Analgesic activity of (+)-1-(3-methyl-4-morpholino-2:2-diphenylbutyryl) pyrrolidine (R.875) in student volunteers.

(+)-1-(3-Methyl-4-morpholino-2:2-diphenylbutyryl)pyrrolidine (R.875) raised the threshold to ischaemic pain in healthy human volunteers. The peak effect for all doses was reached after about 2 hr. The drug frequently caused nausea and vomiting but no euphoria. Muscular weakness was experienced by many subjects and was sometimes followed 1 to 2 hr. later by hiccup and muscle twitching, suggesting that R.875 may have an effect on striped muscle.