A 60 years old woman with diabetes complains of thickening and yellowish
discoloration of right big toe. The physician diagnosed it as onychomycosis of toe nail.
What are the drugs useful in treatment of this patient. Explain the mechanism of
action and adverse effects of any one drug. (2+2+2)
Q26 marksEssays
Answer
Drugs useful in treatment of onychomycosis
Oral: Terbinafine (drug of choice), Itraconazole, Fluconazole
Topical (for mild/adjunctive therapy): Ciclopirox nail lacquer, Amorolfine
Mechanism of action of Terbinafine
An allylamine antifungal
Inhibits fungal squalene epoxidase, blocking conversion of squalene to lanosterol (an ergosterol precursor)
This causes accumulation of toxic squalene within the fungal cell and depletes ergosterol, leading to fungal cell death (fungicidal)
Adverse effects of Terbinafine
GI upset (nausea, diarrhoea)
Hepatotoxicity (requires liver function monitoring with prolonged oral therapy)
