Morphine palliative care

Methadone is an opioid analgesic that is available for oral and parenteral administration. It is used in severe pain, in palliative care and as an adjunct in the management of opioid dependence. Compared with morphine, it is less sedating and has a longer duration of action. It may lead to addiction and can still cause toxicity when used in adults with non-opioid dependency. Because of the long duration of action, in overdosage, patients need to be monitored for long periods. 

Kamboj SK, Tookman A, Jones L, Curran HV. The effects of immediate-release morphine on cognitive functioning in patients receiving chronic opioid therapy in palliative care. Pain 2005 117(3) 388-95. 

Tricyclic antidepressants may reduce morphine requirement in palliative care without noticeably altering mood. 

Control of severe pain without objectionable sedation can be achieved in palliative care by morphine with adjuvant drugs (given orally) in up to 80% of patients. Oral use preserves patients independence as well as reducing the unpleasantness of frequent injections. 

Dose. There is much individual variation given s.c. or i.m. morphine 10 mg is usually adequate with 15 mg unwanted effects increase more than does analgesia i.v. give (slowly) one-quarter to one-half of the i.m. dose. For oral dosage see Palliative care, page 329. Continuous pain suppression can be achieved by morphine orally and s.c. 4-hourly. 

Methadone is a synthetic drug structurally and pharmacologically similar to morphine it acts mainly at the p-receptor. Methadone is largely metabolised to products that are excreted in the urine (t) 8 h). The principal feature of methadone is its duration of action. Analgesia may last for as long as 24 h. If used for chronic pain in palliative care (12-hourly) an opioid of short t) should be provided for breakthrough pain rather than an extra dose of methadone. 

The strategies used in managing the adverse effects of oral morphine have been reassessed in another special article compiled by the Expert Working Group of the European Association of Palliative Care Network (5). Factors that predict opioid adverse effects include ... 

Hanks GW, Conno F, Cherny N, Hanna M, Kalso E, McQuay HJ, Mercadante S, Meynadier J, Poulain P, Ripamonti C, Radbruch L, Casas JR, Sawe J, Twycross RG, Ventafridda V Expert Working Group of the Research Network of the European Association for Palliative Care. Morphine and alternative opioids in cancer pain the EAPC recommendations. Br J Cancer 2001 84(5) 587-93. 

Morphine hydrochloride Use in palliative care, pain relief in respect of suspected myocardial infarction or for relief of acute or severe pain after trauma, including in either case postoperative pain relief Rectal... 

This medicine is about 1000-fold more potent than morphine and is not addictive, but it must be administered directly into the cerebrospinal fluid (intrathecally for palliative care). Clinical results of Phase III trials have been presented by Staats et al. (2004) and researches for orally active conotoxins are in progress (Clark et al, 2010). For relationships between a9-nicotinic acetylcholine receptors and the treatment of pain, see McIntosh et al (2009). 

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