Food interaction pharmacokinetic study of cordaflex 20 mg retard filmtablet in healthy volunteers.

The aim of the present study was to investigate the effect of food consumption on the pharmacokinetics of Cordaflex 20 mg retard filmtablet in healthy volunteers through measuring nifedipine plasma levels by an HPLC-ED method both after fasting and food ingestion. The food interaction pharmacokinetic study of Cordaflex 20 mg retard filmtablet was carried out in 12 healthy male volunteers treated with a single dose of the preparation both after fasting and after food ingestion, in a crossover design allowing 1 week of wash-out period between the 2 treatments. Nifedipine concentration of plasma samples were determined by an isocratic HPLC-ED method [Horvai et al. 1994] with robotic sample processing [Horváth et al. 1995, 1996]. The pharmacokinetic parameters (AUC0-infinity, AUC0-t, Cmax, MRT) were analyzed by calculating 90% confidence interval for logarithmic transformed test/reference ratio values, and Schuirmann's statistical tests, the tmax and HVD values were analyzed by Wilcoxon's nonparametric statistical test. The above statistical tests of the present food interaction study indicated significant differences for each one of the respective pharmacokinetic parameter pairs calculated for treatments after fasting and after food ingestion. On the basis of the above findings and also by comparing the mean pharmacokinetic curves, it was evident, that, in agreement with the data of literature [Kleinbloesem et al. 1993, Schall et al. 1994], food ingestion increased the relative bioavailability and maximum plasma concentration (Cmax). Considering the average of the parameter values and also the respective statistical tests, it was also apparent that the time to maximum plasma concentration (tmax), the mean residence time (MRT), and the half-value duration (HVD) all decreased significantly upon the effect of food ingestion.

Automated determination of levodopa and carbidopa in plasma by high-performance liquid chromatography-electrochemical detection using an on-line flow injection analysis sample pretreatment unit.

An automated analytical procedure is described for the parallel determination of L-3,4-dihydroxyphenylalanine (levodopa, L-dopa, LD) and the analogous hydrazine compound carbidopa (CD) in dog plasma by ion-pair high-performance liquid chromatography with electrochemical detection (HPLC-ED). After deproteinization of the plasma samples with perchloric acid the catecholamines were extracted from the supernatant by adsorption on a small column filled with alumina. The extraction and redissolution were automatically performed in a flow injection analysis unit (FIA) coupled to the HPLC system. The performance of the whole system was tested on dog plasma samples including specimens taken after oral administration of the anti-Parkinsonism drug Duellin, which is a combination tablet of levodopa and carbidopa.

Food interaction study of a new theophylline (Egifilin) 200 and 400 mg retard tablet in healthy volunteers.

The aim of the present food interaction study was to determine the blood plasma levels of theophylline upon the administration of new Egifilin 200 and 400 mg retard tablets, either on an empty stomach or after meal, and to make comparative pharmacokinetic evaluation in 26 healthy volunteers. For determination of the plasma levels of theophylline an improved isocratic HPLC-UV method was used in the concentration range of 0.1-18 micrograms/ml. The mean pharmacokinetic curves obtained with 200 and 400 mg tablets before and after meal were in good agreement also on the basis of statistical evaluation, although, as usual with theophylline, the evaluation of the individual pharmacokinetic curves indicated great variations. The pharmacokinetic parameters (AUCzero-t, AUCzero-infinity, HVD, MRT, Cmax, tmax) calculated for Egifilin 200 and 400 mg retard tablets were analyzed by ANOVA, ANOVAlog, Wilcoxon, and Schuirmann statistical tests as well as by the confidence interval calculation. As it was found, under the circumstances of the present food interaction study, food consumption did not have a biologically significant effect on the pharmacokinetic parameters of either the 200 or the 400 mg Egifilin retard preparations.

Sensitive high-performance liquid chromatographic determination of nifedipine in dog plasma using an automated sample preparation system with laboratory robot.

Nifedipine, a calcium-channel blocking drug was analysed in dog plasma after oral dosing with two different formulations. Sample preparation was automated with a laboratory robot. Quantitative determination of the drug was performed on a reversed-phase HPLC system with electrochemical detection (ED) using an internal standard. Validation of the analytical method showed that the system is well suited for pharmacokinetic studies on dogs. The assay was linear in the range 1-50 ng/ml. Inter-day and intra-day variability were between 6.43-18.15% C.V. and 1.57-5.53% C.V., respectively.