Correct Answer: B. Clotrimazole
The clinical presentation describes oral candidiasis (thrush)—white patchy lesions on the tongue and buccal mucosa in a patient on inhaled corticosteroids. Inhaled steroids suppress local oral immunity and alter the normal flora, creating a permissive environment for Candida albicans overgrowth. Clotrimazole is the first-line topical antifungal for oral candidiasis in India, available as lozenges, oral suspension, or cream. It is a broad-spectrum imidazole that inhibits fungal cell membrane ergosterol synthesis, causing fungal cell lysis. Clotrimazole achieves high local concentrations in the oral cavity when used as lozenges (10 mg, dissolved slowly 4–5 times daily) or suspension (10 mL, 1% solution, 4 times daily for 7–14 days). It is non-systemic, safe, and does not interact with inhaled steroids. The patient should also be counseled to rinse the mouth after each steroid inhalation to reduce local deposition and risk of candidiasis—a key preventive measure in Indian clinical practice.
Why the other options are wrong
A. Griseofulvin — Griseofulvin is a systemic antifungal used for dermatophyte infections (tinea corporis, tinea capitis, onychomycosis), not candidiasis. It is ineffective against Candida species and is not indicated for oral thrush. Additionally, it requires hepatic metabolism and is not suitable for topical oral use. C. Flucytosine — Flucytosine is a systemic antifungal reserved for serious invasive candidiasis (e.g., candida meningitis, disseminated candidiasis) and cryptococcal infections. It is not used for superficial oral candidiasis and carries risk of bone marrow suppression with prolonged use. Overkill for a localized mucosal infection. D. Terbinafine — Terbinafine is an allylamine antifungal primarily effective against dermatophytes and Malassezia species; it has poor activity against Candida albicans. It is used systemically for onychomycosis and tinea infections, not for oral candidiasis. Not indicated in this clinical scenario.
High-Yield Facts
- Oral candidiasis is a common adverse effect of inhaled corticosteroids due to local immunosuppression and flora disruption.
- Clotrimazole lozenges (10 mg, 4–5 times daily) are the gold-standard topical treatment for oral thrush in India.
- Mouth rinsing after each steroid inhalation is the most effective preventive measure for steroid-induced candidiasis.
- Imidazoles (clotrimazole, miconazole) inhibit ergosterol synthesis and are preferred for superficial candidiasis; triazoles (fluconazole) are reserved for systemic disease.
- Griseofulvin and terbinafine are dermatophyte-specific agents; flucytosine is for invasive candidiasis—none are first-line for oral thrush.
Mnemonics
THRUSH TOPICALS Clotrimazole (lozenges) → Candiasis (superficial) | Fluconazole → Fungemia (systemic) | Amphotericin B → Acute/invasive. Use this to remember: topical candidiasis = clotrimazole first. STEROID INHALATION SIDE EFFECT PREVENTION RINSE: Rinse mouth after inhalation, Inhibit candida overgrowth, Normal flora preserved, Superficial infection prevented, Early clotrimazole if thrush develops. Bedside pearl for asthma counseling.
NBE Trap
NBE pairs systemic antifungals (griseofulvin, flucytosine, terbinafine) with oral candidiasis to trap students who confuse dermatophyte and invasive fungal treatments with superficial mucosal infections. The key discriminator is topical vs. systemic and candida vs. dermatophyte.
Clinical Pearl
In Indian outpatient asthma clinics, steroid-induced oral candidiasis is one of the most common preventable adverse effects. A simple counseling point—"rinse your mouth with water after each puff"—reduces incidence by >50%. When thrush develops, clotrimazole lozenges dissolve slowly in the mouth, ensuring high local drug concentration and rapid symptom relief within 3–5 days.
_Reference: KD Tripathi Pharmacology Ch. 49 (Antifungals); Harrison Ch. 196 (Candidiasis)_