Sulfasalazine

Sulfasalazine (brand name Azulfidine in the U.S., Salazopyrin in Europe) is a sulfa drug, a derivative of Mesalazine (5-aminosalicylic acid abbreviated as 5-ASA), used primarily as an anti-inflammatory agent in the treatment of inflammatory bowel disease as well as for rheumatoid arthritis. It is not a pain killer.

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Indications

See also Disease-modifying antirheumatic drugs for its role in rheumatoid arthritis

Sulfasalazine is mainly used for treatment of inflammatory bowel disease, including ulcerative colitis and Crohn's disease. It is also effective in several types of arthritis, particularly rheumatoid arthritis.

However, in recent British research involving animal studies, and more recently, human trials for the treatment of chronic alcoholics, sulfasalazine has been found to reverse the scarring associated with cirrhosis of the liver. Apparently, cells called myofibroblasts, that cause scar tissue to form in a diseased liver, also give off proteins that prevent the breakdown of the scar tissue. Sulfasalazine appears to retard the secretion of these proteins.

It is usually not given to children under 2 years of age.

The use of sulfasalazine has declined. 5-ASA, and other derivatives of 5-ASA, are now usually preferred, despite their increased cost, due to their more favourable side-effect profile (they do not yield the metabolite sulfapyridine - see below).

Mode of action

Sulfasalazine, and its metabolite 5-ASA, are poorly absorbed. Its main mode of action is therefore believed to be inside the intestine. In Crohn's disease and ulcerative colitis, it is thought to be an antinflammatory drug that is essentially providing topical relief inside the intestine.

When treatment for arthritis is successful, pain, joint swelling and stiffness will be reduced and this may slow down or stop the development of joint damage. The precise reasons why sulfasalazine is effective in various forms of arthritis is not clearly understood.

Because sulfasalazine and its metabolite 5-ASA are poorly absorbed into the bloodstream, it is surprising that the drug is effective against symptoms outside of the intestine. One possible explanation is that, given that ulcerative colitis produces arthritic symptoms, it is possible that, in some cases, the arthritic symptoms are actually a product of unrecognized ulcerative colitis, which is effectively treated with sulfazalazine.

Talk to your doctor if you have ulcerative colitis, as some patients that have both sets of symptoms of ulcerative colitis and arthritis may have ankylosing spondylitis, which is a genetic condition, and have the antigen HLA-B27. This is a genetic marker, and there is a test available for it. Sulfasalazine is also good for this.

The other metabolite, sulfapyridine, is absorbed into the blood, and is believed to be the source of the side-effects discussed below. It is possible that the sulfapyridine is responsible for some of the anti-arthritic effects of sulfasalazine.

Side effects

The most common side effect is nausea but often this can be controlled by a reduction in dose. Sometimes other medications may be needed. Occasionally mouth ulcers, a sore mouth or loose bowel motions may occur. Certain patients may develop a headache or slight dizziness but adjusting the dosage may bring things under control.

A rash may develop which may be itchy, but usually resolves quite quickly once the drug is stopped. Sulfasalazine can in rare cases cause a drop in the numbers of white blood cells which are needed to fight infection. If the blood count is monitored closely, it is unusual for this to be serious. Sulfasalazine can decrease the numbers of platelets, cells which help to stop bleeding, but again it is rare for this to actually cause problems. If however you develop a sore mouth, mouth ulcers, easy bruising, nosebleeds or bleeding gums, your doctor should be notified immediately.

The other potential problem is that sulfasalazine can cause a type of hepatitis (liver inflammation). This is most commonly minor and does not cause symptoms. Most often we find that some of the blood tests which reflect liver function may become a little abnormal but these soon return to normal if the treatment is stopped. A study at University of Newcastle found that the drug may also act to aid the healing of cirrhosis of the liver.[1]

Sulfasalazine always causes some orange discolouration of the urine and your perspiration may be a little orange-tinged. This will generally wash out of clothes, but will damage some nylon fabrics. Contact lenses, particularly extended-wear soft lenses may be permanently stained. It also causes semen to turn orange.

Sulfasalazine in rare cases can cause severe depression in young males.

Lastly, sulfasalazine may cause a decrease in the sperm count in men which may result in temporary infertility. This reverses when the drug is stopped. Temporary infertility may also occur in women. Sulfasalazine is considered to be safe in pregnancy, but should you wish to become pregnant, you should discuss this with your rheumatologist.

Sulfsalazine metabolizes to sulfapyridine. Serum levels should monitored every three months, and more frequently at the outset. Serum levels above 50 micrograms/L are associated with side effects.