Cefaclor

Mechanism-of-action class: Enzyme Inhibitors.

• To reduce the development of drug-resistant bacteria and maintain the effectiveness of cefaclor extended-release tablets USP and other antibacterial drugs, cefaclor extended-release tablets USP should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy.

• Cefaclor extended-release tablets are contraindicated in patients with known hypersensitivity to cefaclor and other cephalosporins.contraindicated

The absorption of cefaclor extended-release tablets is enhanced when it is administered with food. (See CLINICAL PHARMACOLOGY .) Therefore, cefaclor extended-release tablets should be administered with meals (i.e., at least within one hour of eating) . The extended-release tablets should not be cut, crushed, or chewed. See INDICATIONS AND USAGE for information about patients for whom cefaclor extended-release tablets are indicated. NOTE: 500 mg BID of cefaclor extended-release tablets is clinically equivalent to 250 mg TID of cefaclor immediate-release as a capsule in those indications listed in the INDICATIONS AND USAGE section of this label. 500 mg BID of cefaclor extended-release tablets is NOT equivalent to 500 mg TID of other cefaclor formulations. Adults (age 16 years and older): Type of Infection (as qualified in the INDICATIONS AND USAGE section of this labeling) Total Daily Dose Dose and Frequency Duration Acute Bacterial Exacerbations of Chronic Bronchitis due to H. influenzae (non-ß-lactamase-producing strains only). Moraxella catarrhalis (including ß-lactamase-producing strains), or Streptococcus pneumoniae (See INDICATIONS AND USAGE .) 1000 mg 500 mg q 12 hours 7 days Pharyngitis and/or tonsillitis due to S. pyogenes 750 mg 375 mg q 12 hours 10 days Uncomplicated Skin and Skin Structure Infections due to S. aureus (methicillin-susceptible strains) (See INDICATIONS AND USAGE .) 750 mg 375 mg q 12 hours 7 to 10 days Elderly patients with normal renal function do not require dosage adjustments.

BEFORE THERAPY WITH CEFACLOR EXTENDED-RELEASE TABLETS IS INSTITUTED, CAREFUL INQUIRY SHOULD BE MADE TO DETERMINE WHETHER THE PATIENT HAS HAD PREVIOUS HYPERSENSITIVITY REACTIONS TO CEFACLOR, CEPHALOSPORINS, PENICILLINS, OR OTHER DRUGS. IF THIS PRODUCT IS TO BE GIVEN TO PENICILLIN-SENSITIVE PATIENTS, CAUTION SHOULD BE EXERCISED BECAUSE CROSS-SENSITIVITY AMONG BETA-LACTAM ANTIBIOTICS HAS BEEN CLEARLY DOCUMENTED AND MAY OCCUR IN UP TO 10% OF PATIENTS WITH A HISTORY OF PENICILLIN ALLERGY. IF AN ALLERGIC REACTION TO CEFACLOR EXTENDED-RELEASE TABLETS OCCURS, DISCONTINUE THE DRUG. SERIOUS ACUTE HYPERSENSITIVITY REACTIONS MAY REQUIRE TREATMENT WITH EPINEPHRINE AND OTHER EMERGENCY MEASURES, INCLUDING OXYGEN, INTRAVENOUS FLUIDS, INTRAVENOUS ANTIHISTAMINES, CORTICOSTEROIDS, PRESSOR AMINES, AND AIRWAY MANAGEMENT, AS CLINICALLY INDICATED. Clostridium difficile associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including cefaclor and may range in severity from mild diarrhea to fatal colitis. Treatment with antibacterial agents alters the normal flora of the colon leading to overgrowth of C. difficile . C. difficile produces toxins A and B which contribute to the development of CDAD. Hypertoxin producing strains of C. difficile cause increased morbidity and mortality, as these infections can be refractory to antimicrobial therapy and may require colectomy. CDAD must be considered in all patients who present with diarrhea following antibiotic use.

