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Sulfasalazine, mesalazine, olsalazine, and balsalazide are the main drugs for the treatment of inflammatory bowel disease (IBD), but the four drugs are very different. Only by mastering the differences between them can the drug be selected correctly.


I. Ulcerative colitis, the difference between Crohn’s disease

If you don’t understand the difference between the two diseases, you can’t choose the right medicine.

Inflammatory bowel disease is a type of chronic, idiopathic inflammatory disease that occurs in the intestine, including two subtypes of ulcerative colitis and Crohn’s disease.

Ulcerative colitis, mainly in the colon and rectum; Crohn’s disease, can occur throughout the gastrointestinal tract, but occurs in the ileum and colon.

Tips: Inflammatory bowel disease can not only cause diarrhea, abdominal pain, intestinal bleeding, but also related to arthritis and ankylosing spondylitis.


II. Mesalazine, the real prototype drug

Mesalazine, chemically known as 5-aminosalicylic acid.

Oxalazine is an azo compound of two 5-aminosalicylic acids.

Sulfasalazine is an azo compound of 5-aminosalicylic acid and sulfapyridine.

Balsalazide is an azo compound of 5-aminosalicylic acid and an inert compound (no biological activity).

5-Aminosalicylic acid (ie mesalamine) is a common active ingredient of four drugs. Each 1 g of olsalazine, sulfasalazine, and balsalazide are equivalent to 1.00, 0.40 g, and 0.36 g of mesalazine, respectively.


III. Oxalazine, sulfasalazine, balsalazide, are oral targeted drugs

Oxalazine, sulfasalazine, and balsalazide need to pass through the decomposition of bacteria in the colon (which can produce azoreductase) to release 5-aminosalicylic acid (mesalazine) and act as oral Targeting drugs.

The lesions of ulcerative colitis are mostly located in the colon and rectum. Therefore, olsalazine, sulfasalazine, and balsalazide are particularly suitable for the treatment of ulcerative colitis.

Because antibacterial drugs can inhibit bacteria in the colon, in addition to mesalazine, olsalazine, sulfasalazine, balsalazide, should not be combined with antibacterial drugs.


IV. Different dosage forms of mesalazine for different diseases

After oral administration of mesalazine tablets, most of them are rapidly absorbed through the upper digestive tract, so an enteric preparation is required.

Mesalazine enteric-coated tablets and sustained-release tablets (ethylcellulose coating preparation), the release site in the jejunum, ileum, colon, can be used to treat Crohn’s disease (the ileum and colon of the predilection site).

Mesalazine sustained release granules (pH-dependent polymethacrylate coating), the release site at the end of the ileum and the colon, is more suitable for the treatment of ulcerative colitis.

Mesalazine suppository is only used for the treatment of ulcerative colitis involving the rectum; mesalazine enema can be used for the treatment of ulcerative colitis involving the colon.

The release characteristics of mesalazine in different dosage forms vary widely, so they are not interchangeable.


V. Sulfasalazine, the most common adverse reaction

Osalazine = mesalazine + mesalazine; balsalazide = mesalazine + inert compound; sulfasalazine = mesalazine + sulfapyridine.

Sulfapyridine can be absorbed into the blood circulation. Adverse reactions of sulfasalazine = sulfapyridine adverse reactions + mesalazine adverse reactions.

special reminder:

Mesalazine, 5-aminosalicylic acid, is a salicylic acid drug, but its therapeutic effect is independent of its inhibition of cyclooxygenase (COX). Traditional non-steroidal anti-inflammatory drugs, and selective (COX-2) inhibitors (such as celecoxib) can aggravate inflammatory bowel disease.


VI. Medication should be kept in mind

1. Mesalazine, olsalazine, balsalazide, sulfasalazine, can cause reversible male infertility.

2. Mesalazine, olsalazine, balsalazide, sulfasalazine have certain blood toxicity.

– Tell the patient or guardian how to identify symptoms of hematological toxicity: Get medical attention immediately if symptoms such as fever, sore throat, mouth ulcers, blood stasis, or bleeding occur.

3. Liver function should be checked during medication and renal function should be monitored regularly.

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