Absorption of controlled release morphine sulphate in the immediate postoperative period

The absorption of morphine sulphate, given orally as a controlled release preparation, was studied in 10 patients who had undergone peripheral vascular surgery with a standard opioid-based general anaesthetic technique. Serum morphine concentrations were measured (high pressure liquid chromatography) every 2 h for the first 16 h after surgery and the results were strongly suggestive of a decrease in the rate of absorption of morphine in this situation.