[Characterization of the analgetic properties of 3-amino-4-mercapto-6-methylpyridazine as compared with some standard pharmaca (author's transl)].

Using four screening methods (writhing syndrome, electrical stimulation of the root of the tail, tail-flick test and hot-plate test), the author studied the analgetic activities of 3-amino-4-mercapto-6-methylpyridazine (1; pyridazine S1) and several standard pharmaca. When applied subcutaneously, 1 showed an activity that was almost equal to that of aminophenazone. When administered orally, the activity of 1 was comparable to that of phenylbutazone. Indometacin and aminophenazone were more potent than 1; and acetylsalicylic acid and phenacetin were less potent. The synergism of 1 and codeine is superadditive as demonstrated by means of the tail-flick test and the writhing syndrome. When applied orally, 1 and phenacetin have the lowest acute toxicity as evidenced by the LD50 values. Acetylsalicylic acid, indometacin, phenylbutazone and aminophenazone are more toxic. From the results obtained it follows that, of all the substances tested, 1 has the greatest therapeutic index.