[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Beta-lactams](https://durgical.com/en/pharmacology/classes/beta-lactams/) › Oxacillin [Pharmacology](https://durgical.com/en/pharmacology/) · [Beta-lactams](https://durgical.com/en/pharmacology/classes/beta-lactams/) # Oxacillin An intravenous penicillinase-resistant penicillin for serious infections by methicillin-susceptible Staphylococcus aureus. Updated 2026-11-01 - Class: [Beta-lactams](https://durgical.com/en/pharmacology/classes/beta-lactams/) - Enzyme: Penicillin-binding proteins (bacterial transpeptidases) - ATC code: J01CF04 ✂**Penicillin-binding proteins (bacterial transpeptidases)**Oxacillin ⓘ The figure shows Staphylococcus aureus PBP1 inhibited by oxacillin, bonded to the active-site serine. **Target in 3D:** Penicillin-binding proteins (bacterial transpeptidases). PDB structure 8VBU (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/8VBU) · Drag to rotate · pinch to zoom ## Mechanism of action Oxacillin is a parenteral isoxazolyl penicillin. It belongs to the penicillins resistant to staphylococcal β-lactamase: its bulky side chain keeps penicillinase from opening the β-lactam ring, so it acylates the PBPs of penicillinase-producing staphylococci. It does not work against MRSA, whose PBP2a has low affinity for β-lactams. - Staphylococcal penicillinase cannot open its ring - Acylates the staphylococcal PBPs - Peptidoglycan cross-linking stops - The staphylococcus lyses ## Pharmacokinetics **Absorption** Intravenous or intramuscular. **Elimination** By the kidney and by liver inactivation and bile; usually no adjustment in kidney failure. **Half-life** Short, under one hour. ## Indications - Skin and soft-tissue infections due to penicillinase-producing staphylococci. [Cellulitis of the leg →](https://durgical.com/en/conditions/cellulitis-of-the-leg/) - Staphylococcal osteomyelitis and septic arthritis. [Osteomyelitis →](https://durgical.com/en/conditions/osteomyelitis/) - Bacteraemia and endocarditis due to methicillin-susceptible S. aureus. [Infective endocarditis →](https://durgical.com/en/conditions/infective-endocarditis/) ## Adverse effects ### Common - Phlebitis at the infusion site - Rash, fever - Raised transaminases ### Serious (rare, important) - Anaphylaxis - Renal tubular damage and interstitial nephritis - Liver dysfunction with fever, nausea and raised transaminases; blood disorders - Clostridioides difficile diarrhoea, from mild to severe colitis ## Contraindications - History of a hypersensitivity reaction to any penicillin - Dextrose-containing solutions may be contraindicated with corn allergy ## Key interactions **Tetracyclines** Bacteriostatic: they can antagonise the bactericidal effect; the combination is avoided. **Probenecid** Reduces tubular secretion: higher and longer-lasting β-lactam levels. ## What is monitored - Periodic kidney and liver function and blood count in long courses - Cultures and susceptibility ## Administration and safety - Intravenous; premixed bags are for intravenous use only. - Do not confuse oxacillin with other similarly named antistaphylococcal penicillins. ## Nursing care - Before the first dose: ask about allergy to penicillins, cephalosporins and other β-lactams, and what the reaction was. - Watch for fever, rash, urine changes and creatinine (interstitial nephritis). - Check the IV site for phlebitis. - Teach the patient to report watery or bloody diarrhoea, even weeks after the course ends. ## Pregnancy and breastfeeding Animal studies showed no fetal harm and there are no controlled studies in pregnant women; used if clearly needed. ## Memory aid 'OXA-cillin: OK for MSSA, eXit for MRSA': MRSA's PBP2a does not let it work. ## Test yourself Think of the answer, then tap the question to see it. ## Why does oxacillin not work against MRSA? Because MRSA carries PBP2a, a PBP with low affinity for β-lactams. ## Which kidney toxicity is linked to oxacillin? Tubular damage and interstitial nephritis, both uncommon. ## Does oxacillin need adjustment in kidney failure? Generally not, because it is also cleared by the liver and bile. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/oxacillin/) ## Related drugs - [Nafcillin](https://durgical.com/en/pharmacology/nafcillin/) - [Cloxacillin](https://durgical.com/en/pharmacology/cloxacillin/) - [Dicloxacillin](https://durgical.com/en/pharmacology/dicloxacillin/) - [Cefazolin](https://durgical.com/en/pharmacology/cefazolin/) ## Related conditions - [Cellulitis of the leg](https://durgical.com/en/conditions/cellulitis-of-the-leg/) - [Osteomyelitis](https://durgical.com/en/conditions/osteomyelitis/) - [Infective endocarditis](https://durgical.com/en/conditions/infective-endocarditis/) [← Back to the class: Beta-lactams](https://durgical.com/en/pharmacology/classes/beta-lactams/) Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given. Sources: [Oxacillin Injection: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a685020.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [DailyMed - OXACILLIN injection, solution](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=d893e45b-7f18-4c67-b10c-1e2e52a6b3ef) (DailyMed (U.S. National Library of Medicine), 2026); [RCSB PDB - 8VBU: Structure of the monofunctional Staphylococcus aureus PBP1 in its beta-lactam (Oxacillin) inhibited form](https://www.rcsb.org/structure/8VBU) (RCSB Protein Data Bank, 2026); Farmacología básica y clínica (Katzung), cap. 43 (McGraw Hill, 2025). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/pharmacology/oxacillin/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/oxacillin/