LOTRIMIN AF
Clinical safety rating: caution
Comprehensive clinical and safety monograph for LOTRIMIN AF (LOTRIMIN AF).
Inhibits fungal cytochrome P450 14α-demethylase, blocking ergosterol synthesis and disrupting fungal cell membrane integrity.
| Metabolism | Minimal systemic absorption; primarily local metabolism. |
| Excretion | Less than 1% of topical clotrimazole is absorbed; absorbed drug is metabolized in the liver to inactive metabolites and excreted primarily in feces (approximately 69%) and urine (approximately 21%) via biliary and renal routes. |
| Half-life | Terminal elimination half-life of absorbed clotrimazole is approximately 3.5–4 hours, but this is clinically irrelevant due to negligible systemic absorption after topical application. |
| Protein binding | Approximately 90–95% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Vd is approximately 2.5 L/kg after intravenous administration (data for systemic formulation); after topical application, systemic absorption is negligible (<1%), so Vd is not clinically meaningful. |
| Bioavailability | Topical: Systemic bioavailability is <1% after application to intact skin; vaginal tablet: approximately 3–10% absorbed systemically. |
| Onset of Action | Topical: Clinical improvement begins within 24–72 hours; visible resolution of symptoms (e.g., itching, redness) typically occurs within 1–2 weeks of regular application. |
| Duration of Action | Duration of antifungal effect persists for approximately 24 hours after a single application; daily application is required for full treatment course (2–4 weeks for tinea pedis, 2 weeks for tinea cruris/corporis). |
| Molecular Weight | 344.83 |
Topical: Apply twice daily (morning and evening) to affected area for 2-4 weeks. Intravaginal: One 200 mg suppository vaginally at bedtime for 3 days, or one 500 mg vaginal tablet as a single dose.
| Dosage form | Solution |
| Renal impairment | No dosage adjustment required for renal impairment. |
| Liver impairment | No dosage adjustment required for hepatic impairment. |
| Pediatric use | Children ≥2 years: Same as adult dosing for topical application. Children <2 years: Not recommended without physician consultation. |
| Geriatric use | No specific dose adjustment; use same adult dosing with consideration of renal/hepatic function and potential drug interactions. |
| 1st trimester | Topical clotrimazole is considered safe in the first trimester; animal studies have shown no teratogenicity, and human data do not indicate increased risk of malformations. |
| 2nd trimester | Safe for use; no evidence of fetal harm reported with topical application. |
| 3rd trimester | Safe for use; systemic absorption is minimal, and no adverse fetal effects have been demonstrated. |
Clinical note
Comprehensive clinical and safety monograph for LOTRIMIN AF (LOTRIMIN AF).
| Placental transfer | Minimal to no placental transfer due to negligible systemic absorption after topical application. |
| Breastfeeding | Clotrimazole is poorly absorbed systemically after topical application. Breastfeeding during topical use is considered safe; avoid application to the breast area to prevent infant ingestion. |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to clotrimazole or any component of the formulation
| Precautions | For external use only, Avoid contact with eyes, Discontinue if irritation occurs, Not for vaginal or oral use |
| Food/Dietary | No clinically significant food interactions for topical clotrimazole. |
| Clinical Pearls | Lotrimin AF (clotrimazole) is a topical antifungal used for dermatophyte and yeast infections. For tinea pedis, apply twice daily for 4 weeks; shorter courses may lead to recurrence. Do not use in or near eyes. Avoid occlusive dressings unless directed. |
Loading safety data…
| Lactation Rating |
| L2 (Safer) |
| Teratogenic Risk | Clotrimazole (Lotrimin AF) is category B. No evidence of teratogenicity in animal studies. Limited human data from topical use in first trimester show no increased risk of major malformations. Systemic absorption from topical application is minimal (<0.5%), making fetal exposure negligible. No known fetal risks from topical use in any trimester. |
| Fetal Monitoring | No specific maternal or fetal monitoring required for topical clotrimazole use during pregnancy. Routine prenatal care is sufficient. If used intravaginally, standard pregnancy monitoring applies. |
| Fertility Effects | No known adverse effects on human fertility from topical clotrimazole. Animal studies show no impairment of fertility at doses significantly higher than human exposure. |
| Patient Advice | Apply a thin layer to affected skin twice daily, morning and evening. · Wash hands before and after application unless treating hands. · Continue use for the full prescribed duration even if symptoms improve. · Avoid contact with eyes, mouth, or open wounds. · Do not cover treated area with bandages or plastic unless instructed. |