[Efficacy and safety of continuous subcutaneous injection of the compound oxycodone in cancer pain management: the first 4-year audit].

The compound oxycodone injection, but not pure oxycodone, has been available since the 1920's in Japan. The compound, containing oxycodone and hydrocotarnine, can be subcutaneously administered. Hydrocotarnine is a non-narcotic opium alkaloid. Nowadays, along with the increase in the prescription frequency of oral oxycodone, the compound oxycodone injection is regarded as an important alternative in palliative care. However, few clinical reports about this drug have been documented in Japan. We have intensively introduced the compound for cancer pain control since 4 years ago and we report a study on the safety and efficacy of the continuous subcutaneous administration of the compound injection. Ninety-seven patients were naively administered the compound for cancer pain control and the mean administered period was 18. 0+/-15. 5 days. 61. 9% of all cases were switched from oral oxycodone. The efficacy in cancer pain control was evaluated for the first two weeks using a numeric rating scale (NRS: 0, no pain, and 10, imaginary worst ). They had statically shown pain control improvement from 6. 8+/-2. 8 on administration to 2. 4+/-2. 5 one week later, 1. 7+/-1. 9 two weeks later, and 2. 3 +/-2. 6 on the last observation day of the study (p<0. 001). One week later on administration, no significant adverse effects were found in the serology, conscious level, and subjective symptoms of nausea and vomiting. But adverse effects difficult to manage were experienced in 7. 2%, including delirium, constipation, nausea and vomiting, vertigo, and local skin toxicity on the injected site. All episodes were experienced within 16 days of compound administration, which had been followed by switching to fentanyl or subcutaneous morphine injection. The conversion ratio from compound oxycodone injection to oral oxycodone was 1. 43 without adjustment required(n=35). We speculate that the compound can be regarded as a pure oxycodone injection using continuous subcutaneous administration. While our clinical audit is a primitive one, we may conclude that the continuous subcutaneous administration of the compound oxycodone injection should be effective and safe in clinical use for cancer pain control.