Cefetamet pivoxil: a review of its microbiology, toxicology, pharmacokinetics and clinical efficacy

Abstract

Cefetamet pivoxil is an oral, third-generation cephalosporin whose broad spectrum of antibacterial activity and favorable pharmacokinetic profile make it particularly suitable for the treatment of a wide range of infectious diseases. Cefetamet has high in vitro activity against both gram-positive and gram-negative bacteria that cause a number of respiratory tract and urinary tract infections. These include penicillin-sensitive Streptococcus pneumoniae, Streptococcus spp, Haemophilus influenzae, Moraxella catarrhalis, Escherichia coli, Proteus spp., Klebsiella spp. and Neisseria gonorrhoeae. It is not active against staphylococci, enterococci, Pseudomonas spp. or Bacteroides fragilis but does inhibit most bile-sensitive (oral) Bacteroides spp. Animal toxicology studies indicate that neither cefetamet pivoxil nor the active compound cefetamet have significant teratogenic, mutagenic, photogenic or allergenic potential. Cefetamet is eliminated unchanged in the urine with a half-life of 2.2 h. Volume of distribution approximates the extracellular fluid space (0.3 1/kg), protein binding is minima (22%) and oral bioavailability of cefetamet pivoxil is approximately 50% when taken with food. No significant drug interactions have been noted to date. The efficacy and tolerability of cefetamet pivoxil have been evaluated in the treatment of gram-positive and gram-negative infections in almost 5,000 patients. In comparative studies, cefetamet pivoxil was at least as effective, and in many cases clinically superior, to most currently recommended antibiotics for the treatment of urinary tract infections including gonorrhea and complicated infections in high risk patients. Efficacy has also been demonstrated in acute exacerbations of chronic bronchitis, pneumonia and infections of the ear, nose and throat. Clinical trials have shown that a 7 day treatment period with cefetamet pivoxil is as effective as a 10 day course of phenoxymethylpenicillin in the treatment of pharyngotonsillitis. Cefetamet pivoxil has been well-tolerated in clinical trials with only 1.2% of patients on standard doses discontinuing therapy prematurely. The most common adverse effects are gastrointestinal (diarrhea, nausea, vomiting) which occur in less than 10% of patients. Many current antibiotic treatment regimens involve the administration of three or more daily doses. However, standard doses of cefetamet pivoxil 500 mg twice daily provide unbound plasma concentrations of cefetamet which generally exceed the MIC 90 for susceptible organisms throughout the dosing interval and have been demonstrated to be clinically effective. This should result in good compliance with therapy in out-patients. Dosing regimens for cefetamet pivoxil should be adjusted in patients with impaired renal function while standard doses can be given to elderly patients and those with liver disease. Standard doses in children are 10 mg/kg or alternatively, children may receive a dose reduced in proportion to the ratio of their body surface area to that of an adult.