diamorphine hydrochloride: clinical use

Prescribing considerations

• Agree the therapeutic aim, review and withdrawal strategy before ongoing opioid treatment.
• Assess respiratory reserve, frailty, age, renal and hepatic function, bowel-obstruction risk and concurrent CNS depressants.
• Document substance use, mental health history and opioid-use-disorder risk factors.
• Use additional caution in asthma, reduced respiratory reserve, hypotension, shock, seizure disorders, adrenal or thyroid insufficiency and urinary outflow obstruction.
• Consider opioid-induced hyperalgesia if pain becomes diffuse or unexpectedly increases during prolonged treatment.

Contraindications and cautions

• Acute respiratory depression
• Hypersensitivity to diamorphine or formulation components
• Phaeochromocytoma
• Biliary colic
• Coma, raised intracranial pressure or head injury
• Acute alcoholism
• Risk of paralytic ileus
• Specified acute diarrhoeal conditions

Monitoring

• Respiratory rate, oxygenation, consciousness and sedation
• Blood pressure and cardiovascular status
• Analgesic response and signs of opioid-induced hyperalgesia
• Constipation, bowel function and urinary retention
• Renal and hepatic function where clinically relevant
• Tolerance, withdrawal, misuse, dependence and opioid use disorder
• Neonatal respiratory depression or withdrawal after pregnancy exposure

Clinical pharmacology

Diamorphine is a lipophilic opioid with rapid central nervous system entry. It is quickly converted to monoacetylmorphine and then morphine; metabolites are eliminated mainly through the kidneys.

Formulation and product differences

• The selected product is a sterile, white to off-white freeze-dried powder for reconstitution and injection.
• It contains no detectable excipient other than residual water for injections.
• Use the reconstituted solution immediately.
• Physical incompatibility or precipitation can occur with some medicines, including cyclizine, haloperidol and dexamethasone. Mixtures with metoclopramide may discolour and should be discarded.
• Licensed routes are intravenous, intramuscular and subcutaneous administration; intrathecal administration is not licensed for the selected product.

Injection

Route: Parenteral

Strengths: 5 mg, 10 mg, 30 mg, 100 mg