|Systematic (IUPAC) name|
|(7R)-3-Methyl-7- (α- D -phenylglycylamino) -3-cephem-4-carboxylic acid monohydrate|
|Trade names||Keflex, Cepol, Ceporexine, Ceporex|
|Licence data||US FDA:|
|Pregnancy cat.||A (AU) B (US)|
|Legal status||Prescription Only (S4) (AU) POM (UK) ℞-only (US)|
|Metabolism||80% excreted unchanged in urine within 6 hours of administration|
|Half-life||For an adult with normal renal function, the serum half-life is 0.5-1.2 hours|
|ATC code||J01 QJ51|
|Mol. mass||347.39 g/mol|
|(what is this?)|
Cefalexin (INN, BAN) or cephalexin (USAN, AAN) // is an antibiotic useful for the treatment of a number of bacterial infections. It is taken by mouth and is active against gram positive bacteria and some gram negative bacteria. It is in the class of first generation cephalosporins and has similar activity to other agents within this group including the intravenous agent cefazolin.
Cefalexin is used to treat a number of bacterial infections including: middle ear infections, strep throat, bone and joint infections, pneumonia, skin infections, and urinary tract infections. It may be used to prevent bacterial endocarditis. It is ineffective against methicillin-resistant Staphylococcus aureus. It may be used in those who have mild or moderate allergies to penicillin but is not recommended is those with severe allergies. It has no effect against viral infections.
Possible side effects include: allergies, stomach and intestinal upset, and Clostridium difficile diarrhea among others. It is pregnancy category B in the United States and category A in Australia meaning that there is no evidence of harm after being taken by many pregnant women. Use during breast feeding is okay. It is suitable for use in children and those over 65 years of age. Doses may need to be decreased in those with kidney problems.
In 2012, cefalexin was one of the top 100 most prescribed medications in the United States. In Australia it is one of the 15 most prescribed medications. It was developed in 1967 and first marketed in 1969 and 1970 by a number of companies including Glaxo Wellcome and Eli Lilly and Company under the names Keflex and Ceporex among others. It is available as a generic drug under several other trade names and is not very expensive. It is on the World Health Organization's List of Essential Medicines, a list of the most important medication needed in a health system.
Cefalexin is used to treat a number of infections including: otitis media, streptococcal pharyngitis, bone and joint infections, pneumonia, cellulitis, and urinary tract infections. It may be used to prevent bacterial endocarditis. It can also be used for the prevention of recurrent urinary-tract infections.
Cefalexin is a useful alternative to penicillins in patients with penicillin intolerance. For example, penicillin is the treatment of choice for respiratory tract infections caused by Streptococcus, but cefalexin may be used as an alternative in penicillin intolerant patients. Caution must be exercised when administering cephalosporin antibiotics to penicillin sensitive patients, because cross sensitivity with beta-lactam antibiotics has been documented in up to 10% of patients with a documented penicillin allergy.
The most common adverse effects of cefalexin, like other oral cephalosporins, are gastrointestinal disturbances and hypersensitivity reactions. Gastrointestinal disturbances include nausea, vomiting, and diarrhea. Hypersensitivity reactions include skin rashes, urticaria, fever, and anaphylaxis. Pseudomembranous colitis has been reported with use of cephalexin.
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, but it is seen in 1% to 10% of patients with a penicillin allergy.
Like other beta-lactam antibiotics, renal excretion of cefalexin is delayed by probenecid. Alcohol consumption does not have a negative interaction with cefalexin, but reduces the rate at which it is absorbed.
Mechanism of action
Cefalexin is a beta-lactam antibiotic. It is bactericidal and acts by inhibiting synthesis of the bacterial cell wall. It is most active against gram-positive cocci, and has moderate activity against some gram-negative bacilli.
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