The calcium entry blockers: anti-manic drugs?

The reported property of calcium antagonists as antimanic drugs has been investigated in three models of hyperactivity in mice. The hyperactivity was induced by amphetamine, oxolinic acid or reserpine after inhibition of monoamine oxydase (MAO). Nicardipine (a dihydropyridine derivative) reduces the three hyperactivities, verapamil (a diphenylalkylamine derivative) reduces only oxolinic acid hyperactivity, and diltiazem (a benzothiazepine derivative) was active except in the MAOI-reserpine test. Levomepromazine used as a reference drug reduced the three hyperactivities. The three calcium entry-blockers reduce the different hyperactivities at doses which already decrease motor activity. And so, it seems that their action was not specific. On the contrary, levomepromazine antagonizes MAOI-reserpine induced hypermotility at a dose which is not sedative. These results do not strengthen the property of calcium antagonists as antimanic drugs.