Bioequivalence of vildagliptin/metformin fixed-dose combination tablets and a free combination of vildagliptin and metformin in healthy subjects.

OBJECTIVE: To assess the bioequivalence of vildagliptin/metformin fixed-dose combination tablets (at doses of 50/500, 50/850 and 50/1,000 mg) with free combination of the individual drugs in healthy subjects. METHODS: The pharmacokinetics of vildagliptin and metformin following administration of a fixed-dose combination tablet of vildagliptin/metformin at doses of 50/500 mg (Study I), 50/850 mg (Study II) and 50/1,000 mg (Study III) compared with administration of the individual drugs as free combinations were investigated. All three studies were open-label, single-center, randomized, two-period, two-treatment crossover studies in healthy subjects. RESULTS: Pharmacokinetic parameters (AUC(0-infinity), C(max), t(max), t(1/2) and CL/F) for vildagliptin and metformin across the three studies were similar whether vildagliptin and metformin were administered as a single fixed-dose combination tablet (vildagliptin/metformin 50/500, 50/850 or 50/1,000 mg) or as the respective individual tablets. The point estimates and 90% CI of the geometric mean ratios for vildagliptin and metformin C(max), AUC(0-t), and AUC(0-infinity) were all within the predefined bioequivalence range of 0.80 - 1.25. Administration of the vildagliptin/metformin combination tablets was well tolerated; the incidence of adverse events was similar to that observed with the respective free combinations of vildagliptin and metformin, and the most common individual adverse events were mild gastrointestinal events, which are commonly observed with metformin treatment. CONCLUSIONS: The fixed-dose combination tablet of vildagliptin/metformin is bioequivalent to administration of the individual drugs as a free combination at dose levels of 50/500, 50/850 and 50/1,000 mg and is well tolerated. Consequently, the fixed-dose combination tablets are considered therapeutically equivalent and exchangeable to the free combination in clinical practice. Furthermore, the fixed-dose combination tablets are expected to enhance convenience and thereby improve compliance and improve glycemic control for patients with Type 2 diabetes on both medications.

The influence of hepatic impairment on the pharmacokinetics of the dipeptidyl peptidase IV (DPP-4) inhibitor vildagliptin.

OBJECTIVE: Vildagliptin is a potent and selective dipeptidyl peptidase-IV (DPP-4) inhibitor that improves glycemic control in patients with type 2 diabetes mellitus by increasing alpha- and beta-cell responsiveness to glucose. This study investigated the pharmacokinetics of vildagliptin in patients with hepatic impairment compared with healthy subjects. METHODS: This was an open-label, parallel-group study in patients with mild (n = 6), moderate (n = 6) or severe (n = 4) hepatic impairment and healthy subjects (n = 6). All subjects received a single 100-mg oral dose of vildagliptin, and plasma concentrations of vildagliptin and its main pharmacologically inactive metabolite LAY151 were measured up to 36 h post-dose. RESULTS: Exposure to vildagliptin (AUC(0-infinity) and C(max)) decreased non-significantly by 20 and 30%, respectively, in patients with mild hepatic impairment [geometric mean ratio (90% CI): AUC(0-infinity), 0.80 (0.60, 1.06), p = 0.192; C(max), 0.70 (0.46, 1.05), p = 0.149]. Exposure to vildagliptin was also decreased non-significantly in patients with moderate hepatic impairment [-8% for AUC(0-infinity), geometric mean ratio (90% CI): 0.92 (0.69, 1.23), p = 0.630; -23% for C(max), geometric mean ratio (90% CI): 0.77 (0.51, 1.17), p = 0.293]. In patients with severe hepatic impairment, C(max) was 6% lower than that in healthy subjects [geometric mean ratio (90% CI): 0.94 (0.59, 1.49), p = 0.285], whereas AUC(0-infinity) was increased by 22% [geometric mean ratio (90% CI): 1.22 (0.89, 1.68), p = 0.816). Across the hepatic impairment groups, LAY151 AUC(0-infinity) and C(max) were increased by 29-84% and 24-63%, respectively, compared with healthy subjects. The single 100-mg oral dose of vildagliptin was well tolerated by patients with hepatic impairment. CONCLUSIONS: There was no significant difference in exposure to vildagliptin in patients with mild, moderate or severe hepatic impairment; therefore, no dose adjustment of vildagliptin is necessary in patients with hepatic impairment.

Mycophenolic acid metabolite profile in renal transplant patients receiving enteric-coated mycophenolate sodium or mycophenolate mofetil.

