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Systematic (IUPAC) name
7-[(2-amino-2-phenyl-acetyl)amino]- 3-chloro-8-oxo-5-thia-1-azabicyclo [4.2.0] oct-2- ene-2- carboxylic acid
CAS number 53994-73-3
ATC code J01DC04
PubChem 2609
DrugBank APRD00243
Chemical data
Formula C15H14ClN3O4S 
Mol. mass 367.808 g/mol
Pharmacokinetic data
Bioavailability Well absorbed, independent of food intake
Metabolism 15% to 40%
Half life 0.6 to 0.9 hours
Excretion Renal
Therapeutic considerations
Pregnancy cat.

B1(AU) B(US)

Legal status

Prescription only

Routes Oral

Cefaclor, also known as cefachlor or cefaclorum (brand names Ceclor, Distaclor, Keflor, Raniclor), is a second-generation cephalosporin antibiotic used to treat certain infections caused by bacteria such as pneumonia and ear, lung, skin, throat, and urinary tract infections.



Cefaclor belongs to the family of antibiotics known as the cephalosporins (cefalosporins). The cephalosporins are broad-spectrum antibiotics which are used for the treatment of septicaemia, pneumonia, meningitis, biliary-tract infections, peritonitis, and urinary-tract infections. The pharmacology of the cephalosporins is similar to that of the penicillins, excretion being principally renal. Cephalosporins penetrate the cerebrospinal fluid poorly unless the meninges are inflamed; cefotaxime is a more suitable cephalosporin than cefaclor for infections of the central nervous system, e.g meningitis. Cefaclor is active against many bacteria, including both Gram-negative and Gram-positive organisms.

Cautions and contraindications

Cautions include known sensitivity to beta-lactam antibacterials, such as penicillins (Cefaclor should be avoided if there is a history of immediate hypersensitivity reaction); renal impairment (no dose adjustment required, although manufacturer advises caution); pregnancy and breast-feeding (but appropriate to use); false positive urinary glucose (if tested for reducing substances) and false positive Coombs test. Cefaclor has also been reported to cause a serum sickness-like reaction in children.[1][2]

Cefaclor is contraindicated in case of hypersensitivity (i.e. allergy) to cephalosporins.

Side effects

The principal side effect of the cephalosporins is hypersensitivity. Up to about 10% of penicillin-sensitive patients will also be allergic to the cephalosporins, depending on the cephalosporin generation. Allergic reactions may present as, for example, rashes, pruritus (itching), urticaria, serum sickness-like reactions with rashes, fever and arthralgia, and anaphylaxis.

Other side effects include gastrointestinal disturbances (e.g. diarrhea, nausea and vomiting, abdominal discomfort, disturbances in liver enzymes, transient hepatitis and cholestatic jaundice), headache, and Stevens-Johnson syndrome. Rare side effects include eosinophilia and blood disorders (including thrombocytopenia, leucopenia, agranulocytosis, aplastic anaemia and haemolytic anaemia); reversible interstitial nephritis; hyperactivity, nervousness, sleep disturbances, hallucinations, confusion, hypertonia, and dizziness.

Toxic epidermal necrolysis has been reported. In the UK, The Committee on the Safety of Medicines (CSM) has warned that the risk of diarrhea and rarely antibiotic-associated colitis are more likely with higher doses.

Interactions with other medications

Coumarins (e.g. Warfarin): Cephalosporins possibly enhance the anticoagulant effect of coumarins- change in patient's clinical condition, particularly associated with liver disease, intercurrent illness, or drug administration, necessitates more frequent testing of INR, and dose adjustment as necessary. Probenecid: excretion of cephalosporins is reduced by probenecid (resulting in increased concentrations of drug in the blood plasma). Antacids: Absorption of cefaclor is reduced by antacids; therefore antacids should not be taken at the same time as cefaclor.

Safety in pregnancy and breastfeeding

Cefaclor is passed into the breast milk in small quantities, but is generally accepted to be safe to take during breastfeeding. Cefaclor is not known to be harmful in pregnancy, although the potential risk of harm to the fetus must be balanced against the therapeutic benefits to mother and child of the drug.


Adults: 250 mg every 8 hours, doubled for severe infections, to a maximum of 4 g daily. Children over 1 month: 20 mg/kg daily in 3 divided doses, doubled for severe infections, to a maximum of 1 g daily; or 1 month–1 year, 62.5 mg every 8 hours; 1–5 years, 125 mg; over 5 years, 250 mg; doses doubled for severe infections.


  1. ^ Hebert A, Sigman E, Levy M (1991). "Serum sickness-like reactions from cefaclor in children". J Am Acad Dermatol 25 (5 Pt 1): 805–8. PMID 1802903.
  2. ^ Parra F, Igea J, Martín J, Alonso M, Lezaun A, Sainz T (1992). "Serum sickness-like syndrome associated with cefaclor therapy". Allergy 47 (4 Pt 2): 439–40. PMID 1456417.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Cefaclor". A list of authors is available in Wikipedia.
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