KEFTAB
Clinical safety rating: caution
Comprehensive clinical and safety monograph for KEFTAB (KEFTAB).
Cephalexin binds to penicillin-binding proteins (PBPs) on the bacterial cell wall, inhibiting transpeptidation and disrupting peptidoglycan cross-linking, leading to cell lysis via autolytic enzymes.
| Metabolism | Cephalexin is poorly metabolized; less than 5% undergoes hepatic metabolism. Primarily eliminated unchanged via renal tubular secretion and glomerular filtration. |
| Excretion | Renal: 90-95% unchanged via glomerular filtration and tubular secretion; biliary/fecal: <5% |
| Half-life | 0.8-1.2 hours (prolonged to 6-8 hours in renal impairment; requires dose adjustment for CrCl <50 mL/min) |
| Protein binding | 65-80% (primarily to serum albumin) |
| Volume of Distribution | 0.2-0.3 L/kg (indicates limited extravascular distribution; confined to extracellular fluid space) |
| Bioavailability | Oral: 85-95% (well absorbed; food delays absorption but does not reduce extent); IM: >90% |
| Onset of Action | IV: immediate; IM: 15-30 minutes; Oral: 30-60 minutes |
| Duration of Action | 6-8 hours (dose-dependent; prolonged in renal impairment; recommended dosing every 12-24 hours in CKD) |
Cefuroxime axetil (KEFTAB) 250-500 mg orally twice daily for 7-10 days. For uncomplicated urinary tract infections: 250 mg twice daily; for acute otitis media: 500 mg twice daily.
| Dosage form | TABLET |
| Renal impairment | CrCl 30-50 mL/min: dose every 12 hours; CrCl 10-29 mL/min: dose every 24 hours; CrCl <10 mL/min: dose every 48 hours; hemodialysis: 250 mg after each dialysis session. |
| Liver impairment | No dose adjustment required for mild to moderate hepatic impairment; no data for severe impairment (Child-Pugh Class C). |
| Pediatric use | Children (3 months to 12 years): acute otitis media or impetigo: 15 mg/kg/dose (max 500 mg) twice daily for 10 days; pharyngitis/tonsillitis: 10 mg/kg/dose (max 250 mg) twice daily for 10 days. |
| Geriatric use | Use with caution due to age-related renal decline; adjust dose based on creatinine clearance. No specific geriatric dose adjustment beyond renal adjustment. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for KEFTAB (KEFTAB).
| Breastfeeding | Cefalexin (KEFTAB) is excreted in breast milk in small amounts (M/P ratio approximately 0.01-0.03). Generally considered compatible with breastfeeding; may alter infant gut flora and cause diarrhea or allergic reaction. Use with caution in infants with G6PD deficiency or previous hypersensitivity. |
| Teratogenic Risk | Category B: Animal reproduction studies have not demonstrated fetal risk, but no adequate human studies in pregnant women. First trimester: no evidence of teratogenicity. Second and third trimesters: safe for use when indicated; theoretical risk of kernicterus in neonates if administered near term due to bilirubin displacement from albumin binding sites. |
■ FDA Black Box Warning
None
| Serious Effects |
Absolute: Known hypersensitivity to cephalexin or any cephalosporin. Relative: History of immediate-type hypersensitivity reaction to penicillins (cross-sensitivity in approximately 5-10% of patients).
| Precautions | Serious hypersensitivity reactions (anaphylaxis) have been reported, especially in penicillin-allergic patients. Clostridioides difficile-associated diarrhea (CDAD) can occur. Prolonged use may result in overgrowth of non-susceptible organisms. Dosage adjustment is required in renal impairment (CrCl < 50 mL/min). Use with caution in patients with a history of gastrointestinal disease, particularly colitis. |
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| Fetal Monitoring | No specific fetal monitoring required. Maternal renal function should be assessed prior to and during therapy, especially in patients with renal impairment or preeclampsia. Monitor for signs of superinfection or Clostridium difficile-associated diarrhea. |
| Fertility Effects | No known adverse effects on human fertility. Animal studies have not shown impaired fertility. |