Analysis of Opioid Disposal in Hospitalized Patients According to Dosage Form, Dose, Cost, and Admission Type: A Retrospective Study

Opioids are essential for cancer pain management but often require dose or route adjustments, leading to disposal of unused medications. This study investigated opioid disposal by dosage form, dose, economic impact, and admission type.

This retrospective observational study included patients who received oral or transdermal opioids at Ogaki Municipal Hospital between January 2023 and December 2024. Opioid disposal, defined as nonreusable opioids discarded according to narcotics management records, was identified retrospectively. Disposal volume, cost, and reasons for disposal were evaluated. Costs were calculated using official drug prices (April 2025). Associations between admission type and disposal reasons were analyzed using the Chi-square test.

Eighty-eight patients experienced opioid disposal. The total disposal volume was 3022 units, with a total cost of JPY 599,736 (mean: JPY 6815 per patient). Disposal frequently involved low-dose oral opioid formulations, particularly sustained-release oxycodone (5, 10 mg). Pareto analysis showed that the top five drugs accounted for 59.5% of total disposal costs. Disposal reasons differed significantly by admission type (χ ² = 40.8, df = 4, P < 0.001): death-related disposal occurred only in emergency admissions, whereas planned admissions were more frequently associated with drug changes and represcriptions.

Opioid disposal in hospitalized patients occurs frequently, including with low-dose oral formulations. Costs are concentrated in a limited number of drugs and vary by admission type. Optimizing opioid selection and early assessment of administration routes may help reduce unnecessary disposal while maintaining adequate pain control.