Medications and Drugs

Pharmacy Author: Omudhome Ogbru, PharmD
Medical and Pharmacy Editor: Jay W. Marks, MD

GENERIC NAME: mesalamine (5-aminosalicylic acid)

BRAND NAMES: Pentasa, Rowasa, Asacol, Lialda, Canasa

DRUG CLASS AND MECHANISM: Mesalamine is a drug used for treating ulcerative colitis. The exact mechanism of mesalamine is not known but is believed to be by reducing inflammation in the colon. Ulcerative colitis and other inflammatory diseases cause excessive production of chemicals, for example, prostaglandins, that produce inflammation in the colon. Prostaglandins are produced by the enzymes, cyclooxygenase and lipoxygenase. These enzymes are over-active in individuals with ulcerative colitis. Mesalamine may work by blocking the activity of cyclooxygenase and lipoxygenase, thereby, reducing the production of prostaglandins. Reduced production of prostaglandins decreases inflammation in the colon and the symptoms associated with ulcerative colitis. Available forms of mesalamine differ in their route of administration and how often they are administered. Mesalamine was approved by the FDA in December 1987.

PRESCRIPTION: Yes

GENERIC AVAILABLE: Yes (rectal enema)

PREPARATIONS:

• Tablets (delayed release): 400 mg (Asacol), 1.5 g (Lialda).
• Capsules (extended or delayed release): 375 mg (Apriso); 250, 500 mg (Pentasa).
• Rectal enema (Rowasa): 4 g per 60 mL.
• Rectal suppositories (Canasa): 1000 mg.

STORAGE: The tablets, capsules, and enemas should be stored at room temperature, 15-30 C (59-86 F). The suppositories should be stored below 25 C (77 F) without freezing.

PRESCRIBED FOR: Mesalamine is used for the treatment of mild to moderately severe ulcerative colitis. The suppositories are limited to use in ulcerative colitis involving only the rectum (proctitis) and the enemas to colitis involving only the part of the colon close to the rectum (distal colitis) or proctitis. While the benefits of mesalamine can be seen within 3 to 21 days of starting therapy, it may take up to three to six weeks for the enemas and suppositories, six weeks for the tablets, and eight weeks for the capsules to have maximum effect.

DOSING:

• Lialda: 2.4-4.8 g once daily with food
• Apriso: 1.5 g orally once daily
• Pentasa: 1 g four times daily
• Asacol: 800 mg two or three times daily
• Rowasa: One rectal application (4 g per 60 mL) once a day, preferably at bedtime, and retained for approximately 8 hours.
• Canasa: One suppository (1,000 mg) daily at bedtime. The suppository should be retained in the rectum for one to three hours or more if possible to achieve maximum benefit.

DRUG INTERACTIONS: Oral mesalamine formulations are associated with several drug interactions. Combining mesalamine with drugs that affect kidney function, for example, nonsteroidal antiinflammatory drugs (NSAIDs) or ibuprofen may increase the likelihood of reduced function of the kidneys. Concurrent use of mesalamine and 6-mercaptopurine or azathioprine (Imuran) may increase the likelihood of disorders of the blood cells, particularly reduced numbers of cells. Mesalamine may increase the blood thinning effect of warfarin (Warfarin).

PREGNANCY: There are no adequate human studies of mesalamine during pregnancy. Mesalamine is known to cross the placenta into the fetus, but animal studies revealed no evidence of harm to the fetus. Mesalamine should only be used during pregnancy if it is felt that the benefit of its use justifies the unknown risks.

NURSING MOTHERS: Mesalamine is excreted in breast milk. Mesalamine should only be used by nursing mothers if it is felt that the benefit of its use justifies the potential but unknown risk to the infant.

SIDE EFFECTS: The most common side effects of mesalamine are headache and flatulence. Hair loss and itching also may occur. Infrequent side effects include increased heart rate, acne, pancreatitis, back pain, fatigue, tremor, ear pain, and blood disorders.

Kidney dysfunction has been associated with mesalamine. Kidney function should be evaluated prior to and periodically during mesalamine therapy.

Mesalamine may cause an acute intolerance syndrome that resembles a flare of inflammatory bowel disease (Crohn's disease or ulcerative colitis) with cramping, abdominal pain, and bloody diarrhea. Fever, headache, itching, and rash also may occur. Symptoms usually subside once mesalamine is discontinued.

Mesalamine enemas contain sulfites and should be avoided in persons who are sensitive to sulfites.

Since mesalamine is related to aspirin in structure, individuals who are allergic to aspirin should not take mesalamine.

Reference: FDA Prescribing Information

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