In vitro activity of Ro 15-8074, a new oral cephalosporin, against Neisseria gonorrhoeae

Cefetamet pivoxil clinical pharmacokinetics

Cefetamet pivoxil is an orally absorbed prodrug ester of the microbiologically active cephalosporin, cefetamet. The prodrug ester is completely hydrolysed to the active compound cefetamet on its first pass through the gut wall, the liver or both. Cefetamet is classified as a third generation cephalosporin with excellent activity against streptococci, Enterobacteriaceae, Neisseria and Haemophilus species. It has enhanced stability against beta-lactamases compared with penicillins and first and second generation cephalosporins. The antibacterial spectrum is comparable with that of cefotaxime except for its poor activity against staphylococci. Following a 20-minute zero-order intravenous infusion, cefetamet had a rapid distribution phase followed by a monoexponential decline. The average pharmacokinetic parameters from 152 healthy volunteers were: total body clearance 136 ml/min (8.16 L/h); renal clearance 119 ml/min (7.14 L/h); nonrenal clearance 17 ml/min (1.02 L/h); volume of distribution at steady-state 0.29 L/kg; terminal elimination half-life 2.2 hours; 88% of the dose recovered in the urine. Cefetamet is not extensively bound to plasma proteins. Consequently, these data indicate that cefetamet is predominantly eliminated unchanged by the kidney via glomerular filtration with possibly a minor component of tubular secretion. Cefetamet has a relatively small apparent volume of distribution consistent with that of other beta-lactam antibiotics. Results following ascending intravenous doses of cefetamet in healthy young male volunteers demonstrated that the pharmacokinetics of intravenous cefetamet are independent of the dose. The absolute bioavailability of cefetamet tablets following oral cefetamet pivoxil administration is enhanced by the presence of food. Under fed conditions, 50 to 60% of the final oral dose is absorbed into the systemic circulation. This food effect is observed when cefetamet pivoxil is administered within 1 hour of a meal. Food also produces a slight delay in the time to reach peak plasma concentrations of this drug. Changes in fluid volume intake with cefetamet pivoxil administration have no effect on the bioavailability of this drug. Similar absorption characteristics have been observed for all of the tablet dosage formulations studied during clinical development. The absolute bioavailability of the final syrup dosage formulation was between 38 and 47%. Little improvement in the bioavailability of this preparation has been observed with food. The absorption and disposition of cefetamet in human subpopulations [i.e. children, elderly (< 75 years of age), renal impairment, liver disease and patients taking concomitant drugs] have been studied extensively. Only impaired renal function appears to significantly alter the elimination of this drug.(ABSTRACT TRUNCATED AT 400 WORDS)

Cefetamet pivoxil. A review of its antibacterial activity, pharmacokinetic properties and therapeutic use

Cefetamet pivoxil is an oral third-generation cephalosporin which is hydrolysed to form the active agent, cefetamet. Cefetamet has excellent in vitro activity against the major respiratory pathogens Streptococcus pneumoniae, Haemophilus influenzae, Moraxella (Branhamella) catarrhalis and group A beta-haemolytic streptococci; it is active against beta-lactamase-producing strains of H. influenzae and M. catarrhalis, but has poor activity against penicillin-resistant S. pneumoniae. Cefetamet has marked activity against Neisseria gonorrhoeae and possesses a broad spectrum of activity against Enterobacteriaceae. Both staphylococci and Pseudomonas spp. are resistant to cefetamet. Cefetamet pivoxil has been investigated in the treatment of both upper and lower community-acquired respiratory tract infections and has demonstrated equivalent efficacy to a number of more established agents, namely cefaclor, amoxicillin and cefixime. In patients with group A beta-haemolytic streptococcal pharyngotonsillitis, a 7-day course of cefetamet pivoxil was as effective as a 10-day course of the standard agent, phenoxymethylpenicillin, in this indication. In complicated urinary tract infections, cefetamet pivoxil showed similar efficacy to cefadroxil, cefaclor and cefuroxime axetil. Cefetamet pivoxil was effective in the treatment of otitis media, pneumonia, pharyngotonsillitis and urinary tract infections in children. Preliminary data indicate that single dose cefetamet pivoxil can effectively eradicate N. gonorrhoeae from both men and women. Cefetamet pivoxil has a tolerability profile similar to that of other oral cephalosporins, with gastrointestinal effects being the most commonly reported adverse events. To date, no symptoms of carnitine deficiency have been reported with cefetamet pivoxil. Cefetamet pivoxil offers effective alternative oral therapy for outpatient treatment of community-acquired respiratory tract infections, with the advantage of improved activity against H. influenzae and increased beta-lactamase stability. However, its use in areas with a high incidence of penicillin-resistant S. pneumoniae is likely to be limited. Cefetamet pivoxil is also effective in the treatment of urinary tract infections, although further trials are required to define any comparative advantages over other oral agents.

