|Trade names||Distaclor, Medacef, Keflor, others|
|Drug class||Antibiotic (2nd generation cephalosporin)|
|Main uses||Pneumonia, middle ear infections, strep throat, cellulitis, urinary tract infections|
|Side effects||Rash, diarrhea, vaginitis, nausea, headache|
|Bioavailability||Well absorbed, independent of food intake|
|Metabolism||15% to 40%|
|Elimination half-life||0.6 to 0.9 hours|
|Chemical and physical data|
|Molar mass||367.80 g·mol−1|
|3D model (JSmol)|
|(what is this?)|
Cefaclor, sold under the brand name Ceclor among others, is an antibiotic used to treat bacterial infections such as pneumonia, middle ear infections, strep throat, cellulitis, and urinary tract infections. It is taken by mouth with food. It may be used in children as young as a month old.
Common side effects include rash, diarrhea, vaginitis, nausea, and headache. Other side effects may include anxiety, low red blood cells, joint pains, allergic reactions, jaundice, and swollen glands. It is not known to cause harm in pregnancy and may be used when breastfeeding. It is a second-generation cephalosporin.
Cefaclor was patented in 1975 and approved for medical use in 1979. In the United Kingdom, a course of treatment generally costs the NHS less than £10, as of 2021. This amount in the United States costs about 22 USD.
Spectrum of activity
Cefaclor is frequently used against bacteria responsible for causing skin infections, otitis media, urinary tract infections, and others. Cefaclor has been shown to be active against most strains of the following microorganisms, both in vitro and in clinical infections: Gram positive aerobes - Staphylococci (including coagulase-positive, coagulase-negative, and penicillinase-producing strains), Streptococcus pneumoniae, and Streptococcus pyogenes (group A β-hemolytic streptococci).  The following represents MIC susceptibility data for a few medically significant microorganisms:
- Haemophilus influenzae: 0.03 μg/mL - 128 μg/mL
- Staphylcoccus aureus: 0.6 μg/mL - 128 μg/mL
- Streptococcus pyogenes: 0.06 μg/mL - 4 μg/mL
In adults it is generally take at a dose of 250 to 500 mg 3 times a day for the immediate release preparation. The modified release formulation may be used at a dose of 375 to 750 mg twice per day.
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.
Cefaclor is contraindicated in case of hypersensitivity (i.e. allergy) to cephalosporins.
The principal side effect of the cephalosporins is hypersensitivity. Penicillin-sensitive patients will also be allergic to the cephalosporins, depending on the cephalosporin generation. The previous percentage of 10% cross reactivity rates are often overestimated. Allergic reactions may present as, for example, rashes, pruritus (itching), urticaria, serum sickness-like reactions with rashes, fever and arthralgia, and anaphylaxis. The frequency and severity of serum sickness-like reactions in children has led researchers to question its role in pediatric illness. 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.
Pregnancy and breastfeeding
Cephalosporins possibly enhance the anticoagulant effect of coumarins (e.g. Warfarin) - 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.
Mechanism of action
Cefaclor belongs to the family of antibiotics known as the cephalosporins (cefalosporins). The cephalosporins are broad-spectrum antibiotics that 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 kidneys. 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.
Society and culture
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