Other Mesalamine Prodrugs. Olsalazine (Dipentum) and balsalazide (Colazal) are similar to sulfasalazine, in that they are broken down by intestinal bacteria into two components, one of which is mesalamine. Unlike sulfasalazine, however, the other component in each drug is a harmless molecule that does not produce the adverse side effects of the sulfa component. (Mesalamine side effects in all three drugs are the same.) Studies suggest that these newer preparations are effective both for first-line treatment and for maintenance in mild-to-moderate UC. Major 2002 analyses suggest that although they may be more effective in inducing remission than sulfasalazine, they are not as effective for maintenance. They are also considerably more expensive. They may have greater adverse effects on the kidney than sulfasalazine, so kidney function should be monitored periodically.
Mesalamine Enemas and Suppositories. Mesalamine enemas (Rowasa) and suppositories (Canasa) are available. Rowasa is effective for ulcerative colitis in the rectum and lower colon. Canasa is useful only in the rectum. Rowasa relieves mild-to-moderately active UC and prevents relapse. According to a 2000 review, mesalamine enemas are more effective than steroid enemas and oral therapies for left-sided ulcerative colitis.
Delayed or Sustained Release Mesalamines. Formulations have been developed that allow mesalamine alone to reach the lower intestine without the need for the sulfa component. A number of oral forms of mesalamine use coatings or time-released formulations to prevent absorption in the upper intestine. Different brands affect different regions in the intestine:
- Pentasa is an oral sustained-release mesalamine that is coated in a substance called ethyl cellulose. It is slowly released from the stomach through the intestine and is the only aminosalicylate that works in both the small intestine and colon. Twelve-month remission rates of up to 64% have been reported in patients with mild-to-moderate ulcerative colitis.
- Asacol and Salofalk are coated with an acrylic, and the active drug is released in an alkaline environment. It is therefore effective from the colon through the last section of the ileum. Studies have indicated that it has resulted in symptomatic improvement, including remission, in nearly three-quarters of patients with mild-to-moderate ulcerative colitis. In low doses, Asacol does not appear to be as effective as olsalazine for maintaining remission, although higher doses or combinations may improve its effectiveness.
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