How sulfasalazine works
Sulfasalazine is used as a basic treatment for rheumatic diseases and inflammatory bowel disease (IBD). Rheumatism is a group of autoimmune diseases. This means that the immune system attacks and breaks down the body’s own tissue (such as joint cartilage). Chronic inflammatory bowel diseases are also caused by a faulty reaction of the immune system.
5-ASA is apparently responsible for the positive effect on IBD, while sulfapyridine seems to be mainly effective in rheumatism. Accordingly, sulfasalazine is used for both conditions.
Sulfasalazine is one of the few drugs from which two active ingredients are formed in the body at the same time.
Absorption, degradation and excretion
More than 90 percent of sulfapyridine is absorbed, while about 30 percent of 5-ASA is absorbed. Sulfapyridine is metabolized in the liver and excreted in the urine.
When is sulfasalazine used?
Sulfasalazine is used in the following areas of application (indications):
- Acute treatment and relapse prevention (relapse prophylaxis) of ulcerative colitis.
- Acute treatment of mild to moderate Crohn’s disease involving the colon (a section of the large intestine)
- Basic therapy of chronic polyarthritis (rheumatoid arthritis)
How sulfasalazine is used
Sulfasalazine is taken as a tablet. The dosage is determined individually by the doctor. To reduce side effects, the drug should be “phased in” slowly. This means that the treatment is started with a low dose, which is then slowly increased.
It is taken on a long-term basis, even when the patient is feeling better and has hardly any/no complaints. This is because if treatment is discontinued, the disease may worsen again. Sometimes sulfasalazine is used in combination with other medications.
What are the side effects of sulfasalazine?
Possible symptoms include nausea, vomiting, diarrhea and abdominal pain. Headaches, dizziness and fatigue may also occur. Such side effects are most noticeable in the first few weeks of treatment.
Some patients develop hair loss, itching, a skin rash, and painful blisters in the mouth and/or throat during treatment. Blood count changes may also occur.
In men, the active substance can impair fertility because it reduces sperm count (oligospermia) for the duration of use and for up to three months afterwards. Therefore, before starting treatment, any desire to have children in male patients should be clarified.
What should be considered when using sulfasalazine?
Contraindications
Sulfasalazine must not be taken in:
- glucose-6-phosphate dehydrogenase deficiency (a hereditary disease)
- pre-existing blood count abnormalities or diseases of the blood-forming organs
- severe liver or kidney dysfunction
- intestinal obstruction
- porphyria (a rare metabolic disorder)
- concurrent therapy with methenamine (a drug for excessive sweating)
Drug interactions
Conversely, antibiotics can reduce the breakdown of sulfasalazine into sulfapyridine and 5-ASA by disrupting the intestinal flora, thereby weakening its effect.
Other interactions are possible. Patients should therefore inform their doctor about all medications they are using – including over-the-counter preparations – before starting therapy.
Age restriction
Sulfasalazine is contraindicated in children under two years of age.
Pregnancy and lactation
However, if the active ingredient mesalazine shows the same therapeutic efficacy in patients with inflammatory bowel disease, it should be preferred over sulfasalazine.
How to obtain medicines containing sulfasalazine
Sulfasalazine requires a prescription in Germany, Austria, and Switzerland, so it is only available from pharmacies against a prescription.
