Pharmacokinetics

Nystatin is not absorbed from intact skin or mucous membrane.

Microbiology

Nystatin is an antibiotic which is both fungistatic and fungicidal in vitro against a wide variety of yeasts and yeast-like fungi, including Candida albicans, C. parapsilosis, C. tropicalis, C. guilliermondi, C. pseudotropicalis, C. krusei, Torulopsis glabrata, Trichophyton rubrum, T. mentagrophytes.

Nystatin acts by binding to sterols in the cell membrane of susceptible species resulting in a change in membrane permeability and the subsequent leakage of intracellular components.  On repeated subculturing with increasing levels of nystatin, Candida albicans does not develop resistance to nystatin.  Generally, resistance to nystatin does not develop during therapy.  However, other species of Candida (C. tropicalis, C. guilliermondi, C. krusei, and C. stellatoides) become quite resistant on treatment with nystatin and simultaneously become cross resistant to amphotericin as well. This resistance is lost when the antibiotic is removed.

Nystatin exhibits no appreciable activity against bacteria, protozoa, or viruses.

General

Nystatin topical powder should not be used for the treatment of systemic, oral, intravaginal or ophthalmic infections.

If irritation or sensitization develops, treatment should be discontinued and appropriate measures taken as indicated.  It is recommended that KOH smears, cultures, or other diagnostic methods be used to confirm the diagnosis of cutaneous or mucocutaneous candidiasis and to rule out other infection caused by other pathogens.

INFORMATION FOR THE PATIENT

Patients using this medication should receive the following information and instructions:

1. The patient should be instructed to use this medication as directed (including the replacement of missed doses). This medication is not for any disorder other than that for which it is prescribed.
2. Even if symptomatic relief occurs within the first few days of treatment, the patient should be advised not to interrupt or discontinue therapy until the prescribed course of treatment is completed.
3. If symptoms or irritation develop, the patient should be advised to notify the physician promptly.

Laboratory Tests

If there is lack of therapeutic response, KOH smears, cultures, or other diagnostic methods should be repeated. 

Carcinogenesis, Mutagenesis, Impairment of Fertility

No long-term animal studies have been performed to evaluate the carcinogenic potential of nystatin.  No studies have been performed to determine the mutagenicity of nystatin or its effects on male or female fertility.

Pregnancy

Teratogenic Effects

Category C

Animal reproduction studies have not been conducted with any nystatin topical preparation.  It also is not known whether these preparations can cause fetal harm when used by a pregnant woman or can affect reproductive capacity.  Nystatin topical powder should be prescribed for a pregnant woman only if the potential benefit to the mother outweighs the potential risk to the fetus.

Nursing Mother

It is not known whether nystatin is excreted in human milk.  Caution should be exercised when nystatin is prescribed for a nursing woman.

Pediatric Use

Safety and effectiveness have been established in the pediatric population from birth to 16 years.  (See DOSAGE AND ADMINISTRATION.)

Geriatric Use

Clinical studies with nystatin topical powder did not include sufficient numbers of subjects aged 65 years and older to determine whether they respond differently than younger subjects.  Other reported clinical experience has not identified differences in responses between elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out.

Adults and Pediatric Patients (Neonates and Older)

Apply to candidal lesions two or three times daily until healing is complete.  For fungal infections of the feet caused by Candida species, the powder should be dusted on the feet, as well as, in all foot wear.

STORAGE

Store at 20°C to 25°C (68°F to 77°F)[see USP Controlled Room Temperature]; avoid excessive heat (40°C/104°F).

Keep tightly closed.