Cloxacillin

Treatment of infections caused by penicillinase-producing staphylococci. May be used to initiate therapy in suspected cases of resistant staphylococcal infections prior to the availability of laboratory test results.

Oral
Staphylococcal infections resistant to benzylpenicillin
Adult: 250-500 mg 4 times daily.
Child: 50-100 mg/kg in divided doses every 6 hr.

Incompatibility: Incompatible with aminoglycosides and a number of other antimicrobials.

Hypersensitivity to penicillins.

Serious and occasionally fatal hypersensitivity (anaphylactic shock with collapse) reactions reported; initiate only after a comprehensive drug and allergy history has been obtained. Caution with history of allergy and/or asthma. Should not be relied upon in patients with severe illness, N/V, gastric dilatation, cardiospasm, or intestinal hypermotility. May result in bacterial resistance with prolonged use or use in the absence of a proven/suspected bacterial infection or a prophylactic indication; take appropriate measures if superinfection develops. Change to another active agent if culture tests fail to demonstrate the presence of staphylococci. Monitor organ system functions (eg, renal, hepatic, and hematopoietic) periodically with prolonged use. If renal impairment is suspected/known, reduce dose and monitor blood levels. Monitor for possible liver function abnormalities.

Allergic reactions, N/V, diarrhea, stomatitis, black or hairy tongue, GI irritation, agranulocytosis, rash, Sore mouth or tongue.
Potentially Fatal: Neuromuscular hypersensitivity; pseudomembranous colitis; anaphylaxis.

Co-admin of probenecid or disulfiram may result in higher cloxacillin concentration. Chloramphenicol and tetracycline antagonise bactericidal effect of penicillins.
Potentially Fatal: Increased hypoprothrombinaemic effects of oral anticoagulants.

Delayed absorption in the presence of food.

Cloxacillin is resistant to degradation by penicillinases. It is particularly useful against penicillinase-producing staphylococci. Highly active against S aureus, S pyogenes, S viridans and S pneumoniae.
Absorption: Incompletely absorbed from the GI tract with peak plasma concentrations after 1-2 hr (oral); may be reduced in the presence of food. Completely absorbed with peak plasma concentrations after 30 min (IM).
Distribution: Pleural and synovial fluids and bone (therapeutic concentrations), CSF (small amounts except when the meninges are inflamed; crosses the placenta and enters the breast milk. Protein-binding: 94%
Metabolism: Minimal metabolism.
Excretion: Via the urine by glomerular filtration and renal tubular secretion (35% of an oral dose); via the bile (Up to 10%). Not removed by dialysis; 0.5-1 hr (elimination half-life).

B: Animal reproduction studies have failed to demonstrate a risk to the fetus and there are no adequate and well-controlled studies in pregnant women OR Animal studies have shown an adverse effect, but adequate and well-controlled studies in pregnant women have failed to demonstrate a risk to the fetus in any trimester.