Treatment of bacterial infections including endocarditis, pneumonia, bone and joint infections, skin and soft-tissue infections, and sepsis that are caused by susceptible strains of penicillinase-producing staphylococci. Note: Exhibits good activity against Staphylococcus aureus; has activity against many streptococci, but is less active than penicillin and is generally not used in clinical practice to treat streptococcal infections.
Antibiotic Class: Penicillin (penicillinase-resistant penicillin)

Exerts bactericidal activity via inhibition of bacterial cell wall synthesis

Antimicrobial Spectrum: Staphylococcus spp., Streptococcal spp.

Mechanism of Action:

Exerts bactericidal activity via inhibition of bacterial cell wall synthesis by binding one or more of the penicillin binding proteins (PBPs). Exerts bacterial autolytic effect by inhibition of certain PBPs related to the activation of a bacterial autolytic process.

Adverse Effects:

Hematologic: neutropenia, inhibition of platelet aggregation
CNS: seizures
Hepatic: transient increases in transaminases
Other: Jarisch-Herxheimer Reaction (fever, chills, sweating, tachycardia, hyperventilation, flushing, and myalgia)


Adult: 250-500mg po q6h
Pediatric: above 1 month and above 20 kg: 50-100 mg/kg/day po in 4 divided doses
 20 kg and above: usual adult dose

Contraindications: Anaphylaxis to cloxacillin or other penicillins
Precautions: Cephalosporin hypersensitivity

Drug Interactions:
Contraceptives - decreased contraceptive effectiveness
Live Typhoid Vaccine - decreased immunological response to the typhoid vaccine
Probenecid - increased cloxacillin levels
Warfarin - decreased anticoagulant effectiveness

Category B: No evidence of risk in humans but studies inadequate.