EFFECT OF PROLONGED ADMINISTRATION OF RANITIDINE ON PITUITARY AND THYROID HORMONES, AND THEIR RESPONSE TO SPECIFIC HYPOTHALAMIC-RELEASING FACTORS

We have studied, in a double blind controlled trial, 30 male patients with duodenal ulcer to evaluate the effect of prolonged oral administration of ranitidine (150 mg bd for 4 weeks), a new H2-receptor antagonist, on basal PRL, LH, FSH and TSH concentrations, on their response to specific releasing hormones, and on basal and TRH-stimulated levels of thyroid hormones. Neither the basal levels of PRL, FSH, LH and TSH, nor their response to stimulation with appropriate releasing hormone were affected by ranitidine. Basal concentrations of T4 and its levels after TRH stimulation at 40 min (but not at 20, 60 and 120 min) were lower after ranitidine treatment (P < 0·05); basal and stimulated T3 and rT3 were unaffected. These results could suggest a possible role of histamine in thyroxine regulation but further studies are required.