The drug will be either injected into a large muscle (such as your ... 30 minutes, four to six times a day.Ampicillin eliminates bacteria that cause many kinds of infection, ... www.nlm.nih.gov/medlineplus/druginfo/meds/a601133.html - Drugs and SupplementsAmpicillin Oral Ampicillin is a penicillin-like antibiotic used to treat certain infections caused by bacteria such as pneumonia; ...