VERSAPEN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for VERSAPEN (VERSAPEN).
Bactericidal; inhibits cell wall synthesis by binding to penicillin-binding proteins (PBPs), inhibiting peptidoglycan cross-linking.
| Metabolism | Partially metabolized to penicilloic acid; primarily renal excretion via tubular secretion and glomerular filtration. |
| Excretion | Renal: 60-70% unchanged via glomerular filtration and tubular secretion. Biliary: <10% excreted unchanged. Fecal: 20-30% as metabolites. |
| Half-life | 0.5-1.0 hour (normal renal function); prolonged to 10-20 hours in anuria. Requires dose adjustment in renal impairment. |
| Protein binding | 18-22% bound to albumin. |
| Volume of Distribution | 0.3-0.5 L/kg. Moderate Vd indicates distribution into extracellular fluid; limited CNS penetration unless inflamed meninges. |
| Bioavailability | IM: ~90%; Oral: 30-50% (highly variable due to gastric acid instability and first-pass metabolism). |
| Onset of Action | IV: immediate; IM: 15-30 minutes; Oral: 30-60 minutes. Onset faster with IV due to rapid bactericidal levels. |
| Duration of Action | IM/IV: 4-6 hours; Oral: 6-8 hours. Duration limited by rapid renal clearance and susceptibility to beta-lactamase. |
500 mg IV every 6 hours or 1 g IV every 8 hours for moderate infections; 2 g IV every 4 hours for severe infections.
| Dosage form | FOR SUSPENSION |
| Renal impairment | CrCl >50 mL/min: 500 mg-1 g every 6 hours; CrCl 10-50 mL/min: 500 mg every 6-12 hours; CrCl <10 mL/min: 500 mg every 12-24 hours. |
| Liver impairment | No specific guidelines; caution in severe hepatic impairment (Child-Pugh C) due to potential accumulation; consider dose reduction based on clinical response and tolerance. |
| Pediatric use | Infants >1 month: 25-50 mg/kg IV every 6 hours; maximum 2 g per dose. Neonates: 25 mg/kg IV every 12 hours (0-7 days) or every 8 hours (8-28 days). |
| Geriatric use | No specific dose adjustment is required other than based on renal function; monitor for renal impairment and adjust according to CrCl. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for VERSAPEN (VERSAPEN).
| Breastfeeding | Hetacillin is excreted into human milk in low concentrations. The milk-to-plasma (M/P) ratio is approximately 0.1-0.2. It is considered compatible with breastfeeding. Caution should be exercised, especially if infant has history of allergy or diarrhea. Monitor infant for rash, diarrhea, or fungal infections. |
| Teratogenic Risk | VERSAPEN (hetacillin) is a penicillin-class antibiotic. Animal studies have not revealed evidence of fetal harm. There are no adequate and well-controlled studies in pregnant women. However, penicillins are generally considered low risk in pregnancy. Use only if clearly needed. Risk cannot be ruled out. First trimester: No known teratogenicity. Second trimester: No known adverse fetal effects. Third trimester: No known adverse fetal effects; theoretical risk of alteration of gut flora. |
■ FDA Black Box Warning
Serious and occasionally fatal hypersensitivity reactions (anaphylaxis) have been reported in patients on penicillin therapy.
| Serious Effects |
Known hypersensitivity to penicillins or cephalosporins
| Precautions | Severe hypersensitivity reactions including anaphylaxis; pseudomembranous colitis; superinfection; caution in renal impairment; risk of neurotoxicity with high doses. |
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| Fetal Monitoring | Monitor for signs of hypersensitivity reactions (rash, urticaria, anaphylaxis) in mother. No specific fetal monitoring required. Observe for maternal gastrointestinal effects (nausea, diarrhea). Prolonged use may lead to bacterial or fungal superinfection. No routine laboratory monitoring necessary. |
| Fertility Effects | No known adverse effects on fertility. Animal studies have not shown impaired fertility. No human data available. |