Mycophenolate mofetil (MMF), a prodrug of mycophenolic acid (MPA), is an effective immunosuppressive treatment in renal transplant recipients but is known to have gastrointestinal side effects. Enteric-coated mycophenolate sodium (EC-MPS; myfortic) is a new formulation for delivering MPA. This open-label, two-period, cross-over study was carried out to characterize the time course of MPA and its metabolites, mycophenolic acid glucuronide (MPAG) and acyl mycophenolic acid glucuronide (AcMPAG) in stable renal transplant patients (n = 40) after 28-day chronic dosing with EC-MPS (720 mg bid) or MMF (1000 mg bid). The relative abundance and exposure of all three compounds was also assessed. EC-MPS demonstrated the typical pharmacokinetic profile of an enteric-coated formulation with a delayed release of MPA compared with MMF (Tmax 2.5 versus 1.0 hours, respectively). Consistent with a similar disposition of MPA, both EC-MPS and MMF treatments resulted in the same ratio of MPAG to MPA exposure, 23:1. Furthermore, comparison of the AUC of MPAG and AcMPAG for both treatments indicated that steady state MPAG exposure was 75 to 90 times that of AcMPAG, confirming MPAG as the predominant metabolite of MPA. AcMPAG has been identified as a possible active metabolite of MPA; the present study indicates that AcMPAG may contribute around 14% of the exposure to active drug after administration of MPA. Both EC-MPS and MMF treatments were well tolerated over the 1-month period of chronic treatment. In summary, consistent with its enteric-coated design, EC-MPS delays delivery of MPA, but results in similar exposure to that provided by MMF.

The pharmacokinetics of the novel promotile drug, tegaserod, are similar in healthy subjects-male and female, elderly and young.

BACKGROUND: Tegaserod (HTF 919) is a selective 5-HT4 receptor partial agonist in development for the treatment of irritable bowel syndrome. AIM: This study aimed to assess the effect of age and gender on the single-dose pharmacokinetics of tegaserod. METHODS: In a parallel-group, open-label study, a single dose of tegaserod (12 mg) was administered to four groups of healthy young male, young female, elderly male and elderly female subjects (n=10 per group). Blood samples were collected from 0 to 24 h postdose. Non-compartmental pharmacokinetics evaluation and statistical analysis (ANOVA and Wilcoxon signed ranks test for tmax) were performed. RESULTS: Tegaserod was well tolerated in all groups. There was no effect of age or gender on tmax and Cmax. Gender did not affect AUC0-infinity and AUC0-tz; there was a statistically significant effect of age on these parameters. AUC0-infinity and AUC0-tz in the elderly were greater than in the young (AUC0-infinity ratio 1.37, P < 0.001; AUC0-tz ratio 1.23, P=0.029). This increase in exposure is judged not to be clinically relevant because it is within the variability in the pharmacokinetics parameters of tegaserod and because the dose-response relationship of tegaserod is relatively shallow. CONCLUSIONS: No dose adjustment for age or gender is recommended in tegaserod therapy.

Pharmacokinetics and tolerability of 40-0-[2-hydroxyethyl]rapamycin in de novo liver transplant recipients.

BACKGROUND: 40-0-[2-Hydroxyethyl]rapamycin (RAD), a novel macrolide with potent immunosuppressive and antiproliferative activities, prevents rejection in animal allotransplantation models. This phase I trial assessed the effects of bile diversion, administration route, and time after transplant on RAD pharmacokinetics after single-dose administration in de novo liver allograft recipients. The influence of RAD on cyclosporine (CsA) pharmacokinetics and the safety of RAD were also evaluated. METHODS: Twenty-six de novo liver allograft recipients were assigned to one of four treatment groups based on the presence or absence of a T tube, administration route (nasogastric or nasoduodenal), and timing of RAD administration. Patients received a single 7.5-mg RAD dose on one to three occasions in addition to CsA (Neoral) and corticosteroids. Steady-state cyclosporine profiles with and without RAD coadministration were evaluated. Results. Recipients with bile diversion demonstrated lower peak concentration (Cmax) than those without, but overall drug exposure (AUC) was not altered. Cmax and AUC were not influenced by administration route. A trend towards higher Cmax on postoperative day 3 than on postoperative day 1 was noted, although AUC was not altered. Single-dose RAD coadministration did not affect steady-state CsA pharmacokinetics. RAD was well tolerated and caused few drug-related adverse effects. RAD administration did not increase infection rates or produce clinically significant changes in laboratory parameters. Conclusions. In de novo liver transplant recipients, the overall extent of RAD absorption was not influenced by bile diversion, administration route, or time of administration. CsA pharmacokinetics were not affected by single-dose RAD coadministration. RAD capsules administered in single doses of 7.5 mg were well tolerated and safe.

