absorption of the former vras faster. Sulfagiaanidine was absorbed more 

 slowly and reached a lower concentration than sulfadiazine and both 

 attained lower levels than either sulfamerazine or sulfamethazine. 

 Sulfathiazole was only slightly absorbed, Suifathalidine and 

 snlfaquinoxaline were net taken up from the intestinal tract. All 

 sulfonamides were given to fingerlings weighing 2.5 to 4,0 gm, at a 

 dose rate of 20 rag. per 100 gm, of fish per day- 



The concentration of sulfamerazine in yearling brook trout (S. 

 f ontinalis ) increases most rapidly and reaches the highest levels in 

 blood and liver (Snieszko and Friddie 19:51). These were found to be 

 slightly over 25 mg, percent by the ninth day for blood and about 22 mg. 

 percent ty the same day in the case of liver. For these experiments 

 sulfamerazine was given at the rate of 20 mg, per 100 gm. of fish per 

 day. Results for kidney and muscle were approximately 12.5 and 9 mg. 

 percent, respectively^ The concentration of the drug increased rapidly 

 up to the ninth day but then dropped sharply even though the dosage was 

 continued at the same rate. In the g-at^ the drug concentration remained 

 well over 100 mg, percent during treatment. This indicates that either 

 sulfamerazine is accumulated in the alimentary tract or is excreted 

 until some balance is achieved between the concentration in blood and 

 the intestine. When the diet containing sulfamerazine was discontinued 

 (after the thirteenth day)c, the concentration of the drug decreased 

 uniformly in blood and other tissues. 



The tissue concentrations of sulfamerazine given at constant rates 

 have been found to be higher in older trout than in younger trout, even 

 though the former were fed at lower rates. Whether this is related to 

 age or not;, can only be determined by further experiments (Snieszko and 

 Friddie 1951), 



To test the effect of high initial doses Snieszko and Friddie 

 (1951) treated brook trout fingerlings (S, f ontina lis ) with sulfamerazine 

 at first at the relatively high rate of 30 mg, per 100 gm. of fish per 

 day. The tissue concentration slowly rose until it began to level off 

 on the 4-th day at 9 mg, percent. From the sevtnth day„ fish in each of 

 three groups received sulfamerazine at different rates of 30j 20, and 10 

 mg, percent. In these receiving 10 and 20 mg, daily doses,, the tissue 

 level dropped considerably within several days. However,, it was only 

 slightly higher than in trout used in other experiments in vrfiich fishes 

 were treated with identical dosages but without the benefit of the high 

 initial doses. The only advantage of high initial dosage in trout was 

 the somewhat shortened time with wnich the higher tissue level was 

 reached. The subsequent lower doses did not permit the maintenance of 

 T.he high tissue concentration obtained by the high initial dosage. 



Dosage, duration of treatment and final recommendations 



In the treatment of trout for funmculosis, it is essential that 

 a relatively high initial dose of sulfonamide be given. EX'-idence from 

 recent work (Flakas 1950b) would indicafce that when B, salrnonlcida enters 



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