This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fungal infections, Subject name: Dental
All the following drugs are effective in the treatment of Pityriasis Versicolor except: 
Select and explain. 
A. Selenium Sulphide, B. Ketoconazole, C. Griseofulvin, D. Clotrimazole
C: Griseofulvin
Answer: C: Griseofulvin 
Explanation: Griseofulvin has no role in treatment of tinea versicolor. Griseofulvin is used systemically for dermotophytes (microsporum infection). It is ineffective topically. Treatment of Tinea/ Pityriasis versicolar Systemic (oral) Local (Shampoo/cream) New treatment Old Treatment Ketocoazole Itraconazole Micoconazole Econazole Ketoconazole Clotrimazole Whitfield's ointment (3% salicylic acid and 6% Benzoic acid) Selenium disulphide Sodium Thiosulphate