Gastric function in the elderly: effects on absorption of ketoconazole.

The authors studied effects of age-related changes in gastric function on absorption of ketoconazole. Eighteen men and women age 65 years or older swallowed 200 mg ketoconazole on two occasions, once as tablets with water and once as tablets crushed in acidic juice. The sequence was randomly determined. Gastric pH was measured by radiotelemetry and gastric emptying rate by radiolabeled technetium with a gamma camera. Plasma ketoconazole was assayed by high-performance liquid chromatography (HPLC). Subjects with gastric pH less than or equal to 4.5 absorbed ketoconazole equally well from intact tablets and tablets crushed in acid. When pH was 5.0 or higher, ketoconazole was absorbed well from acid-crushed tablets but not from intact tablets. Gastric emptying was shown to be rapid in all subjects. Since the prevalence of such hypoacivity is approximately 5% in the elderly, and other parameters of gastric function are usually normal, impaired absorption of drugs such as ketoconazole should be uncommon with normal aging.