The penicillin G preparation with the longest duration

Penicillin G due to it's rapid tubular secretion, it is very sho acting. It's duration of action is increased with probenecid which compete with penicillin at tubular pump. Procaine penicillin G and benzathine penicillin G are administered IM and serve as depot forms. They are slowly absorbed into the circulation and persist at low levels over a long time period. Specially Benzathine penicillin G has longest duration of action. Penicillin G are not effective orally as it is acid labile. Penicillin which are acid stable are : - V : Penicillin V- O: Ofloxacillin- D: Dicloxacillin- K: Cloxacillin- A: Amoxicilin/Ampicillin