BMA Concise Guide to Medicine & Drugs

Morphine/Diamorphine

Brand names Depodur, Morphgesic SR, MST Continus, MXL, Oramorph, Oramorph SR, Sevredol, Zomorph

Used in the following combined preparations Cyclimorph, Diocalm, J. Collis Browne’s Mixture, J. Collis Browne’s Tablets

QUICK REFERENCE

Drug group Opioid analgesic

Overdose danger rating High

Dependence rating High

Prescription needed Yes (except low-dose antidiarrhoea and cough medicines)

Available as generic Yes

GENERAL INFORMATION

Morphine and diamorphine are opioid analgesics and are used to relieve severe pain that can be caused by heart attack, injury, surgery, or chronic diseases such as cancer. They are also sometimes given as premedication before surgery.

The drugs’ painkilling effect wears off quickly and they may be given in a slow-release (long-acting) form to relieve continuous severe pain.

These drugs are habit-forming, and dependence and addiction can occur. However, most patients who take them for pain relief over brief periods of time do not become dependent and are able to stop taking them without difficulty.

Morphine is also included in very small amounts in some over-the-counter medicines for treating diarrhoea and suppressing coughs. These are not covered in the information given here.

INFORMATION FOR USERS

Your drug prescription is tailored for you. Do not alter your dosage without checking with your doctor.

How taken/used Tablets, SR tablets, capsules, SR capsules, liquid, SR granules, injection, suppositories, SR suppositories.

Frequency and timing of doses Every 4 hours; every 12–24 hours (SR preparations).

Adult dosage range 2.5–25mg per dose; however, some patients may need 75mg or more per dose. Doses vary considerably for each individual.

Onset of effect Within 1 hour; within 4 hours (SR preparations).

Duration of action 4 hours; up to 24 hours (SR preparations).

Diet advice None.

Storage Keep in original container at room temperature out of the reach of children.

Missed dose Take as soon as you remember. Return to your normal dosing schedule as soon as possible.

Stopping the drug If the reason for taking the drug no longer exists, you may stop the drug and notify your doctor.

OVERDOSE ACTION

Seek immediate medical advice in all cases. Take emergency action if symptoms such as slow or irregular breathing, severe drowsiness, or loss of consciousness occur.

POSSIBLE ADVERSE EFFECTS

Nausea, vomiting, and constipation are common, especially with high doses, and anti-nausea drugs or laxatives may be needed to counteract these symptoms. Drowsiness and dizziness are also common. Discuss with your doctor if you experience dizziness, if any of the other common side effects are severe, or if the drug causes confusion. If breathing difficulties or impaired consciousness occur, stop taking the drug and contact your doctor immediately.

INTERACTIONS

Monoamine oxidase inhibitors (MAOIs) These drugs may produce a severe rise in blood pressure when taken with morphine and diamorphine.

Esmolol The effects of esmolol may be increased by morphine and diamorphine.

Sedatives Morphine and diamorphine increase the sedative effects of other sedating drugs including antidepressants, antipsychotics, sleeping drugs, and antihistamines.

SPECIAL PRECAUTIONS

Be sure to tell your doctor if:

· You have long-term liver or kidney problems.

· You have heart or circulatory problems.

· You have a lung disorder such as asthma or bronchitis.

· You have thyroid disease.

· You have a history of epileptic seizures.

· You are taking other medicines.

Pregnancy Not usually prescribed. May cause breathing difficulties in the newborn baby. Discuss with your doctor.

Breast-feeding The drug passes into the breast milk, but at low doses adverse effects on the baby are unlikely. Discuss with your doctor.

Infants and children Reduced dose necessary.

Over 60 Increased likelihood of adverse effects. Reduced dose may therefore be necessary.

Driving and hazardous work People on morphine treatment are unlikely to be well enough to undertake such activities.

Alcohol Avoid. Alcohol may increase the sedative effects of these drugs.

PROLONGED USE

The effects of these drugs usually become weaker during prolonged use as the body adapts. Dependence may occur if they are taken for extended periods although this is unusual in patients taking the correct dose for pain relief.