Morphine in cancer pain management: a practical guide

Abstract

Morphine is the most practical and versatile analgesic for the relief of severe pain associated with advanced cancer. Information is available in the literature about its use in routine clinical practice. Morphine induces analgesia by reducing neurotransmitter release presynaptically and hyperpolarizing dorsal horn neurons at the postsynaptic level, thus preventing rostral transmission of nociception. Morphine has a unique metabolism via glucuronidation (UGT2B7), which results in an active metabolite (morphine-6-glucuronide). The pharmacokinetics of morphine relate to its hydrophilic characteristic, volume of distribution, route of administration and clearance. Renal failure alters its pharmacokinetics more than cirrhosis. The age of the patient and multiple medications will alter morphine pharmacokinetics. Morphine can be given by several different routes: oral, rectal, subcutaneous (s.c.), intravenous (i.v.), epidural and intrathecal. Recent experience confirms benefits of topical morphine for cutaneous pain associated with benign or malignant ulcers. Guidelines for morphine administration are reviewed, and in particular those of the Harry R. Horvitz Center for Palliative Medicine are outlined.

Morphine Glucuronosyltransferase Activity in Human Liver Microsomes is Inhibited by a Variety of Drugs that are Co-administered with Morphine

“…It is used as the most practical and versatile analgesic for the relief of severe pain associated with advanced cancer in palliative care. 1) Morphine is extensively glucuronidated, and this pathway accounts for approximately two-thirds of the elimination of morphine in humans. Morphine is metabolized to morphine 3-and 6-glucuronides by UDP-glucuronosyltransferases (UGTs) in liver.…”

Pain Management in Mesothelioma

“…Immediate release preparations are by many favoured for initial dose titration and subsequent breakthrough analgesia while sustained release preparations are more typically saved for long term use (8). However, a direct titration using sustained released opioids is equally feasible (7). Patients may require large quantities of opioids to help control their pain.…”

The Role of Opioid Analgesics in the Treatment of Pain in Cancer Patients

“…The starting daily dose of oral morphine is usually 20 to 30 mg (for opioid-naïve patients) or 40 to 60 mg (for patients unsuccessfully treated with weak opioids) (Ripamonti et al, 2009). The dose of parenteral (SC or IV) morphine is one third of the morphine oral dose (Donnelly et al, 2002). …”