title: Age and renal clearance of cimetidine.
abstract: In 35 patients (ages 20 to 86 yr) receiving cimetidine therapeutically two serum samples and all urine formed in the interim were collected for analysis of cimetidine by high-pressure liquid chromatography and for creatinine. Cimetidine clearance decreased with age. The extrapolated 6-hr serum concentration of cimetidine per unit dose, after intravenous cimetidine, increased with age of the patients. The ratio of cimetidine clearance to creatinine clearance (Rc) averaged 4.8 +/- 2.0, indicating net tubular secretion for cimetidine. Rc seemed to be independent of age and decreased with increasing serum concentration of cimetidine, suggesting that secretion of cimetidine is a saturable process. There was only one case of dementia possibly due to cimetidine (with a drug level of 1.9 microgram/ml 6 hr after a dose) in a group of 13 patients without liver or kidney disease who had cimetidine levels above 1.25 microgram/ml. Thus, high cimetidine levels alone do not always induce dementia.
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging; D002927:Cimetidine / Q000009:adverse effects / Q000378:metabolism*; D003404:Creatinine / Q000652:urine; D003704:Dementia / Q000139:chemically induced; D005260:Female; D006146:Guanidines / Q000378:metabolism*; D006801:Humans; D007668:Kidney / Q000378:metabolism*; D008297:Male; D008875:Middle Aged
chemical_list: D006146:Guanidines; D002927:Cimetidine; D003404:Creatinine