ABSENCE OF ANXIOLYTIC EFFECTS OF CALCIUM-CHANNEL ANTAGONISTS

The potential anxiolytic effects of some calcium channel antagonists (nifedipine, nicardipine, and +/- verapamil) were investigated in the elevated plus-maze test in mice. The acute effects of the above-mentioned drugs were compared with those of phenobarbitone and +/- propanolol. Results showed that control mice spent less time in the open than in the closed arms, reflecting increased anxiety. Both phenobarbitone (20 mg/kg i.p.) and +/- propanolol (5 mg/kg i.p.) increased the percentage of entries into open arms as well as the time spent on the open arms. Nifedipine (2 and 4 mg/kg i.p.), nicardipine (0.5 and 1.0 mg/kg i.p.), and +/- verapamil (5 and 10 mg/kg i.p.) failed to alter significantly the behavior of mice. In summary, although there have been some reports based on other tests that calcium antagonists may have potential anxiolytic properties, this conclusion has not been supported by our results from the elevated plus-maze test.