PRINCIPEN '250'
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PRINCIPEN '250' (PRINCIPEN '250').
Ampicillin is a beta-lactam antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), leading to cell lysis and death.
| Metabolism | Ampicillin is primarily excreted unchanged by the kidneys via glomerular filtration and tubular secretion. Some hepatic metabolism occurs, but it is minimal. |
| Excretion | Primarily renal (60-80% unchanged), with some biliary/fecal excretion (approximately 10-20%) |
| Half-life | 1.0-1.5 hours in normal renal function; prolongation in renal impairment requires dose adjustment |
| Protein binding | 20-25% bound to serum albumin |
| Volume of Distribution | 0.2-0.3 L/kg, indicating limited extravascular distribution |
| Bioavailability | Oral: 25-40% (acid-labile, food reduces absorption) |
| Onset of Action | Oral: 30-60 minutes; IM: 15-30 minutes |
| Duration of Action | 4-6 hours; shorter in severe renal impairment |
| Molecular Weight | 334.39 |
250 mg orally every 6 hours
| Dosage form | CAPSULE |
| Renal impairment | CrCl 10-50 mL/min: 250 mg every 12-24 hours; CrCl <10 mL/min: 250 mg every 24-48 hours |
| Liver impairment | No dosage adjustment required for mild to moderate hepatic impairment. Severe impairment (Child-Pugh C): reduce dose by 50% or extend interval to every 12 hours |
| Pediatric use | Children >1 month: 12.5-25 mg/kg orally every 6 hours; maximum 4 g/day |
| Geriatric use | Monitor renal function; adjust dose based on CrCl as for adults with renal impairment. Avoid in elderly with CrCl <10 mL/min unless necessary. |
| 1st trimester | Use only if clearly needed; crosses placenta; no well-controlled studies; potential risk cannot be ruled out. |
| 2nd trimester | Generally considered safe; animal studies have not shown fetal harm; limited human data. |
| 3rd trimester | Generally considered safe; crosses placenta; no known fetal adverse effects. |
Clinical note
Comprehensive clinical and safety monograph for PRINCIPEN '250' (PRINCIPEN '250').
| Placental transfer | Crosses placenta; achieves therapeutic concentrations in fetal serum. |
| Breastfeeding | Excreted into breast milk in trace amounts; unlikely to cause adverse effects in nursing infants; may alter infant gut flora. |
| Lactation Rating |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
Hypersensitivity to ampicillin or any penicillinInfections caused by penicillinase-producing organisms
| Precautions | Serious and occasionally fatal hypersensitivity reactions (anaphylaxis) have been reported; contraindicated in patients with penicillin allergy., Clostridium difficile-associated diarrhea (CDAD) can occur and may range in severity from mild diarrhea to fatal colitis., Prolonged use may result in overgrowth of nonsusceptible organisms, including fungi; superinfection may occur., Use with caution in patients with renal impairment; dosage adjustment may be necessary., Cases of drug-induced hepatitis and cholestatic jaundice have been reported. |
| Food/Dietary | Food significantly reduces ampicillin absorption. Avoid taking with meals, dairy products, or acidic beverages (e.g., orange juice). Metal ions (calcium, iron, zinc) and antacids chelate ampicillin, reducing bioavailability. Alcohol does not directly interact but may increase risk of gastrointestinal upset. |
Loading safety data…
| L1 (Safe) |
| Teratogenic Risk | FDA Pregnancy Category B. Animal studies show no fetal risk, but no adequate human studies in first trimester. No known teratogenicity; use during pregnancy only if clearly needed. |
| Fetal Monitoring | Monitor maternal renal function, liver function, and CBC periodically during prolonged therapy. In neonates, monitor for signs of hypersensitivity or diarrhea if maternal use near term. |
| Fertility Effects | No known adverse effects on fertility based on animal studies and clinical data. No evidence of impaired male or female fertility. |
| Clinical Pearls | Principen '250' (ampicillin) is a penicillinase-sensitive aminopenicillin with activity against Gram-positive cocci (except penicillinase-producing staphylococci) and some Gram-negative bacilli. Key pearls: (1) Administer on an empty stomach (1 hour before or 2 hours after meals) to enhance absorption; (2) Monitor for maculopapular rash, especially in patients with infectious mononucleosis or cytomegalovirus infection, where incidence approaches 70-100%; (3) Dose adjustment required in renal impairment (CrCl <30 mL/min); (4) Use caution in patients with history of hypersensitivity to penicillins or cephalosporins; (5) Not effective against penicillin-resistant Streptococcus pneumoniae; (6) Consider drug fever or serum sickness-like reactions as adverse effects. |
| Patient Advice | Take this medication exactly as prescribed, at evenly spaced times, and finish the full course even if you feel better. · Take on an empty stomach, at least 1 hour before or 2 hours after meals, with a full glass of water. · Do not take with antacids, laxatives, or fruit juices, as they may reduce absorption. · Contact your doctor immediately if you develop a skin rash, hives, difficulty breathing, or swelling of the face, lips, or tongue. · Diarrhea is common; do not treat with anti-diarrhea medications without consulting your doctor, as it may indicate a more serious condition. · Inform your doctor if you are pregnant, breastfeeding, or have a history of kidney disease, asthma, or allergic reactions to any antibiotic. · This drug may reduce the effectiveness of oral contraceptives; use an additional barrier method during treatment. |