OXACILLIN SODIUM
Clinical safety rating: safe
Probenecid may decrease excretion Serious and occasionally fatal hypersensitivity reactions have been reported.
Oxacillin is a penicillinase-resistant beta-lactam antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), thereby blocking the transpeptidation step in peptidoglycan cross-linking. It is resistant to staphylococcal beta-lactamase.
| Metabolism | Primarily hepatic metabolism; undergoes hydrolysis to active and inactive metabolites. Also undergoes renal tubular secretion. |
| Excretion | Renal (70-80% unchanged by tubular secretion and glomerular filtration); biliary (minor, approximately 10%) |
| Half-life | 0.3-0.8 hours in adults with normal renal function; prolonged to 1-2 hours in neonates and 2-5 hours in patients with severe renal impairment (CrCl <10 mL/min) |
| Protein binding | 92-94% bound to serum albumin |
| Volume of Distribution | 0.2-0.3 L/kg; indicates distribution primarily into extracellular fluid |
| Bioavailability | Oral: 30-40% (not clinically used due to acid lability); IM: 80-90% |
| Onset of Action | IV: immediate; IM: 30 minutes |
| Duration of Action | 4-6 hours for susceptible organisms; dose adjustment required in renal impairment |
1-2 grams IV every 4-6 hours.
| Dosage form | INJECTABLE |
| Renal impairment | CrCl > 50 mL/min: no adjustment; CrCl 10-50 mL/min: 1-2 grams IV every 6-8 hours; CrCl < 10 mL/min: 1-2 grams IV every 8-12 hours. |
| Liver impairment | Child-Pugh Class A: no adjustment; Child-Pugh Class B and C: no specific guidelines, use with caution and monitor for adverse effects. |
| Pediatric use | For infants and children > 1 month: 50-100 mg/kg/day IV divided every 6 hours; severe infections: up to 200 mg/kg/day IV divided every 6 hours. For neonates 0-4 weeks: 25-50 mg/kg/dose IV every 8-12 hours depending on gestational and postnatal age. |
| Geriatric use | No specific dose adjustment for age alone; consider renal function and adjust accordingly. Max recommended dose: 12 grams/day. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Probenecid may decrease excretion Serious and occasionally fatal hypersensitivity reactions have been reported.
| FDA category | Human |
| Breastfeeding | Excreted in breast milk in small amounts (M/P ratio not established). Considered compatible with breastfeeding by AAP. Monitor infant for diarrhea, rash, or candidiasis. |
| Teratogenic Risk | Pregnancy Category B. No evidence of teratogenicity in animal studies; inadequate human data. Fetal risk cannot be ruled out but is considered low. Use only if clearly needed. |
■ FDA Black Box Warning
No FDA black box warning.
| Common Effects | Diarrhea |
| Serious Effects |
["Hypersensitivity to oxacillin, other penicillins, or any component of the formulation.","History of severe hypersensitivity reaction (e.g., anaphylaxis) to any beta-lactam antibiotic."]
| Precautions | ["Hypersensitivity reactions, including anaphylaxis, have been reported. Cross-sensitivity with other beta-lactams may occur.","Clostridioides difficile-associated diarrhea (CDAD) can occur.","Use with caution in patients with renal impairment; dose adjustment may be required.","Prolonged use may lead to superinfection with resistant organisms.","Neutropenia, agranulocytosis, and thrombocytopenia have been reported with high doses or prolonged therapy."] |
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| Fetal Monitoring | Monitor maternal renal function and CBC with differential during prolonged therapy. Observe for signs of hypersensitivity or diarrhea in mother. No specific fetal monitoring required. |
| Fertility Effects | No known adverse effects on fertility in animal studies. Human data insufficient. |