Ceftibuten

Manufacturing Process

The 1st method of synthesisThe 8-oxo-7-phenylacetylamino-5-thia-1-aza-bicyclo[4.2.0]oct-1-ene-2- carboxylic acid benzhydryl ester is reacted with phosphorus pentachloride/pyridine reagent in methylene dichloride, and the reaction mixture is thereafter cooled to -35°C and treated with methanol to produce hydrochloride of 7-amino-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2- carboxylic acid benzhydryl ester. This hydrochloride is reacted with 4-(3- aminothiophen-2-yl)-5-oxohex-3-enoic acid 3-methylbut-2-enyl ester. Then 7- [2-(2-benzoylamino-thiazol-5-yl)(3-tert-butyl-4,4-dimethylpent-2- enoxycarbonyl)-pent-2-enoylamino]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2- ene-2-carboxylic acid synthesized is reacted with aluminum chloride in anisole and diluted hydrochloric acid and then with dimethylmalonate to give 5-thia- 1-azabicyclo(4.2.0)oct-2-ene-2-carboxylic acid, 7-(((2Z)-2-(2-amino-4- thiazolyl)-4-carboxy-1-oxo-2-butenyl)amino)-8-oxo-, (6R,7R)- (Ceftibuten).The 2st method of synthesisFormulation of the diphenylmethyl thiazoleacetate with ethyl formate leads to 2-(2-aminothiazol-5-yl)-3-hydroxyacrylic acid benzhydryl ester. Condensation of 2-(2-aminothiazol-5-yl)-3-hydroxyacrylic acid benzhydryl ester with the phosphorane from benzyl 2-triphenylphosphonium acetate leads to the 2-(2- aminothiazol-5-ylmethylene)succinic acid 1-benzhydryl ester 4-benzyl ester. Exposure of this ester to trifluoroacetic acid selectively cleaves the diphenylmethyl group over the benzyl ester to give 2-(2-aminothiazol-5- ylmethylene)succinic acid 4-benzyl ester. Condensation of the acid with free amino group in the desmethyl cephalosporin affords the amide of 7-[3-(2- aminothiazol-5-yl)-2-benzoylcarbonylmethylacryloylamino)-8-oxo-5-thia-1- azabicyclo[4.2.1]oct-2-ene-2-carboxylic acid benzyl ester. The remaining benzyl ester protecting groups are removed by means of aluminum chloride to afford 7-[3-(2-aminothiazol-5-yl)-2-benzoylcarbonylmethylacryloylamino)-8- oxo-5-thia-1-azabicyclo[4.2.1]oct-2-ene-2-carboxylic acid or ceftibuten

Antimicrobial activity

A semisynthetic cephalosporin formulated as the dihydrate for oral administration. It exhibits good activity against many Gram-negative bacilli, but its activity against Gram-positive cocci is very poor. It is stable to hydrolysis by the common plasmid-mediated β-lactamases, but not derepressed chromosomal enzymes . It is rapidly and almost completely absorbed by mouth and is excreted in the urine with a half-life of 1.5–3 h. An oral dose of 400 mg achieves a peak plasma concentration of around 15 mg/L. Binding to plasma proteins is 65–77%. Side effects mostly consist of mild gastrointestinal symptoms and mild liver function test changes. Clinical trials have mainly been conducted in urinary tract and respiratory tract infections which, despite the poor in-vitro activity against Str. pneumoniae, have shown ceftibuten to be as efficacious as comparator agents.

Biochem/physiol Actions

Ceftibuten is a third generation cephalosporin antibiotic

Pharmacokinetics

Ceftibuten is highly (75–90%) absorbed on oral administration, but this is decreased significantly by food. Being lipophilic and acidic, it is significantly (65%) serum protein bound. Some isomerization of the geometry of the olefinic linkage appears to take place in vivo before excretion.

Definition

ChEBI: A third-generation cephalosporin antibiotic with a [(2Z)-2-(2-amino-1,3-thiazol-4-yl)-4-carboxybut-2-enoyl]amino substituent at the 7 position of the cephem skeleton. An orally-administered agent, ceftibuten is used as the dihydrate to tre t urinary-tract and respiratory-tract infections.

Brand name

Cedax (Schering);Seftem.