Morphine is the most widely used strong opioid used in cancer pain management and usually the drug of choice. Wherever possible, the preferred route is oral, and it is available as a liquid, tablets or as capsules. There are both normal release (4 hourly) and slow release preparations (12 hourly or 24 hourly).
Morphine is metabolised in the liver, but liver disease does not contraindicate its use. Morphine 6 Glucuronide (M6G), an active metabolite of morphine is excreted by the kidney, so renal dysfunction can increase accumulation of M6G. This can lead to central depression (sedation / respiratory depression) and may require the use of lower doses or changing to another opioid in some cases.
Morphine can also be administered subcutaneously, intramuscularly or intravenously.
Morphine is the standard against which other opioids are measured for potency, and the equivalent morphine dose is used for calculating conversions between opioids. We will look at this later, but first we will look at some of the common side effects of opioids
Last updated August 2004 ---------------------------- -