[Conversion ratio between intravenous oxycodone/hydrocotarnine and sustained-release oral oxycodone in patients with cancer pain].

The demand for oxycodone increases in the treatment of patients with cancer pain, but there is no injection formulation containing oxycodone as a single ingredient in Japan. Instead, we have an oxycodone/hydrocotarnine compound product. Long ago, hydrocotarnine was added to enhance the analgesic effect of oxycodone. However, the mechanism of hydrocotarnine is unclear, and few studies have mentioned the conversion ratio between intravenous and oral oxycodone. In the present study, in order to define the conversion ratio between them, we investigated 18 patients treated by intravenous or oral oxycodone and changed to another administration route during their treatment. We surveyed the change in pain level and adverse effects before and after changing the administration route. The conversion ratio from oral oxycodone to intravenous oxycodone/hydrocotarnine was 0.71+/-0.12 (mean+/-S. D.), and no obvious change in adverse effect was observed.