Effect of food on the bioavailability of triclabendazole in patients with fascioliasis.

AIMS: Preliminary results indicate higher absorption of triclabendazole (TCBZ) administered postprandially. Therefore, the influence of food on the pharmacokinetics of TCBZ and its active sulphoxide (TCBZ-SO) and sulphone (TCBZ-SO2) metabolites was investigated. METHODS: Two single doses (10 mg kg(-1)) of TCBZ were administered to 20 patients with fascioliasis. Ten patients were first given the drug after a high energy breakfast and then, 48 h later, after an overnight fast. The other 10 patients first received the drug in fasting state and then, 48 h later, after breakfast. A low energy breakfast was served 2 h after drug administration for fasting state. RESULTS: Compared with the fasting state, an increased AUC and Cmax after food intake (significant, P < 0.0001) was shown from the values of TCBZ, TCBZ-SO and TCBZ-SO2. The mean AUC for TCBZ (fasting: 1.55, fed: 5.72 micromol l(-1) h), TCBZ-SO (fasting: 177, fed: 386 micromol l(-1) h) and TCBZ-SO2 (fasting: 13.9, fed: 30.5 micromol l(-1) h) indicated a large availability increase with food and the strong systemic predominance of the active sulphoxide metabolite over the unchanged drug. (All patients were cured at the end of the trial except one who required a second course of two postprandial doses of triclabendazole (10 mg kg(-1) each). Tolerability to the treatment among the patients was good. CONCLUSIONS: The administration of triclabendazole with food is recommended for improved systemic availability in patients with fascioliasis or paragonimiasis.

Automated and sensitive method for the determination of formoterol in human plasma by high-performance liquid chromatography and electrochemical detection.

An automated high-performance liquid chromatography (HPLC) method for the determination of formoterol in human plasma with improved sensitivity has been developed and validated. Formoterol and CGP 47086, the internal standard, were extracted from plasma (1 ml) using a cation-exchange solid-phase extraction (SPE) cartridge. The compounds were eluted with pH 6 buffer solution-methanol (70:30, v/v) and the eluate was further diluted with water. An aliquot of the extract solution was injected and analyzed by HPLC. The extraction, dilution, injection and chromatographic analysis were combined and automated using the automate (ASPEC) system. The chromatographic separations were achieved on a 5 microm, Hypersil ODS analytical column (200 mm x 3 mm I.D.), using (pH 6 phosphate buffer, 0.035 M + 20 mg/l EDTA)-MeOH-CH3CN (70:25:5, v/v/v) as the mobile phase at a flow-rate of 0.4 ml/min. The analytes were detected with electrochemical detection at an operating potential of +0.63 V. Intra-day accuracy and precision were assessed from the relative recoveries of calibration/quality control plasma samples in the concentration range of 7.14 to 238 pmol/l of formoterol base. The accuracy over the entire concentration range varied from 81 to 105%, and the precision (C.V.) ranged from 3 to 14%. Inter-day accuracy and precision were assessed in the concentration range of 11.9 to 238 pmol/l of formoterol base in plasma. The accuracy over the entire concentration range varied from 98 to 109%, and precision ranged from 8 to 19%. At the limit of quantitation (LOQ) of 11.9 pmol/l for inter-day measurements, the recovery value was 109% and C.V. was 19%. As shown from intra-day accuracy and precision results, favorable conditions (a newly used column, a newly washed detector cell and moderate residual cell current level) allowed us to reach a LOQ of 7.14 pmol/l of formoterol base (3 pg/ml of formoterol fumarate dihydrate). Improvement of the limit of detection by a factor of about 10 was reached as compared to the previously described methods. The method has been applied for quantifying formoterol in plasma after 120 microg drug inhalation to volunteers. Formoterol was still measurable at 24 h post-dosing in most subjects and a slow elimination of formoterol from plasma beyond 6-8 h after inhalation was demonstrated for the first time thanks to the sensitivity of the method.

Rapid determination of propyphenazone in plasma by high-performance liquid chromatography.

