Drug Class and Mechanism

Mesalamine is a derivative of salicylic acid and is thought to be the active component of sulfasalazine (Azulfidine), a combination of a sulfa drug and salicylic acid. Mesalamine works as an antiinflammatory agent in treating ulcerative colitis and Crohn's disease. Its benefit is believed to be due to a topical effect on the inflamed bowel. Following rectal administration of mesalamine (by enema or suppository), only 15% of a dose is absorbed. Following oral administration, 28% of a dose is absorbed. Mesalamine was approved by the FDA in December 1987.

Preparations

sustained-action gelatin capsules (Pentasa) containing 250mg; enteric coated tablets containing 400mg; rectal enema (Rowasa) containing 4 grams per 60 mL enema; rectal suppositories (Rowasa) containing 500mg.

Storage

The tablets, capsules, and enemas should be kept at room temperature, 15-30°C (59-86°F). The suppositories should be stored between 19-26°C (66-79°F).

Prescribed for

Mesalamine is used for the treatment of mild to moderately severe colitis. The suppositories are limited to use in proctitis, the enemas to distal colitis (colitis involving only the part of the colon close to the rectum) or proctitis.

Dosing

The enema is inserted rectally, generally once daily at bedtime. It should be retained for at least 8 hours. The bottle should be shaken well prior to use. The protective sheath must be removed. Many physicians recommend that the patient lie on his/her left side with the lower leg extended and the upper (right) leg flexed forward for balance for ease of administration.

The suppositories are often given twice daily; each should be retained for 1 to 3 hours or longer.

The 400mg delayed release (enteric-coated) tablets (Asacol) are generally taken 3 times a day. The sustained-action capsules (Pentasa) are generally taken 4 times a day during the acute phase, in order to induce remission.

While the benefits of mesalamine can be seen within 3 to 21 days of starting therapy, it may take up to 3 to 6 weeks for the enemas and suppositories, 6 weeks for the tablets, and 8 weeks for the capsules to have maximum effect.

Drug Interactions

There are no known drug interactions with any of the mesalamine products.

Pregnancy

There are no adequate studies of mesalamine in pregnant women; however, studies in animals suggest no important effects on the fetus. Therefore, mesalamine may be used in pregnancy if the physician feels that it is necessary. It also should be noted that there is no effect of mesalamine on sperm count as there is with sulfasalazine (Azulfidine).