The alimentary absorption of diamorphine and morphine in man as indicated by urinary excretion studies.

1 Urine was collected over 24 h from 40 patients with advanced malignant disease who had received a known four-hourly oral dose of either diamorphine or morphine in an elixir or of diamorphine by injection for at least 3 days. 2 Samples were assayed for total urinary morphine (free and conjugated) by gas-liquid chromatography. 3 The percentage of the administered dose recovered as morphine was: (a) diamorphine hydrochloride by injection: 70% (s.d. 25) (b) diamorphine hydrochloride by mouth: 77% (s.d. 27) (c) morphine sulphate by mouth: 56% (s.d. 21) 4 It is suggested that diamorphine hydrochloride is completely absorbed by the gastro-intestinal tract but that morphine sulphate is only some two-thirds absorbed.