Generic Name

Clotrimazole

Mechanism

• Inhibits lanosterol 14‑α‑demethylase (cytochrome‑P450 enzyme) CYP51, blocking conversion of lanosterol to ergosterol, a key component of fungal cell membranes.
• Disruption of ergosterol synthesis leads to increased membrane permeability and fungicidal activity against dermatophytes, yeasts, and some Candida species.
• Because it acts locally and has negligible systemic absorption, it rarely interferes with host sterol biosynthesis.

Pharmacokinetics

Indications

• Cutaneous Tinea (athlete’s foot, ringworm, jock itch).
• Vulvovaginal Tinea & Candidiasis (3 % cream, 50 mg/0.5 mL).
• Oral/Cutaneous Candidiasis (topical formulation, not systemic).
• Nail Fungus (Onychomycosis) – topical formulations are adjunctive; often combined with systemic agents.
• Preventive prophylaxis for atrophic skin in immunocompromised patients when used carefully.

Contraindications

• Allergic Reaction – Known hypersensitivity to clotrimazole or other imidazole antifungals.
• Active Skin Trauma – May cause local irritation or increased absorption.
• Pregnancy & Lactation – Generally safe; topical use carries minimal risk, but avoid application to large skin areas or mucosa on a daily basis.
• Concurrent Use – Avoid concomitant topical steroids >10 µg/m² unless necessary; potential for additive immunosuppression locally.
• Systemic Immunocompromise – Should only be used when evidence of local infection; systemic therapy may be required.

Dosing

• Topical Cream (1 %):
• Skin – Apply 1–2 g to affected area twice daily for 2–4 weeks.
• Vulvovaginal – Apply 0.5 mL (50 mg) daily for 7–10 days.
• Solution (0.3 %, 5 mg/mL):
• Oral – 5 mg for 1–2 weeks for symptomatic oral candidiasis.
• Nail (0.1 % ointment): Apply once daily to clean, dry nail plate; duration up to 6 months; often combined with systemic terbinafine.
• Guidelines – Tailor duration based on infection severity and response; stop therapy if symptoms resolve to avoid unnecessary exposure.

Adverse Effects

Monitoring

• Clinical response – Symptom resolution, clearance of lesions within 2–4 weeks.
• Repeat assessment – For nail disease, follow‑up at 3, 6 months to confirm improvement.
• Re‑inoculation or recurrence – Monitor for relapse; advise lifestyle modifications.
• Pregnancy & lactation safety – No routine monitoring required for topical use.

Clinical Pearls

1. Non‑systemic safety – Clotrimazole’s negligible systemic absorption makes it ideal for treating sensitive skin (e.g., perianal, vulvovaginal) where systemic agents pose higher risk.
2. Imidazole spectrum – While effective against *Trichophyton* and *Candida*, it is ineffective against *Aspergillus* and *Cryptococcus*. For systemic molds, switch to azoles with broader activity.
3. Adjunctive therapy in onychomycosis – Use topical clotrimazole with oral terbinafine to target both surface and deeper fungal elements; improves cure rates >20 % over terbinafine alone.
4. Pre‑eclampsia & kidney disease – Safe to use topically in pregnancy and renal impairment; no dosage adjustment needed.
5. Application technique – Apply thin layer, allow to absorb, then cover with non‑vacuum‑sealed dressing only if necessary; occlusion increases local irritation risk.
6. Differential diagnosis – Use when lesions lack follicular pustules or scaling typical for eczema; fungal infections present with ring‑like, itchy, well‑marginated plaques.
7. Patch test – A 10 % clotrimazole solution can identify patients with contact allergy and reduce dermatitis incidence.

> *Remember*: clotrimazole’s ease of use, broad topical safety profile, and mechanism of ergosterol synthesis inhibition make it a cornerstone of superficial mycosis management.