[Synthesis of cefatrizine by recombinant alpha-amino acid ester hydrolase].

To explore the enzymatic route of cefatrizine synthesis, alpha-amino acid ester hydrolase (AEH) gene was cloned from the whole genome of Xanthomonas rubrillineans, and expressed heterologously in Escherichia coli BL21 (DE3). The effects of temperature, pH and substrates' molar ratio upon the transformation yield of cefatrizine by purified recombinant AEH were investigated. The monomer of AEH was determined as 70 kDa by SDS-PAGE. The optimal pH and temperature reaction were (6.0 +/- 0.1) and 36 degrees C for cefatrizine synthesis. The transformation yield was 64.3% under 36 degrees C, pH (6.0 +/- 0.1), when the concentrations of two substrates were about 30 mmol/L (7-ATTC) and 120 mmol/L (HPGM x HCl), respectively, and the enzyme consumption was 22 U/mL. The results pave the way for optimization of the industrial enzymatic synthesis of cefatrizine.

Dose dependency in the gastrointestinal absorption of cefatrizine: correlation between in vivo and in situ.

We evaluated the dose-dependent (saturable) gastrointestinal absorption of cefatrizine, an aminocephalosporin transported by peptide carriers, in rats by a physiological mechanism-based approach to clarify its absorption characteristics and to examine the in vitro (in situ)-in vivo correlation in intestinal transport. With an increase in oral dose (mumol/5 ml/kg) from 5 (low) to 50 (high), the intestinal absorption rate constant (ka), which was estimated by analysis of gastrointestinal disposition, decreased markedly, from 0.301 to 0.056 min-1. This decrease was ascribable to the saturability of intestinal membrane transport, of which the concentration dependency in the perfused intestine was similar in extent to the dose dependency in ka. However, the apparent absorption rate constant (ka'), which was estimated by analysis of plasma concentrations after oral administration, decreased only modestly from 0.037 to 0.023 min-1. This was associated with the result that, at the low dose, ka' was far smaller than ka and comparable with k(g) (gastric emptying rate constant), suggesting gastric emptying-limited absorption. At the high dose, where intestinal cefatrizine absorption was less efficient, ka' was closer to ka than k(g). It was also observed that the bioavailability was close to unity, independent of dose, suggesting that the intestinal transit time is long enough to achieve complete absorption, even at the high dose, where intestinal cefatrizine absorption is less efficient. Thus, it was found that the effect of saturability in the intestinal transport of cefatrizine is apparently attenuated in its overall gastrointestinal absorption because of the involvement of gastric emptying and intestinal transit time as additional physiological factors to define absorption. It was also found that a scaling factor is required to correlate the intestinal membrane transport between in vitro (in situ) and in vivo, though this remains to be verified to be utilized for developing oral drug delivery strategies and optimizing oral drug therapy.

Kinetics of cefatrizine penetration into gynaecological tissues after oral administration.

Twenty-four patients, hospitalized in order to undergo radical gynaecological surgery, were orally administered cefatrizine in a single dose of 1 g at different times before surgery. The tissue levels determined in the organs considered (uterus, ovary, tubae, vagina) proved that cefatrizine possesses good absorption in the genital tract, reaching concentrations near to the MICs of most gram-negative and gram-positive sensitive bacteria lasting even 12 h after administration.

Pharmacokinetics of cefatrizine after oral administration in human volunteers.

The oral bioavailability of cefatrizine was studied in four groups, each of ten healthy young male volunteers. Capsules and suspension formulations were each administered at doses of 250 and 500 mg. Both the capsules and suspensions had mean peak plasma levels at 1.6 h at both dose levels. Mean peak plasma levels were 4.1 and 4.3 micrograms/ml for the 250 mg capsule and suspension doses respectively and 7.1 and 7.5 micrograms/ml for the 500 mg capsules and suspension doses respectively. The overall mean half-life was 1.7 h. For both types of formulations and at both dose levels 63-65% of the doses were excreted in the urine as intact cefatrizine, 85% of this amount within 8 h. The overall mean renal clearance was 157 ml/min. The cefatrizine capsule and suspension formulations were completely bioequivalent in regard to both rate and extent of bioavailability. Plasma concentrations and urinary recoveries of cefatrizine were higher than those previously reported, due to precautions taken in sample collection and storage.

Determination of cefatrizine levels in blood, tonsils, paranasal sinuses and middle ear.

Levels of cefatrizine, a new oral cephalosporin, were determined in blood and in tonsils, paranasal sinus secretions and middle ear exudates from 18 patients with acute infections at these sites. Three and six hours after administration of 500 mg cefatrizine satisfactory levels of the antibiotic were found at all the sites examined. Levels in the tonsils and middle ear were higher than those in blood, while lower levels were recorded in nasal secretions.

Determinations of tissue levels of cefatrizine in blood, lungs and bronchi.

