Telenzepine dihydrochloride

Neuropharmacology of the muscarinic antagonist telenzepine in myenteric ganglia of the guinea-pig small intestine.[Pubmed:1868879]

Eur J Pharmacol. 1991 Apr 3;195(3):333-9.

Intracellular recording methods were used to investigate the actions of the putative M1 muscarinic receptor antagonist telenzepine on the electrical and synaptic behavior of myenteric neurons. Telenzepine had no effect on resting membrane potential, input resistance, excitability and antidromic potentials in both AH/type 2 and S/type 1 neurons, when applied in concentrations of 0.1-2000 nM, although higher concentrations (10-100 microM) did have a significant non-specific effect on the postsynaptic membrane. Micromolar concentrations of telenpzepine (1-2 microM) had no effect on excitatory responses to substance P, vasoactive intestinal peptide, the nicotinic agonist 1,1-dimethyl-4-phenylpiperazinium or the nicotinic action of acetylcholine. Nicotinic fast excitatory postsynaptic potentials were also unaffected by 2 microM telenzepine. In contrast, at submicromolar concentrations (100 nM), telenzepine abolished responses to either muscarine or the muscarinic component of the acetylcholine response. The excitatory effect of muscarine at postsynaptic M1 receptors was dose dependently inhibited by telenzepine (0.1-1000 nM) at concentrations which had no effect on the electrical properties of the cells. This effect was slowly reversible, usually requiring more than 60 min for significant recovery. The threshold dose of telenzepine as an antagonist of the muscarinic depolarization in AH/type 2 neurons was in the range of 0.1-1 nM. The IC50 concentration of telenzepine needed to abolish the response was 8.5 nM. A small proportion of stimulus-evoked slow excitatory postsynaptic potentials in both AH/type 2 and S/type 1 cells were abolished by 1 microM telenzepine, while the majority of them remained unaffected, indicating that some slow excitatory postsynaptic potentials are mediated by the muscarinic action of released acetylcholine.(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction of telenzepine with muscarinic receptors in mammalian sympathetic ganglia.[Pubmed:2776837]

Eur J Pharmacol. 1989 Aug 11;167(1):1-10.

The interaction of the antimuscarinic drug telenzepine with muscarinic receptors was studied in rabbit and rat isolated superior cervical sympathetic ganglia. Radioligand binding demonstrated two muscarinic receptor sites in rabbit ganglia, with the characteristics of M1- and M2-receptors. Telenzepine bound to the M1 sites with a KI of 0.94 nmol/l and to the M2 sites with a KI of 17.8 nmol/l; the corresponding values for pirenzepine were 18.6 and 588 nmol/l; for AF-DX 116 the values were 891 and 33 nmol/l respectively. [3H]Telenzepine dissociated from the M1-receptors with a half time of 46 min at 37 degrees C. Electrophysiological experiments demonstrated that telenzepine reduced the amplitude of the extracellularly recorded slow excitatory postsynaptic potential and the slow inhibitory postsynaptic potential (ED50: 38 and 253 nmol/l respectively). In rat ganglia, application of muscarine or the M1-receptor agonist McN-A-343 increased the amplitude of submaximal population action potentials. This facilitation of synaptic transmission was potently blocked by telenzepine and pirenzepine but only weakly by AF-DX 116 (ED50: ca. 30, 150 and 20 mumol/l, respectively). It is concluded that telenzepine blocks the generation of the slow excitatory postsynaptic potential and the excitatory action of muscarine and McN-A-343 via an action on muscarinic M1-receptors.

Pharmacological evidence for selective inhibition of gastric acid secretion by telenzepine, a new antimuscarinic drug.[Pubmed:4029260]

Eur J Pharmacol. 1985 Jun 7;112(2):211-24.

The new antisecretory drug, telenzepine (4,9-dihydro-3-methyl-4-[(4-methyl-1-piperazinyl)acetyl]-10H-thieno-[3,4 - b][1,5]benzodiazepin-10-one), was investigated for its inhibition of functionally intact muscarinic receptors involved in gastric acid secretion in rabbit fundic glands, perfused mouse stomach in vitro, perfused rat stomach in situ, gastric fistula in rats and dogs with a Heidenhain pouch. The effects on these receptors were contrasted with effects on receptors located on smooth muscle and heart, i.e. isolated rat urinary bladder, stomach and atrium. The results were compared to those values obtained with nonselective antimuscarinic drugs (N-methylscopolamine, atropine) and the selective M-1 antagonist pirenzepine. Telenzepine was found to be 4-10 times more potent than pirenzepine with respect to depressing both gastric acid secretion and smooth muscle or myocardial responses. Based on -log EC50 and pA2 values, both drugs exhibited a similar selectivity profile differing from the pattern of effects observed with atropine or a second reference compound, zolenzepine. As compared with atropine, telenzepine exhibited a 5 fold higher relative affinity to muscarinic receptors involved in gastric acid secretion. It was concluded that telenzepine is selective to discriminate between muscarinic receptors mediating gastric acid secretion and affecting muscle contractility and that this finding supports the concept of muscarinic receptor heterogeneity.