5-ASA (mesalamine) preparations were the first drugs to be used for IBD. 5-ASA preparations are a combination of sulfapyridine and the 5-ASA mesalamine to create sulfasalazine. These drugs have been shown since the 1940s to reduce the severity of bowel symptoms in ulcerative colitis.
They are generally more useful for colitis than Crohn's. They are usually taken orally and are considered to be topical in this case because they coat the colon, which is why they are more useful for colitis (which affects the inner lining of the colon) rather than Crohn's. These drugs are considered first-line in the treatment of colitis.
Scientists do not yet know why sulfasalazine is effective in colitis but studies have shown it may be due to the mesalamine component, and as a result, other formulations have been created that include mesalamine. These drugs are thought to act as anti-inflammatory agents that inhibit certain proteins and alter parts of our metabolism.
Examples of these medications include mesalamine, sulfasalazine, and olsalazine. They come in different forms in addition to oral medications, including suppositories.
Here is a summary of the effectiveness of sulfasalazine/5-ASAs for management of IBD:
5-ASAs are very effective at inducing remission in active mild-to-moderate ulcerative colitis.
5-ASAs are very effective at preventing relapse in inactive ulcerative colitis.
5-ASAs are NOT effective at inducing remission in active Crohn's disease or preventing relapse in inactive Crohn's disease.
5-ASAs are considered very safe because they do not reach the bloodstream. Common side effects include rash, nausea, headaches, increased diarrhea, reduced appetite, or hair loss.
Sulfapyridine can cause dose-related and hypersensitivity side effects, including reduction in male fertility (which goes back to normal after stopping the drug) and the rare risk of a disease called blood dyscrasia.
Rare side effects of the mesalamine component of these drugs include interstitial nephritis (a kidney disorder), pancreatitis (inflammation of the pancreas), pneumonitis (lung inflammation), pericarditis (inflammation of a tissue surrounding the heart), and hepatitis (liver inflammation).