nystatin

polyene antifungal· Brands: Mycostatin, Nystan, Nilstat, NystopPOTOP

Mechanism of action

Nystatin is a polyene antifungal that binds to ergosterol in the fungal cell membrane. This binding creates pores that increase membrane permeability, allowing leakage of potassium, sugars and other intracellular contents, which leads to cell death. It is fungicidal against susceptible Candida species. It lacks activity against dermatophytes, Aspergillus species and bacteria. Resistance is uncommon, and cross-resistance with other polyenes can occur but is rare.

Pharmacokinetics

Nystatin is poorly absorbed from the gastrointestinal tract after oral administration and is not absorbed through intact skin or mucous membranes to any clinically significant extent. It is not used for systemic infections because adequate plasma concentrations are not achieved. Absorbed drug, if any, is largely excreted unchanged in faeces, with minimal urinary excretion. Topical and oral forms act locally at the site of application. There is no significant hepatic metabolism. In patients with denuded skin or impaired mucosal integrity, small amounts may be absorbed, but systemic toxicity remains unlikely.

Indications & dosing

Oropharyngeal candidiasis (oral thrush) in adults

Oral suspension 100,000 units/mL; usually swished around the mouth and swallowed, continued for 48 hours after lesions resolve. Higher strengths exist in some formularies.

adult · PO: 100000 units QID · Oral suspension 100,000 units/mL; usually swished around the mouth and swallowed, continued for 48 hours after lesions resolve. Higher strengths exist in some formularies.

Oropharyngeal candidiasis in neonates and infants

Apply half the dose to each side of the mouth with a dropper or sponge applicator. Treat concurrent maternal breast candidiasis to prevent reinfection.

neonatal · PO: 100000 units QID · Apply half the dose to each side of the mouth with a dropper or sponge applicator. Treat concurrent maternal breast candidiasis to prevent reinfection.

Oesophageal candidiasis (swish and swallow)off-label

Not first-line: systemic azoles are preferred for oesophageal disease because nystatin is not absorbed. Used in some local protocols for mild disease or when azoles are unsuitable.

adult · PO: 100000–200000 units QID · Not first-line: systemic azoles are preferred for oesophageal disease because nystatin is not absorbed. Used in some local protocols for mild disease or when azoles are unsuitable.

Gastrointestinal candidiasis or fungal overgrowth in the gutoff-label

Acts luminally because it is not absorbed from the gut. Evidence for benefit is limited and practice varies widely between centres.

adult · PO: 100000–200000 units QID · Acts luminally because it is not absorbed from the gut. Evidence for benefit is limited and practice varies widely between centres.

Cutaneous candidiasis, including candidal intertrigo and nappy rash

Apply cream or ointment thinly to clean, dry skin. Combination products with a corticosteroid are used for inflamed intertrigo but increase the risk of skin atrophy.

adult · TOP: 100000 units/g BD · Apply cream or ointment thinly to clean, dry skin. Combination products with a corticosteroid are used for inflamed intertrigo but increase the risk of skin atrophy.

Vulvovaginal candidiasis

Vaginal pessary or tablet inserted at night for 14 days. Azoles are usually preferred; nystatin is an option in pregnancy or azole intolerance depending on local formulary.

adult · PV: 100000 units once daily · Vaginal pessary or tablet inserted at night for 14 days. Azoles are usually preferred; nystatin is an option in pregnancy or azole intolerance depending on local formulary.

Prevention of oral candidiasis in immunosuppressed patients or inhaled corticosteroid usersoff-label

Often paired with mouth rinsing after inhaled corticosteroids. Evidence for prophylaxis is weak and practice differs by institution.

adult · PO: 100000 units BD · Often paired with mouth rinsing after inhaled corticosteroids. Evidence for prophylaxis is weak and practice differs by institution.

Contraindications & precautions

Known hypersensitivity to nystatin or any excipient in the formulation · Discontinue and seek an alternative if an allergic reaction occurs.
Systemic fungal infections · Nystatin is not absorbed from the gastrointestinal tract or skin and is ineffective for systemic mycoses. Use an appropriate systemic antifungal.
Nystatin is for topical or oral local treatment of candidiasis only; it is not effective for systemic infections.
For oral suspension, shake well before use and advise the patient to hold the liquid in the mouth before swallowing to maximise contact with affected areas.
Avoid contact with the eyes when applying topical formulations; if accidental exposure occurs, rinse thoroughly with water.
In immunocompromised patients or those with severe candidiasis, systemic antifungal therapy may be required instead of or in addition to nystatin.
Sucrose-containing oral suspensions may affect glycaemic control in diabetes; consider a sugar-free formulation where available.
Monitor for signs of hypersensitivity during treatment and discontinue if an allergic reaction occurs.

Adverse effects

Local irritation at application site
Nausea, vomiting, or diarrhoea
Abdominal pain or discomfort
Skin rash or contact dermatitis
Hypersensitivity reactions including angioedema and anaphylaxisserious
Stevens-Johnson syndromeserious
Bitter taste or mouth irritation

Monitoring, pregnancy & toxicity

Clinical response (resolution of oral or cutaneous candidiasis) · Daily during treatment
Gastrointestinal tolerance (nausea, vomiting, diarrhoea) for oral suspension · During therapy
Local irritation or hypersensitivity for topical preparations · At each application
Signs of systemic fungal infection in immunocompromised patients · If no improvement after 1 week
Pregnancy: Nystatin is poorly absorbed from the gastrointestinal tract and intact skin, so systemic exposure is negligible. Use during pregnancy if clearly indicated. No well-controlled studies in pregnant women, but animal studies show no teratogenic effects. Topical and oral use is considered low risk. For lactation, nystatin is safe. If applied to nipples for candidiasis, wipe off before breastfeeding to minimise infant exposure.
Toxicity: Gastrointestinal upset (nausea, vomiting, diarrhoea) after large oral doses · Reduce dose or stop; symptomatic treatment with antiemetics or antidiarrhoeals as needed. Nystatin is not absorbed, so systemic toxicity is unlikely.
Toxicity: Local irritation, burning, itching, or rash at application site · Discontinue use, wash area, apply soothing topical agents. Antihistamines for pruritus.
Toxicity: Hypersensitivity reactions (rare): urticaria, angioedema, anaphylaxis · Stop nystatin immediately; give antihistamines, corticosteroids, or adrenaline as appropriate for severity.

Clinical notes

Nystatin is used for local treatment of Candida infections. Oral suspension or tablets are used for oral thrush, oesophageal or gastrointestinal candidiasis, and as prophylaxis in some immunocompromised patients. Topical formulations treat cutaneous and mucocutaneous candidiasis, including nappy rash, intertrigo and paronychia. Vaginal formulations are available in some regions for vaginal candidiasis. It is not effective for systemic mycoses. For oral thrush, the suspension should be retained in the mouth for as long as possible before swallowing; in some patients it may be swished and spat out. Treatment should continue for several days after symptoms resolve to reduce relapse. Topical preparations should be applied thinly to affected areas and rubbed in gently. Avoid contact with the eyes. Formulations, strengths and sugar content vary by region and formulary; sugar-free suspensions are preferred in diabetes. Nystatin has few drug interactions, but adherence and correct application technique are important for efficacy.

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BNF; local formulary; manufacturer's prescribing information