Morphine is a commonly used analgesic in acute and chronic pain. It has been around for a very long time!
It can be given intravenously, intramuscularly and orally.
In emergency medicine it is usually given intravenously. On the ward it is often given intramuscularly, particularly in palliative care. In chronic pain it is often given orally.
Failure of morphine is usually due to dose – not giving enough! In the emergency setting give it early and give repeated doses if it is not working. There is no maximum dose – titrate to effect. Make sure the patient is closely monitored and has oxygen and pulse oximetry. It is easily titrated, and reversible – with naloxone – but try not to get to that point!
Typical IV morphine doses in the emergency department might include:
- Children – 0.1mg/Kg IV as an initial dose. Titrate as required
- Adults – 5mg boluses IV – titrate as required
- Elderly – 1-2.5mg IV boluses
All patients receiving IV morphine should be on oxygen and pulse oximetry monitoring
In palliative care it is often used in a syringe driver as an IV or IM infusion, with additional bolus doses as required. A typical 24 hour dose might be 10-20mg, with 1-5mg boluses as required.
The use of opiates in chronic pain is widespread, although not without controversy. Opiate dependence is a big problem in many western societies. In the UK, many chronic pain patients, as well as cancer patients, take MST – morphine sulphate. Typical daily doses of MST can be anywhere from 40 – 200mg.
In chronic pain in the absence of cancer, the use of opiates should be discouraged as much as possible and many GPs and pain specialist work hard on ‘de-prescribing’ – slowly reducing the amount of opiates prescribed over time. Going ‘cold-turkey’ is not recommended!
These are similar in all opiates
- Itching – due to histamine release
- Respiratory depression – all patients receiving IV morphine should be on oxygen and pulse oximetry monitoring. Keep an eye on the respiratory rate!
- Hypotension – thought to be secondary to histamine release