PROSTAPHLIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PROSTAPHLIN (PROSTAPHLIN).
Prostaphlin (oxacillin) is a penicillinase-resistant penicillin that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), specifically PBP1 and PBP3, leading to inhibition of transpeptidation and cell lysis. It is resistant to staphylococcal beta-lactamases.
| Metabolism | Hepatic metabolism via hydrolysis and oxidation; minor renal excretion. |
| Excretion | Primarily renal (70-80% unchanged via glomerular filtration and tubular secretion); minor biliary/fecal elimination (<10%). |
| Half-life | 0.4-0.8 hours in adults with normal renal function; prolonged in renal impairment (up to 4-6 hours in anuria). |
| Protein binding | 80-90% bound to serum albumin. |
| Volume of Distribution | 0.3-0.4 L/kg (confined to extracellular fluid; poor CNS penetration unless meninges inflamed). |
| Bioavailability | Oral: 30-40% (due to acid lability and first-pass metabolism); IM: 70-80%. |
| Onset of Action | Intravenous: immediate; intramuscular: 15-30 minutes; oral: 30-60 minutes. |
| Duration of Action | 4-6 hours following IV/IM administration; requires frequent dosing (q4-6h) for sustained bactericidal levels. |
250-500 mg IM or IV every 4-6 hours for moderate to severe infections. For oral use: 250-500 mg every 6 hours on empty stomach.
| Dosage form | FOR SOLUTION |
| Renal impairment | No dose adjustment for GFR >30 mL/min. For GFR 10-30 mL/min: 250-500 mg every 8 hours. For GFR <10 mL/min: 250-500 mg every 12 hours. |
| Liver impairment | No specific guidelines; use caution in severe hepatic impairment (Child-Pugh C) and monitor for toxicity. |
| Pediatric use | Infants and children: 50-100 mg/kg/day IM or IV divided every 6 hours. Neonates: 25-50 mg/kg/day divided every 8 hours. |
| Geriatric use | No specific adjustments required, but monitor renal function and adjust accordingly based on GFR. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for PROSTAPHLIN (PROSTAPHLIN).
| Breastfeeding | Oxacillin is excreted into breast milk in small amounts (M/P ratio approximately 0.5). It is considered compatible with breastfeeding by the American Academy of Pediatrics. However, potential for infant sensitization and diarrhea exists. Monitor infant for rash or gastrointestinal disturbances. |
| Teratogenic Risk | Prostaphlin (oxacillin) is a penicillinase-resistant penicillin. Animal studies have not shown teratogenicity. There are no adequate and well-controlled studies in pregnant women. FDA Pregnancy Category B. Risk cannot be ruled out but is considered low. Use only if clearly needed. |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
["Hypersensitivity to penicillins","History of severe penicillin allergy"]
| Precautions | ["Hypersensitivity reactions including anaphylaxis","Clostridioides difficile-associated diarrhea","Neutropenia and interstitial nephritis with prolonged use","Use with caution in patients with renal impairment"] |
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| Fetal Monitoring | Monitor for signs of hypersensitivity reactions, including rash, urticaria, and anaphylaxis. Assess renal function periodically due to rare interstitial nephritis. No specific fetal monitoring required. |
| Fertility Effects | No known adverse effects on fertility. Animal studies have not reported impairment of fertility. |