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 |
| Molecular Weight | 423.41 |
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 | Generally considered safe; no known teratogenicity. Use only if clearly needed. |
| 2nd trimester | Safe for use; no reported fetal harm. |
| 3rd trimester | Safe but monitor for potential maternal diarrhea and subsequent electrolyte imbalance. |
Clinical note
Probenecid may decrease excretion Serious and occasionally fatal hypersensitivity reactions have been reported.
| FDA category | Human |
| Placental transfer | Crosses placenta in low concentrations; not associated with fetal harm. |
| Breastfeeding | Minimal excretion into breast milk; considered compatible with breastfeeding. |
■ FDA Black Box Warning
No FDA black box warning.
| Common Effects | Diarrhea |
| Serious Effects |
Hypersensitivity to penicillins or beta-lactam antibiotics
| 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. |
| Food/Dietary | No significant food interactions. Oxacillin absorption is unaffected by food. However, avoid alcohol while taking any antibiotic to reduce risk of adverse effects and support recovery. |
Loading safety data…
| Lactation Rating | L1 (Safe) |
| 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. |
| 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. |
| Clinical Pearls | Oxacillin sodium is a penicillinase-resistant penicillin used primarily for infections caused by methicillin-susceptible Staphylococcus aureus (MSSA). It is not effective against methicillin-resistant S. aureus (MRSA). Administer via IV or IM; for IV, infuse over 10-30 minutes to avoid phlebitis. Monitor renal function, especially in elderly or renally impaired patients, as dose adjustment may be needed. Risk of hepatotoxicity; check liver enzymes periodically. Contains sodium (approximately 2.8 mEq per gram); use with caution in patients with heart failure or hypertension. Cross-allergenicity with other penicillins; contraindicated in patients with history of immediate hypersensitivity reactions to penicillins. |
| Patient Advice | Take this medication exactly as prescribed, even if you feel better. · Report any signs of allergic reaction, such as rash, itching, swelling, or difficulty breathing, immediately. · Complete the full course of therapy; do not stop early or skip doses. · Inform your doctor if you have kidney disease, heart failure, or high blood pressure. · Notify your doctor if you experience severe diarrhea, stomach cramps, or bloody stools, as this may indicate a serious intestinal condition. · Store unopened vials at room temperature; reconstituted solution must be used within a certain time (check pharmacy instructions). · Report any unusual bleeding or bruising, as this may indicate a low platelet count. |