Bioavailability of controlled release mesalazine (5-ASA) preparations.

Salazosulfapyridine was generated by Nanna Svartz in 1941. Mesalazine (5-ASA) was demonstrated in 1977 to be the therapeutically active moiety of salazosulfapyridine. Since then, a number of alternatives to salazosulfapyridine have appeared: olsalazine and salicylazobensoic acid, which are as salazosulfapyridine azo-preparations. Also, pure mesalazine drugs have been developed: Asacol, Claversal, and Pentasa. Despite the many similarities of these pure mesalazine controlled-release drugs, there are also significant differences. Some of these are due to different pharmaceutical designs of the delivery principle. Other important parameters are gastrointestinal pH variations in the healthy and diseased gut, and variations in ventricular emptying and in intestinal transit patterns.