Investigations on the penetration of ranitidine into the cerebrospinal fluid and a comparison of the effects of ranitidine and cimetidine on male sex hormones.

Cerebrospinal fluid (CSF) ranitidine concentrations were measured in 13 normal subjects undergoing routine myelography following either one, or two doses ranitidine 200 mg. Small amounts of the drug were detectable in the CSF. A separate investigation of duodenal ulcer patients compared the effects of ranitidine 150 mg twice-daily and cimetidine 1 g daily on basal and stimulated levels of male reproductive hormones in the plasma. Although cimetidine treatment resulted in a small rise in basal and stimulated testosterone, neither drug was associated with significant changes in basal or stimulated hormone levels.