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What is mesalamine, and how does it work (mechanism of action)?
Mesalamine is a drug used for treating ulcerative colitis and mild to moderate Crohn's disease. 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.
What are the side effects of mesalamine?
The most common side effects of mesalamine are:
- headache,
- flatulence,
- hair loss, and
- itching.
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.
What is the dosage for mesalamine?
(see dosing instructions provided by manufacturer)
- Lialda: 2.4-4.8 g once daily with food
- Apriso: 1.5 g orally once daily
- Pentasa: 1 g four times daily
- Asacol HD: 1.6 g 3 times daily
- Delzicol: 800 mg 3 times daily (has replaced Asacol; also available in extended release tablets)
- Rowasa: One rectal application (4 g per 60 mL enema) 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.
Which drugs or supplements interact with mesalamine?
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 (Coumadin).
Is mesalamine safe to take if I’m pregnant or breastfeeding?
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.
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.
What else should I know about mesalamine?
Generic forms of mesalamine are available for mesalamine rectal and suppository.
You need a prescription from your doctor or other health care professional for this medication.
Mesalamine is available as:
- Tablets (delayed release): 800 mg (Asacol), 1.2 g (Lialda).
- Capsules (extended or delayed release): 375 mg (Apriso); 250, 500 mg (Pentasa); 400 mg (Delzicol)
- Rectal enema (Rowasa, SfRowasa): 4 g per 60 mL.
- Rectal suppositories (Canasa): 1000 mg.
Pentasa, Rowasa, Asacol HD, Lialda, Canasa, Apriso, SfRowasa, and Delzicol are the brand names available for mesalamine in the US.
The tablets, capsules, and enemas should be stored at room temperature, 15 C – 30 C (59 F – 86 F). The suppositories should be stored below 25 C (77 F) without freezing.