MYCOSTATIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for MYCOSTATIN (MYCOSTATIN).
Mycostatin (nystatin) is a polyene antifungal antibiotic that binds to ergosterol in the fungal cell membrane, forming pores that increase membrane permeability, leading to leakage of intracellular contents and cell death.
| Metabolism | Not substantially absorbed through intact skin or mucous membranes; minimally metabolized; excreted in feces as unchanged drug. |
| Excretion | Nystatin is not absorbed from the gastrointestinal tract, skin, or mucous membranes. After oral administration, virtually all of the drug is excreted unchanged in feces. Renal excretion is negligible (<0.1%). |
| Half-life | Not applicable (nystatin is not absorbed systemically; no meaningful plasma half-life exists). For reference, if absorbed, the terminal half-life would be approximately 4-6 hours, but this is not clinically relevant. |
| Protein binding | Not applicable (nystatin is not absorbed; no systemic protein binding). If absorbed, it would be highly protein bound (>90%) to albumin. |
| Volume of Distribution | Not applicable (no systemic absorption). If absorbed, Vd would be approximately 0.8-1.2 L/kg, indicating distribution into extracellular fluid. |
| Bioavailability | Oral: <0.1% (virtually nil). Topical and vaginal: negligible systemic absorption; bioavailability is considered zero for systemic effects. |
| Onset of Action | Oral suspension/suspension: onset of antifungal effect on Candida within 24-48 hours of starting therapy. Topical: onset of action is within 24-72 hours. Vaginal tablets: onset within 2-3 days. |
| Duration of Action | Oral: requires multiple daily doses (every 6 hours) due to lack of absorption and rapid transit. Topical: applied 2-3 times daily; clinical improvement usually seen within 1-2 weeks. Vaginal: once daily for 14 days. |
| Molecular Weight | 926.1 |
Nystatin suspension: 400,000-600,000 units (4-6 mL) orally four times daily for 7-14 days. Nystatin pastilles: 200,000-400,000 units (1-2 pastilles) orally four to five times daily for 7-14 days.
| Dosage form | OINTMENT |
| Renal impairment | No dosage adjustment required for renal impairment; nystatin is not significantly absorbed. |
| Liver impairment | No dosage adjustment required for hepatic impairment; nystatin is not significantly absorbed. |
| Pediatric use | Neonates and infants: 100,000 units (1 mL) orally four times daily. Children: 100,000-200,000 units (1-2 mL) orally four times daily. For oral thrush, continue for 48 hours after lesions resolve. |
| Geriatric use | No specific dose adjustment; use standard adult dosing. Monitor for adherence and potential drug interactions. |
| 1st trimester | Nystatin is poorly absorbed from the gastrointestinal tract and is not absorbed from intact skin or mucous membranes. Systemic toxicity is minimal. Animal studies have not shown fetal harm. It is considered safe for use during the first trimester when indicated. |
| 2nd trimester | Safe for use. No known fetal risk based on lack of systemic absorption and animal data. |
| 3rd trimester | Safe for use. No known risk to the fetus near term. |
Clinical note
Comprehensive clinical and safety monograph for MYCOSTATIN (MYCOSTATIN).
| Placental transfer | Nystatin is not absorbed systemically; therefore, placental transfer is negligible or nonexistent. |
| Breastfeeding | Nystatin is not absorbed systemically after oral or topical use; therefore, it is unlikely to be excreted into breast milk in clinically significant amounts. The American Academy of Pediatrics considers nystatin compatible with breastfeeding. However, caution should be exercised when applying to the breast to avoid infant ingestion of large amounts from the nipple area. |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to nystatin or any component of the formulation
| Precautions | For local use only; avoid contact with eyes; discontinue if irritation or sensitization occurs; not effective for systemic infections; use with caution in hepatic impairment. |
| Food/Dietary | No significant food interactions. For oral suspension, avoid food or drink for 30 minutes after use to prolong contact time. |
| Clinical Pearls | Mycostatin (nystatin) is a polyene antifungal that binds to ergosterol in fungal cell membranes, causing leakage. Not absorbed orally; used topically for Candida infections. For oral thrush, suspend in mouth for 2 minutes before swallowing. In immunocompromised patients, consider systemic antifungals. Do not use for systemic fungal infections. |
Loading safety data…
| Lactation Rating | L1 |
| Teratogenic Risk | Nystatin is poorly absorbed from the gastrointestinal tract and skin, with minimal systemic exposure. No teratogenic effects have been reported in animal studies or human case reports. The risk to the fetus is considered low across all trimesters. It is classified as FDA Pregnancy Category A (old system) but not formally assigned in current labeling; however, it is generally considered safe for use during pregnancy. |
| Fetal Monitoring | No specific maternal or fetal monitoring is required beyond standard pregnancy care. Monitor for local irritation or allergic reactions. Systemic toxicity is extremely rare due to lack of absorption. |
| Fertility Effects | No adverse effects on fertility have been reported in animal studies or human data. Nystatin is not known to impair male or female reproductive function. |
| Patient Advice | Use as directed for full course, even if symptoms improve. · Shake suspension well before use. · Hold oral suspension in mouth for 2 minutes before swallowing. · Clean affected areas thoroughly before applying cream or ointment. · Continue treatment for at least 48 hours after symptoms resolve. · Avoid contact with eyes. |