Ulcerative Colitis

  • Medical Author: Adam Schoenfeld, MD
  • Medical Author: George Y. Wu, MD, PhD
  • Medical Editor: Jay W. Marks, MD
    Jay W. Marks, MD

    Jay W. Marks, MD

    Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

Quick GuideUlcerative Colitis Symptoms, Causes, and Treatment

Ulcerative Colitis Symptoms, Causes, and Treatment

5-ASA Compounds

5-ASA (5-aminosalicylic acid), also called mesalamine, is chemically similar to aspirin. Aspirin (acetylsalicylic acid) has been used for many years in treating arthritis, bursitis, and tendinitis (conditions of tissue inflammation). Aspirin, however, is not effective in treating ulcerative colitis. On the other hand, 5-ASA can be effective in treating ulcerative colitis if the drug can be delivered directly (topically) onto the inflamed colon lining. For example, Rowasa enema is a 5-ASA solution that is effective in treating inflammation in and near the rectum (ulcerative proctitis and ulcerative proctosigmoiditis). However, the enema solution cannot reach high enough to treat inflammation in the upper colon. Therefore, for most patients with ulcerative colitis, 5-ASA must be taken orally. When pure 5-ASA is taken orally, however, the stomach and upper small intestine absorb most of the drug before it reaches the colon. Therefore, to be effective as an oral agent for ulcerative colitis, 5-ASA has to be modified chemically to escape absorption by the stomach and the upper intestines. These modified 5-ASA compounds are sulfasalazine (Azulfidine), mesalamine (Pentasa, Rowasa, Asacol, Lialda, Apriso), and olsalazine (Dipentum).


Sulfasalazine (Azulfidine) has been used successfully for many years in inducing remission among patients with mild to moderate ulcerative colitis. Inducing remission means decreasing intestinal inflammation and relieving symptoms of abdominal pain, diarrhea, and rectal bleeding. Sulfasalazine has also been used for prolonged periods of time to maintain remissions.

Sulfasalazine consists of a 5-ASA molecule linked chemically to a sulfapyridine molecule. (Sulfapyridine is a sulfa antibiotic). Connecting the two molecules together prevents absorption by the stomach and the upper intestines prior to reaching the colon. When sulfasalazine reaches the colon, the bacteria in the colon will break the linkage between the two molecules. After breaking away from 5-ASA, sulfapyridine is absorbed into the body and then excreted in the urine. Most of the active 5-ASA drug, however, remains in the colon to treat colitis.

Most of the side effects of sulfasalazine are due to the sulfapyridine molecule. These side effects include nausea, heartburn, headache, anemia, skin rashes, and, in rare instances, hepatitis and kidney inflammation. In men, sulfasalazine can reduce the sperm count. The reduction in sperm count is reversible, and the count usually returns to normal after discontinuing sulfasalazine or by changing to a different 5- ASA compound.

The benefits of sulfasalazine generally are dose related. Therefore, high doses of sulfasalazine may be necessary to induce remission. Some patients cannot tolerate high doses because of nausea and stomach upset. To minimize stomach upset, sulfasalazine generally is taken after or with meals. Some patients find it easier to take Azulfidine-EN (enteric-coated form of sulfasalazine). Enteric-coating helps decrease stomach upset. The newer 5-ASA compounds do not have the sulfapyridine component and have fewer side effects than sulfasalazine.


Asacol is a tablet consisting of the 5-ASA compound, mesalamine, surrounded by an acrylic resin coating. (Asacol is sulfa free.) The resin coating prevents the 5-ASA from being absorbed as it passes through the stomach and the small intestine. When the tablet reaches the terminal ileum and the colon, the resin coating dissolves, thus releasing 5-ASA into the colon.

Asacol is effective in inducing remissions in patients with mild to moderate ulcerative colitis. It also is effective when used for prolonged periods of time to maintain remissions. The recommended dose of Asacol to induce remission is two 400-mg tablets three times daily (total of 2.4 grams a day). Two tablets of Asacol twice daily (1.6 grams a day) is recommended for maintaining remission. Occasionally, the maintenance dose is higher.

As with Azulfidine, the benefits of Asacol are dose-related. If patients do not respond to 2.4 grams a day of Asacol, the dose frequently is increased to 3.6 grams a day (and sometimes even higher) to induce remission. If patients fail to respond to the higher doses of Asacol, then alternatives, such as corticosteroids, are considered.


Lialda (mesalamine multi matrix, MMX) is an extended release formulation. It is a 5-ASA medication within an inert matrix that is surrounded by a coating. When the capsule reaches the distal ileum, the outer coating (the capsule) dissolves. The intestinal fluid then is absorbed into the matrix forming a gel-like substance which prolongs the contact of the medication with the colonic wall as the mesalamine slowly separates from the matrix. This extended release formulation allows for higher doses to be taken less frequently throughout the day and might and improve compliance.

The most common side effects experienced while taking Lialda are flatulence, abdominal pain, headache, nausea, and dyspepsia.


