OMNIPEN-N
Clinical safety rating: caution
Comprehensive clinical and safety monograph for OMNIPEN-N (OMNIPEN-N).
Omnipen-N (ampicillin sodium) is a beta-lactam antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), thereby interfering with transpeptidation and resulting in cell lysis.
| Metabolism | Ampicillin is primarily excreted unchanged by the kidneys via tubular secretion and glomerular filtration; minimal hepatic metabolism. |
| Excretion | Primarily renal (80-90% unchanged via tubular secretion); minor biliary/fecal (<10%). |
| Half-life | 30-60 minutes (normal renal function); prolonged to 7-10 hours in severe renal impairment (CrCl <10 mL/min). |
| Protein binding | Approximately 20-30% bound, primarily to serum albumin. |
| Volume of Distribution | 0.15-0.3 L/kg; reflects distribution primarily into extracellular fluid. |
| Bioavailability | Oral: 30-45% (incompletely absorbed, acid-labile); IM: ~100%. |
| Onset of Action | IV: Immediate; IM: 15-30 minutes; Oral: 60-90 minutes. |
| Duration of Action | IV/IM: 4-6 hours; Oral: 6-8 hours. Duration may be extended in renal impairment. |
250-500 mg orally every 6 hours for adults; for severe infections, up to 1 g every 6 hours.
| Dosage form | INJECTABLE |
| Renal impairment | CrCl >50 mL/min: No adjustment. CrCl 10-50 mL/min: Administer every 8-12 hours. CrCl <10 mL/min: Administer every 12-18 hours. |
| Liver impairment | No specific adjustment recommended for hepatic impairment; monitor liver function. |
| Pediatric use | Children >1 month: 50-100 mg/kg/day divided every 6 hours; maximum 4 g/day. Neonates <1 month: 50 mg/kg/day divided every 12 hours. |
| Geriatric use | Use lower end of dosing range; monitor renal function and adjust based on creatinine clearance. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for OMNIPEN-N (OMNIPEN-N).
| Breastfeeding | Ampicillin is excreted into breast milk in low concentrations (M/P ratio approximately 0.04–0.12). Sulbactam is also excreted in low levels. The American Academy of Pediatrics considers ampicillin compatible with breastfeeding. Potential risks: diarrhea, rash, or sensitization in the infant. Use with caution. |
| Teratogenic Risk | OMNIPEN-N (ampicillin/sulbactam) is classified as FDA Pregnancy Category B. Animal studies have not demonstrated fetal harm. No well-controlled human studies exist; however, ampicillin has been widely used in pregnancy with no documented teratogenicity. Sulbactam is not known to cause fetal harm. Theoretical risk of kernicterus in neonates if used near delivery due to bilirubin displacement by ampicillin. |
■ FDA Black Box Warning
No FDA black box warning is currently present for ampicillin, though serious and occasionally fatal hypersensitivity reactions (anaphylaxis) have been reported.
| Serious Effects |
["Hypersensitivity to ampicillin, other penicillins, or any component of the formulation","Infections caused by penicillinase-producing organisms (e.g., Staphylococcus aureus)"]
| Precautions | ["Hypersensitivity reactions including anaphylaxis","Clostridioides difficile-associated diarrhea (CDAD)","Superinfection with non-susceptible organisms","Renal impairment (dose adjustment required)","Prolonged therapy may lead to neutropenia, thrombocytopenia, or other blood dyscrasias"] |
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| Fetal Monitoring | Monitor for signs of maternal hypersensitivity reactions, including rash, urticaria, anaphylaxis. Monitor renal function, hepatic function, and CBC if prolonged therapy. Fetal monitoring not required routinely; consider fetal heart rate monitoring if maternal sepsis or significant adverse reaction occurs. |
| Fertility Effects | No known adverse effects on fertility in humans. Animal studies have not reported impairment of fertility. Antibiotic effects on gut flora may transiently alter menstrual regularity but no evidence of fertility impairment. |