Structure determination of the primary renal metabolite of the penem FCE 22101

Simultaneous determination of an active metabolite and open-ring metabolites by high performance liquid chromatography and pharmacokinetic studies of a penem antibiotic, FCE22891, in dogs

A sensitive high performance liquid chromatographic method for the simultaneous determination of an active metabolite (FCE22101) and open-ring metabolites (P1, P2) of a penem antibiotic, FCE22891, in dog plasma was developed. Plasma samples were pretreated only by ultrafiltration for the determination of the metabolites. The filtrates were directly analyzed by a reversed-phase high-performance liquid chromatographic system using a two-sided bracketing injection technique. The quantitation limits of FCE22101, P1 and P2 were 0.03, 0.1 and 0.15 microgram ml-1, respectively. Analysis of the spiked plasma samples demonstrated the good accuracy and precision of the method. The proposed method was applied to the pharmacokinetic studies of an active metabolite and open-ring metabolites after oral administration of a penem antibiotic, FCE22891, in dogs. In addition, the plasma levels of unchanged FCE22891 and the possible changes of formaldehyde and acyl-L-carnitine levels in plasma, which will be generated from the ester group of FCE22891, were also investigated.

Qualitative analysis of potential metabolites and degradation products of a new antiinfective drug in rat urine, using HPLC with radiochemical detection and HPLC-mass spectrometry

High-performance liquid chromatography (HPLC) was used in combination with radioactivity detection and mass spectrometry (MS) to elucidate the metabolic fate of GV104326, a novel tricyclic beta-lactam antibacterial agent. Metabolic profiles were obtained by analysis of rat urine samples collected after intravenous administration of the 14C-labelled drug at the dose of 50 mg kg-1 (12.95 MBq kg-1). Methods for solid-phase extraction from urine samples and for reversed-phase chromatographic separation of drug related material were developed. HPLC-MS was used to confirm that the parent compound corresponded to the principal peak in the chromatograms, and two minor peaks were identified as potential metabolites of GV104326. They were shown to be an open beta-lactam ring derivative (GV173923) and a dimeric compound (GV196359).

Pharmacokinetics of [14C]FCE 22891, a penem antibiotic, following oral administration to healthy volunteers

FCE 22891 is a prodrug of the penem antibiotic FCE 22101 and is suitable for oral administration. The pharmacokinetics of FCE 22891 were investigated in four healthy male volunteers following the oral administration of 500 mg of [14C]FCE 22891. Levels of radioactivity in plasma were always higher and persisted for longer than those of FCE 22101. The time to the maximum concentration of radioactivity in plasma generally coincided with that of FCE 22101. The respective values for the maximum concentrations of radioactivity in plasma were, on average, 8.57 +/- 2.95 micrograms equivalent/ml and 2.97 +/- 2.05 micrograms/ml. Over a 5-day period, mean urinary and fecal recovery of radioactivity accounted for 53.2 and 41.0% of the dose, respectively. The average amount of FCE 22101 excreted in urine and feces corresponded to 9.0 and 1.6% of the dose, respectively. The urinary recovery of the open-ring metabolite P1 and of its 5-S epimer P2 accounted for about 6.5 and 1.2% of the dose, respectively. Other chromatographic peaks corresponding to nonidentified compounds accounted for about 14.0% (polar metabolite fraction; peak P), 3.7% (less polar fraction; peak X), and 15.4% (least polar fraction) of the dose. Elimination of radioactivity and FCE 22101 in urine was rapid. Intersubject variability in the kinetics of total radioactivity in plasma was far less than that observed for FCE 22101. The results of the present study support suggestions that presystemic metabolism of FCE 22101 and/or transformation of the prodrug to compounds other than FCE 22101 are the main cause of intersubject variability in the kinetics of FCE 22101 produced in plasma following oral administration of its prodrug.

Pharmacokinetics of FCE 22891, a new oral penem

FCE 22891 is the oral prodrug of FCE 22101, a new broad-spectrum penem. The pharmacokinetics of FCE 22891 after single-dose administration, its absolute bioavailability, and the effect of food intake on its absorption were investigated in three different randomized crossover studies in healthy volunteers. Drug levels in blood and urine were measured by high-pressure liquid chromatography and bioassay. For optimal comparison of the results of all studies, and since there was good agreement of both methods, only the high-pressure liquid chromatography results are included. The pharmacokinetics of the penem were linear, and its bioavailability after oral administration was 42 +/- 11%. Food intake increased the total area under the curve from 0 h to infinity from 11.9 +/- 3.5 to 14.1 +/- 2.4 mg.h/liter. A specific side effect, i.e., bladder complaints, was registered in some volunteers taking FCE 22891 at doses greater than or equal to 1.0 g.

High-performance liquid chromatographic method for the simultaneous assay of a new synthetic penem molecule and its salt-forming agent in injectable formulations

Rapid, stability-indicating, reversed-phase high-performance liquid chromatographic method for the direct and simultaneous determination of a new beta-lactam molecule and its salt-forming agent in finished dosage forms was studied for the development of injectable formulations.

Pharmacokinetics and tolerance of a new penem antibiotic, FCE 22101, in healthy volunteers after a single intravenous dose

The clinical tolerance and pharmacokinetics of FCE 22101 (sodium (5R, 6S)-6-[(1R)-hydroxyethyl]-2-carbamoyloxymethyl-2-penem-3-carboxylate), a new penem antibiotic, have been studied after giving a single i.v. dose of 4 mg.kg-1 to ten healthy male volunteers. The pharmacokinetics was estimated according to a two-compartment open model. The peak plasma concentration (Cmax) was 15.5 (1.08) micrograms.ml-1, mean (SEM). FCE 22101 was rapidly cleared from the systemic circulation [t 1/2 lambda z = 44.2 (4.2) min; CL = 7.21 (0.47) ml.kg-1.min-1]. The mean apparent volume of distribution at steady-state was 246 (16.9) ml.kg-1. The mean residence time relative to the 10 min infusion was 39.4 (1.5) min. Urinary recovery of FCE 22101 showed wide inter-subject variation, ranging from 10.2 to 53.6% of the dose. No subject complained of adverse effects.