title: Effect of naproxen on gastrointestinal microbleeding following acetylsalicylate medication.
abstract: This study was undertaken to determine if substitution of naproxen for ASA does influence salicylate-induced gastrointestinal bleeding. Twelve normal volunteers were selected and given increasing doses of salicylate until guaiac tests were consistently positive. Autologous labeling of their red blood cells with 51-Cr was used to quantitate the microbleeding. After two weeks on ASA, six subjects were double blindly switched to naproxen and six to placebo for another two weeks of observation. Two-way analysis of variance on the raw data shows a significant treatment effect associated with a significant interaction in both groups. Final analysis on a logarithmic scale permits orthogonal contrasts to be accurately made without any significant remaining interaction. It is concluded that substitution of naproxen for ASA at a dose of 500 mg daily is accompanied by a rapid reduction of microbleeding to "normal" levels.
mesh_terms: D000704:Analysis of Variance; D000893:Anti-Inflammatory Agents / Q000009:adverse effects*; D001241:Aspirin / Q000009:adverse effects*; D006471:Gastrointestinal Hemorrhage / Q000139:chemically induced*; D006801:Humans; D009280:Naphthaleneacetic Acids / Q000009:adverse effects*; D009288:Naproxen / Q000009:adverse effects*; D010919:Placebos; D013997:Time Factors
chemical_list: D000893:Anti-Inflammatory Agents; D009280:Naphthaleneacetic Acids; D010919:Placebos; D009288:Naproxen; D001241:Aspirin