This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
All of the following can precipitate porphyria except ? 
Select and explain. 
A. Steroids, B. Griesiofulvin, C. Penicillin, D. Estrogen
C: Penicillin
Answer: C: Penicillin 
Explanation: Ans. is 'c' i.e., Penicillin Penicillin is a safe drug in acute intermittent porphyria Drugs precipitating acute intermittent porphyria Barbiturates Griseofulvin Chlorpropramide Rifampicin Oral contraceptives Estrogen Phenytoin Sulfonamides