Pharmacokinetics of Camonagrel in experimental animal: rat, rabbit and dog.

Camonagrel is a novel selective thromboxane synthetase inhibitor. The aim of this study was to determine its main pharmacokinetic parameters in rats, rabbits and dogs after intravenous and oral administration at doses of 10 mg kg(-1). Plasma and urine concentrations of camonagrel were analyzed by HPLC with UV detection. Pharmacokinetics of camonagrel was generally fitted to a two-compartmental model and the values which defined the absorption process were: Cmax = 15.96 microg.ml(-1), Tmax approximately 0.33 h, AUC(0-infinity) (oral) approximately 12.45 microg x h x ml(-1) (rat, n=3 per pont); Cmax approximately 2.04 mg x ml(-1), Tmax approximately 1.50 h, AUC(0-infinity) (oral) approximately 4.85 microg x h x ml(-1) (rabbit, n=3); Cmax approximately 18.60 microg x ml(-1), Tmax approximately 0.44 h, AUC(0-infinity) (oral) approximately 13.40 microg x h x ml(-1) (dog, n=4). The more representative values in the distribution and elimination phase were: protein binding rate approximately 80% in the three species ("in vitro" experiment); t(1/2beta) approximately 0.22 h (rat, i.v.), = 0.28 h (rabbit i.v.) and approximately 0.45 h (dog i.v.); CI approximately 635.73 ml x h(-1) (rat i.v.), approximately 448.26 ml x h(-1) (rabbit i.v.) and approximately 463.8 ml x h(-1) (dog i.v.). The absolute bioavailability of camonagrel was approximately 79.1% in rat, approximately 21.7% in rabbit and approximately 59.3% in dog. Available elimination data in rat indicated that Camonagrel was mainly excreted in urine (approximately 80%) as unchanged drug. An unknown minor metabolite (approximately 10%) was observed only after oral dosing. Finally, the main pharmacokinetic parameters of camonagrel in rats, rabbits and dogs are presented, which allow to define its absorption, distribution and elimination processes in these species.

Metabolism of ebrotidine. A review.

A hypothetical metabolic pathway for ebrotidine (N-[(E)-[[(2-[[[2-[(diaminomethylene]amino]-4-thiazolyl] methyl]thio]ethyl]amino]methylene-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) has been proposed on the basis of previous data on the metabolism of other H2-receptor antagonists as well as on in vitro degradation assays of ebrotidine. Its potential metabolites have been synthesized and characterized, and their presence in human urine has been investigated by high-performance liquid chromatography (HPLC). Analytical-scale HPLC allowed the identification of metabolites by means of their retention time and UV spectrum, while semipreparative-scale HPLC allowed their identification through FT-IR and 1H-NMR. Mass spectrometry using atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI) for HPLC-MS coupling allowed the identification of all metabolites in human urine. The quantitative determination of ebrotidine and its derivatives has been performed according to a newly designed method which consisted of a liquid-liquid extraction in a basic medium followed by reversed-phase HPLC with ion-pair formation. This method was sensitive, precise and no chromatographic interferences with other drugs which might be administered in combination with ebrotidine were observed. In order to elucidate the excretion of ebrotidine, the analytical method was applied to the analysis of the urine collected from 2 healthy volunteers 96 h after receiving 400 mg of ebrotidine.

Pharmacokinetics of ebrotidine in healthy volunteers. A summary.

Several clinical pharmacokinetic studies of ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl] methyl]thio]ethyl]amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) administered by oral route in single and multiple doses to healthy volunteers have been performed. Dosage levels were 150, 300, 400, 500, 600 and 800 mg. Plasma concentrations of unchanged ebrotidine and its major metabolite, ebrotidine sulfoxide, excreted in the urine were determined. The main pharmacokinetic parameters were calculated from the experimental data. Absorption was relatively rapid (Imax = 2 h) and unrelated to dose. Drug behavior was considered as reasonably linear: Cmax = 364-1168 ng/ml and AUC0-12 h = 1427-5997 ng.h/ml (doses from 150 mg to 800 mg). The mean values of terminal elimination half-life (t1/2 beta) ranged from 13.9 to 20.3 h (doses of 400, 600 and 800 mg). After multiple dosing there was no drug accumulation, and no significant changes in the mean values of the main pharmacokinetic parameters were observed. The steady state was reached from the second day of administration, 10-24% of the ebrotidine administered dose was excreted in urine mainly as its major metabolite, ebrotidine sulfoxide, as well as unchanged drug and other minor metabolites. These percentages were constant and independent of the dose administered.

Determination of ebrotidine and its metabolites in human urine by reversed-phase ion-pair high-performance liquid chromatography.

