Absorption of different oral dosage forms of oxycodone in the elderly: a cross-over clinical trial in patients undergoing cystoscopy.

PURPOSE

To characterize the pharmacokinetics (PK) of oxycodone following intravenous injection and administration of three oral dosage forms (solution, capsule, and controlled-release tablet) in elderly patients (age 76-89 years) undergoing cystoscopy.

METHODS

This was an open, randomized study with two sequences and two visits in 15 elderly patients. The patients were given intravenous injection (over 10 min) of 5 mg of oxycodone hydrochloride trihydrate. Oxycodone hydrochloride (5 mg in all forms) was orally administered as a solution, a capsule, and a controlled-release tablet. Venous blood samples were collected up to 17 h after oxycodone administration. Population PK parameters were calculated with NONMEM VI 2.0. For intravenous injection we calculated clearance, volume of distribution at steady state, and the half-life of elimination, and for oral dosage forms also the absolute bioavailability.

RESULTS

Clearance of the intravenous injections was 28.9 L/h; the volume of distribution at steady state and the half-life of elimination were 186 L and 5.2 h, respectively. The absolute bioavailability of oxycodone was 59 % from oral solutions, 64 % from capsules, and 55 % from controlled-release tablets.

CONCLUSIONS

Our results indicate that, in the elderly, the bioavailability of the three different oral dosage forms of oxycodone is fairly similar.