Possible mechanisms of a new type of antispasmodic drug, BTM-1042(cis-(--)-2,3-dihydro-3-(4-methyl-piperazinyl)methyl-2-phenyl-1,5-benzothiazepin-4(5H)-one dihydrochloride)

In vitro and in vivo antimuscarinic effects of (-)cis 2,3-dihydro-3-(4-methylpiperazinylmethyl)-2-phenyl-1,5 benzothiazepin-4-(5H)one HCl (BTM-1086) in guinea pig peripheral tissues

The potency and selectivity of (-)cis-2,3-dihydro-3-(4-methylpiperazinylmethyl)-2-phenyl-1,5 benzothiazepin-4-(5H)one HCl (BTM-1086) for muscarinic receptor subtypes was compared in functional assay systems, in guinea pig peripheral tissues, to known reference drugs: atropine (nonselective), pirenzepine (M1), AF-DX 116 (M2) and HHSiD (M3). Like atropine, BTM-1086 was a potent, nonselective, competitive muscarinic antagonist with no detectable antispasmodic activity in urinary bladder or ileal muscle. In vivo, in the guinea pig cystometrogram, BTM-1086 depressed intravesical bladder pressure (PvesP) with the same efficacy and potency as oxybutynin, a drug used clinically for the treatment of urinary incontinence. The pharmacological profile of BTM-1086, however, suggests that it may not be suitable for development for bladder dysfunction disorders.

cis(-)-2,3-Dihydro-3-(4-methylpiperazinylmethyl)-2-phenyl-1,5- benzothiazepin-4(5H)-one monohydrochloride and its butylbromide as M1-receptor antagonists

Selectivity of cis(-)-2,3-dihydro-3-(4-methylpiperazinylmethyl)-2-phenyl-1,5-b enzothiazepin-4 (5H)-one monohydrochloride (BTM-1086) and its butylbromide (BTM-1073) to subtypes of muscarinic receptor, M1-and M2-receptors were tested, using pirenzepine, a M1-selective antagonist and atropine, a nonselective antagonist as reference drugs. Like pirenzepine, BTM-1086 and BTM-1073 were M1-selective antagonists. BTM-1086 was most selective among the test drugs. BTM-1073, a butylbromide of BTM-1086 was more potent than BTM-1086 in antimuscarinic activity tested on the isolated ileal longitudinal muscle, suggesting that quarternarization increased selectivity to M2-receptor but not to M1-receptor.

Antiulcer effect of (-)-cis-2,3-dihydro-3-(4-methylpiperazinylmethyl) -2-phenyl-1,5-benzothiazepin-4-(5H)-one hydrochloride (BTM-1086) in experimental animals

Effects of (-) cis-2,3-dihydro-3-(4-methylpiperazinylmethyl)-2-phenyl-1,5-benz othiazepin-4-(5H ) -one hydrochloride (BTM-1086) on various experimental gastric and duodenal ulcers were studied in rats. In the pylorus-ligated ulcer, restraint and water immersion stress ulcer, and drug-induced ulcer (indomethacin, aspirin, reserpine, serotonin, cysteamine), BTM-1086 prevented the development of ulcer at a dose of 0.1 to 1 mg/kg, p.o., but only weakly inhibited the histamine-induced gastric ulcer. The inhibitory activities of BTM-1086 were significantly higher than those of atropine sulfate. In the healing experiment with the acetic acid-induced stomach ulcer, BTM-1086 (1 mg/kg/day, p.o., X 14) showed a significant healing effect, which was higher than that of propantheline bromide. BTM-1086 at a dose of 0.2 mg/kg, i.d., remarkably inhibited the gastric secretion 6 hr after pylorus ligation. The aspirin-induced reductions of the total acid and K+ as well as the increments of the volume and Na+ in the gastric secretion were prevented dose-dependently by pretreatment with BTM-1086.

Action of nicotine on guinea-pig isolated bronchial smooth muscle preparation

In the isolated bronchial preparation of the guinea-pig, nicotine induced a contraction but not a relaxation. The contractile response of the bronchial preparation to nicotine was inhibited by hexamethonium and d-tubocurarine but not influenced by atropine and tetrodotoxin. In the isolated tracheal preparation of the guinea-pig where nicotine stimulated nicotinic receptor in nervous tissues, the contractile response to nicotine as considerably accelerated by the treatment of the guinea-pig with egg-albumin, while the contractile response of the bronchial preparation to nicotine was not influenced by the same treatment. These results suggest that a possible site of action of nicotine in the isolated bronchial preparation is not on the nervous cells but on the smooth muscle cells. However, we could not rule out a contribution by chemical mediators released by nicotine in the contractile mechanisms in the bronchial preparation.

Acetylcholine release elicited by electrical stimulation and its sites of action in smooth muscle of Mytilus

The effects of strychnine (ST), BTM-1042, hexamethonium (Hexa), tetraethylammonium (TEA), atropine (AT), benactyzine ( Bena ) and dithiothreitol (DTT) on phasic contraction in response to electrical pulses in Mytilus smooth muscle ( ABRM ) have been examined. ST (10(-7) to 5 X 10(-5) M), BTM-1042 (10(-5) to 10(-3) M), Hexa (10(-5) to 10(-3) M) and TEA (10(-5) to 10(-3) M) dose-dependently depressed the contraction. AT (10(-5) to 10(-3) M) had a little influence on the depression of the contraction, while Bena (5 X 10(-6) to 5 X 10(-4) M) dose-dependently depressed the contraction. DTT (10(-4) to 3 X 10(-3) M) depressed the contraction. These findings suggest that the mechanism of acetylcholine-release from excitatory nerve endings is partly similar to its release in the mammalian smooth muscle, and that the cholinergic receptors in ABRM are more like nicotinic receptors than muscarinic ones.