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We thank Hallasz for his interesting comments. In our study, comparing the group of patients receiving sulfasalazine with those receiving placebo, there was no significant difference in the mean corpuscular volume of red blood cells after 4 weeks of sulfasalazine therapy (by which time signs of significant clinical improvement of psoriasis had usually occurred). We agree that the possibility that sulfasalazine may be beneficial in psoriasis treatment by acting as a folate inhibitor needs to be pursued and future studies should incorporate more specific tests, including serum folate levels (and better still, red blood cell folate levels). Such studies would need to monitor other factors that may affect tissue folate stores, including drug and dietary intake, presence of diseases that may affect folate metabolism, and hemolysis due to other causes.Sulfasalazine does not exhibit the dose-dependent toxic effects of bone marrow suppression and gastrointestinal ulceration that methotrexate can. Therefore, sulfasalazine
Gupta AK, Voorhees JJ. Sulfasalazine as Folic Acid Inhibitor in Psoriasis-Reply. Arch Dermatol. 1990;126(11):1516-1517. doi:10.1001/archderm.1990.01670350132026