All of the following are true regarding penicillin except: March 2005: (A) Probenecid decreases it duration of action, (B) All penicillin are active against gram positive organisms, (C) Splits into 6-amino penicillanic acid by amidase, (D) Acts by inhibiting cell wall synthesis
Answer is A. Ans. A: Probenecid decreases it duration of action Drug interactions have been deliberately used to prolong the effect of penicillin, such as co-administering probenecid with penicillin prior to mass production of penicillin. Because penicillin was difficult to manufacture, it was wohwhile to find a way to reduce the amount required. Probenecid retards the excretion of penicillin, so a dose of penicillin persists longer when taken with it and it allowed patients to take less penicillin over a course of therapy.