Title: Carbenicillin
CAS Registry Number: 4697-36-3
CAS Name: (2S,5R,6R)-6-[(Carboxyphenylacetyl)amino]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid
Additional Names: N-(2-carboxy-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]hept-6-yl)-2-phenylmalonamic acid; a-carboxybenzylpenicillin; 6-(a-carboxyphenylacetamido)penicillanic acid; a-phenyl(carboxymethylpenicillin)
Molecular Formula: C17H18N2O6S
Molecular Weight: 378.40
Percent Composition: C 53.96%, H 4.79%, N 7.40%, O 25.37%, S 8.47%
Literature References: Semi-synthetic antibiotic related to penicillin. Prepn of monopotassium salt: Hobbs, US 3142673 (1964 to Pfizer); of disodium salt: BE 646991; Brain, Nayler, US 3282926 (1964, 1966 both to Beecham). Activity studies and pharmacology: Naumann, Kempf, Arzneim.-Forsch. 19, 1222 (1969). Chemistry and mode of action: Butler et al., J. Infect. Dis. 122, Suppl., 81 (1970). Clinical data: Hoffler et al., ibid. 1233; Gritz, Naumann, ibid. 1237. Toxicity data: E. I. Goldenthal, Toxicol. Appl. Pharmacol. 18, 185 (1971).
Derivative Type: Disodium salt
CAS Registry Number: 4800-94-6
Additional Names: Carbenicillin disodium
Manufacturers' Codes: BRL-2064; CP-15639-2
Trademarks: Carbapen (Commonwealth); Carbecin (Sanfer); Geopen (Roerig); Hyoper (Bordet); Microcillin (Bayer); Pyocianil (Farmitalia); Pyopen (SKB)
Molecular Formula: C17H16N2Na2O6S
Molecular Weight: 422.36
Percent Composition: C 48.34%, H 3.82%, N 6.63%, Na 10.89%, O 22.73%, S 7.59%
Properties: White powder. LD50 i.p. in rats: >2000 mg/kg (Goldenthal).
Toxicity data: LD50 i.p. in rats: >2000 mg/kg (Goldenthal)
Derivative Type: Phenyl sodium
CAS Registry Number: 21649-57-0
Additional Names: Carfecillin sodium
Manufacturers' Codes: BRL-3475
Trademarks: Gripenin-O (Fujisawa); Urocarf (SPA)
Molecular Formula: C23H21N2NaO6S
Molecular Weight: 476.48
Percent Composition: C 57.98%, H 4.44%, N 5.88%, Na 4.82%, O 20.15%, S 6.73%
Literature References: Prepn and activity studies: Clayton et al., J. Med. Chem. 18, 172 (1975).
Properties: Crystals from ethanol, [a]D20 +216.2° (H2O).
Optical Rotation: [a]D20 +216.2° (H2O)
Therap-Cat: Antibacterial.
Keywords: Antibacterial (Antibiotics); ?Lactams; Penicillins.
Carbenoxolone Carbetapentane Carbetocin Carbic Anhydride Carbimazole

Systematic (IUPAC) name
heptane-2-carboxylic acid
Clinical data
Trade names Geocillin
AHFS/ monograph
Pregnancy cat. B (US) Passes into breast milk
Legal status -only (US)
Routes Oral, parenteral
Pharmacokinetic data
Bioavailability 30 to 40%
Protein binding 30 to 60%
Metabolism Minimal
Half-life 1 hour
Excretion Renal (30 to 40%)
CAS number 4697-36-3 YesY
ATC code J01CA03
PubChem CID 20824
DrugBank DB00578
ChemSpider 19599 YesY
Chemical data
Formula C17H18N2O6S 
Mol. mass 378.401 g/mol
 YesY (what is this?)  (verify)

Carbenicillin is a bacteriolytic antibiotic belonging to the carboxypenicillin subgroup of the penicillins. It was discovered by scientists at Beecham and marketed as Pyopen. It has Gram-negative coverage which includes Pseudomonas aeruginosa but limited Gram-positive coverage. The carboxypenicillins are susceptible to degradation by beta-lactamase enzymes, although they are more resistant than ampicillin to degradation. Carbenicillin is also more stable at lower pH than ampicillin.