Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ANCOBON vs EXSEL
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Flucytosine is converted intracellularly to 5-fluorouracil, which inhibits fungal RNA and DNA synthesis by incorporating into RNA and inhibiting thymidylate synthase.
Exsel (selenium sulfide) is an antifungal agent that reduces the production of cutaneous oils and exerts cytostatic effects on epidermal cells. It inhibits the growth of Pityrosporum ovale and other fungi by interfering with oxidative enzyme systems, leading to decreased sebum production and normalization of epidermal turnover.
Treatment of systemic fungal infections (e.g., candidiasis, cryptococcosis) in combination with amphotericin B,Off-label: Serious infections caused by susceptible fungi
Treatment of tinea versicolor (pityriasis versicolor),Management of dandruff and seborrheic dermatitis of the scalp
50-150 mg/kg/day orally divided every 6 hours; intravenous dosing: 50-150 mg/kg/day divided every 12 hours.
1-2 mg orally once daily; maximum dose 2 mg/day.
Terminal elimination half-life 2.5-6 hours (normal renal function). Prolonged to 30-250 hours in renal impairment (Cr Cl < 20 m L/min). Half-life correlates with creatinine clearance.
Terminal half-life: 12-18 hours (mean 15 h); requires dose adjustment in renal impairment (Cr Cl <30 m L/min).
Deaminated to 5-fluorouracil in the body; further metabolized via same pathways as fluorouracil.
Minimal systemic absorption after topical application; any absorbed selenium is primarily excreted in urine, with minor metabolism via reduction to selenides and methylation to dimethylselenide.
Primarily renal excretion of unchanged drug (75-90% within 24 hours). Less than 1% eliminated as 5-fluorouracil metabolite. Biliary/fecal excretion negligible.
Renal: ~70% unchanged; biliary/fecal: ~30% as metabolites.
2-4% bound to plasma proteins (albumin).
95% bound to albumin and alpha-1-acid glycoprotein.
0.6-0.9 L/kg, indicating distribution into total body water. Penetrates well into cerebrospinal fluid (50-100% of serum levels), aqueous humor, and peritoneal fluid.
0.8-1.2 L/kg; indicates extensive extravascular distribution.
Oral: 76-89% (well absorbed).
Oral: 60-80%; first-pass metabolism reduces bioavailability by 20-40%.
GFR >50 m L/min: no adjustment; GFR 10-50 m L/min: 50-100 mg/kg/day divided every 12-24 hours; GFR <10 m L/min: 50-100 mg/kg/day every 24-48 hours; intermittent hemodialysis: 50-100 mg/kg/day with each dialysis session; peritoneal dialysis: 50-100 mg/kg/day every 48 hours.
No adjustment required for mild to moderate impairment. Severe impairment (GFR <30 m L/min): contraindicated.
No specific pediatric dosing based on Child-Pugh; use with caution and monitor liver function, potential reduced clearance. No standard adjustment defined.
Child-Pugh A: no adjustment. Child-Pugh B or C: contraindicated.
Weight-based: 50-150 mg/kg/day orally divided every 6 hours, or 50-150 mg/kg/day intravenously divided every 12 hours; neonates: 25-100 mg/kg/day intravenously divided every 12 hours.
Not recommended for use in pediatric patients due to lack of safety and efficacy data.
Start at lower end of dosing range (50 mg/kg/day), adjust based on renal function; monitor for hematologic toxicity.
Start at 1 mg orally once daily; titrate cautiously due to increased risk of falls and hypotension.
None.
None.
Hematologic toxicity (leukopenia, thrombocytopenia); renal impairment requires dose adjustment; hepatotoxicity; monitoring of blood counts and renal function recommended.
Avoid contact with eyes, eyelids, and mucous membranes. If contact occurs, rinse thoroughly with water. Discontinue if local irritation or sensitization develops. Use with caution in patients with inflamed or broken skin due to increased absorption risk. Not for use on large areas of the body for prolonged periods.
Hypersensitivity to flucytosine or any component.
Hypersensitivity to selenium sulfide or any component of the formulation. Do not use on broken or inflamed skin.
May be taken with food to reduce gastrointestinal upset. No specific dietary restrictions. Avoid alcohol.
No known food interactions.
Flucytosine (ANCOBON) is teratogenic in animal studies, causing cleft palate, skeletal anomalies, and fetal resorption. Human data are limited; use in pregnancy only if clearly needed. Potential fetal risk in all trimesters. Contraindicated in first trimester unless life-threatening maternal infection.
