NYSTOP
Clinical safety rating: caution
Comprehensive clinical and safety monograph for NYSTOP (NYSTOP).
Nystatin binds to ergosterol in fungal cell membranes, forming pores that disrupt membrane integrity, leading to leakage of intracellular ions and cell death.
| Metabolism | Nystatin is not absorbed from intact skin, mucous membranes, or gastrointestinal tract; systemic metabolism is negligible. |
| Excretion | Nystatin is not absorbed from the gastrointestinal tract or intact skin/mucous membranes; when administered topically or orally, it is excreted almost entirely in feces as unchanged drug (>99%). Less than 1% is excreted renally if ingested. No quantified biliary excretion reported. |
| Half-life | Not applicable for systemic pharmacokinetics due to minimal absorption; local half-life on mucosal surfaces is not defined. For intravenous administration (not approved), the terminal half-life is approximately 2-4 hours, but this route is not clinically used. |
| Protein binding | Not determined in humans due to negligible absorption; in vitro, nystatin is not significantly protein-bound (estimated <5%, no specific binding proteins identified). |
| Volume of Distribution | Not applicable due to lack of systemic absorption; if intravenously administered (not approved), Vd is estimated to be 1-2 L/kg based on animal data, indicating extensive tissue distribution. |
| Bioavailability | Oral: <1% (negligible) due to poor gastrointestinal absorption and degradation; topical: not absorbed through intact skin or mucous membranes (<0.1%). Not administered parenterally. |
| Onset of Action | Oral: Onset of antifungal effect on Candida in the oropharynx occurs within 24-72 hours; topical: onset of clinical improvement in cutaneous candidiasis occurs within 48-96 hours. |
| Duration of Action | Oral: Duration of effect persists as long as contact with mucosal surfaces is maintained (typically 2-3 days after last dose); topical: clinical resolution of infection requires 2-4 weeks of therapy. No systemic duration. |
| Molecular Weight | 926.09 |
Apply a thin layer to affected area 2-3 times daily or as directed. Nystatin is not absorbed systemically; topical use only.
| Dosage form | POWDER |
| Renal impairment | No adjustment required. Nystatin has negligible systemic absorption after topical application. |
| Liver impairment | No adjustment required. Nystatin has negligible systemic absorption after topical application. |
| Pediatric use | Same as adult dosing: apply thin layer to affected area 2-3 times daily. For diaper dermatitis, apply to diaper area at each diaper change. |
| Geriatric use | No specific dose adjustment needed. Use same topical application as younger adults, with attention to skin integrity and reduced application area if skin is fragile. |
| 1st trimester | No evidence of teratogenicity in animal studies; limited human data; use only if clearly needed. |
| 2nd trimester | No known fetal risk; minimal systemic absorption. |
| 3rd trimester | Considered safe; minimal systemic absorption; use near term only if benefit outweighs risk. |
Clinical note
Comprehensive clinical and safety monograph for NYSTOP (NYSTOP).
| Placental transfer | Negligible placental transfer due to minimal systemic absorption; molecular weight >500 Da limits crossing. |
| Breastfeeding | Nystatin is poorly absorbed from the skin and gastrointestinal tract; not detected in breast milk; considered compatible with breastfeeding. |
| Lactation Rating |
■ FDA Black Box Warning
None.
| Serious Effects |
Hypersensitivity to nystatin or any component of the formulation
| Precautions | May cause hypersensitivity reactions; discontinue if irritation or sensitization occurs. Avoid contact with eyes. Use with caution in patients with hepatic impairment (no systemic absorption, but caution with topical application on denuded skin). |
| Food/Dietary | No clinically significant food interactions. Nystatin is not absorbed systemically when applied topically. |
| Clinical Pearls |
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| Teratogenic Risk | FDA Pregnancy Category C. Animal reproduction studies are inadequate; nystatin is poorly absorbed and not expected to cause fetal harm. No known teratogenic risk in any trimester. |
| Fetal Monitoring | No specific monitoring required due to minimal systemic absorption. Use standard monitoring for underlying infection if present. |
| Fertility Effects | No known effects on fertility in animal studies or human data. |
| Nystop (nystatin) is a topical antifungal for cutaneous candidiasis. Apply sparingly; avoid occlusion to prevent maceration. For intertriginous areas, ensure skin is dry before application. Not effective against dermatophytes or bacteria. |
| Patient Advice | Apply thin layer to affected area 2-3 times daily. · Continue use for 1-2 weeks after symptoms resolve to prevent recurrence. · Do not use on eyes or mucous membranes unless directed. · Wash hands before and after application. · Avoid tight clothing that traps moisture. · Consult healthcare provider if no improvement in 1 week. |