GEOPEN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for GEOPEN (GEOPEN).
Carbenicillin is a bactericidal penicillin antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), leading to cell lysis and death. It has activity against Gram-negative and some Gram-positive bacteria.
| Metabolism | Carbenicillin is primarily eliminated unchanged by the kidneys via glomerular filtration and tubular secretion. Minimal hepatic metabolism occurs, forming inactive metabolites. |
| Excretion | Renal: 80-90% unchanged via glomerular filtration and tubular secretion. Biliary/fecal: <2%. |
| Half-life | Terminal half-life 4-6 hours in normal renal function; prolonged to 10-20 hours in moderate renal impairment (CrCl 10-50 mL/min) and up to 30-50 hours in severe impairment (CrCl <10 mL/min). |
| Protein binding | 50-60% bound to serum albumin. |
| Volume of Distribution | 0.18 L/kg, approximating extracellular fluid volume. |
| Bioavailability | Oral: not absorbed; IM: ~70% relative to IV. |
| Onset of Action | IV: immediate; IM: peak serum levels within 30 minutes. |
| Duration of Action | 6-8 hours for susceptible organisms; prolonged in renal impairment. |
| Molecular Weight | 520.6 |
2 g intravenously every 6 hours for susceptible infections.
| Dosage form | INJECTABLE |
| Renal impairment | CrCl 30-50 mL/min: 2 g every 8 hours; CrCl 10-29 mL/min: 2 g every 12 hours; CrCl <10 mL/min: 1 g every 12 hours. |
| Liver impairment | No specific dose adjustment required; use standard dosing. |
| Pediatric use | 50-100 mg/kg/day intravenously divided every 6 hours; maximum 2 g per dose. |
| Geriatric use | Initiate at lower end of dosing range; monitor renal function and adjust based on CrCl. |
| 1st trimester | Avoid unless essential; limited human data, animal studies show no significant risk. |
| 2nd trimester | Use only if clearly needed; crosses placenta, but no known teratogenicity. |
| 3rd trimester | Caution; possible kernicterus in neonates, especially with hyperbilirubinemia or prematurity. |
Clinical note
Comprehensive clinical and safety monograph for GEOPEN (GEOPEN).
| Placental transfer | Crosses placenta; achieves therapeutic concentrations in fetal serum and amniotic fluid. |
| Breastfeeding | Excreted in breast milk in low concentrations; risk of diarrhea, candidiasis, or allergic sensitization in infant. Use with caution. |
| Lactation Rating |
■ FDA Black Box Warning
Serious and occasionally fatal hypersensitivity reactions (anaphylaxis) have been reported in patients on penicillin therapy. Before initiating therapy, careful inquiry should be made concerning previous hypersensitivity reactions to penicillins, cephalosporins, or other allergens.
| Serious Effects |
Hypersensitivity to penicillinsAnaphylactic reaction to any beta-lactam
| Precautions | Hypersensitivity reactions (anaphylaxis, rash, fever), Clostridium difficile-associated diarrhea, Electrolyte disturbances (hypernatremia with disodium salt), Bleeding abnormalities due to platelet dysfunction, Neurologic toxicity (seizures) in patients with renal impairment, Superinfection with resistant organisms |
| Food/Dietary | No specific food interactions reported. However, due to sodium content, avoid high-sodium foods if salt intake is restricted. Maintain adequate hydration. No known interactions with caffeine or alcohol. |
Loading safety data…
| L2 (Probably Compatible) |
| Teratogenic Risk | GEOPEN (carbenicillin) is classified as FDA Pregnancy Category B. Animal studies have not demonstrated fetal risk, but no adequate human studies exist. First trimester: No evidence of teratogenicity. Second and third trimesters: No known fetal harm; however, use only if clearly needed. |
| Fetal Monitoring | Monitor maternal renal function and complete blood counts periodically. For high-dose therapy, monitor serum electrolytes and bleeding times. No specific fetal monitoring required unless maternal infection warrants ultrasound or NST. |
| Fertility Effects | No known adverse effects on fertility in animal studies. Limited human data; unlikely to impair fertility. |
| Clinical Pearls | GEOPEN (carbenicillin disodium) is a carboxypenicillin antibiotic active against Pseudomonas aeruginosa and indole-positive Proteus species. It is typically administered intravenously, often in combination with an aminoglycoside for synergy. Due to high sodium content (4.7 mEq Na+ per gram), use with caution in patients with heart failure or hypertension. It is inactivated by beta-lactamases but retains activity against some gram-negative organisms. Dose adjustment required in renal impairment; monitor renal function regularly. |
| Patient Advice | Take this medication exactly as prescribed; it is usually given intravenously in a hospital setting. · Report any signs of allergic reaction (rash, itching, swelling, difficulty breathing) immediately. · Inform your doctor if you have a history of heart failure, hypertension, or kidney disease due to sodium content. · This medication may cause diarrhea; contact your doctor if severe or bloody diarrhea occurs. · If you are on a sodium-restricted diet, notify your healthcare provider as this drug contains significant sodium. |