Benzolamide is not a membrane-impermeant carbonic anhydrase inhibitor.

Article Details


Supuran CT, Scozzafava A

Benzolamide is not a membrane-impermeant carbonic anhydrase inhibitor.

J Enzyme Inhib Med Chem. 2004 Jun;19(3):269-73.

PubMed ID
15499999 [ View in PubMed

Benzolamide, an orphan drug belonging to the pharmacological class of sulfonamide carbonic anhydrase (CA, EC inhibitors (CAIs) is widely used in many physiological and pharmacological studies, together with the clinically employed classical drugs, acetazolamide, methazolamide, ethoxzolamide or dichlorophenamide, it being frequently stated that benzolamide is a membrane-impermeant inhibitor. We prove here that this is false: in fact benzolamide is rather similar to acetazolamide from the point of view of penetrability through blood red cell membranes. Unlike these neutral drugs, the cationic, positively-charged CAIs incorporating either tetraalkyl ammonium or pyridinium moieties, due to their salt-like character are indeed membrane-impermeant, being the only type of low molecular weight compound possessing such properties. Selective inhibition of membrane-associated CA isozymes is relevant indeed in many physiological studies and also pharmacologically, since the tumor-associated isozymes (CA IX and XII) are both membrane-bound.

DrugBank Data that Cites this Article

Binding Properties
DrugTargetPropertyMeasurementpHTemperature (°C)
5-[(phenylsulfonyl)amino]-1,3,4-thiadiazole-2-sulfonamideCarbonic anhydrase 2Ki (nM)97.420Details
AcetazolamideCarbonic anhydrase 1Ki (nM)9007.420Details
AcetazolamideCarbonic anhydrase 2Ki (nM)127.420Details
AcetazolamideCarbonic anhydrase 4Ki (nM)2207.420Details
MethazolamideCarbonic anhydrase 1Ki (nM)7807.420Details
MethazolamideCarbonic anhydrase 2Ki (nM)147.420Details
MethazolamideCarbonic anhydrase 4Ki (nM)2407.420Details