Clinical Trials There were 3272 patients treated with multiple doses of cefaclor extended-release tablets in controlled clinical trials and an additional 211 subjects in pharmacology studies. There were no deaths in these trials thought to be related to toxicity from cefaclor extended-release tablets. Treatment was discontinued in 1.7% of patients due to adverse events thought to be possibly or probably drug-related. The following adverse clinical and laboratory events were reported during the cefaclor extended-release tablets clinical trials conducted in North America at doses of 375 mg or 500 mg BID; however, relatedness of the adverse events to the drug was not assigned by clinical investigators during the trials (see TABLES 4 and 5 ). Table 4: ADVERSE CLINICAL EVENTS - CEFACLOR EXTENDED-RELEASE TABLETS MULTIPLE DOSE DOSING REGIMENS CLINICAL TRIALS - NORTH AMERICA (n = 1400) Incidence Equal to or Greater Than 1% Event Incidence Headache 4.9% Rhinitis 3.9% Diarrhea 3.8% Nausea 3.4% Vaginitis n = 934 for these events (subset of female participants).

Usage in Pregnancy Teratogenic Effect Reproduction studies using cefaclor have been performed in mice, rats and ferrets at doses up to 3 to 5 times the maximum human dose (1500 mg/day) based on mg/m 2 . These studies have revealed no harm to the fetus due to cefaclor. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, cefaclor extended-release tablets should be used during pregnancy only if clearly needed.

The toxic symptoms following an overdose of cefaclor may include nausea, vomiting, epigastric distress, and diarrhea. The severity of the epigastric distress and the diarrhea are dose-related. Absorption of drugs from the gastrointestinal tract may be decreased by giving activated charcoal, which, in many cases, is more effective than emesis or lavage. Consider charcoal instead of or in addition to gastric emptying. Repeated doses of charcoal over time may hasten elimination of some drugs that have been absorbed. Although cefaclor is considered dialyzable, neither forced diuresis, peritoneal dialysis, hemodialysis, nor charcoal hemoperfusion have been demonstrated to be beneficial in an overdose of cefaclor.

• Sep 4, 2002ANDAANDA065058Teva
• Jan 22, 2004ANDAANDA065146Yung Shin Pharm
• Feb 17, 2012ANDAANDA065412Yung Shin Pharm

1. 1Drug Hypersensitivity24316%
2. 2Vomiting15810%
3. 3Nausea15410%
4. 4Fatigue1369.0%
5. 5Pyrexia1218.0%
6. 6Dizziness1097.2%
7. 7Infection1056.9%
8. 8Diarrhoea1036.8%
9. 9Drug Ineffective976.4%
10. 10Drug Intolerance956.3%
11. 11Therapeutic Product Effect Incomplete946.2%
12. 12Rash936.1%
13. 13International Normalised Ratio Fluctuation895.9%
14. 14Dyspnoea855.6%
15. 15Malaise765.0%

Recent PubMed references pinned to Cefaclor as a MeSH major topic. Citations link to pubmed.ncbi.nlm.nih.gov.

• Chemical instability of cefaclor in simple suspensions alkalinized with magnesium oxide and the structural elucidation of the degradation products.
  Journal of pharmaceutical sciences · 2026 · Kato G, Mitome H, Yamanaka M, et al.
  PMID 41238187DOI 10.1016/j.xphs.2025.104063
• Simultaneous determination of cefmetazole and cefaclor in urine from pediatric patients with urinary tract infections using a newly developed high-performance liquid chromatography assay method.
  International journal of clinical pharmacology and therapeutics · 2025 · Maeda E, Abe K, Takayama I, et al.
  PMID 40338119DOI 10.5414/CP204741
• Diagnostic Accuracy of Skin Test in Patients With Cefaclor-Induced Anaphylaxis.
  The journal of allergy and clinical immunology. In practice · 2025 · Sim DW, Yu JE, Koh YI, et al.
  PMID 39984040DOI 10.1016/j.jaip.2025.02.009
• Structure-Based Analysis of Cefaclor Pharmacokinetic Diversity According to Human Peptide Transporter-1 Genetic Polymorphism.
  International journal of molecular sciences · 2024 · Jang JH, Jeong SH
  PMID 38999989DOI 10.3390/ijms25136880
• Application of Cefaclor in Orthodontics through Micro-Implant Anchorage in Patients with Periodontitis.
  Annali italiani di chirurgia · 2024 · Xu F
  PMID 38918968DOI 10.62713/aic.3281
• Exploring the pharmacokinetics of second-generation cephalosporin, cefaclor: a systematic review in healthy and diseased populations.
  Xenobiotica; the fate of foreign compounds in biological systems · 2024 · Saleem T, Zamir A, Rasool MF, et al.
  PMID 38517680DOI 10.1080/00498254.2024.2333009
• Activated carbon fiber as an efficient co-catalyst toward accelerating Fe(2+)/Fe(3+) cycling for improved removal of antibiotic cefaclor via electro-Fenton process using a gas diffusion electrode.
  Environmental research · 2024 · Zhao Y, Wang A, Ren S, et al.
  PMID 38301762DOI 10.1016/j.envres.2024.118254
• Cefaclor causes vagus nerve-mediated depression-like symptoms with gut dysbiosis in mice.
  Scientific reports · 2023 · Joo MK, Shin YJ, Kim DH, et al.
  PMID 37726354DOI 10.1038/s41598-023-42690-1

