Generic Name

Nystatin

Mechanism

• Ergosterol binding – Nystatin specifically binds ergosterol, a key fungal membrane component.
• Pore formation – The drug–ergosterol complex creates transmembrane ion channels, leading to leakage of vital ions (K⁺, Ca²⁺, Mg²⁺) and proton imbalance.
• Cell death – Loss of membrane integrity and ionic homeostasis disrupts energy production, ultimately causing fungal cell lysis.

Key point: The drug has negligible activity against bacteria because it preferentially targets ergosterol.

Pharmacokinetics

• Topical formulation
• Minimal dermal absorption; >95 % remains on the surface.
• Limited systemic exposure, even after repeated application.
• Not affected by liver metabolism; excretion largely unchanged.
• Oral suspension
• Very poor gastrointestinal absorption (<1 %).
• Predominantly excreted unchanged in feces/urine.
• Half‑life – ~2–3 h in systemic circulation (if absorbed).
• Protein binding – Minimal ( Clinical note: Systemic absorption may occur in compromised skin barrier (e.g., burns, excoriations) but remains low.

Indications

Contraindications

• Allergy to nystatin or any component of the formulation.
• Local severe skin irritation or vesiculation – discontinue.
• Intact skin in immunocompromised patients: use with care; monitor for systemic signs.
• Use with caution in patients with renal impairment (rare systemic absorption).
• Avoid in patients on concomitant nephrotoxic drugs if systemic absorption occurs.

> Warning: A 5‑year study showed rare cases of systemic candidiasis in patients applying nystatin nightly over large surface areas; limit chronic use to prophylactic scenarios.

Dosing

• Cutaneous
• 0.25 % cream: 2–3 g applied thrice nightly (soaked in a clean cloth).
• Apply to the most heavily colonized area; can treat the whole body in neutropenic settings.
• Oral
• 0.05 % suspension: 25 mL (10 mg) every 2–3 h awake.
• Avoid ingestion of dairy or calcium‑rich foods for 1 h before and after dosing (calcium may bind the drug).
• Vaginal
• 0.6 % cream: 2 g four–five times per day for 7–14 days.
• Administration Tips
• 2–3 minutes of each dose to allow drug adhesion.
• If using with other topical agents, let previous ointment dry (~5 min) before applying nystatin.
• Store at 2–25 °C; avoid freezing.

Adverse Effects

• Common local reactions
• Burning, itching, stinging, tingling, pigmentation changes.
• Mild erythema with prolonged use.
• Serious
• Systemic allergic reaction (rare).
• Trichophytosis or secondary bacterial infection if skin barrier compromised.
• Hepatic enzyme changes not linked to nystatin (but monitor in polypharmacy).

Monitoring

• Periodic visual inspection for skin irritation or rash.
• For prophylactic use in immunocompromised:
• Baseline: CBC, renal, liver function.
• Repeat every 4–6 weeks.
• Observe for signs of systemic candidiasis (e.g., fever, oropharyngeal lesions) after widespread topical application.

Clinical Pearls

• “Quanto”… The drug works best where the epidermal layer is partially intact; saturated vesicles smear can reduce efficacy.
• Drug–drug synergy – When combined with *clotrimazole* for atypical candida, a 1‑hour staggered application can reduce irritation.
• Alternative formulation – Liposomal nystatin increases bioavailability (aids absorption for oral thrush) and decreases local irritation.
• Vaginal application – Using a menstrual cup with a 0.6 % cream for nights can significantly cut down on traditional daily applicators.
• Prophylaxis – In neutropenic patients, apply over 8–12 cm² per hand per day to reduce nosocomial fungal transmission even though systemic absorption remains negligible.

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• *This drug card offers concise, high‑yield information for clinicians. Refer to the latest prescribing information or institutional protocols for updated guidance.*