A rapid and simple high-performance liquid chromatographic assay for the determination of propyphenazone in plasma is described. Phenylbutazone was used as the internal standard. Plasma proteins were precipitated with acetonitrile before injection onto a 3-microns Supelcosil LC-18 column. The mobile phase, ethanol containing 0.2% (v/v) heptylamine-0.005 M potassium dihydrogenphosphate (30:70, v/v), was used at a flow-rate of 1.3 ml/min. The quantitation was performed by ultraviolet detection at a wavelength of 270 nm. The chromatographic time was 7 min. The within- and between-day coefficients of variation were less than 6% and the recoveries close to 100% for concentrations between 0.4 and 22 mumol/l. The limit of quantitation was 0.4 mumol/l (ca. 100 ng/ml).

Fast liquid chromatography for the determination of drugs in plasma and combination with liquid-solid extraction in a fully automated system.

Fast liquid chromatography was applied to the assay of several drugs in plasma. Short columns, 3.3-4 cm long, packed with C18 material, 3 microns particle size, were used. The peaks were little subject to extra-column band-broadening because the investigated drugs were eluted with high capacity factors in order to obtain an adequate separation from plasma components. The main influences on efficiency were the response time of the detector and the solvent composition of the injected sample. Conventional apparatus was used. A fully automated analytical system combining liquid-solid extraction via disposable extraction columns and fast liquid chromatography on a small-dimensioned 3 microns particle size column is described for the assay of drugs in plasma. Automation was accomplished by using the Automatic Sample Preparation with Extraction Columns system.

Automated microanalysis of carbamazepine and its epoxide and trans-diol metabolites in plasma by column liquid chromatography.

A fully automated high-performance liquid chromatographic procedure for the simultaneous determination of carbamazepine and its main metabolites, epoxycarbamazepine and dihydroxycarbamazepine, in plasma is described. Liquid-solid extraction on disposable C18 columns and reversed-phase chromatography on a 3 microns particle size C18 column were combined and automated by using the Automatic Sample Preparation with Extraction Columns system. Ultraviolet detection was performed at 210 nm. 5,6-Dihydro-11-oxo-11H-dibenz[b,e]azepine-5-carboxamide was used as internal standard. A small plasma volume (100 microliters) was required. The total run time for the assay of one sample was about 10 min. The assay demonstrated good reproducibility. The limit of quantitation was 0.1 mumol/l (about 25 ng/ml).

Fully automated analytical system using liquid-solid extraction and liquid chromatography for the determination of CGP 6140 in plasma.

Liquid-solid extraction on disposable extraction columns (DECs) and liquid chromatography can be combined in a completely automated analyser. The Gilson ASPEC system was used to develop a procedure for the determination of CGP 6140 in plasma. Both sample preparation via C8 Bond-Elut DECs and injection were fully automatic. The fully automated system prepared the samples by performing the same operations as for a manual procedure. The DEC was first wetted with methanol, then with water. A 400-microliters volume of plasma and 40 microliters of the internal standard solution, diluted with 1 ml of water, were applied to the DEC, rinsed with 10(-2) mol/l dipotassium hydrogenphosphate and eluted from the DEC with 300 microliters of acetonitrile-methanol (50:50, v/v). The eluting strength of the eluate was reduced by dispensing 1 ml of water into each vial prior to direct injection into a Spherisorb ODS column via a 1-ml loop. This allowed the reconcentration of the extracted compounds on the top of the column, as they were injected in a large volume of solvent of lower eluting strength than the mobile phase [acetonitrile-methanol-4 x 10(-3) mol/l ammonia solution (54.5:5:40.5, v/v/v)]. Reproducibility results are presented.

Liquid chromatographic determination of dihydralazine and hydralazine in human plasma and its application to pharmacokinetic studies of dihydralazine.

An analytical method is described for the concurrent determination of dihydralazine (1) and hydralazine (2) in human plasma as unchanged or apparent compounds. For the assay of the unchanged compounds, plasma samples were acidified with 0.02 M HCI and derivatized first with nitrous acid, and afterwards with sodium methylate. For the assay of the apparent compounds, plasma samples were acidified with 3 M HCI, incubated at 90 degrees C for 30 min and derivatized as above. The derivatives were extracted and chromatographed by reversed-phase mode on a C18 mu Bondapak column. The fluorescence of the compounds was measured (excitation wavelength = 230 nm, emission wavelength = 430 nm). The limits of quantitation were 0.5 ng/mL for the unchanged compounds and 1 ng/ml for the apparent compounds. After oral administration of 25 mg of 1 to 2 healthy volunteers, the mean areas under the plasma concentration-time curves were respectively 43.7 and 590 ng X h/mL for unchanged and apparent 1. The corresponding mean elimination half-lives were 1.03 and 3.9 h. The mean area under the curve measured for 2 amounted to 6.3% of that obtained for 1 for the unchanged compounds and to 10.3% for the apparent compounds.