PRINCIPEN '125'
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PRINCIPEN '125' (PRINCIPEN '125').
Ampicillin is a penicillin beta-lactam antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins, leading to cell lysis.
| Metabolism | Ampicillin is metabolized by hydrolysis to penicilloic acid, primarily in the liver. It also undergoes renal tubular secretion. |
| Excretion | Renal: approximately 60-80% of the dose excreted unchanged in urine via tubular secretion and glomerular filtration. Biliary/fecal: minimal, <10%. |
| Half-life | Terminal elimination half-life: 0.7-1.4 hours in adults with normal renal function. Prolonged in renal impairment (up to 7-10 hours in anuria). |
| Protein binding | Approximately 20-30% bound to serum proteins, primarily albumin. |
| Volume of Distribution | 0.3-0.4 L/kg, approximating extracellular fluid volume. Higher in neonates and critically ill patients due to increased extracellular water. |
| Bioavailability | Oral: 30-50% due to acid lability and incomplete absorption. IM: nearly 100%. |
| Onset of Action | Oral: 30-60 minutes after oral administration. IM: 15-30 minutes. Intravenous: immediate. |
| Duration of Action | 4-6 hours for susceptible organisms when administered every 6 hours. Clinical effect persists as long as serum levels exceed MIC. |
| Molecular Weight | 349.4 |
250-500 mg orally every 6 hours for mild to moderate infections; 500 mg to 1 g every 6 hours for severe infections.
| Dosage form | FOR SUSPENSION |
| Renal impairment | CrCl 10-50 mL/min: Administer every 6-12 hours. CrCl <10 mL/min: Administer every 12-16 hours. |
| Liver impairment | No dose adjustment required. |
| Pediatric use | Infants and children: 12.5-25 mg/kg orally every 6 hours. For severe infections: up to 50 mg/kg/day in divided doses every 6 hours. |
| Geriatric use | Dose based on renal function; use lower end of dosing interval due to age-related decline in renal function. |
| 1st trimester | Ampicillin crosses the placenta. Human data suggest low risk; however, avoid unnecessary use in first trimester if alternatives exist. Considered safe for use when clearly needed. |
| 2nd trimester | Safe to use; ampicillin is commonly used for infections during pregnancy with no known teratogenic risk. Dose adjustments may be needed due to increased renal clearance. |
| 3rd trimester | Safe; ampicillin is widely used for intrapartum prophylaxis against group B Streptococcus. Monitor for maternal diarrhea and potential neonatal sensitization. |
Clinical note
Comprehensive clinical and safety monograph for PRINCIPEN '125' (PRINCIPEN '125').
| Placental transfer | Ampicillin crosses the placenta readily; therapeutic concentrations are achieved in fetal serum and amniotic fluid. Peak fetal levels are approximately 50% of maternal serum levels. |
| Breastfeeding | Ampicillin is excreted into breast milk in low concentrations (less than 1% of maternal dose). Generally considered compatible with breastfeeding. Potential for disruption of infant's gastrointestinal flora or allergic reaction, but risk is low. Use with caution in infants with history of penicillin allergy. |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
Hypersensitivity to ampicillin or other penicillinsHypersensitivity to cephalosporins (rare cross-reactivity)
| Precautions | Serious and occasionally fatal hypersensitivity reactions (anaphylaxis) have occurred., Clostridium difficile-associated diarrhea (CDAD) reported with nearly all antibacterial agents., Prolonged use may result in overgrowth of nonsusceptible organisms including fungi., Dosage adjustment required in renal impairment., Safety in pregnancy: Category B; use only if clearly needed. |
| Food/Dietary | Take on an empty stomach. Food, especially acidic beverages or fruit juices, may reduce absorption. Avoid alcohol concurrently. No specific dietary restrictions. |
Loading safety data…
| Lactation Rating | L1 (Safe) |
| Teratogenic Risk | FDA Pregnancy Category B. No evidence of teratogenicity in animal studies. Inadequate human data in first trimester; risk cannot be excluded. Penicillins are generally considered low risk throughout pregnancy. |
| Fetal Monitoring | Monitor maternal renal function if high doses used. No specific fetal monitoring required unless allergic reaction occurs. |
| Fertility Effects | No known adverse effects on fertility. Animal studies show no impairment. |
| Clinical Pearls | Principen '125' (ampicillin) is a broad-spectrum penicillin. Note that it is inactivated by beta-lactamases; use with a beta-lactamase inhibitor for resistant organisms. Administer on an empty stomach (1 hour before or 2 hours after meals) for optimal absorption. Monitor for hypersensitivity reactions, especially rash; ampicillin rash is common in patients with Epstein-Barr virus or concurrent allopurinol use. Adjust dose in renal impairment (CrCl <30 mL/min). |
| Patient Advice | Take this medication on an empty stomach, at least 1 hour before or 2 hours after meals. · Complete the entire prescribed course even if you feel better. · Inform your doctor if you develop a rash, diarrhea, or signs of an allergic reaction. · Avoid alcohol while taking ampicillin to reduce side effects. · Use effective contraception if applicable; ampicillin may reduce oral contraceptive efficacy. |