Comparative in vitro activity of the two new oral cephalosporin metabolites RO 19-5247 and RO 15-8074

A total of 629 clinical strains of gram positive and gram negative bacteria were tested for their susceptibility to RO 19-5247, RO 15-8074, and other antimicrobial agents. Both RO 19-5247 and RO 15-8074 had good activity against strains of Enterobacteriaceae; however, resistance was found among some strains of Enterobacter, Citrobacter, Klebsiella and Morganella spp. Both compounds showed moderate to poor active against Acinetobacter spp., Pseudomonas aeruginosa, staphylococci and Streptococcus faecalis. Against strains of Haemophilus influenzae, Neisseria gonorrhoeae, Gardnerella vaginalis, Streptococcus pneumoniae and streptococci (not enterococci), each compound was highly active in vitro. RO 19-5247 and RO 15-8074 had comparable activity to cotrimoxazole, ceftazidime and ceftizoxime. Each new compound had considerably better activity then did cefaclor and amoxicillin/potassium clavulanate.

Preliminary antimicrobial susceptibility interpretive criteria for cefetamet (Ro 15-8074) and cefteram (Ro 19-5247) disk tests

Preliminary interpretive zone criteria were calculated for cefetamet (Ro 15-8074) and cefteram (Ro 19-5247) by using 10- and 30-micrograms disks and three possible MIC susceptibility breakpoints. Absolute interpretive agreement between MICs and zone size criteria ranged from 91.8 to 97.2%. Very major errors (false susceptibility) were less than or equal to 1.2% for both cephalosporin disk tests. Morganella morganii strains appeared to produce the highest rates of very major interpretive errors with cefetamet disks.

In vitro activity of ceftriaxone, cefetamet (Ro 15-8074), ceftetrame (Ro 19-5247; T-2588), and fleroxacin (Ro 23-6240; AM-833) versus Neisseria gonorrhoeae and Haemophilus ducreyi

We examined 300 strains of Neisseria gonorrhoeae and 100 strains of Haemophilus ducreyi to determine their in vitro susceptibility to two new cephalosporins, cefetamet (Ro 15-8074) and ceftetrame (Ro 19-5247; T-2588), and a new fluroquinolone, fleroxacin (Ro 23-6240; AM-833). Their activity was compared with that of ceftriaxone, penicillin, spectinomycin, tetracycline, and erythromycin. Cefetamet, ceftetrame, and fleroxacin had excellent in vitro activity against both groups of microorganisms. beta-Lactamase production did not significantly affect the MICs of these agents. The Mtr phenotype of N. gonorrhoeae raised the MICs two- to fourfold, but the MICs remained within the range of achievable levels in serum. These newer compounds have a distinct advantage over existing therapeutic agents in that they can be administered orally. Clinical trials are warranted to assess their usefulness in the therapy of gonorrhea and chancroid.

In vitro activity of Ro 15-8074 and Ro 19-5247 in comparison to cefaclor and cefalexin

805 clinical isolates were investigated for their in vitro sensitivity against Ro 15-8074 and Ro 19-5247 in comparison to cefaclor and cefalexin in a serial dilution test on solid medium. Ro 19-5247 had the strongest activity of all drugs tested against streptococci (except Streptococcus faecalis) and was as active as cefaclor and cefalexin against most strains of Staphylococcus aureus. Ro 19-5247 was the only oral cephalosporin active against Bordetella pertussis. It was on average 160 times more active than cefaclor against Haemophilus influenzae. In its activity against enterobacteria Ro 19-5247 was always superior to cefaclor and cefalexin. Only a few strains of Enterobacter aerogenes, Enterobacter cloacae, Klebsiella pneumoniae, Proteus vulgaris and Serratia marcescens were resistant to Ro 19-5247 as were all strains of Enterobacter agglomerans and Klebsiella ozaenae. Ro 15-8074 was inactive against staphylococci but ten times more active than cefaclor and cefalexin against Streptococcus pyogenes. There was no difference in the activity against Streptococcus pneumoniae and Streptococcus agalactiae. Against Haemophilus influenzae Ro 15-8074 acted 12 times stronger than cefaclor and 100 times stronger than cefalexin. The activity against enterobacteria corresponded to that of Ro 19-5247. Ro 15-8074 was also active against most strains of Enterobacter cloacae and Proteus vulgaris which were resistant to cefaclor and cefalexin.

