Introduction
Nystatin is a polyene antifungal medication first isolated in 1950 from Streptomyces noursei. It remains a cornerstone in the treatment of fungal infections, particularly those caused by Candida species. As one of the first antifungals developed, nystatin has maintained clinical relevance due to its efficacy, safety profile, and minimal systemic absorption when administered topically or orally.
Mechanism of Action
Nystatin exerts its antifungal effect by binding to ergosterol, a essential component of fungal cell membranes. This binding creates pores in the membrane that disrupt cellular permeability, leading to leakage of intracellular contents including potassium ions and other cellular components. The resulting disruption of electrochemical gradients ultimately causes cell death. Nystatin demonstrates specificity for fungal cells due to their ergosterol-containing membranes, while having minimal effect on human cells which contain cholesterol instead of ergosterol.
Indications
- Oral candidiasis (thrush)
- Cutaneous candidiasis
- Vulvovaginal candidiasis
- Intestinal candidiasis
- Prophylaxis in immunocompromised patients at risk for fungal infections
- Off-label: Esophageal candidiasis (as oral suspension)
Dosage and Administration
Oral suspension (100,000 units/mL):- Adults: 4-6 mL (400,000-600,000 units) qid
- Pediatric: 2-4 mL (200,000-400,000 units) qid
- Infants: 1-2 mL (100,000-200,000 units) qid
- Cream, ointment, powder: Apply to affected areas 2-4 times daily
- Vaginal tablets: 100,000 units inserted vaginally daily for 14 days
- Oral suspension should be swished in mouth for several minutes before swallowing
- Continue treatment for at least 48 hours after symptoms resolve
- Typical treatment duration: 7-14 days
- Renal impairment: No dosage adjustment required
- Hepatic impairment: No dosage adjustment required
- Elderly: No specific dosage recommendations
Pharmacokinetics
Absorption: Poor systemic absorption from gastrointestinal tract (<5%) and intact skin. Minimal absorption from vaginal mucosa. Distribution: Primarily local action at site of administration. Negligible distribution to tissues when administered orally or topically. Metabolism: Not significantly metabolized. Elimination: Primarily excreted unchanged in feces. Elimination half-life not established due to minimal systemic absorption.Contraindications
- Hypersensitivity to nystatin or any component of the formulation
- History of anaphylactic reaction to nystatin
Warnings and Precautions
- For topical use only on skin and mucous membranes
- Discontinue if irritation or sensitivity develops
- Use with caution in patients with pre-existing skin conditions
- Oral suspension contains sucrose - use caution in diabetic patients
- Prolonged use may result in overgrowth of non-susceptible organisms
- Not for ophthalmic use
Drug Interactions
Nystatin has minimal systemic absorption and therefore has few clinically significant drug interactions. However:
- May potentially reduce absorption of concurrently administered chloroquine
- No known interactions with cytochrome P450 enzymes
- No significant interactions with warfarin or other highly protein-bound drugs
Adverse Effects
Common (≥1%):- Gastrointestinal: nausea, vomiting, diarrhea (oral form)
- Dermatological: irritation, burning, itching (topical forms)
- Vaginal: irritation, burning (vaginal forms)
- Hypersensitivity reactions
- Stevens-Johnson syndrome (very rare)
- Contact dermatitis
Monitoring Parameters
- Clinical response to therapy
- Signs of superinfection or lack of improvement
- For prolonged therapy: monitor for gastrointestinal side effects
- In immunocompromised patients: monitor for treatment failure
- No laboratory monitoring typically required
Patient Education
- Complete full course of therapy even if symptoms improve
- For oral suspension: swish medication throughout mouth before swallowing
- Avoid eating or drinking for 30 minutes after oral dose
- For topical forms: apply to clean, dry affected areas
- Report any signs of worsening condition or new symptoms
- Store medication at room temperature, away from moisture
- Shake oral suspension well before each use
- For vaginal tablets: use even during menstruation
References
1. Pappas PG, Kauffman CA, Andes DR, et al. Clinical Practice Guideline for the Management of Candidiasis: 2016 Update by the Infectious Diseases Society of America. Clin Infect Dis. 2016;62(4):e1-e50. 2. Lexicomp Online. Nystatin: Drug Information. Wolters Kluwer Clinical Drug Information, Inc. 2023. 3. Micromedex Solutions. Nystatin. IBM Watson Health. 2023. 4. FDA Prescribing Information: Nystatin Oral Suspension. Revised 2018. 5. Sobel JD. Vulvovaginal candidosis. Lancet. 2007;369(9577):1961-1972. 6. Clinical and Laboratory Standards Institute. Reference Method for Broth Dilution Antifungal Susceptibility Testing of Yeasts. 4th ed. CLSI standard M27. 2017.