• Type: Penicillinase-resistant penicillin
  • Dosage Forms: 250,500
  • Common Trade Names:

Adult Dosing

Skin infections, staphylococcal

  • 125-500mg PO q6h (1h before or 2h after meals)


  • 250-500mg PO q6h (1h before or 2h after meals)

Pediatric Dosing

Skin infections, staphylococcal

  • <40 kg: 12.5-25mg/kg/day PO divided q6h
  • >40kg: 125-500mg PO q6h


  • <40kg: 50-100mg/kg/day PO divided q6h
  • >40kg: 250-500mg PO q6h

Special Populations

  • Pregnancy risk: B (no evidence of risk)
  • Lactation: safety unknown
  • Renal Dosing
    • Adult: no adjustment
    • Pediatric: no adjustment
  • Hepatic Dosing
    • Adult: not defined
    • Pediatric: not defined


  • Allergy to class/drug
  • caution in asthma
  • caution in seizure disorder
  • caution in renal impairment

Adverse Reactions


  • anaphylaxis
  • serum sickness-like reaction
  • superinfection
  • C-diff
  • hemolytic anemia
  • leukopenia
  • agranulocytosis
  • neutropenia
  • thrombocytopenia
  • esophagitis
  • esophageal ulcer


  • nausea/vomiting
  • diarrhea
  • epigastric pain
  • urticaria
  • pruritus
  • fever
  • rash
  • eosinophilia
  • stomatitis
  • black hairy tongue
  • LFTs elevated


  • Half-life: 0.7h, if GFR < 10 then 1.8h
  • Metabolism: liver partially
  • Excretion: urine 50-70% (primarily unchanged), bile 10%
  • Mechanism of Action: inhibits cell wall mucopeptide synthesis

Antibiotic Sensitivities[1]

Group Organism Sensitivity
Gram PositiveStrep. Group A, B, C, GS
Strep. PneumoniaeS
Viridans strepI
Strep. anginosus gpS
Enterococcus faecalisR
Enterococcus faeciumR
Staph. EpidermidisS
C. jeikeiumR
L. monocytogenesR
Gram NegativesN. gonorrhoeaeR
N. meningitidisR
Moraxella catarrhalisR
H. influenzaeR
E. coliR
Klebsiella spR
E. coli/Klebsiella ESBL+R
E coli/Klebsiella KPC+R
Enterobacter sp, AmpC negR
Enterobacter sp, AmpC posR
Serratia spR
Serratia marcescensX1
Salmonella spR
Shigella spR
Proteus mirabilisR
Proteus vulgarisR
Providencia sp.R
Morganella sp.R
Citrobacter freundiiR
Citrobacter diversusR
Citrobacter sp.R
Aeromonas spR
Acinetobacter sp.R
Pseudomonas aeruginosaR
Burkholderia cepaciaR
Stenotrophomonas maltophiliaR
Yersinia enterocoliticaR
Francisella tularensisX1
Brucella sp.X1
Legionella sp.R
Pasteurella multocidaR
Haemophilus ducreyiX1
Vibrio vulnificusX1
MiscChlamydophila spR
Mycoplasm pneumoniaeR
Rickettsia spX1
Mycobacterium aviumX1
Bacteroides fragilisR
Prevotella melaninogenicaR
Clostridium difficileX1
Clostridium (not difficile)X1
Fusobacterium necrophorumX1
Peptostreptococcus sp.S


  • 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


  1. Sanford Guide to Antimicrobial Therapy 2014
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