Drug reference

Cephalexin

Cephalosporin · Antibiotic

Also known as Cefalexin

CephalosporinAntibioticATC null

CDSCO approved

EXCRETION

—

not curated

INTERACTIONS

1 major

incl. contraindicated

PREGNANCY

Not known to be harmful.

FDA category + note

Top interactionssee all 9 →

Pasteurella MultocidaContraindicatedTextbookHarrison 22e · p1054

Mechanism

The provided textbook excerpts do not describe the mechanism of action for Cephalexin, including its molecular target, affected pathway, or clinical consequence.

Indications

Susceptible infections due to sensitive Gram-positive and Gram-negative bacteriaSkin infectionsSoft-tissue infectionsUncomplicated urinary-tract infectionsHospital-acquired pneumoniaAcute diverticulitis (in combination with metronidazole)Prophylaxis of recurrent urinary-tract infectionAcute pyelonephritisUrinary-tract infection (catheter-associated)Skin and soft-tissue infectionsMild-to-moderate upper respiratory tract infectionsMild-to-moderate urinary tract infectionsSurgical prophylaxisSimilar spectrum to cefazolinuncomplicated acute UTI (empirical option)prophylaxis of recurrent cystitis (especially in women likely to get pregnant)secondary infection of eczematous skin with Staphylococcus aureusOral therapy for skin and soft tissue infections sensitive to methicillin

Dosing

Adult: For susceptible infections: 250 mg every 6 hours, alternatively 500 mg every 8–12 hours; increased to 1–1.5 g every 6–8 hours for severe infections. For skin infections, soft-tissue infections, uncomplicated urinary-tract infections: 0.5–1 g twice daily.…
Pediatric: For susceptible infections: Child 1–11 months: 12.5 mg/kg twice daily, alternatively 125 mg twice daily. Child 1–4 years: 12.5 mg/kg twice daily, alternatively 125 mg 3 times a day. Child 5–11 years: 12.5 mg/kg twice daily, alternatively 250 mg 3 times a day. Child 12–17 years: 500 mg 2–3 times a day.…
Renal adjustment: In adults: 1 g initially, then 500 mg every 12 hours if eGFR 26–50 mL/minute/1.73 m2. 1 g initially, then 500 mg every 24 hours if eGFR 11–26 mL/minute/1.73 m2. 1 g initially, then 500 mg every 36 hours if eGFR less than 11 mL/minute/1.73 m2. In children: Reduce dose if estimated glomerular filtration rate less than 50 mL/minute/1.73 m2.
Max dose: 6 g daily (adults, for severe infections); 1 g per dose, up to 4 times a day (children 1 month-11 years)

Pharmacokinetics

Half-life

60 min

Bioavailability

90 ± 9%

Protein binding

14 ± 3%

Excretion

90% excreted unchanged in the kidney; plasma clearance 4.3 mL/min/kg

Side effects

Common

DyspepsiaGlossitisGastrointestinal side effects (e.g., diarrhea)

Serious

Arthralgia
Drug fever
Fatigue
Hepatic disorders
Insomnia
Nervousness
Serum sickness-like reaction
Hypersensitivity reactions (rash to anaphylaxis)
Serum sickness
Stevens-Johnson syndrome
Nephropathy
Hematologic reactions (neutropenia, prolonged use)
Neurotoxicity (seizure, high doses, renal impairment)

Pregnancy & lactation

Pregnancy

Not known to be harmful.

Lactation

Present in milk in low concentration, but appropriate to use.

Drug interactions

Pasteurella Multocida

Contraindicated

Textbook

ineffective treatment

Pasteurella multocida is resistant to cephalexin; other β-lactam antimicrobial agents, quinolones, tetracycline, and erythromycin are sensitive. Amoxicillin-clavulanate, ampicillin-sulbactam, and cefoxitin are good choices.

Source: Harrison 22e · p1054

Azithromycin

Moderate

Textbook-cited

Reduced antibacterial efficacy.

Avoid concurrent use

Source: KDT 7e · p949

Chloramphenicol

Moderate

Textbook-cited

Reduced antibacterial efficacy

Avoid concurrent use