Nystatin

Nystatin is a polyene antifungal that is not absorbed from the gut, skin or mucous membranes, so it acts only where it is applied. It treats and prevents mucocutaneous candidiasis of the mouth, gut, skin and vagina. It has no role in invasive or oesophageal candidiasis and no systemic toxicity.

Class. Polyene antifungal.

Mechanism. Binds ergosterol in the fungal membrane, forming pores and causing leakage of cell contents. Candida resistance is rare.

Pharmacokinetics. Negligible absorption after oral, topical or vaginal use. Excreted unchanged in faeces after oral dosing.

Oropharyngeal candidiasis (suspension 100,000 units/mL). - Adults and children over 12 years: 400,000 to 600,000 units (4 to 6 mL) four times daily after food, held in the mouth, for 7 days and for 48 hours after symptoms resolve. - Infants: 100,000 units (1 mL) four times daily; children under 12 years: 100,000 to 200,000 units four times daily. - Maximum: 600,000 units four times daily.

Intestinal candidiasis. Tablets 500,000 to 1,000,000 units three times daily for 7 days.

Cutaneous candidiasis. Cream or ointment 100,000 units/g applied 2 to 3 times daily until 2 weeks after clearance.

Vulvovaginal candidiasis. Pessary 100,000 units, 1 or 2 inserted nightly for 14 nights.

Loading dose, maintenance dose and titration. Not applicable.

Main alternatives. Miconazole oral gel, clotrimazole, or oral fluconazole when topical therapy fails or in immunosuppression.

Contraindications. Hypersensitivity to nystatin.

Serious adverse effects. Rare hypersensitivity including Stevens-Johnson syndrome.

Common adverse effects. Nausea, vomiting and diarrhoea at high doses; local irritation; unpleasant taste.

Interactions. No clinically important interactions.

Common prescribing errors. Stopping at symptom relief, swallowing the suspension at once instead of holding it in the mouth, using it for oesophageal or systemic infection, and not cleaning dentures.

Special groups. - Pregnancy: safe; not absorbed. - Breastfeeding: compatible; treat nipple and infant mouth together when both are infected. - Children: suitable from birth; weight-based volumes. - Older adults: usual dose; treat dentures. - Kidney impairment: no adjustment. - Liver impairment: no adjustment.

Formulations. Oral suspension 100,000 units/mL; tablets 500,000 units; cream; ointment; vaginal pessary 100,000 units.

Administration. Oral suspension after feeds, swished and held in the mouth for several minutes, then swallowed; remove and soak dentures overnight.

Baseline. Confirm the diagnosis and look for the cause (inhaled corticosteroid, antibiotics, diabetes, HIV).

Monitoring. Review at 7 days.

Stopping thresholds. Stop for hypersensitivity.

Referral and escalation. Review for treatment failure, dysphagia (oesophageal disease), recurrent episodes or unexplained persistent candidiasis, which should prompt HIV and glucose testing.