Some initial animal and human pharmacological studies with benapryzine (BRL 1288)

1. The pA2 anti-acetylcholine activity in vitro for benapryzine was 6.55 compared with 9.02 for benzhexol.2. In vivo, the anti-acetylcholine activity of benapryzine relative to benzhexol was 0.038 as assessed by the mydriatic response of mice after subcutaneous administration. The relative activity assessed by the inhibition of pilocarpine-induced salivation was 0.13 after oral administration and 0.056 following subcutaneous administration of the drugs.3. Benapryzine had the same order of activity as benzhexol in inhibiting oxotremorine-induced tremors in mice.4. Benapryzine had anticonvulsant properties but no analgesic activity, whilst in high doses it antagonized the extrapyramidal symptoms induced by perphenazine in rats.5. In patients benapryzine was effective in reducing the symptoms of Parkinson's disease without overt anti-cholinergic effects or central hallucinogenic actions.6. Benapryzine abolished the excess tremor and reduced the rigidity and akinesia induced by physostigmine in Parkinsonian subjects.