Medications and Drugs

Swine Flu (H1N1) Vaccine Slideshow Swine Flu (H1N1) FAQ Slideshow Strep or Sore Throat Slideshow

Pharmacy Author: Omudhome Ogbru, PharmD
Medical and Pharmacy Editor: Jay W. Marks, MD

GENERIC NAME: penicillin V

BRAND NAME: Veetids (Pen-Vee-K is no longer available in the U.S.)

DRUG CLASS AND MECHANISM: Penicillin V is an oral form of the antibiotic, penicillin, that is used to treat bacterial infections. 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.

Today, many derivatives of penicillin have been developed which inhibit more types of bacteria than the original, life-saving drug. Penicillin stops 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. Penicillin is most effective when bacteria are actively multiplying and forming cell walls. Penicillin itself is active against Streptococci (including Streptococcus pneumoniae), Listeria, Neisseria gonorrhoeae, Clostridium, Peptococcus, and Peptostreptococcus. Most staphylococci now are resistant to penicillin.

PRESCRIPTION: Yes

GENERIC AVAILABLE: Yes

PREPARATIONS: Tablets: 250, 500mg. Powder: 125, 250 mg/5 mL.

STORAGE: Tablets should be kept between 15 C (59  F) and 30 C (86 F). The solution should be kept refrigerated and can be used for up to 14 days after it is reconstituted by the pharmacist. It must be shaken before each use and should be kept well-sealed.

PRESCRIBED FOR: Penicillin V is effective for treatment of laryngitis, bronchitis, pneumonia, and soft tissue and skin infections caused by susceptible bacteria. It also is used for preventing recurrence of rheumatic fever and chorea (a disorder of uncontrolled movement of the body). Only mild to moderate infections are treated with oral penicillin V. Patients with more severe infections are given penicillin by injection.

DOSING: The usual adult dose of penicillin V is 125 to 500 mg every 6-8 hours.

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

PREGNANCY: Penicillin is considered safe during pregnancy.

NURSING MOTHERS: Penicillin is excreted in breast milk and may cause diarrhea or allergic responses in nursing infants. If penicillin is used while nursing, the potential benefit of penicillin for the mother should be weighed against the potential risk of side effects in the infant.

SIDE EFFECTS: Common side effects of penicillin V include nausea, vomiting, diarrhea, abdominal pain, rash, and itching. Patients with a history of allergic reactions to other penicillins should not receive penicillin V. Persons who are allergic to the cephalosporin class of antibiotics, which are related to the penicillins, for example, cefaclor (Ceclor), cephalexin (Keflex), and cefprozil (Cefzil), may or may not be allergic to penicillins. Serious but rare reactions include seizures, severe allergic reactions (anaphylaxis), and low platelet or red blood cell count. Penicillins can alter the normal bacteria in the colon and encourage overgrowth of some bacteria such as Clostridium difficile which causes inflammation of the colon (pseudomembranous colitis). Patients who develop signs of pseudomembranous colitis after starting penicillin (diarrhea, fever, abdominal pain, and possibly shock) should contact their physician immediately.

Reference: FDA Prescribing Information