The 10 most recently updated of 11 ClinicalTrials.gov registrations naming Cefaclor as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

• Optimizing the Diagnostic Approach to Cephalosporin Allergy Testing
  Recruiting · Phase 2 · Interventional · 300 enrolled · Massachusetts General Hospital
  NCT06406114updated 2026-05-26
• Preventive Effect of Prophylactic Oral Antibiotics Against Cholangitis After Kasai Portoenterostomy
  Recruiting · Interventional · 356 enrolled · Children's Hospital of Fudan University
  NCT05925309updated 2026-05-15
• Oral Antimicrobial Treatment vs. Outpatient Parenteral for Infective Endocarditis
  Recruiting · Phase 4 · Interventional · 360 enrolled · Fundacion Clinic per a la Recerca Biomédica
  NCT05398679updated 2026-02-25
• German Corneal Cross Linking Register
  Active not recruiting · Observational · 7,500 enrolled · Suphi Taneri
  NCT00560651updated 2025-01-10
• LED Therapy for Third Molar Surgery
  Not yet recruiting · Early phase 1 · Interventional · 50 enrolled · Huashan Hospital
  NCT06640439updated 2024-10-15
• Patients Response to Early Switch To Oral:Osteomyelitis Study
  Terminated · Early phase 1 · Interventional · 11 enrolled · Julio Ramirez
  NCT02099240updated 2021-04-06
• The Effects of Antibiotic Combinations on Stem Cells
  Completed · Observational · 3 enrolled · Eskisehir Osmangazi University
  NCT04713436updated 2021-01-19
• Is it Fair to Use Antibiotics After Laparoscopic Cholecystectomy for the Patients With Acutely Inflamed Gallbladder?
  Completed · Interventional · 198 enrolled · Taeho Hong
  NCT02490293updated 2017-04-07
• Comparing Healthcare Utilization Between Adenotonsillectomy Patients With and Without Postoperative Antibiotic Use
  Completed · Interventional · 58 enrolled · University of Missouri-Columbia
  NCT01561703updated 2017-01-19
• Use of Antibacterial Cement in Infected Dentin
  Completed · Interventional · 45 enrolled · University of Pernambuco
  NCT01449136updated 2011-10-10

Frequently asked questions

How does Cefaclor work?

Mechanism-of-action class: Enzyme Inhibitors.

What is Cefaclor used for?

According to FDA labeling, Cefaclor carries indications including: To reduce the development of drug-resistant bacteria and maintain the effectiveness of cefaclor extended-release tablets USP and other antibacterial drugs, cefaclor extended-release tablets USP should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.

What class of drug is Cefaclor?

Cefaclor is classified as Second-generation cephalosporins, Enzyme Inhibitors, Decreased Cell Wall Synthesis & Repair.

What are the contraindications for Cefaclor?

Cefaclor labeling lists contraindications including: Cefaclor extended-release tablets are contraindicated in patients with known hypersensitivity to cefaclor and other cephalosporins.. Always consult the full prescribing information and a clinician.