Mesalamine is the common name of the compound 5-aminosalicylic acid or 5-ASA

Medications in this class (aminosalicyclates) are effective in inducing and maintaining remission of mild to moderate forms of ulcerative colitis. They exert a therapeutic effect through modulation of the chemical mediators that regulate inflammation of the inflammatory response, particularly prostaglandins and leukotrienes. Although it is usually absorbed quickly in the GI tract, different formulations allow the drug to target the affected intestines before it is absorbed.

(Salazopyrin ®
SAS ®)

Sulfasalazine is a conjugate of 5-ASA bonded to sulfapyridine, a sulfa drug. The sulfa component does not treat the disease but prevents 5-ASA from being absorbed until it reaches the colon. Intestinal bacteria break the drug down to release the active agent that treats the disease. Bacteria degrade sulfasalazine into its two components.

Sulfasalazine is useful for treating mild to moderate attacks of ulcerative colitis and for maintaining remission. It is helpful for some Crohn's disease patients whose disease occurs in the colon, but it is not effective in the small intestine and does not prevent recurrence there.

5-ASA Delayed Release Preparations
To reduce side effects, researchers developed newer formulations that allow 5-ASA to reach the lower intestine without the need for a sulfa component. They may use special coatings or time-released formulations to prevent the absorption of 5-ASA in the upper intestine. Different brands (listed below) target different regions in the GI tract.
Pentasa ®
This tablet is formulated to release microgranules of 5-ASA throughout the intestines that is useful for disease in the small intestine and colon.
Asacol ® This tablet is effective in the terminal ileum (last section of small intestine) and the colon.
Salofalk ® This tablet is designed to release 5-ASA in the ileum and colon
Mezavant ® This tablet is designed to release 5-ASA in the colon. It can be taken once per day instead of the divided daily doses that are usually necessary for other 5-ASA preparations.
Olsalazine (Dipentum) ®
Olsalazine is similar to sulfasalazine in that intestinal bacteria break it down into two components.
5-ASA Enemas & Suppositories 5-ASA Enemas and suppositories help patients with ulcerative colitis of the lower colon (rectum, sigmoid colon). They are sometimes used in combination with oral 5-ASA delayed release preparations for patients with ulcerative colitis involving more than just the lower colon.

Side Effects of 5-ASA Preparations:

With all 5-ASA preparations, taking it with food can minimize the some of the side effects. Rarely, 5-ASA can cause kidney problems and pancreatitis.

The sulfa component of sulfasalazine is responsible for most of this drug's side effects. Some side effects may include allergic reactions, loss of appetite, dizziness, anemia, fatigue, and skin reactions. The drug may temporarily lower sperm count in men and can turn urine a bright orange-yellow colour. Rare but serious side effects include lupus-like disorder, liver damage, pancreatitis and blood disorders.