated in the treatment of fungal blepharitis and fungal conjunctivitis caused by susceptible organisms. ^{04}

Keratitis, fungal (treatment)—Ophthalmic natamycin is indicated in the treatment of fungal keratitis caused by susceptible organisms, including Fusarium solani . ^{04}

Note: Not all species or strains of a particular organism may be susceptible to natamycin.



Pharmacology/Pharmacokinetics

Physicochemical characteristics:

Chemical group—
    Tetraene polyene antifungal. ^{{01} {04}}
Molecular weight—
    665.73


Chemical name
    Pimaricin. ^{04}


pH
    5.0 to 7.5. ^{03}

Mechanism of action/Effect:

Natamycin probably exerts its antifungal effects by binding to sterols in the fungal cell membrane to produce a change in membrane permeability that allows loss of essential cellular constituents. ^{04} Following topical application, natamycin is retained in the conjunctival fornices and attains effective concentrations within the corneal stroma. Significant drug concentration is usually not attained in the intraocular fluid. ^{04}


Precautions to Consider

Carcinogenicity/Mutagenicity

Studies have not been done. ^{04}

Pregnancy/Reproduction
Fertility—
Studies have not been done. ^{04}

Pregnancy—
Studies have not been done in humans. ^{04}

Studies have not been done in animals. ^{04}

FDA Pregnancy Category C. ^{04}

Breast-feeding

It is not known whether natamycin is distributed into breast milk. ^{04} However, problems in humans have not been documented.

Pediatrics

Appropriate studies on the relationship of age to the effects of natamycin have not been performed in the pediatric population. Safety and efficacy have not been established. ^{04}


Geriatrics


Appropriate studies on the relationship of age to the effects of natamycin have not been performed in the geriatric population. However, no geriatrics-specific problems have been documented to date.

Medical considerations/Contraindications
The medical considerations/contraindications included have been selected on the basis of their potential clinical significance (reasons given in parentheses where appropriate)— not necessarily inclusive (» = major clinical significance).


Except under special circumstances, this medication should not be used when the following medical problem exists:
» Sensitivity to natamycin^{04}
Patient monitoring
The following may be especially important in patient monitoring (other tests may be warranted in some patients, depending on condition; » = major clinical significance):

Monitoring of tolerance to medication    (recommended at least twice a week when natamycin is used in the treatment of fungal keratitis ^{04})




Side/Adverse Effects
The following side/adverse effects have been selected on the basis of their potential clinical significance (possible signs and symptoms in parentheses where appropriate)—not necessarily inclusive:

Those indicating need for medical attention
    
Conjunctival chemosis or hyperemia^{04} (eye irritation, redness, or swelling not present before therapy)




Patient Consultation
As an aid to patient consultation, refer to Advice for the Patient, Natamycin (Ophthalmic).

In providing consultation, consider emphasizing the following selected information (» = major clinical significance):

Before using this medication
»   Conditions affecting use, especially:
Sensitivity to natamycin ^{04}

Proper use of this medication
Proper administration technique for ophthalmic suspension

» Compliance with full course of therapy

» Proper dosing
Missed dose: Applying as soon as possible

» Proper storage

Precautions while using this medication
Regular visits to physician to check progress during therapy

Checking with physician if no improvement within 7 to 10 days


Side/adverse effects
Signs of potential side effects, especially conjunctival chemosis or hyperemia


General Dosing Information
Although some manufacturers recommend a dose of 2 drops of an ophthalmic solution at appropriate intervals, the conjunctival sac will usually hold only 1 drop.

In fungal keratitis, therapy should be continued for 14 to 21 days or until the active keratitis is resolved; ^{04} however, if there is no improvement after 7 to 10 days of natamycin therapy, re-evaulation of the condition is recommended. ^{04}


Ophthalmic Dosage Forms

NATAMYCIN OPHTHALMIC SUSPENSION^{03} USP

Usual adult and adolescent dose
Blepharitis, fungal or
Conjunctivitis, fungal
Topical, to the conjunctiva, 1 drop every four to six hours initially. ^{{02} {04}}

Keratitis, fungal
Topical, to the conjunctiva, 1 drop every one or two hours for the first three or four days, the dosage being reduced to 1 drop six to eight times a day thereafter. ^{04}


Usual pediatric dose
Safety and efficacy have not been established. ^{04}

Strength(s) usually available
U.S.—


5% (Rx) [Natacyn^{04} (benzalkonium chloride 0.02%)]

Canada—
Not commercially available.

Packaging and storage:
Store below 40 °C (104 °F), preferably between 15 and 30 °C (59 and 86 °F), unless otherwise specified by manufacturer. Store in a tight, light-resistant container. Protect from freezing. ^{{03} {04}}

Auxiliary labeling:
   • For the eye.
   • Shake well.
   • Keep container tightly closed.
   • Continue medicine for full time of treatment.

Revised: 05/16/1994

References

1. Natacyn package insert (Alcon—US), Rev 1/81, Rec 3/18/85.
   

2. Natacyn package insert (Alcon—US). In: PDR Physicians' desk reference for Ophthalmology. 16th ed. 1988. Montvale, NJ: Medical Economics Data, 1988: 84.
   

3. The United States pharmacopeia. The national formulary. USP 22nd revision (January 1, 1990). NF 17th ed (January 1, 1990). Rockville, MD: The United States Pharmacopeial Convention, Inc., 1990: 920.
   

4. Natacyn (Alcon). In: PDR Physicians' desk reference for Ophthalmology. 22nd ed. 1994. Montvale, NJ: Medical Economics Data. 1994: 227.
   

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