Apriso is another formulation of 5-ASA that consists of extended-release mesalamine granules encased in microcrystalline cellulose within a capsule. Dissolution of the capsule occurs in the distal ileum, and, since the granules are encased in the cellulose and only slowly separates from the cellulose, there is prolonged delivery of medication as the cellulose and mesalamine travel through the colon.

The most common side effects of this medication are headache, diarrhea, abdominal pain, nausea, nasopharyngitis, influenza-like illness, and sinusitis.


Pentasa is a capsule consisting of the 5-ASA compound mesalamine inside controlled-release spheres. Like Asacol, it is sulfa free. As the capsule travels down the intestines, the 5-ASA inside the spheres is slowly released into the intestines. Unlike Asacol, the mesalamine in Pentasa is released into the small intestine as well as the colon. Therefore, Pentasa can be effective in treating inflammation in the small intestine and the colon. Pentasa is currently the most logical 5-ASA compound for treating mild to moderate Crohn's disease involving the small intestine. Pentasa also is used to induce remission and maintain remission among patients with mild to moderate ulcerative colitis.

Olsalazine (Dipentum)

Olsalazine (Dipentum) consists of two 5-ASA molecules linked together. It is sulfa free. The linked 5-ASA molecules travel through the stomach and the small intestine unabsorbed. When the drug reaches the terminal ileum and the colon, the normal bacteria in the intestine break the linkage and release the active drug into the colon and the terminal ileum. Olsalazine has been used in treating ulcerative colitis and in maintaining remissions. A side effect unique to olsalazine is secretory diarrhea (diarrhea resulting from excessive production of fluid in the intestines). This condition occurs in some patients, and the diarrhea sometimes can be severe.

Balsalazide (Colazal

Balsalazide (Colazal) is a capsule in which the 5-ASA is linked by a chemical bond to another molecule that is inert (without effect on the intestine) and prevents the 5-ASA from being absorbed. This drug is able to travel through the intestine unchanged until it reaches the end of the small bowel (terminal ileum) and colon. There, intestinal bacteria break apart the 5-ASA and the inert molecule, releasing the 5-ASA. Because intestinal bacteria are most abundant in the terminal ileum and colon, Colazal is used to treat inflammation predominantly localized to the colon.

More clinical trials are needed to compare the effectiveness of Colazal to the other mesalamine compounds such as Asacol in treating ulcerative colitis. Therefore in the United States, choosing which 5-ASA compound has to be individualized. Some doctors prescribe Colazal for patients who cannot tolerate or fail to respond to Asacol. Others prescribe Colazal for patients with predominantly left sided colitis, since some studies seem to indicate that Colazal is effective in treating left sided colitis.

Side Effects of 5-ASA Compounds

The sulfa-free 5-ASA compounds have fewer side effects than sulfasalazine and also do not impair male fertility. In general, they are safe medications for long-term use and are well-tolerated.

Patients allergic to aspirin should avoid 5-ASA compounds because they are chemically similar to aspirin.

Rare kidney inflammation has been reported with the use of 5-ASA compounds. These compounds should be used with caution in patients with known kidney disease. It also is recommended that blood tests of kidney function be obtained before starting and periodically during treatment.

Rare instances of acute worsening of diarrhea, cramps, and abdominal pain may occur which is at times may be accompanied by fever, rash, and malaise. This reaction is believed to represent an allergy to the 5-ASA compound.

Rowasa Enema

Rowasa is the 5-ASA compound mesalamine in enema form and is effective in ulcerative proctitis and ulcerative proctosigmoiditis (two conditions where active 5-ASA drugs taken as enemas can easily reach the inflamed tissues directly). Each Rowasa enema contains 4 grams of mesalamine in 60 cc of fluid. The enema usually is administered at bedtime, and patients are encouraged to retain the enema through the night.

The enema contains sulfite and should not be used by patients with sulfite allergy. Otherwise, Rowasa enemas are safe and well-tolerated.

Rowasa also comes in suppository form for treating limited proctitis. Each suppository contains 500 mg of mesalamine and usually is administered twice daily.

While some patients improve within several days of starting Rowasa, the usual course of treatment is three to six weeks. Some patients may need even longer courses of treatment for optimal benefit. In patients who do not respond to Rowasa, oral 5-ASA compounds (such as Asacol) can be added. Some studies have reported increased effectiveness in treating ulcerative proctitis and proctosigmoiditis by combining oral 5-ASA compounds with Rowasa enemas. Oral 5-ASA compounds also are used to maintain remission in ulcerative proctitis and proctosigmoiditis.

Another alternative for patients who fail to respond to Rowasa or who cannot use Rowasa is cortisone enemas (Cortenema). Cortisone is a potent anti-inflammatory agent. Oral corticosteroids are systemic drugs with serious and predictable long-term side effects. Cortenema is a topical corticosteroid that has less absorption into the body than oral corticosteroids, and, therefore, it has fewer and less severe side effects.

Medically Reviewed by a Doctor on 2/29/2016

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