morphine hydrochloride

Last reviewed 01/2018

Morphine hydrochloride is an antitussive and analgesic compound used for the relief of cough and pain in terminal disease.

It is contraindicated in other situations because of its addictive properties, and its tendency to cause sputum retention and ventilatory failure.

Morphine remains the standard against which other opioid analgesics are compared - it is still a very popular treatment in terminal care.

It produces analgesia by reducing the sensation of pain and reducing distress. Accompanying this are a sense of euphoria, depression of the cough reflex, nausea and vomiting in a minority, and pupillary constriction. Even small doses of morphine cause measurable respiratory depression.

Morphine has an active metabolite which may accumulate when repeated doses are given to patients with renal impairment. The dose should be titrated to effect.

• systemic bioavailability of oral morphine is variable (15-64%) - this partly explains why the effective analgesic dose of normal-release morphine for patients with cancer pain can range from 5mg to 1,000mg every 4 hours
• in terms of analgesia in a palliative care setting, most patients need no more than 200-300mg of oral morphine daily
  • patients should have immediate access to analgesia for breakthrough pain, in the form of normal-release morphine

Reference:

1. Drug and Therapeutics Bulletin 2005;43(2):9-11.