1) As a preliminary experiment, toxicity and analgesic effect (by the modified Haffner method) of dialkylaminoacylamino derivatives of p-phenetidine and antipyrine against mice were tested and it was found that 4-dimethylaminoacetylaminoantipyrine (V) and 4-α-dimethylaminopropionylaminoantipyrine (VII) possessed far stronger actions than the other compounds tested.
2) As a result of the determination of pain threshold in man with radiant heat apparatus, analgesic effect of (VII) was found to be stronger than that of (V) which possessed stronger effect than aminopyrine.
3) Neither (V) nor (VII) effected the lowering of body temperature in febrile rabbits and normal mice.
4) Effect on respiration and blood pressure of dogs was the weakest in (V), (VII) having weaker effect than aminopyrine.
5) Successive intravenous administration of (VII) for 5 days to rabbits failed to give any apparent effect on leucocyte counts.
6) Solubility of (V) and (VII) in water was over 30%.
7) The purpose of the preparation of the derivatives and observations of experimental results were made.
