Choice of strong analgesic in terminal cancer: Diamorphine or morphine?

Abstract

A controlled trial of diamorphine (diacetylmorphine, heroin) and morphine is reported in which the two drugs were administered regularly by mouth in individually determined effective analgesic doses. Elixirs contained cocaine hydrochloride 10 mg/dose; other drugs were prescribed when indicated clinically. 699 patients entered the trial and, of these, 146 crossed from diamorphine to morphine, or vice versa, after about two weeks using an oral potency ratio of 1.5/1 determined in a pilot trial. Additional medication and survival were closely similar in both treatment groups. In the female crossover patients, no difference was noted in relation either to pain or the other symptoms evaluated. On the other hand, male crossover patients experienced more pain, and were more depressed, while receiving diamorphine. In these, the potency ratio of diamorphine to morphine appeared to be less than 1.5/1. If this is allowed for, then the difference in mood is probably not significant. Compared with male patients, fewer females required a dose of 10 mg or more, but more were prescribed an anxiolytic. The ability to do without a 2 a.m. dose appeared to be related more to the size of the dose than to gender or treatment. It is concluded that, provided allowance is made for the difference in potency, morphine is a satisfactory substitute for orally administered diamorphine. However, when injections are necessary, the greater solubility of its hydrochloride gives diamorphine an important practical advantage over morphine, especially when large doses are required.

Serum morphine concentration after oral administration of diamorphine hydrochloride and morphine sulphate.

“…This fact has encouraged physicians at St Christopher's Hospice and similar units to use, when indicated, higher oral doses of morphine sulphate or diamorphine hydrochloride than formerly, resulting (Twycross, 1977). Moreover, Twycross et al (1974) suggested that diamorphine hydrochloride was better absorbed from the alimentary tract than morphine sulphate; and that the difference in absorption probably accounted for the difference in potency.…”

“…Blood samples were obtained within 30 min of the 09.00 h dose from patients receiving individually determined doses of either diamorphine hydro-* Present address: The Churchill Hospital, Headington, Oxford chloride or morphine sulphate (Macfarlan Smith Ltd) regularly every 4 h. All were in-patients at either St Joseph's Hospice or St Christopher's Hospice, London, and most were participating in a comparative trial of diamorphine and morphine (Twycross, 1977). All the patients gave permission for blood to be taken for research purposes.…”

The Unique Role of Diamorphine in British Medical Practice: A Survey of General Practitioners and Hospital Doctors

“…When used in palliative care by the parenteral route, diamorphine is preferred to morphine, because it is more soluble and can be given in a smaller volume [19,20]. It also causes less nausea and hypotension than morphine.…”

Pathophysiology of opioid tolerance and clinical approach to the opioid-tolerant patient

“…These patients may develop tolerance to opioids. Thus, perioperative requirements are higher [2]. Yet their postoperative increase in opioid requirements may be interpreted as opioid craving and their increased requirements may not be met.…”