Cephalexin: Difference between revisions

(Replace manual dosing with dynamic SMW tables (Adult + Pediatric))
(Remove disease-specific entries now covered by AntibioticDose (3 sections))
 
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==Adult Dosing==
==Adult Dosing==
===General===
*250-500mg PO q6h
*Max: 4g/day
===Indications by Disease===
===Indications by Disease===
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==Pediatric Dosing==
==Pediatric Dosing==
===General===
*25-50mg/kg/day PO divided q6-12h
*Max: 500mg/dose
===Skin Infections===
*25-50mg/kg/day PO divided q12h
*Max: 500mg/dose
===Indications by Disease===
===Indications by Disease===
{{#ask: [[Has DrugName::Cephalexin]] [[Has Population::Pediatric]]
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Latest revision as of 11:08, 20 March 2026

General

  • Type: 1st generation cephalosporin
  • Dosage forms
    • Tabs: 250mg, 500mg, 750mg
    • Liquid: 125mg/5mL; 250mg/5mL
  • Common Trade Names: Keflex, Keftab, Biocef

Adult Dosing

General

  • 250-500mg PO q6h
  • Max: 4g/day

Indications by Disease

DiseaseDoseContext
Acute cystitis250mg QID x 5dOutpatient, Women Uncomplicated
Cellulitis500mg PO q6hrsOutpatient
Erysipelas500mg (6.25mg/kg) PO q6hrs x 10 daysAlternative
Felon500mg PO q6hrs daily x 7 daysOutpatient
Impetigo500mg (6.25mg/kg) PO q6hrs x 10 daysOral therapy
Mastitis500mg PO q6hrsFirst line alternative
Pyelonephritis500mg QID PO x 10-14 days (OR consider 1000mg BID)Outpatient
Streptococcal pharyngitis20 mg per kg PO BID (maximum 500 mg per dose) x 10 daysPenicillin Allergy (mild)
Suppurative parotitis500mg (12.5mg/kg) PO four times dailyOutpatient

Pediatric Dosing

General

  • 25-50mg/kg/day PO divided q6-12h
  • Max: 500mg/dose



Skin Infections

  • 25-50mg/kg/day PO divided q12h
  • Max: 500mg/dose


Indications by Disease

DiseaseDoseContext
Acute cystitis25-50mg/kg/day PO divided q6-8h x 7-10 days (max 500mg/dose)Pediatric
Acute otitis media75-100mg/kg/day PO divided q12h x 10 days; Max: 4,000mg/24hOtitis Media
Cellulitis25-50mg/kg/day PO divided q6-8h (max 500mg/dose)Pediatric Outpatient
Endocarditis50mg/kg PO (max 2g)Pediatric Dental Prophylaxis, mild PCN Allergy
Erysipelas25-50mg/kg/day PO divided q6-8h x 10 days (max 500mg/dose)Pediatric
Impetigo25-50mg/kg/day PO divided q6-8h x 7-10 days (max 500mg/dose)Pediatric Oral
Pharyngitis40mg/kg/day PO divided q12h x 10 days; Max: 500mg/doseStreptococcal Pharyngitis (>1 Year)
Pyelonephritis25-50mg/kg/day PO divided q6-8h x 10-14 days (max 500mg/dose)Pediatric Outpatient
Streptococcal pharyngitis20mg/kg PO BID x 10 days (max 500mg/dose)Pediatric PCN Allergy
Suppurative parotitis50mg/kg/day PO divided QID (max 500mg/dose)Pediatric Outpatient

Special Populations

  • Pregnancy Rating: B
  • Lactation risk categories: Enters breast milk/L3
  • Renal
    • Adult
      • CrCl 50-90: give q6-8h
      • CrCl 10-50: give q8-12h
      • CrCl <10: give q12-24h
      • Hemodialysis: give dose after dialysis, no supplement
      • Peritoneal dialysis: no supplement
    • Pediatric
      • CrCl 30-50: give q8h
      • CrCl 10-29: give q12h
      • CrCl <10: give q24h
      • Hemodialysis: give dose after dialysis, no supplement
      • Peritoneal dialysis: no supplement
  • Hepatic (Adult & Pediatric)
    • Not defined

Contraindications

Adverse Drug Reactions

Serious

Common

Pharmacology

  • Half-life: 1h (~20hr ESRD)
  • Metabolism: Minimal
  • Excretion: Primarily urine (>90% unchanged)
  • Mechanism of Action:
    • Bactericidal, inhibits cell wall

Antibiotic Sensitivities[1]

Group Organism Sensitivity
Gram Positive Strep. Group A, B, C, G S
Strep. Pneumoniae S
Viridans strep S
Strep. anginosus gp X1
Enterococcus faecalis R
Enterococcus faecium X1
MSSA S
MRSA R
CA-MRSA R
Staph. Epidermidis I
C. jeikeium R
L. monocytogenes R
Gram Negatives N. gonorrhoeae R
N. meningitidis R
Moraxella catarrhalis R
H. influenzae R
E. coli S
Klebsiella sp S
E. coli/Klebsiella ESBL+ R
E coli/Klebsiella KPC+ R
Enterobacter sp, AmpC neg R
Enterobacter sp, AmpC pos R
Serratia sp R
Serratia marcescens X1
Salmonella sp R
Shigella sp R
Proteus mirabilis S
Proteus vulgaris R
Providencia sp. R
Morganella sp. R
Citrobacter freundii R
Citrobacter diversus R
Citrobacter sp. R
Aeromonas sp X1
Acinetobacter sp. R
Pseudomonas aeruginosa R
Burkholderia cepacia R
Stenotrophomonas maltophilia R
Yersinia enterocolitica X1
Francisella tularensis X1
Brucella sp. X1
Legionella sp. R
Pasteurella multocida R
Haemophilus ducreyi X1
Vibrio vulnificus X1
Misc Chlamydophila sp X1
Mycoplasm pneumoniae X1
Rickettsia sp X1
Mycobacterium avium X1
Anaerobes Actinomyces X1
Bacteroides fragilis R
Prevotella melaninogenica X1
Clostridium difficile X1
Clostridium (not difficile) X1
Fusobacterium necrophorum X1
Peptostreptococcus sp. S

Key

  • S susceptible/sensitive (usually)
  • I intermediate (variably susceptible/resistant)
  • R resistant (or not effective clinically)
  • S+ synergistic with cell wall antibiotics
  • U sensitive for UTI only (non systemic infection)
  • X1 no data
  • X2 active in vitro, but not used clinically
  • X3 active in vitro, but not clinically effective for Group A strep pharyngitis or infections due to E. faecalis
  • X4 active in vitro, but not clinically effective for strep pneumonia

See Also

References

  1. ↑ Sanford Guide to Antimicrobial Therapy 2014
  • Sanford 2010
  • Epocrates
  • Lexicomp
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