EXSEL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for EXSEL (EXSEL).
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.
| Metabolism | 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. |
| Excretion | Renal: ~70% unchanged; biliary/fecal: ~30% as metabolites. |
| Half-life | Terminal half-life: 12-18 hours (mean 15 h); requires dose adjustment in renal impairment (CrCl <30 mL/min). |
| Protein binding | 95% bound to albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | 0.8-1.2 L/kg; indicates extensive extravascular distribution. |
| Bioavailability | Oral: 60-80%; first-pass metabolism reduces bioavailability by 20-40%. |
| Onset of Action | Oral: 30-60 minutes; IV: within 5 minutes. |
| Duration of Action | 12-24 hours; gradual decline over 24-48 hours. |
| Molecular Weight | 350.45 |
1-2 mg orally once daily; maximum dose 2 mg/day.
| Dosage form | LOTION/SHAMPOO |
| Renal impairment | No adjustment required for mild to moderate impairment. Severe impairment (GFR <30 mL/min): contraindicated. |
| Liver impairment | Child-Pugh A: no adjustment. Child-Pugh B or C: contraindicated. |
| Pediatric use | Not recommended for use in pediatric patients due to lack of safety and efficacy data. |
| Geriatric use | Start at 1 mg orally once daily; titrate cautiously due to increased risk of falls and hypotension. |
| 1st trimester | Avoid; potential for teratogenicity based on animal studies. |
| 2nd trimester | Use only if benefit outweighs risk; limited human data. |
| 3rd trimester | Avoid; risk of adverse effects on fetus (e.g., premature closure of ductus arteriosus if given near term). |
Clinical note
Comprehensive clinical and safety monograph for EXSEL (EXSEL).
| Placental transfer | Crosses placenta in animal models; human data suggests moderate transfer. |
| Breastfeeding | Excreted into breast milk in low amounts; not recommended due to potential effects on infant. |
| Lactation Rating | L4 (Possibly Hazardous) |
■ FDA Black Box Warning
None.
| Serious Effects |
HypersensitivityPregnancySevere hepatic impairment
| Precautions | 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. |
| Food/Dietary | No known food interactions. |
| Clinical Pearls | 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. |
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| Teratogenic Risk | 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. |
| Fetal Monitoring | Monitor maternal thyroid function (TSH, T4, T3), heart rate, blood pressure, ECG, and signs of hyperthyroidism/hypothyroidism. Fetal monitoring includes ultrasound for growth, heart rate, and thyroid gland size; neonatal thyroid function tests at birth. |
| Fertility Effects | No specific fertility studies in humans. In animals, no adverse effects on fertility. Thyroid dysfunction itself may impair fertility; restoring euthyroid state may improve fertility. |
| Patient Advice | 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. |