Pharmacokinetic and bioequivalence evaluation of two formulations of 100 mg trimebutine maleate (Recutin™ and Polybutin™) in healthy male volunteers using the LC–MS/MS method

BACKGROUND

Trimebutine maleate is a prokinetic agent that acts directly on the smooth muscle of the GI tract. A bioequivalence (BE) study of 2 oral formulations of 100 mg trimebutine maleate (TMB) was carried out in 24 healthy male Korean volunteers according to a crossover-randomized design.

METHODS

Subjects were given a single dose of 2 100 mg tablets of each formulation. The test and reference formulations were Recutin (Hutax Co., South Korea) and Polybutin (Samil Co., South Korea), respectively. Each set of tablets was administered with 240 ml of water to subjects after 10 h overnight fasting on 2 treatment days separated by a 1 week washout period. After dosing, serial blood samples were collected for a period of 36 h. Plasma was analyzed for the main metabolite of TMB, N-monodesmethyl trimebutine (nor-TMB), by a validated LC with MS/MS detection capacity for nor-TMB in the range 5-1500 ng/ml, with a lower limit of quantification (LLOQ) of 5 ng/ml. Several pharmacokinetic (PK) parameters (including AUC(t), AUC(infinity), C(max), T(max), T(1/2), and K(e)) were determined from the plasma concentrations of nor-TMB of both formulations. AUC(t), AUC(infinity), and C(max) were tested for BE after log-transformation of the data.

RESULTS

No significant difference was found based on ANOVA; 90% confidence intervals (98.98%112.03% for AUC(t); 98.60%-113.20% for AUC(infinity); 90.85%-107.87% for C(max)) for the test and reference were found within KFDA acceptance range of 80-125%.

CONCLUSIONS

Based on these statistical inferences, it was concluded that Recutin is bioequivalent to Polybutin and can be used interchangeably in a clinical setting.

Pharmacokinetic study of trimebutine maleate in rabbit blood using in vivo microdialysis coupled to capillary electrophoresis

In vivo microdialysis was used together with capillary electrophoresis (CE) to monitor the concentration of trimebutine maleate (TM) in rabbit blood. Dialysis probe was perfused at 3 microl/min resulting in relative recovery of 26.6+/-3.1% (n=3). After a one step sample preparation the samples were injected directly into the capillary. TM was detected on-column using UV detector at 214 nm. Separation of TM from other components in the dialysate was achieved within 15 min. Evaluation was based on the relative collected peak height (TM/IS). The response for TM in the blood dialysate was linear over the range of 0.5-100 microg/ml. The detection limit of TM in the blood dialysate was 0.1 microg/ml (S/N=3). This method has been successfully applied to the pharmacokinetic study of trimebutine maleate in rabbit blood following oral administration of 200 mg/kg. It provides a fast and simple technique for the pharmacokinetic study of TM in vivo.

[Pharmacokinetics and bioequivalence of trimebutine dispersive tablet in healthy subjects]

AIM

To develop an HPLC-ESI-MS assay for determination of trimebutine in human plasma and to investigate the pharmacokinetics and bioequivalence of two trimebutine tablets in human.

METHODS

After being made alkaline with saturated sodium bicarbonate, plasma was extracted by cyclohexane and separated by HPLC on a reversed-phase C18 column with a mobile phase of 10 mmol x L(-1) ammonium acetate buffer solution (pH 3.5)-methanol (18:82). HPLC-ESI-MS was performed in the selected ion monitoring (SIM) mode using target ions at m/z 388 for trimebutine and m/z 280 for the internal standard (sibutramine, IS). The fragmentor voltage was 50 V. A randomized cross-over design was performed in 20 healthy volunteers. In the two study periods, a single 100 mg dose of each tablet was administered to each volunteer.

RESULTS

Calibration curve was linear over the range of 0.3 - 150 microg x L(-1). The main pharmacokinetic parameters of T1/2, Tmax and Cmax were (9.2 +/- 2.8) h, (1.0 +/- 0.3) h and (40 +/- 20) microg x L(-1) for the reference tablet; (9.2 +/- 2.3) h, (0.9 +/- 0.4) h and (41 +/- 20) microg x L(-1) for the test tablet. The relative bioavalability of the test tablet was (97 +/- 13)%. The results of variance analysis and two one-sided t-test showed that there was no significant difference between the two formulations in the AUC and Cmax.

CONCLUSION

The assay was proved to be sensitive, accurate and convenient. The two formulations were bioequivalent.

Quantitative determination of trimebutine maleate and its three metabolites in human plasma by liquid chromatography-tandem mass spectrometry

A sensitive and selective HPLC-MS-MS method was developed for the determination of trimebutine maleate (TM) and its major metabolites N-monodemethyltrimebutine (TM-MPB), N-didemethyltrimebutine (APB) and 3,4,5-trimethoxybenzoic acid (TMBA) in human plasma. The analytes were extracted from plasma samples by liquid-liquid extraction and chromatographed on a YMC J'sphere C(18) column. The mobile phase consisted of 2 mM ammonium acetate buffer (pH 6.5)-methanol (20:80, v/v), and at a flow-rate of 0.2 ml/min. Detection was carried out on a triple quadrupole tandem mass spectrometer in multiple reactions monitoring (MRM) mode using positive-negative switching electrospray ionization (ESI). The method was validated over the concentration range of 1-100 ng/ml for trimebutine maleate and APB, 1-500 ng/ml for MPB, and 50-10,000 ng/ml for TMBA. Inter- and intra-day precision (RSD%) for trimebutine maleate and its three metabolites were all within +/-15% and the accuracy was within 85-115%. The limit of quantitation was 1 ng/ml for trimebutine maleate, TM-MPB and APB, and 50 ng/ml for TMBA. The extraction recovery was on average 58.2% for trimebutine maleate, 69.6% for MPB, 51.2% for APB and 62.5% for TMBA. The method was applied to the pharmacokinetic study of trimebutine maleate and its metabolites in healthy Chinese volunteers.