Ebrotidine is a new H2-receptor antagonist with powerful antisecretory activity, demonstrated gastroprotection and the ability to inhibit protease and lipase activities of Helicobacter pylori. As a tool in the clinical pharmacokinetic study of ebrotidine, an analytical method for the simultaneous determination of ebrotidine an its metabolites in human urine was developed. An ion-pair reversed-phase HPLC separation using 1-hexanesulfonic acid and acetonitrile as mobile phase with gradient elution was optimized. In addition, several procedures of preconcentration and clean-up were tested, including solid-phase and liquid-liquid extraction, the mixture dichloromethane-2-propanol (9:1, v/v) at pH 11 being the most efficient. The quality parameters of the whole analytical method were established, the calibration curves were linear over the range studied (1-200 micrograms/ml) and the reproducibility of the method was high (inter-day R.S.D. values lower than 4.4%). The limits of detection were between 26 and 110 ng/ml of urine for ebrotidine and its metabolites. The method was applied to the analysis of urine collected from two volunteers during 96 h following oral administration of ebrotidine at a dose of 400 mg.

Investigation of the metabolism of ebrotidine in human urine by liquid chromatography-atmospheric pressure chemical ionization mass spectrometry.

Ebrotidine is a new H2-receptor antagonist that, in addition to its antisecretory activity, exhibits a remarkable ability for gastric mucosal protection and acts as a potent inhibitor of protease and lipase enzymes elaborated by Helicobacter pylori. To study the metabolism of ebrotidine in human urine, HPLC/MS with an atmospheric pressure chemical ionization (APCI) interface and simultaneous UV detection was conducted. HPLC/MS separation of the reference compounds was performed, and positive and negative APCI mass spectra were obtained. Compounds of low molecular weight (M(r) < 300) showed predominantly the quasi-molecular ion. Intermediate size compounds (300 < M(r) < 400) gave a different type of spectra, depending on the ion mode: the positive mass spectra showed only the protonated molecular ion, whereas in the negative mass spectra many fragments appeared in addition to the deprotonated molecular ion. For molecules with a higher molecular weight (M(r) > 400), high fragmentation was observed. LC/MS with an APCI interface in positive and negative modes allowed the identification of ebrotidine, 4-bromobenzenesulfonamide, and four S-oxidized metabolites in human urine.

Ebrotidine and its metabolites studied by mass spectrometry with electrospray ionization. Comparison of tandem and in-source fragmentation...

Electrospray ionization was used for the analysis of ebrotidine and its potential metabolites. Since standard electrospray gave only the quasi-molecular ions for most of the compounds, two collision-induced dissociation (CID) experiments were carried out in order to obtain structural information: tandem mass spectrometry (MS/MS) and in-source fragmentation by increasing the cone voltage (CVF, cone voltage fragmentation). CVF produced more fragmentation than MS/MS, and the intensities of the fragments formed were also greater. Unlike Ms/MS spectra, CVF spectra gave ions which showed retention of the bromine isotope pattern, adducts with acetate and dehydration. The general fragmentation pathways observed for ebrotidine and its derivatives were basically the same for the CVF and MS/MS experiments. Most of the fragments were formed by the breaking of bonds to heteroatomics. In order to analyse biological samples containing ebrotidine and its biotransformation products, an HPLC/MS separation procedure with simultaneous UV detection was developed, allowing the identification of ebrotidine and its metabolites in human urine.

Metabolites of ebrotidine, a new H2-receptor antagonist, in human urine.

Ebrotidine is a new H2-receptor antagonist which exhibits a remarkable ability for gastric mucosal protection. A preliminary metabolic pathway for this compound was proposed and the hypothetic metabolites were synthesized. The presence of ebrotidine and its metabolites ebrotidine S-oxide and 4-bromobenzenesulfonamide in human urine has been confirmed by HPLC separation and spectroscopic characterization of the collected fractions by FT-IR and 1H NMR. Ebrotidine S,S-dioxide has been identified by HPLC using diode-array detection.

Determination of sertaconazole nitrate, a new imidazole antifungal, by high-performance liquid chromatography.

A high-performance liquid chromatographic method is developed for the determination of bulk sertaconazole nitrate and related compounds (potential impurities and degradation products) as well as a sertaconazole nitrate cream formulation. A 10-microns Spherisorb CN column is used along with a mobile phase consisting of acetonitrile and aqueous 0.01 M sodium phosphate (37:63, v/v). The sertaconazole nitrate peak is monitored at a wavelength of 260 nm; the retention time being 19.3 min. The detector response for sertaconazole nitrate is linear over the concentration range from 64 to 96 micrograms ml-1. The method is found to be sufficiently selective for the reliable determination of related compounds, FI-7001, FI-7009 and FI-7011, as indicated by same-day and between-day relative standard deviations (RSD) for replicate assays of 1.72% (n = 9) and 2.17% (n = 24), respectively. The application of this method to a cream formulation of sertaconazole nitrate is found to give a mean percentage recovery of 99.4% with RSD of 1.14% (n = 9); none of the cream vehicle peaks are found to interfere with the determination of sertaconazole nitrate.