GEOPEN

Clinical safety rating: caution

Comprehensive clinical and safety monograph for GEOPEN (GEOPEN).

How it works

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.

What the body does with it

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.

Classification & Brands

Dosing & administration

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.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for GEOPEN (GEOPEN).

Breastfeeding	Carbenicillin is excreted in human milk in low concentrations. The M/P ratio is approximately 0.02. Considered compatible with breastfeeding; however, monitor infant for potential gastrointestinal disturbances or allergic reactions.
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.

Warnings & precautions

■ 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.

Side Effect Profile

Serious Effects

Absolute Contraindications

["Hypersensitivity to penicillins or any component of the formulation","History of immediate-type hypersensitivity reactions (e.g., anaphylaxis, urticaria) to other beta-lactam antibiotics (e.g., cephalosporins)"]

Clinical Precautions

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"]

Clinical Tips & Counseling

Drug interactions

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GEOPEN

Clinical safety rating: caution

Comprehensive clinical and safety monograph for GEOPEN (GEOPEN).

How it works

What the body does with it

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.

Classification & Brands

Dosing & administration

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.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for GEOPEN (GEOPEN).

Breastfeeding	Carbenicillin is excreted in human milk in low concentrations. The M/P ratio is approximately 0.02. Considered compatible with breastfeeding; however, monitor infant for potential gastrointestinal disturbances or allergic reactions.
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.