Cefmenoxime

Cefmenoxime is an aminothiazolyl cephalosporin administered intravenously or intramuscularly. Like other 'third-generation' cephalosporins it is active in vitro against most common Gram-positive and Gram-negative pathogens, is a potent inhibitor of Enterobacteriaceae (including beta-lactamase-producing strains), and is resistant to hydrolysis by beta-lactamases. Cefmenoxime has a high rate of clinical efficacy in many types of infection and is at least equal in clinical and bacteriological efficacy to several other cephalosporins in urinary tract infections, respiratory tract infections, postoperative infections and gonorrhoea. Cefmenoxime, like latamoxef, cefoperazone and cefamandole, has an N-methyltetrazole side chain at the 3-position of the cephalosporin nucleus and thus possesses the potential for producing hypoprothrombinaemic bleeding and disulfiram-like reactions. However, these reactions have been reported very rarely and the antibacterial is generally well tolerated. It is likely that cefmenoxime will most closely resemble cefotaxime and ceftizoxime in therapeutic profile and usefulness.

Cefmenoxime was evaluated in an open trial consisting of 41 patients. Forty infections in 36 patients could be evaluated. Thirteen patients had pyelonephritis due to Escherichia coli (two bacteremic), Pseudomonas aeruginosa, Klebsiella pneumoniae, or Streptococcus faecalis; all improved and 12 of 13 were clinically cured, but one relapse (S. faecalis) occurred at two weeks. Six patients with cystitis due to E. coli, Citrobacter freundii, Serratia marcescens, P. aeruginosa, or S. faecalis all improved, but relapse or reinfection, or both, occurred in five due to P. aeruginosa, S. faecalis, C. fruendii, or E. coli. Neurogenic bladder or other complications were present in five of 13 patients with pyelonephritis and five of six with cystitis. Ten patients with pneumonia and one with tracheobronchitis due to Hemophilus influenzae, S. pneumoniae, S. agalactiae, or Neisseria meningitidis all improved and seven had resolution without relapse, but P. aeruginosa emerged in two patients, one of whom died. Eight soft tissue infections due to Staphylococcus aureus, Peptococcus prevotti, Streptococcus species, or infections of mixed origin resolved in six. Sterility of blood cultures was obtained in one patient with endocarditis due to S. anginosus, but other therapy was substituted. Clinical resolution of the toxic shock syndrome and subsequent negative endocervical cultures for S. aureus occurred in one. Granulocytopenia of unverified cause in four (with less than 1,500 mm3) and two (with less than 2,000 mm3) was reversible. Headache during treatment occurred in six patients and a possible disulfiram-like effect in three. Elevations of serum glutamic oxalacetic transaminase and alkaline phosphatase occurred in five, Coombs' positivity in two, and diarrhea in three. Clinical efficacy of cefmenoxime was significant. Possible side effects require further study.

Certain drugs are known to compete with bilirubin for albumin binding; therefore, all drugs administered to neonates should be tested to determine the degree of competition. The effect of cefmenoxime on bilirubin-albumin binding was determined by comparing the oxidation rate of free bilirubin in the presence and absence of drug. The reserve albumin concentration (RAC) of pooled cord serum was also measured using the MADDS dialysis rate method. We show that cefmenoxime competes with bilirubin for albumin binding with a displacement constant, of 3.1 x 10(3) l/mol. The maximal displacement factor (MDF) is used to determine the clinical effect of the drug at usual serum concentrations. The MDF for cefmenoxime is 1.10, representing approximately a 10% increase in free bilirubin concentration. In comparison, the MDF for a known bilirubin displacing drug, sulfisoxazole, is 2.43. The MADDS method showed an estimated 28% decrease in the RAC at 150 mumol/l, the mean peak serum concentration (MPSC) of cefmenoxime. These results show while cefmenoxime affects bilirubin-albumin binding, the degree of the effect is relatively small. However, cefmenoxime may pose a hazard to very sick, premature infants, especially if the infant is jaundiced.