Morphine and diamorphine in the terminally ill patient

Abstract

In cancer, the use of morphine is dictated by intensity of pain and not by brevity of prognosis. It is a reliable and safe drug when given in simple aqueous solution and is the strong analgesic of choice at most hospices. The oral-parenteral potency rate is 1:3. The effective analgesic dose varies from as little as 2.4 mg to more than 100 mg by mouth every 4 h, though most patients do not need more than 30 mg. Most patients require antiemetic and laxative medication concomitantly; many benefit by the concurrent use of aspirin, corticosteroid or other "coanalgesic". By mouth, morphine and diamorphine have similar actions and unwanted effects, though the latter is about 1.5 times more potent. When injections are necessary, diamorphine hydrochloride is used at all hospices in Britain. It is considerably more soluble than morphine sulphate which means that the volume injected need never be large. The main indication for parenteral administration, apart from the last few hours of life, is intractable vomiting despite the prescription of antiemetic. Most patients can be maintained on oral medication. Neither morphine nor diamorphine should be regarded as the panacea for severe cancer pain. To achieve maximum benefit they must be used within the context of "broad spectrum" pain control and comprehensive patient care and family support.