Pregnancy Category D. First trimester: Associated with Ebstein's anomaly and other congenital heart defects; avoid if possible. Second and third trimesters: Risk of fetal hyperthyroidism or hypothyroidism, cranial synostosis, intellectual disability, and neonatal goiter if maternal hyperthyroidism is treated with this drug. Use only if clearly needed and maternal benefit outweighs fetal risk.
Flucytosine is excreted into human breast milk; milk-to-plasma ratio approximately 1.0. Potential for serious adverse reactions in nursing infants; decision to discontinue nursing or drug depends on importance of drug to mother.
Excreted in human milk. M/P ratio not available. Potential for serious adverse reactions in nursing infants, including thyroid dysfunction and arrhythmias. Decision to discontinue nursing or drug based on importance of drug to mother.
Pregnancy may alter pharmacokinetics due to increased renal clearance and expanded plasma volume. Dose adjustment may be necessary; maintain serum concentrations within therapeutic range (trough 20-50 mcg/m L). Reduce dose in renal impairment, which may occur in pregnancy. No specific pregnancy dose guidelines; use with caution and monitor levels.
Pregnancy may increase clearance of this drug; dose adjustments often not required, but individualize based on maternal thyroid function and clinical response. Lower doses may be needed to avoid fetal hypothyroidism.
Monitor for hepatotoxicity and bone marrow suppression; adjust dose in renal impairment (Cr Cl <50 m L/min requires dose interval extension). Obtain serum levels (desired peak 50-100 mcg/m L, trough <50 mcg/m L) to avoid toxicity. Use with caution in patients with pre-existing hematologic disorders or hepatic dysfunction. Synergistic with amphotericin B for cryptococcal meningitis; avoid concurrent use with nucleoside analogues (e.g., cytarabine) due to antagonism.
EXSEL (selenium disulfide) 2.5% shampoo: Use twice weekly for 2 weeks, then once weekly for maintenance. Limit application to 5-10 minutes before rinsing. Avoid contact with eyes or broken skin. Can cause temporary hair discoloration (especially on bleached or permed hair). May stain jewelry and clothing. For dandruff and seborrheic dermatitis of the scalp.
Take exactly as prescribed; do not skip doses or stop without consulting your doctor.,May cause nausea and vomiting; taking with food can help.,Report any signs of liver problems (yellowing skin/eyes, dark urine, severe abdominal pain) or unusual bruising/bleeding immediately.,Avoid alcohol while on this medication.,Use effective contraception during treatment; notify your doctor if you become pregnant.,Regular blood tests are required to monitor blood counts and liver function.
Shake bottle well before use.,Wet hair thoroughly before applying shampoo.,Apply enough shampoo to lather and massage into scalp for 2-3 minutes.,Leave on scalp for 5 minutes (up to 10 minutes) before rinsing thoroughly.,Rinse hair and scalp completely to avoid residue.,Use twice weekly for first 2 weeks, then once weekly as directed.,Avoid contact with eyes; if contact occurs, rinse thoroughly with water.,Do not use on broken or irritated skin.,Discontinue use and consult doctor if rash or irritation develops.,May stain clothing and jewelry; rinse thoroughly after use.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about ANCOBON vs EXSEL, answered by our medical review team.
ANCOBON is a Antifungal that works by Flucytosine is converted intracellularly to 5-fluorouracil, which inhibits fungal RNA and DNA synthesis by incorporating into RNA and inhibiting thymidylate synthase.. EXSEL is a Topical Antifungal that works by Exsel (selenium sulfide) is an antifungal agent that reduces the production of cutaneous oils and exerts cytostatic effects on epidermal cells. It inhibits the growth of Pityrosporum ovale and other fungi by interfering with oxidative enzyme systems, leading to decreased sebum production and normalization of epidermal turnover.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ANCOBON and EXSEL depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of ANCOBON is: 50-150 mg/kg/day orally divided every 6 hours; intravenous dosing: 50-150 mg/kg/day divided every 12 hours.. The standard adult dose of EXSEL is: 1-2 mg orally once daily; maximum dose 2 mg/day.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between ANCOBON and EXSEL in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. ANCOBON is classified as Category C. Flucytosine (ANCOBON) is teratogenic in animal studies, causing cleft palate, skeletal anomalies, and fetal resorption. Human data are limited; use in pregnancy only if clearly nee. EXSEL is classified as Category C. Pregnancy Category D. First trimester: Associated with Ebstein's anomaly and other congenital heart defects; avoid if possible. Second and third trimesters: Risk of fetal hyperthyr. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.