Oxacillin

Oral
Infections due to staphylococci resistant to benzylpenicillin

Parenteral
Infections due to staphylococci resistant to benzylpenicillin

Intramuscular:
Add 5.7 mL or 11.4 mL of sterile water for inj to the vial containing 1 g or 2 g of oxacillin, respectively, to provide soln containing 167 mg/mL (250 mg/1.5 mL).
Intravenous:
Add 10 mL or 20 mL of sterile water for inj or NaCl 0.45% or 0.9% inj to the vial containing 1 g or 2 g of oxacillin, respectively. For IV infusion, dilute further w/ a compatible IV soln to a concentration of 0.5-40 mg/mL.

Caffeine citrate, Na bicarbonate, verapamil. Variable: Doxapram, vit B complex w/ vit C.

Hypersensitivity to to oxacillin and other penicillins.

Patient w/ history of asthma, β-lactam allergy. Pregnancy and lactation.

Fever, rash, nausea, diarrhoea, vomiting, eosinophilia, leucopenia, neutropenia, thrombocytopenia, agranulocytosis, hepatotoxicity, increased AST, acute interstitial nephritis, haematuria, serum sickness-like reactions.
Potentially Fatal: Anaphylactic shock w/ collapse, Clostridium difficile-associated diarrhoea (CDAD).

IM/IV/Parenteral: B

Monitor blood cultures, WBC, differential cell counts, urinalysis, BUN, serum creatinine, AST and ALT values. Observe for signs and symptoms of anaphylaxis during 1st dose.

Symptoms: Neuromuscular hypersensitivity (e.g. agitation, hallucinations, asterixis, encephalopathy, confusion, and seizures), electrolyte imbalance (if the preparation contains K or Na salts, esp in renal failure). Management: Symptomatic and supportive treatment.

Tetracycline may antagonise the bactericidal effect of oxacillin. Enhanced plasma concentrations by probenecid.

May interfere w/ urinary glucose tests using cupric sulfate (Benedict's soln). False-positive urinary and serum proteins.

Description:
Mechanism of Action: Oxacillin inhibits bacterial cell wall synthesis by binding to 1 or more of the penicillin-binding proteins (PBPs); which in turn inhibits the final transpeptidation step of peptidoglycan synthesis in bacterial cell walls. Bacteria eventually lyse due to ongoing activity of cell wall autolytic enzymes (autolysins and murein hydrolases) while cell wall assembly is arrested.
Pharmacokinetics:
Absorption: Incompletely absorbed from the GI tract. Absorption is reduced by the presence of food. Time to peak plasma concentration: 1 hr (oral); 30 min (IM).
Distribution: Distributed into synovial, pleural pericardial and ascitic fluids; bone, lungs, sputum and bile; cord serum and amniotic fluid. Crosses the placenta and enters breast milk. Volume of distribution: 0.39-0.43 L/kg. Plasma protein binding: Approx 93%.
Metabolism: Partially metabolised to active and inactive metabolites in the liver.
Excretion: Via urine (oral: approx 20-30%; IM: >40%) as unchanged drug and metabolites and bile. Plasma half-life: Approx 30 min.

Source: National Center for Biotechnology Information. PubChem Database. Oxacillin, CID=6196, https://pubchem.ncbi.nlm.nih.gov/compound/Oxacillin (accessed on Jan. 22, 2020)

Store between 20-25°C.

Penicillins

Anon. Oxacillin. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 24/06/2014.

Buckingham R (ed). Oxacillin Sodium. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 24/06/2014.

McEvoy GK, Snow EK, Miller J et al (eds). Oxacillin Sodium. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 24/06/2014.

Oxacillin Sodium Powder for Solution (AuoMedics Pharma LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 24/06/2014.

Wickersham RM. Oxacillin Injection. Facts and Comparisons [online]. St. Louis, MO. Wolters Kluwer Clinical Drug Information, Inc. https://www.wolterskluwercdi.com/facts-comparisons-online/. Accessed 24/06/2014.