cephalexin, Keflex, Keftabs

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GENERIC NAME: cephalexin


DRUG CLASS AND MECHANISM: Cephalexin belongs to a class of antibiotics called cephalosporins. They are similar to penicillin in action and side effects. They stop or slow the growth of bacterial cells by preventing bacteria from forming the cell wall that surrounds each cell. The cell wall protects bacteria from the external environment and keeps the contents of the cell together. Without a cell wall, bacteria are not able to survive. Bacteria that are susceptible to cephalexin include Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, E. coli and several others. Cephalexin was approved by the FDA in January 1971.



PREPARATIONS: Tablets: 250 and 500 mg, and 1 g. Capsules: 250, 333, 500 and 750 mg. Powder for Suspension: 125 and 250 mg/5 ml.

STORAGE: Tablets and capsules should be stored at room temperature, 15-30°C (59-86°F). Suspensions should be refrigerated and discarded after 14 days.

PRESCRIBED FOR: Cephalexin is used to treat infections caused by bacteria that are susceptible to the effects of cephalexin. Common infections that are treated with cephalexin include infections of the middle ear, tonsils, throat, larynx (laryngitis), bronchi (bronchitis) and pneumonia. It also is used for treating urinary tract, skin, and bone infections.

DOSING: The dose of cephalexin for adults is 1 to 4 grams in divided doses. Children are treated with 25-100 mg/kg/day in divided doses. The dosing interval may be every 6 or 12 hours depending on the infection.

DRUG INTERACTIONS: Serious interactions of cephalexin with other drugs are uncommon.

PREGNANCY: There are no good studies of cephalexin in pregnant women. Cephalexin should only be used during pregnancy if there are no other safe alternatives.

NURSING MOTHERS: Most cephalosporins are excreted in breast milk. Nursing mothers should avoid using cephalosporins or stop breastfeeding while taking a cephalosporin.

SIDE EFFECTS: The most common side effects of cephalexin are diarrhea, nausea, abdominal pain, vomiting, headaches, dizziness, skin rash, fever, abnormal liver tests and vaginitis. Individuals who are allergic to penicillin may also be allergic to cephalexin.

Cephalexin, like almost all antibiotics, may cause mild or severe cases of pseudomembranous colitis, a mild to severe inflammation of the colon. Antibiotics, including cephalexin alter the normal flora of the colon and permit overgrowth of a bacterium called Clostridium difficile. Studies indicate that a toxin produced by Clostridium difficile is a primary cause of pseudomembranous colitis.

Reference: FDA Prescribing Information

Last Editorial Review: 1/10/2008

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