A study was carried out in 12 patients, divided into two groups of 6, to determine tissue levels of cefatrizine in lung (group I) and bronchial secretions (group II) following a single oral dose of 500 mg. In group I, specimens of blood and lung tissue were collected after 2 h from one subgroup of 3 patients and after 3 h from the other subgroup of 3. Average levels were 8.5 and 7.0 mcg/ml for blood and 1.2 and 1.4 mcg/ml for lung tissue respectively. In group II blood and bronchial secretion concentrations were evaluated at the 2nd, 3rd and 6th hours from administration. Average values were 9.1 and 7.7 mcg/ml in blood at 2h and 3h respectively, whereas the average bronchial secretion concentration at the 3rd hour was 10.4 mcg/ml in the first subgroup. In the second subgroup the mean level in blood collected at the 2nd hour was 8.9 mcg/ml, and 2.5 and 4.1 mcg/ml respectively in blood and bronchial secretions at the 6th hour. Cefatrizine levels in bronchial secretions were higher than those in blood at both the 3rd and the 6th hour from administration: this kinetic peculiarity of the drug will doubtless play an important role in the therapeutic efficacy of cefatrizine.

Human intravenous pharmacokinetics and absolute oral bioavailability of cefatrizine.

Cefatrizine was administered intravenously and orally at dose levels of 250, 500, and 1,000 mg to normal male volunteers in a crossover study. Intravenous pharmacokinetics were dose linear over this range; mean peak plasma concentrations at the end of 30-min infusions were, respectively, 18, 37, and 75 micrograms/ml, total body clearance was 218 ml/min per 1.73 m2, renal clearance was 176 ml/min per 1.73 m2, and mean retention time in the body was 1.11 h. Cumulative urinary excretion of intact cefatrizine was 80% of the dose, and half-lives ranged from 1 to 1.4 h. Steady-state volume of distribution was 0.22 liters/kg. On oral administration, the absolute bioavailabilities of cefatrizine were 75% at 250 and 500 mg and 50% at 1,000 mg. The mean peak plasma concentrations and peak times were, respectively, 4.9, 8.6, and 10.2 micrograms/ml at 1.4, 1.6, and 2.0 h, mean residence times were 2.4, 2.6, and 3.1 h, and mean absorption times were 1.3, 1.6, and 1.9 h. Oral renal clearance and half-life values corresponded well to the intravenous values. Cumulative urinary excretion of intact cefatrizine (as percentage of dose) was 60 at 250 mg, 56 at 500 mg, and 42 at 1,000 mg. It is hypothesized that the lack of oral dose linearity between the 500- and 1,000-mg doses is due to a component of cefatrizine absorption by a saturable transport process. Relative absorption at the high dose would be sufficiently slow that an absorption "window" would be passed before maximum bioavailability could be attained. It is not expected that the observed bioavailability decrease at doses exceeding 500 mg will have any therapeutic significance, since clinical studies are establishing efficacy for a recommended unit dosage regimen of 500 mg.

[Experimental and clinical studies of cefatrizine in oral infections (author's transl)].

Investigation was made on the therapeutic effect of a new antibiotic, cefatrizine(CFT), in oral infections according to the following procedure. Results are summarized as follows. Determination was made on the MIC of CFT against 8 clinical isolates of S. epidermidis, 5 of S. aureus and 7 of E. coli in comparison with those of CEX and PBPC. MICs of CFT against S aures were demonstrated 3.13 to 6.25 mcg/ml which were superior to those of CEX and ABPC. CFT was administered orally in a dose of 500 mg at an hour and a half before the extraction of the impacted wisdom tooth in the mandibula. During the operation, gingival and blood specimens were collected and each CFT level was determined. The mean CFT level in the gingiva reached to 0.95 mcg/ml and that in the blood to 5.77 mcg/ml. According to these experimental results, CFT was administered to patients with moderate oral infection at a dose of 500 mg and clinical assessment was made according to the criteria established by Japanese Society of Oral Surgeons. As the results, the effectiveness rate of CFT was 85%. No serious side effect was observed. From the results of the present study, CFT may be effective for moderate oral surgery infections.

Cefatrizine activity compared with that of other cephalosporins.

Cefatrizine, a new orally administered cephalosporin, was tested against 400 clinical isolates. Cefatrizine had excellent activity against gram-positive cocci, inhibiting all except enterococci at minimal inhibitory concentrations below 1 mug/ml. Cefatrizine inhibited the majority of Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, and Salmonella at concentrations below 12.5 mug/ml. Although cefatrizine was not hydrolyzed by many beta-lactamases, it did not inhibit a number of strains of Enterobacter, Serratia, or indole-positive Proteus. Cefatrizine was more active than cephalothin or cephalexin against E. coli, Klebsiella, Enterobacter, Citrobacter, Salmonella, and Shigella. Its overall activity was less than that of cefoxitin against strains resistant to cephalothin, but its activity against cephalothin-susceptible strains was equivalent to that of cefamandole.