Usage Survey of Opioid Injections Aimed to Introduce a Hospital Formulary in the Palliative Care Unit and Cost Estimation of the Economic Effect

A formulary is the standard use policy of congeneric drugs that is prepared considering medical appropriateness and economic efficiency; therefore, the economic effects of various drugs are reported. Opioid injections are frequently used in palliative care, and the prices of various opioid injection types vary. Therefore, we considered whether the development of a use selection criterion for opioid injections resulted in economic benefit. This study included patients who were newly administered morphine, oxycodone, fentanyl, and hydromorphone in the palliative care ward of Kagoshima Medical Association Hospital from January to December 2024. The opioid injection dose, internal or topical opioid use before the start of injections, renal function, and the presence or absence of respiratory symptoms were surveyed retrospectively. Subsequently, considering economic efficiency, we developed a selection criterion for opioid injections and confirmed whether the administered drugs were in accordance with the recommended drugs in the selection criterion. If there was disagreement, the price difference was calculated assuming that the selection criterion–recommended drug was administered. The overall agreement rate of the actual administered drug with the selection criterion–recommended drug was 56.0％. Hydromorphone injection, which was higher-priced than other opioids, exhibited the lowest agreement rate of 38.2％. The calculated change from the administered drug to the selection criterion–recommended drug revealed a cost reduction of 79,505 yen per year. Our results suggest that developing a formulary for opioid injection can reduce drug costs.