Indications: severe pain, left ventricular failure, pulmonary oedema.

Cautions: hypotension, hypothyroidism, asthma and decreased respiratory reserve; prostatic hypertrophy; hepatic impairment; renal impairment; convulsive disorders; dependence; pregnancy; breast-feeding

Contra-indications: acute respiratory depression; acute alcoholism; raised intracranial pressure and head injury; avoid injection in phaeochromocytoma (risk of pressor response to histamine release).

Side Effects: nausea and vomiting, constipation, drowsiness, respiratory depression and hypotension and muscle rigidity; other side effects include difficulty with micturition, ureteric or biliary spasm, dry mouth, sweating, headache, facial flushing, vertigo, bradycardia, tachycardia, palpitation, postural hypotension, hypothermia, hallucinations, dysphoria, mood changes, dependence, miosis, decreased libido or potency, rashes, urticaria and pruritus.

Dose:

Note: The patient should be closely monitored for pain relief as well as for side effects especially respiratory depression acute pain, by SC or IM injection 10 mg every 4 hours if necessary (15 mg for heavier patients).

Child up to 1 month, 150 mcg/kg; 1-12 months, 200 mcg/kg; 1-5 years, 2.5-5 mg, 6-12 years, 5-10 mg.

doses can be repeated every 4 hours, or more in terminal pain.

By slow IV injection, 1/4-1/2 corresponding IM dose. Acute pulmonary oedema, by slow IV injection (2mg/minute), 10 mg. Followed by a further 5-10 mg if necessary.

Chronic pain, by mouth or by SC or IM injection, 5-20 mg regularly every 4 hours. dose may be increased as necessary; Oral dose = double IM dose.

Myocardial infarction, by slow IV injection (2 mg/minutes), 10 mg followed by a further 5-10 mg if necessary; elderly or frail patients, reduce dose by half. By mouth, initially 10-20 mg twice daily, adjusted according to response.