AND

sulfanilamido-4, 6-dimethylpyrimidine) were synthesized either at the same time as sulfadiazine or shortly thereafter (1-4). Until recently, however, these methyl diazines received scant attention even though preliminary studies (1-7) indicated that both derivatives had promising chemotherapeutic activity. Current con-ditions attendant to warfare in the tropics have stimulated search for a sulfona-mide possessing lower toxicity than sulfadiazine and equal or superior antibac-terial activities. This search again focused attention on sulfamerazine and sulfamethazine, and made it desirable to obtain more complete information on the pharmacology and chemotherapeutic activity of these compounds than has been available heretofore. The present study, an outgrowth of this need, deals with an experimental comparison of the toxicities of sulfamerazine, sul.fametha-zinc and sulfadiazine.’ The subjects investigated in this study include solubility, absorption and excre-tion, acute toxicity and chronic toxicity. Unless otherwise indicated, the acid drugs were used in all the studies described below