Study of tolerance of central muscarinic receptor blockers

: The tolerance of five central muscarinic receptor antagonists has been studied in experimental animals. According to the effect on orientation-exploratory reaction, drugs were arranged in the following order of increasing toxicity: procyclidine 10) in mice. Scopolamine and atropine exhibited anticonvulsant activity at doses exceeding the threshold values by a factor of 6.3 and 3.9, respectively. For procyclidine, the average anticonvulsant dose was threefold lower than the threshold value. Benactizine and procyclidine had maximum tolerance levels in rats. The TD50/ED50 ratio for these drugs was greater than 3 (against 0.5 - 0.7 in groups treated with trihexiphenidyl, atropine and scopolamine).