Determination of trimebutine maleate in rat plasma and tissues by using capillary zone electrophoresis

A simple and rapid capillary zone electrophoresis method was developed for the determination of trimebutine maleate in rat plasma and tissues. Rat plasma and tissue homogenates were mixed with acetonitrile containing internal standard, ephedrine hydrochloride, and then centrifuged. The supernatant was dried under a stream of nitrogen, and the residue was reconstituted in methanol-water (1:1). The electrophoresis was performed in uncoated capillary with 30 mmol/L phosphate buffer of pH 6.0 as the separation electrolyte. The applied voltage was 10 kV and the UV detection was set at 214 nm. The peak height ratio vs concentration in plasma or homogenates was linear over the range of 5-500 ng/mL and the limit of quantitation was 5 ng/mL. The intra- and inter-day precision was RSD < 14% and <15%. The accuracy was relative error (RE) within +/- 14%. This method was applied to studying the pharmacokinetics and tissue distribution after a single dose of trimebutine maleate was administrated to the rats. The T(max), AUC, C(max) and t(1/2) were 30 min, 7.8 x 10(2) (ng/mL) min, 39 ng/mL and 1.7 x 10(2) min. The drug distribution was found in a decreasing order of liver, kidney, spleen, lung and heart.

[HPCE determination of trimebutine maleate in rat plasma and its pharmacokinetics]

AIM

To develop a method for the determination of trimebutine maleate in rat plasma by using high performance capillary electrophoresis. The method was employed to pharmacokinetic analysis of trimebutine maleate.

METHODS

Plasma samples were deproteinized with acetonitrile (containing ephedrine hydrochloride as internal standard) and the supernatant was dried under N2 stream at 50 degrees C. The residue was dissolved with methanol-water (1:1) and injected into the capillary by siphon. The electrophoresis was performed in uncoated fused-silica capillary and the voltage was 10 kV. The running buffer was 0.03 mol.L-1 NaH2PO4(pH 6.0). The eluate was detected at 214 nm by UV detection.

RESULTS

The recovery for trimebutine maleate in rat plasma was 72.8%-87.9%. The calibration curve in plasma was linear over the range 5-200 micrograms.L-1. The limit of quantitation was 5 micrograms.L-1. The intraday relative standard deviation (n = 6) and the interday relative standard deviation (n = 18) were less than 14%. The highest concentration in plasma was observed at 30 min after ig trimebutine maleate to rats. The pharmacokinetic results were AUC0-infinity = 8 micrograms.min.mL-1, T1/2(Ke) = 173 min and Ke = 5.6 x 10(-3) min-1.

CONCLUSION

The method is accurate, sensitive and suitable for pharmacokinetic study of trimebutine maleate.

Pharmacokinetics and bioequivalence of two trimebutine formulations in healthy volunteers using desmethyl-trimebutine levels

Trimebutine tablets (dimethylamino-2-phenyl-2-n-butyl-3,4,5- trimethoxybenzoate maleate, CAS 34140-59-5, reference) and a new tablet formulation (Eurogalena, test) were administered in 24 healthy volunteers of both sexes according to a cross-over design, in a single dose of one 100 mg tablet of each formulation. Blood samples were drawn off over a 24-h period, before (time 0) and after each administration at specific intervals. Trimebutine and its main active metabolite, desmethyl-trimebutine, were measured in plasma using a validated HPLC method with UV detection. For both compounds, the sensitivity was 20 ng.ml-1 and the analytical method was proved to be linear for concentrations between 20 ng.ml-1 and 5000 ng.ml-1, with a variability less than 11%. The non-compartmental method was used for pharmacokinetic analysis. The confidence interval approach was used for comparison of the formulations according to the EU guidance note on bioavailability and bioequivalence on Cmax, AUC0-t and AUC0-infinity, log transformed. Tmax values were statistically compared using the Friedman non-parametric test. No trimebutine concentration was measured in the plasma samples. The obtained data with desmethyl-trimebutine proved the bioequivalence of the two tested formulations.

Synthesis of methylamino-2-phenyl-2-butyl-3,4,5-trimethoxybenzoate, the main bioactive metabolite of trimebutine maleate

The first synthesis of the methylamino-2-phenyl-2-butyl-3,4,5-trimethoxybenzoate (desmethyltrimebutine) I is described. This compound is the main bioactive metabolite of trimebutine II (Debridat, CAS 39133-31-8), an antispasmodic widely used for intestinal diseases since 1969. It was used for pharmacokinetic and bioequivalence studies.