Plasma morphine concentrations during chronic oral administration in patients with cancer pain

Abstract

Plasma concentrations of morphine were studied in 16 patients with chronic pain due to advanced cancer, treated with regular doses of oral morphine chloride. Doses ranged from 20-125 mg every 4 h and a significant, positive linear correlation was found between dose (range 0.22-3.01 mg/kg) and mean plasma concentration (range 22-364 ng/ml). The profile of the 4-h concentration curve is subject to considerable individual variation. Good pain relief can be obtained, if individual requirements as to dose and dose interval are taken into consideration.