[Effects of trimebutine maleate on the gastrointestinal motility in conscious dogs]

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.

Effects of trimebutine on intestinal motility after massive small bowel resection

Effects of trimebutine maleate (TM) on intestinal motility in short bowel syndrome (SBS) were studied in conscious canines in both acute and chronic phases following 80% massive distal small bowel resection (MSBR). TM was administered orally to beagles with MSBR or as controls in the postprandial and fasting states, and given simultaneously with meals. Intestinal motility was measured using bipolar electrodes for approximately 1 month after the electrodes were implanted in each beagle and the data compared between treatment groups. When TM was given with meals, the postprandial period without duodenal migrating myoelectric (or motor) complexes (MMCs) was shorter than in those given meals only. When TM was given in the postprandial state in short bowel beagles, the initial duodenal MMCs occurred earlier, i.e. the postprandial period was shorter. Diarrhea did not occur in these beagles. When TM was given in the fasting state, duodenal MMCs occurred and propagated to the distal intestine. In conclusion, oral TM administration can produce a more appropriate intestinal condition for the next food intake and make enteral nutrition possible even in the acute phase after MSBR. Such feeding can be carried out without overloading gut function as a result of the modulation of gastrointestinal motility by TM.

Dual effects of trimebutine on electrical responses of gastric smooth muscles in the rat

The effects of trimebutine on the electrical properties of smooth muscle membranes were studied in the isolated rat stomach, the objective being to elucidate the dual actions of this drug on gastric motility. Transmural nerve stimulation elicited a cholinergic excitatory junction potential (e.j.p.) and a nonadrenergic noncholinergic inhibitory junction potential (i.j.p.), and trimebutine inhibited the e.j.p. more than the i.j.p., with no significant change in the acetylcholine-induced depolarization. Trimebutine reduced the interval and, at high concentrations, the amplitude of slow waves. In enzymatically dispersed single cells, the Ca2+ current elicited by depolarization of the membrane was also inhibited by trimebutine. Thus, trimebutine increases slow wave frequency and inhibits cholinergic transmission and Ca2+ influx. The former would enhance while the latter two would depress gastric motility.

Effects of trimebutine maleate on electrical activities of isolated mammalian cardiac preparations

The effects of trimebutine maleate on electrical activity in guinea-pig isolated papillary muscles and rabbit sino-atrial nodes have been studied by means of a standard microelectrode method. In papillary muscles, trimebutine (above 10 microM) decreased the maximum rate of rise (Vmax) and the action potential duration at 90% repolarization (APD90), whereas the resting potential was not significantly altered. As to a decrease in Vmax, trimebutine produced a negative shift of the curve relating Vmax to the resting potential along the voltage axis. Trimebutine also depressed the slow action potentials of papillary muscles produced by 27 mM K and 0.2 mM Ba. In spontaneously beating sino-atrial node preparations, trimebutine (above 10 microM) decreased the heart rate, Vmax and the rate of diastolic depolarization. These results indicate that trimebutine maleate possesses a depressant action on the electrical activities of the fast- and slow-response fibres of the heart mainly due to inhibitions of both fast Na+ and slow Ca2+ channels.

Effects of trimebutine maleate (TM-906) on the smooth muscles of isolated guinea pig gallbladder

Effects of trimebutine maleate (TM-906) on the smooth muscles of isolated guinea pig gallbladder were investigated. TM-906 inhibited the contractile responses to cholinergic nerve stimulation (5 Hz) and to acetylcholine (3 X 10(-8) g/ml) to the same extent, both of which produced much the same amplitude of contraction. TM-906 noncompetitively antagonized the contractile response to methacholine, and it caused a parallel shift of dose-response curves for the contractile response to CaCl2 to higher concentrations. Moreover, TM-906 inhibited the contractile response to 50 mM KCl in a dose-dependent manner. On the other hand, TM-906 itself evoked a slight contractile response in a dose-dependent manner. The contractile response induced by TM-906 was prevented by exposure to Ca++-free solution, but not by tetrodotoxin or atropine. From these results, it was suggested that TM-906 inhibited the contractile responses to cholinergic nerve stimulation, acetylcholine, methacholine and 50 mM KCl by reducing the influx of calcium ion across the cell membrane, while it was assumed that TM-906 itself evoked a slight contractile response by increasing in some way the concentration of the intracellular free calcium ion available for the contractile systems.

Effects of trimebutine maleate (TM-906) on electrical and mechanical activities of smooth muscles of the guinea-pig stomach

The effects of trimebutine maleate (TM-906) on electrical and mechanical activities of smooth muscles of the guinea-pig stomach were investigated using a microelectrode and isometric tension recording methods. TM-906 (2 X 10(-5) M) depolarized the membrane of smooth muscles in the antrum to about 10 mV. From the current-voltage relationship and changes in membrane potentials in various [K]0, the TM-906-induced depolarization is considered to be mainly due to a decrease in the K-conductance. TM-906 increased the amplitude of the first spike potential and regularized the rhythm of slow waves. These excitatory effects are presumably due to the K-channel-blocking action during the repolarizing phase of the spikes and to the depolarization. TM-906 reduced the amplitudes of mechanical activities and slow waves. These inhibitory effects are presumably due to the inhibition of Ca-release from storage sites and to the block of Ca-influx. The biphasic effects are possibly due to the local anesthetic properties. TM-906 modified neither the membrane potential nor the membrane conductance of circular muscles in the fundus. This may mean that the circular muscles in the fundus lack the K-channel sensitive to TM-906.