[Selection of an optimum solvent for administration of oxinorm powder through a tube].

Oxinorm powder is a rapid-release preparation of oxycodone hydrochloride for oral administration recently marketed for the first time in Japan. Administration of a powdered drug through a nasal tube is known to involve the risk of tube obstruction by the drug. For narcotic preparations like oxinorm powder, it is desirable from the perspective of drug control, that the drug administered be unlikely to remain in the cup, syringe or catheter used, and that the drug be dispensable in precise amounts. The present study was undertaken to identify problems associated with administration of oxinorm powder through a nasal tube and to determine an appropriate method for its administration. First, the solubility of the powder in various solvents was evaluated macroscopically to select initially appropriate solvents. Then, the drug dissolved in each of these solvents was administered through 3 types of catheters with different raw materials and forms, to simulate drug administration through a nasal tube. Percent residual drug remaining on/within the cup, syringe, and catheter was measured by HPLC, to evaluate the adhesiveness of the drug. When dissolved in distilled water, black vinegar, or milk, the drug was easy to administer through the catheter, with a low percentage of drug remaining on the cup, syringe, and catheter, suggesting that these fluids can be used as solvents for oxinorm powder. Semidigested nutrients such as Ensure.H were found to be unsuitable solvents for oxinorm powder.

[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.

Pharmacokinetics and variation in the clearance of oxycodone and hydrocotarnine in patients with cancer pain.

Compound injections of oxycodone and hydrocotarnine are currently used as one of the treatment options for some cases with cancer pain. However, there have been no reports examining the factors that influence oxycodone and hydrocotarnine clearance, so detailed examination is necessary. As for hydrocotarnine, there have been no reports examining the pharmacokinetics. Therefore in this study, we determined the pharmacokinetics of oxycodone and hydrocotarnine in patients with cancer pain. The study was conducted on 19 patients, in whom pain control was attempted by using the compound injections of oxycodone and hydrocotarnine. We used HPLC-electrochemical detector (ECD) to determine oxycodone and hydrocotarnine serum concentrations, and used the nonlinear least-squares method (MULTI) for calculation of the pharmacokinetic parameters. Furthermore, we examined the factors that influence the clearance of oxycodone and hydrocotarnine by multiple regression analysis (step wise method). The pharmacokinetic parameters were as follows: Oxycodone; V(d)=226.7+/-105.5 l (mean+/-S.D.), CL=37.9+/-25.1 l/h, t(1/2)=4.1+/-1.9 h. Hydrocotarnine; V(d)=276.8+/-237.2 l, CL=95.1+/-64.3 l/h, t(1/2)=2.0+/-0.7 h. The clearance of oxycodone represented by a regression formula was significantly correlated to the age, the presence or absence of within 7 d on the death or liver metastasis, or of the heart failure of the patients. The clearance of hydrocotarnine represented by a regression formula was significantly correlated to the presence or absence of within 7 d on the death or liver metastasis, or of the heart failure of the patients. The clearance also indicated that oxycodone concentration in the blood was likely to be higher in patients having these factors. Oxycodone/hydrocotarnine compound injections should be used with caution and dose reduction may be necessary in such populations.