[Inhibition of carbonic anhydrase by xipamide (4-chloro-sulfamoyl-2',6'-salicyloxylidide) in the modified Philpot test].

The inhibition of carbonic anhydrase by xipamide (4-chloro-5-sulfamoyl-2',6'-salicyloxylidide, Aquaphor), a poorly watersoluble saluretic agent, is determined with the Philpot method in the presence of 5 per cent N,N-dimethyl-formamide. The addition of the amide does not affect the enzyme. For xipamide 1.1 times 10-5 M is found as the 50 per cent inhibitory concentration.