In vitro activity of Ro 15-8074, Ro 19-5247, A-56268, and roxithromycin (RU 28965) against Neisseria gonorrhoeae and Chlamydia trachomatis

In vitro Ro 15-8074 and Ro 19-5247 (T2525), two new oral cephalosporins, were active against 410 penicillin-susceptible and -resistant isolates of Neisseria gonorrhoeae. Two new macrolides, A-56268 and to a lesser extent roxithromycin (RU 28965), were active against Chlamydia trachomatis. A-56268 had activity against N. gonorrhoeae similar to that of erythromycin.

Antimicrobial activity of Ro 15-8074, active metabolite of a new oral cephalosporin (Ro 15-8075), against 7,775 recent clinical isolates

Susceptibility testing of 7,775 recent clinical isolates from four medical centers showed Ro 15-8074 to be 2-to greater than 8-fold more active than either cefaclor or cefuroxime against the Enterobacteriaceae. Ro 15-8074 MICs for 50% of the strains tested were greater than or equal to 32 micrograms/ml for Staphylococcus spp., enterococci, Pseudomonas aeruginosa, and Pseudomonas maltophilia. beta-Lactamase hydrolysis experiments failed to demonstrate significant Ro 15-8074 inactivation by commonly encountered chromosomal or plasmid-mediated enzymes (P99, K1, K14, TEM, and CARB).

In vitro activity and beta-lactamase stability of two oral cephalosporins, ceftetrame (Ro 19-5247) and cefetamet (Ro 15-8074)

Ceftetrame (Ro 19-5247) and cefetamet (Ro 15-8074), two new orally administered aminothiazolyl imimomethoxy cephalosporins, inhibited hemolytic streptococci and Streptococcus pneumoniae at less than or equal to 0.5 micrograms/ml but were less active against staphylococci than were cephalexin and cefaclor. They did not inhibit S. faecalis, S. faecium, Listeria monocytogenes, Corynebacterium JK species, or Pseudomonas aeruginosa. Haemophilus influenzae, Branhamella catarrhalis, and Neisseria gonorrhoeae, including ampicillin-resistant isolates, were inhibited at less than 0.25 micrograms/ml. Both agents inhibited Escherichia coli, Klebsiella pneumoniae, K. oxytoca, Proteus mirabilis, Salmonella species, Shigella species, Citrobacter diversus, and Aeromonas hydrophila resistant to ampicillin, cephalexin, and cefaclor at less than or equal to 2 micrograms/ml, although many isolates of Enterobacter cloacae, Citrobacter freundii, and Serratia marcescens resistant to cefotaxime were not inhibited by these agents. A marked inoculum effect was noted for Enterobacteriaceae carrying the Richmond-Sykes type 1A chromosomally mediated beta-lactamases, but plasmid-mediated beta-lactamases did not hydrolyze the compounds. Both drugs inhibited the chromosomally mediated beta-lactamase of E. cloacae, P99.

In vitro activity of Ro 15-8074 and Ro 19-5247, two orally administered cephalosporin metabolites

The activity of two iminomethoxy aminothiazoly cephalosporins, Ro 15-8074 and Ro 19-5247, was compared with that of other beta-lactams against a total of 491 bacterial strains. Both were highly active (MIC for 90% of the strains tested [MIC 90], less than or equal to 2 micrograms/ml) against the majority of the members of the family Enterobacteriaceae, Haemophilus influenzae, Neisseria spp., and Streptococcus pneumoniae, being at least 16-fold more active than cephalexin and 8-fold more active than cefuroxime. There was no activity against Pseudomonas aeruginosa and poor activity against Morganella morganii (in the case of Ro 15-8074), Enterobacter sp., and Citrobacter sp. Staphylococcus aureus was moderately susceptible to Ro 19-5247 (MIC90, 8 micrograms/ml), but Ro 15-8074 was eightfold less active. The protein binding of the two compounds at 5 micrograms/ml was 9.1% for Ro 15-8074 and 69.9% for Ro 19-5247. The major target site for the two cephalosporins was PBP 3.

Antimicrobial spectrum of Ro 15-8074/001, a new oral cephalosporin

The activity of Ro 15-8074/001 was compared with that of cefaclor, amoxicillin-clavulanic acid, trimethoprim-sulfamethoxazole, norfloxacin, and ceftriaxone against 225 clinical isolates. It was more active than cefaclor, amoxicillin-clavulanic acid, and trimethoprim-sulfamethoxazole against members of the family Enterobacteriaceae and Haemophilus influenzae and had activity similar to that of cefaclor against nonenterococcal streptococci. It was not usefully active against Pseudomonas aeruginosa, Streptococcus faecalis, or most isolates of staphylococci.