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Trade namesDistaclor,[1] Medacef,[2] Keflor, others
Other namesCephaclor
  • (6R,7R)-7-{[(2R)-2-amino-2-phenylacetyl]amino}- 3-chloro-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene- 2-carboxylic acid
Clinical data
Drug classAntibiotic (2nd generation cephalosporin)[3]
Main usesPneumonia, middle ear infections, strep throat, cellulitis, urinary tract infections[4]
Side effectsRash, diarrhea, vaginitis, nausea, headache[4]
  • AU: B1
  • US: B (No risk in non-human studies)
Routes of
By mouth
External links
Legal status
  • In general: ℞ (Prescription only)
BioavailabilityWell absorbed, independent of food intake
Metabolism15% to 40%
Elimination half-life0.6 to 0.9 hours
Chemical and physical data
Molar mass367.80 g·mol−1
3D model (JSmol)
  • O=C2N1/C(=C(/Cl)CS[C@@H]1[C@@H]2NC(=O)[C@@H](c3ccccc3)N)C(=O)O.O
  • InChI=1S/C15H14ClN3O4S.H2O/c16-8-6-24-14-10(13(21)19(14)11(8)15(22)23)18-12(20)9(17)7-4-2-1-3-5-7;/h1-5,9-10,14H,6,17H2,(H,18,20)(H,22,23);1H2/t9-,10-,14-;/m1./s1 checkY

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.[4] It is taken by mouth with food.[1] It may be used in children as young as a month old.[1]

Common side effects include rash, diarrhea, vaginitis, nausea, and headache.[4] Other side effects may include anxiety, low red blood cells, joint pains, allergic reactions, jaundice, and swollen glands.[1] It is not known to cause harm in pregnancy and may be used when breastfeeding.[1] It is a second-generation cephalosporin.[3]

Cefaclor was patented in 1975 and approved for medical use in 1979.[5][6] In the United Kingdom, a course of treatment generally costs the NHS less than £10, as of 2021.[1] This amount in the United States costs about 22 USD.[7]

Medical use

Cefaclor is active against many bacteria, including both Gram-negative and Gram-positive organisms.

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). [8] The following represents MIC susceptibility data for a few medically significant microorganisms:[9]

  • 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.[10] The modified release formulation may be used at a dose of 375 to 750 mg twice per day.[10]

Cefaclor is available as tablet, capsule and a powder for reconstitution.[2] It is usually taken with food.[2]


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.[11][12]

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

Side effects

Skin allergy to cefaclor

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.[13] 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

Cefaclor is passed into the breast milk in small quantities, but is generally accepted to be safe to take during breastfeeding.[14] Cefaclor is not known to be harmful in pregnancy.[15]



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.


Excretion of cephalosporins is reduced by probenecid (resulting in increased concentrations of drug in the blood plasma).


Absorption of cefaclor is reduced by antacids. Therefore antacids should not be taken right before or at the same time as cefaclor.[16][17]

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.


Cefaclor was patented in 1975 by Elli Lilly and Company.[5] Medical use was proved in 1979.[6]

Society and culture

Brand names include Distaclor,[1] Ceclor Pulvules, Ceclor CD, Raniclor Biocef, Medacef,[2] Keflor, among others.


  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 "5. Infection". British National Formulary (BNF) (82 ed.). London: BMJ Group and the Pharmaceutical Press. September 2021 – March 2022. pp. 559–560. ISBN 978-0-85711-413-6.{{cite book}}: CS1 maint: date format (link)
  2. 2.0 2.1 2.2 2.3 "A - Z Drug List from Drugs.com: Cefaclor". Drugs.com. American Society of Health-System Pharmacists. Archived from the original on 17 November 2021. Retrieved 27 November 2021.
  3. 3.0 3.1 Beauduy, Camille E.; Winston, Lisa G. (2020). "43. Beta-lactam and other cell wall - & membrane - active antibiotics". In Katzung, Bertram G.; Trevor, Anthony J. (eds.). Basic and Clinical Pharmacology (15th ed.). New York: McGraw-Hill. pp. 832–834. ISBN 978-1-260-45231-0. Archived from the original on 2021-10-10. Retrieved 2021-11-27.
  4. 4.0 4.1 4.2 4.3 "Cefaclor Monograph for Professionals". Drugs.com. Archived from the original on 26 February 2021. Retrieved 30 December 2021.
  5. 5.0 5.1 Nard, Craig Allen (2020). "7. Enforcing patent rights". The Law of Patents. New York: Wolters Kluwer. p. 694. ISBN 978-1-5438-1368-5. Archived from the original on 2021-12-11. Retrieved 2021-12-01. Cite error: Invalid <ref> tag; name "Nard2020" defined multiple times with different content
  6. 6.0 6.1 Fischer, Jnos; Ganellin, C. Robin (2006). Analogue-based Drug Discovery. John Wiley & Sons. p. 493. ISBN 9783527607495. Archived from the original on 2017-09-10. Retrieved 2020-12-31.
  7. "Cefaclor Prices, Coupons & Savings Tips - GoodRx". GoodRx. Retrieved 30 December 2021.
  8. "Archive copy". Archived from the original on 2016-03-16. Retrieved 2021-10-06.{{cite web}}: CS1 maint: archived copy as title (link)
  9. "Archive copy" (PDF). Archived from the original (PDF) on 2016-03-03. Retrieved 2021-10-06.{{cite web}}: CS1 maint: archived copy as title (link)
  10. 10.0 10.1 BNF 81: March-September 2021. BMJ Group and the Pharmaceutical Press. 2021. p. 554. ISBN 978-0857114105.
  11. 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. doi:10.1016/S0190-9622(08)80973-5. PMID 1802903.
  12. 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. doi:10.1111/j.1398-9995.1992.tb02086.x. PMID 1456417. S2CID 46029579.
  13. King BA, Geelhoed GC (December 2003). "Adverse skin and joint reactions associated with oral antibiotics in children: the role of cefaclor in serum sickness-like reactions". J Paediatr Child Health. 39 (9): 677–81. doi:10.1046/j.1440-1754.2003.00267.x. PMID 14629499. S2CID 25762196.
  14. LactMED. "Summary of Cefaclor's use during lactation". National Library of Medicine. Archived from the original on 29 April 2018. Retrieved 22 May 2011.
  15. Ito, S.; Blajchman A; Stephenson M; et al. (1993). "Prospective follow-up of adverse reactions in breast-fed infants exposed to maternal medication". Am J Obstet Gynecol. 168 (5): 1393–1399. doi:10.1016/s0002-9378(11)90771-6. PMID 8498418.
  16. "Archive copy". Archived from the original on 2021-04-22. Retrieved 2021-10-06.{{cite web}}: CS1 maint: archived copy as title (link)
  17. Satterwhite, JH; Cerimele, BJ; Coleman, DL; Hatcher, BL; Kisicki, J; DeSante, KA (1992). "Pharmacokinetics of cefaclor AF: effects of age, antacids and H2-receptor antagonists". Postgrad Med J. 68 Suppl 3: S3-9. PMID 1287615.

External links