Investigation of Leftover Hyperphosphatemia Drugs in Hemodialysis Outpatients

Abstract

Currently, various hyperphosphatemia drugs are administered orally to hemodialysis patients in order to lower serum phosphorus levels. However, it is known that medication adherence is poor, possibly due to greater pill burden taken each time and their complicated schedules. Therefore, large amounts of unused hyperphosphatemia drugs are likely to be leftover. The increase in leftover prescribed drugs leads to the unnecessary elevation of medical care costs. To date, however, the available information on leftover hyperphosphatemia drugs in hemodialysis outpatients is limited. In this study, we performed an interview survey of medication adherence to hyperphosphatemia drugs among 60 hemodialysis outpatients and evaluated the cost of the leftover drugs. Thirty-four patients showed good adherence. On the other hand, 19 patients self-adjusted to take hyperphosphatemia drugs according to their daily diet. When assessing the serum phosphorus levels for these patients over the past year, the values often exceeded the targeted range (3.5-6.0 mg/mL). Furthermore, 35 patients kept hyperphosphatemia drugs at their home. When estimating the cost derived from leftover drugs using the bootstrap method, main distribution of drug cost was shown to be in the range of 2000 to 2500 yen. This drug cost seemed to in part reflect preparation for an emergency. A serious problem was that 14 patients had previous experience in discarding hyperphosphatemia drugs. This study suggested that more appropriate pharmaceutical care according to each patient's situation is essential in improving phosphorus control in hemodialysis outpatients and in reducing the waste of medical resources.