About terbinafinea synthetic allylamine derivative, antifungal.mechanism of action of terbinafineterbinafine is a fungicidal drug. it interfere the conversion of squalene to ergosterol by inhibiting the enzyme squalene epoxidase.this results in accumulation of squalene in the fungal cells and leads to membrane distortion and death of the fungus.indications for terbinafine1. tinea pedis 2. tinea corporis 3. tinea capitis 4. tinea cruris 5. onychomycosis interactions for terbinafinecimetidine: terbinafine clearance is decreased 33%. rifampicin: terbinafine clearance is increased 100%. terfenadine: terbinafine clearance is decreased 16%. cyclosprorin: clearance of cyclospronine increased by 15%.