penicillin V, ampicillin, amoxicillin, piperacillin, ticarcillin, others (Unasyn, Pipracil, Ticar)

Pharmacy Author:
Medical and Pharmacy Editor:

GENERIC NAME: penicillin V, ampicillin, amoxicillin, piperacillin, ticarcillin, and others

BRAND NAME: Unasyn, Pipracil, Ticar, and Others

DRUG CLASS AND MECHANISM: Penicillins are antibiotics that are similar to penicillin. Penicillin was the first antibiotic made by scientists. In 1928, Alexander Fleming noted that mold belonging to the genus Penicillium inhibited the growth of bacteria. Fleming called this unknown antibacterial substance penicillin. Ten years later, a group at Oxford University began to investigate penicillin in laboratory mice. Penicillin was hailed as a miracle drug and saved countless lives in World War II. Since then many types of penicillins with better absorption from the intestine or activity against infections have been synthesized.

These antibiotics all have a similar mechanism of action. They do not directly kill bacteria, but they stop bacteria from multiplying by preventing bacteria from forming the walls that surround them. The walls are necessary to protect bacteria from their environment and to keep the contents of the bacterial cell together. Bacteria cannot survive without a cell wall. Penicillins are effective against many different bacteria including H. influenzae, N. gonorrhoea, E. coli, Pneumococci, Streptococci, and certain strains of Staphylococci.

PRESCRIPTION: Yes.

GENERIC AVAILABLE: Yes.

PREPARATIONS: Penicillins are available as capsules, chewable tablets, powder for suspension, and powder for injection.

STORAGE: Oral forms are stored at room temperature, 15 C to 30 C (59 F to 86 F). Powders for suspension that are mixed with water should be discarded after 14 days and refrigeration is preferred. Injectable forms are also stored at room temperature.

PRESCRIBED FOR: Penicillins are used to treat infections due to bacteria that are susceptible to the effects of the antibiotic. Common bacterial infections that penicillins are used for include infections of the middle ear, tonsils, throat, larynx (laryngitis), bronchi (bronchitis), lungs (pneumonia), urinary tract, and skin. Some are also used to treat gonorrhea.

DOSING: Dosing and administration varies for each agent. Antibiotics should be continued for the prescribed duration of time even if symptoms stop.

DRUG INTERACTIONS: Probenecid (Benemid) causes an increase in the level of penicillin in the blood by reducing the elimination of penicillin by the kidneys. Sometimes probenecid is combined with penicillin so that a smaller amount of penicillin results in higher blood levels.

PREGNANCY: Penicillins are generally considered safe for use by pregnant women who are not allergic to penicillin.

NURSING MOTHERS: Small amounts of penicillins may be excreted in breast milk and may cause diarrhea or allergic responses in nursing infants. Penicillins are generally considered safe to use while breastfeeding. Penicillins are used to treat infections in the newborn.

Medically Reviewed by a Doctor on 2/19/2014



Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

Pill Finder Tool

Need help identifying pills and medications?
Use the pill identifier tool on RxList.


Back to Medications Index