The pharmacokinetics of oral oxycodone in patients after total gastric resection

Oxycodone is a semi-synthetic opioid with a stronger analgesic effect than morphine and codeine. The efficacy of this opioid in the treatment of postoperative pain has been proved in different groups of patients. The drug has a favourable adverse reaction profile, which encourages doctors and patients to use it more and more widely. The drug is also used in the patients who underwent an abdominal surgery, e.g. stomach resection. Gastrectomy leads to pathophysiological changes within the gastrointestinal tract, which may cause changes in the drug absorption. In consequence this leads to a change in the pharmacokinetics and effect of the drug. The aim of the research was an analysis of the pharmacokinetics of oxycodone from prolonged release tablet in patients after total gastrectomy.

The research was carried out on patients after gastrectomy with Roux-en-Y reconstruction. The patients (n=24; mean [SD] age, 67.6 [9.8] years; weight, 69.1 [13.6] kg; and BMI, 25.2 [4.0] kg/m(2)) received oxycodone in a prolonged release tablet in a single orally administered dose of 10 mg. Blood samples were collected within 12 h after the drug administration. The plasma concentrations of oxycodone and noroxycodone were measured with validated high-pressure liquid chromatography coupled with triple tandem mass spectrometery method.

The main pharmacokinetic parameters for oxycodone in men (n = 14) and women (n = 10) were as follows: Cmax, 14.40 (3.76) and 11.54 (6.98) ng/ml (p = 0.2066); AUC0-∞, 157.87 (56.89) and 106.44 (61.31) ng´h/ml (p = 0.0460); tmax, 2.18 (0.58) and 2.15 (0.58) h (p = 0.8008), respectively.

Total gastrectomy did not affect the pharmacokinetics of oxycodone administered in prolonged release tablets, but the exposure to the drug was significantly lower in women.