Sulfasalazine is classified as a DMARD (Disease-modifying antirheumatic drug) as well as a 5-aminosalicylic acid derivative. The most common use in clinical practice that I’ve seen sulfasalazine used for is rheumatoid arthritis, but it can also play a role in ulcerative colitis and Crohn’s disease. In this post, I’ll discuss important sulfasalazine clinical pearls and what you should watch out for as a practicing healthcare professional.
Adverse Effects
The most common adverse effect of sulfasalazine to remember is GI upset. Nausea, vomiting, GI pain, and diarrhea are all possible complications from the use of the medication. This adverse effect is generally going to appear within the first few days to a week of starting the drug so it is usually pretty easy to identify that sulfasalazine is the culprit based on the timing. Like most adverse effects, this is dose-related. In patients with symptomatic Crohn’s or Ulcerative Colitis, this may be a little tricky to identify so it is critical to pay attention.
Significant but less common adverse effects of sulfasalazine include skin reactions and alterations in CBC. Low white blood cell numbers and low platelets are possible. The most common monitoring parameters for sulfasalazine include CBC and LFTs.
Sulfasalazine Clinical Pearls – Pharmacogenomics
Pharmacogenomics is an important consideration for the use of sulfasalazine and alterations may increase the risk for adverse effects. Particularly, agranulocytosis may be more likely to occur in European patients with the genetic variations of HLA_B*08:01 and HLA-A*31:01.
Skin reactions from sulfasalazine may be more likely in Chinese Han patients. More specifically, the genotype HLA-B*13:01 is at increased risk for these types of reactions. (These types of genetic questions always make for great board exam questions!)
Dietary Considerations – Sulfasalazine
We must not forget about dietary considerations with this medication. Sulfasalazine can block the absorption of folate. Ensuring that there is adequate intake and assessing for folic acid deficiency periodically is appropriate. I don’t typically recommend supplementation unless there is deficiency, but I do recommend occasional monitoring. The package insert also mentions the possibility of renal stone formation and recommends the medication be taken with water. I think that is reasonable advice, but in clinical practice, I have never seen this occur so I would definitely rate it as a rare adverse effect.
Sulfasalazine – Crohn’s Versus Ulcerative Colitis
While sulfasalazine can be used in Crohn’s disease, it is generally more acceptable for use in ulcerative colitis. The reason for this is that sulfasalazine needs to be activated by bacteria that are primarily found in the colon. In Crohn’s disease, the disease tends to be scattered all throughout the GI tract, therefore, rendering the drug less effective in patients who have Crohn’s higher in the GI tract. If it is used in Crohn’s disease, the patient likely has colitis.
What other sulfasalazine clinical pearls are important in your practice?
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