Tolerability of oral pamidronate in elderly patients with osteoporosis and other metabolic bone diseases

Oral pamidronate (APD) is being used increasingly in the treatment of a variety of bone diseases. In a retrospective chart review of patients at three research centers (a 558.3 patient-year sample), the side effects of treatment with oral, low-dose APD administered in enteric-coated, soft gelatin capsules were analyzed in a group composed primarily of elderly women with osteoporosis, Although 21.8% of the patients experienced various gastrointestinal side effects, 89.1% complied with the treatment schedule. Among patients who discontinued therapy, two had duodenal ulcerations and one had hemorrhagic gastritis, There was a statistically significant negative correlation (r < -.90) between duration of treatment and rate of side effects; this correlation was influenced by patients who discontinued treatment early because of side effects. No clear dose-effect relationship could be demonstrated. No differences were detected when patients concomitantly received calcium, vitamin D, or any other nonosteotrophic drug, such as vasodilators or antiarrhythmic drugs, Hematologic abnormalities, including a reversible decrease in leukocyte count, were noted in 9.4% of the 635 patient charts that contained this type of data, This phenomenon is gradual and appears to be different from the sudden hematologic manifestation of the acute reaction phase described with intravenous administration of APD, Thus it may be concluded that oral APD administered to elderly patients for approximately 1 year would be expected to cause gastrointestinal side effects in about 21.8% of patients and the gradual progression of hematologic side effects in about 9.4%.