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Cefalexin, also spelled cephalexin, is an antibiotic that can treat a number of bacterial infections.
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Cefalexin can treat certain bacterial infections, including those of the middle ear, bone and joint, skin, and urinary tract. It can be used in children and those over 65 years of age.
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Cefalexin was developed in 1967. It was first marketed in 1969 under the brand name Keflex. It is available as a generic medication. It is on the World Health Organization's List of Essential Medicines. In 2023, it was the 86th most commonly prescribed medication in the United States, with more than 7million prescriptions. In Canada, it was the fifth most common antibiotic used in 2013. In Australia, it was one of the top 10 most prescribed medications between 2017 and 2023.
Medical uses
thumb|left|A course of cefalexin capsules, commonly prescribed for infections
Cefalexin can treat a number of bacterial infections including otitis media, streptococcal pharyngitis, bone and joint infections, pneumonia, cellulitis, and urinary tract infections.
Pregnancy and breastfeeding
It is categorized in category A in Australia meaning that no evidence of harm has been found after being taken by many pregnant women. Hypersensitivity reactions include skin rashes, urticaria, fever, and anaphylaxis.
Signs and symptoms of an allergic reaction include rash, itching, swelling, trouble breathing, or red, blistered, swollen, or peeling skin. Overall, cefalexin allergy occurs in less than 0.1% of patients. Evidence suggests that it is seen in 1% to 10% of patients with a penicillin allergy.
Interactions
Like other β-lactam antibiotics, renal excretion of cefalexin is delayed by probenecid. Alcohol consumption reduces the rate at which it is absorbed. Cefalexin also interacts with metformin, an antidiabetic drug, Histamine H<sub>2</sub> receptor antagonists like cimetidine and ranitidine may reduce the efficacy of cefalexin by delaying its absorption and altering its antimicrobial pharmacodynamics. It is bactericidal and acts by inhibiting synthesis of the peptidoglycan layer of the bacterial cell wall. As cefalexin closely resembles d-alanyl-d-alanine, an amino acid ending on the peptidoglycan layer of the cell wall, it can irreversibly bind to the active site of PBP, which is essential for the synthesis of the cell wall.
Pharmacokinetics
Cefalexin is rapidly and almost completely absorbed from the gastrointestinal tract with oral administration.
The elimination half-life of cefalexin is approximately 30 to 60 minutes in people with normal renal function. More than 90% of cefalexin is excreted unchanged in the urine within 8 hours.
Brand names
Cefalexin is the International Nonproprietary Name (INN) and the Australian Approved Name (AAN), while cephalexin is the British Approved Name (BAN) and the United States Adopted Name (USAN). Brand names for cefalexin include Keflex, Acfex, Cephalex, Ceporex, L-Xahl, Medoxine, Ospexin, Torlasporin, Bio-Cef, Panixine DisperDose, and Novo-Lexin.
Veterinary uses
Dogs
According to Plumb's Veterinary Medication Guides, cefalexin can be used in treating skin, respiratory tract, and urinary tract infections. Specifically, it can treat pyoderma in dogs. The U.S. Food and Drug Administration (FDA) has approved it for use in humans and dogs but not for other species. Like other drugs approved for human use, cefalexin may be prescribed by veterinarians for animals in certain situations.
Cefalexin (Lexylan) is indicated for the treatment of cattle, dogs, and cats in the European Union.