Histamine and histamine type-2 receptor antagonists in psoriasis. Mechanisms and speculations.
The findings that the immunosuppressant cyclosporine A (CsA) improves psoriasis raise the possibility that cellular immune processes may play a major role in the pathogenesis of this disease. It is broadly agreed that histamine released by mast cells is one of the molecules involved in the pathogenesis. This is supported by the findings that CsA and methotrexate (Mxt) reduce formation and release of histamine. However, the well known side-effects of CsA and Mxt may argue potential use of other agents acting on formation and action of histamine. Such agents may be the histamine-2 receptor antagonists, previously reported to have a clinical effect on psoriasis. But randomised short-term studies have disclosed that these drugs have no beneficial or even an aggravating effect on the disease. This article reports on recent findings of improvement in psoriasis using high doses of the histamine-2 receptor antagonist ranitidine in long-term studies. Also presented are a hypothetical action of histamine in development of psoriasis and a rationale for ranitidine as a potential agent in the therapy of psoriasis.
Department of Surgical Gastroenterology, Hvidovre Hospital, Copenhagen.
H J
HJ
Nielsen
D016572:Cyclosporine / Q000009:adverse effects / Q000494:pharmacology / Q000627:therapeutic use; D006632:Histamine / Q000502:physiology; D006633:Histamine Antagonists / Q000494:pharmacology*; D006635:Histamine H2 Antagonists / Q000494:pharmacology*; D006801:Humans; D008727:Methotrexate / Q000009:adverse effects / Q000494:pharmacology / Q000627:therapeutic use; D011565:Psoriasis / Q000188:drug therapy* / Q000503:physiopathology; D011899:Ranitidine / Q000494:pharmacology / Q000627:therapeutic use
D006633:Histamine Antagonists; D006635:Histamine H2 Antagonists; D006632:Histamine; D016572:Cyclosporine; D011899:Ranitidine; D008727:Methotrexate