Dimetotiazine Mesilate

We investigated the effects of KB-2796 (1-[bis(4-fluorophenyl)methyl]-4-(2,3,4-trimethoxybenzyl)piperazine dihydrochloride), a novel calcium channel blocker, on neurogenic inflammation caused by electrical stimulation in the trigeminal ganglion and on cutaneous reactions induced by inflammatory mediators in rats, by measuring plasma extravasation. Neurogenic inflammation was inhibited by pretreatment with capsaicin (25 mg/kg, s.c.) but not indomethacin (10 mg/kg, i.p.), while phosphoramidon (2.5 mg/kg, i.v.) augmented it. KB-2796 (0.1-1 mg/kg, i.v.) significantly inhibited neurogenic inflammation in a dose dependent manner, without affecting histamine-, bradykinin- or substance P-induced cutaneous reactions. Dimetotiazine (0.3 and 1 mg/kg, i.v.), flunarizine (1 mg/kg, i.v.), mepyramine (1 mg/kg, i.v.) and sumatriptan (1 mg/kg, i.v.) significantly inhibited neurogenic inflammation. However, these compounds also showed complete or partial inhibition of histamine-, bradykinin- or substance P-induced reactions. Nifedipine (0.1 mg/kg, i.v.) did not show marked effects on neurogenic inflammation and cutaneous reactions. The present experiments indicate that neurogenic inflammation is presumably mediated not only by neuropeptides released from trigeminal nerve endings but also by secondarily released histamine, and that KB-2796 like sumatriptan may inhibit neurogenic inflammation caused by trigeminal nerve stimulation probably through inhibition of neuropeptide release but its inhibition may be distinct from the calcium blocking action of the 1,4-dihydropyridine type.

We investigated the effect of lomerizine, an anti-migraine drug, on the Ba2+ current through voltage-gated Ca2+ channels in rat pheochromocytoma (PC12) cells using a whole-cell voltage-clamp technique. Lomerizine inhibited the Ba2+ current with an IC50 value of 1.9 microM. Lomerizine and nicardipine were >4 times more potent than flunarizine, diltiazem, verapamil and dimetotiazine. The time course of inactivation induced by lomerizine was similar to that induced by nicardipine and flunarizine. These data indicate that lomerizine may inhibit the Ca2+ channel in a similar manner to nicardipine and flunarizine, and its potency is almost equal to that of nicardipine.