Morphine

Indications

• Moderate to severe pain
• Acute or chronic pain

Adverse effects

See Adverse effects

Dose

Doses will vary widely depending on the indication, e.g. acute or chronic pain, and previous analgesic requirements. In acute pain and palliative care there is no maximum dose; adverse effects and tolerance limit the morphine dose.

Titrate dose according to response and any adverse effect. Monitor for respiratory depression and sedation, using a sedation score.

Acute Pain

IV

• Initially, 0.5–2 mg; repeat every 10 minutes and titrate. This interval may not represent the true time to peak effect (which may be up to 15 minutes). Use the lower dose in patients >70 years of age.

SC/IM

• initially 2.5–5 mg every 3-4 hours.
• Use lower doses at prolonged intervals in the elderly and in patients with renal impairment.

Oral

• Do not use controlled release products for the initial treatment of acute pain
• Immediate release oral product: initially 5–10 mg every 4 hours (start with 5 mg in patients >70 years).
• More frequent dosing and/or higher doses may be required for severe acute pain; refer to local hospital protocols

Chronic cancer pain: adult

• Initial dosing;

  • Use oral liquid or immediate release oral tablets and give dose every 4 hours.
  • If opioid-naïve; start with 2.5–5 mg (use lower dose in elderly patients)
  • If previously on opioids; consider equianalgesic dose of morphine

• This dose can also be given for breakthrough pain as often as required (up to hourly)

• Titrate doses to effect, and when stable calculate 24-hour morphine requirement for maintenance dosing

Maintenance dosing

• Convert the 24-hour dose of immediate release preparation into an equivalent dose of a controlled release product for maintenance treatment

• 12 hourly oral controlled release tablets (e.g. MS Contin, Momex SR). Total daily dose as determined by immediate release titration, but give half total daily dose every 12 hours.

• OR 24 hourly oral controlled release capsules (e.g. Kapanol, MS Mono). Total daily dose as determined by immediate release titration given every 24 hours.

• SC infusion

  • Calculate 24‑hour oral dose of morphine and give one-third by SC infusion over 24 hours.

Breakthrough pain

Use additional doses of morphine oral liquid or immediate release tablets for breakthrough pain, giving one-sixth of the daily requirement as frequently as required. If repeated breakthrough doses are required, adjust the regular baseline morphine dose.

Chronic non-cancer pain: adult

• Involve a specialist pain team in assessing and managing the patient
• Maximise use of co-analgesics, adjuvants and non-pharmacological methods of pain control
• Avoid opioids if at all possible.

Dose equivalences

• For chronic dosing, 30 mg oral morphine is equivalent to 10 mg SC/IV morphine
• Use the same dose for sulphate, tartrate and hydrochloride salts
• For equivalent doses of other opioids, see Opioid Comparative Information Table

Administration advice

• For IV use, dilute and give over 4 to 5 minutes
• Compatible fluids: sodium chloride 0.9%, glucose 5%, sodium chloride 0.18% with glucose 4%
• Controlled release capsules (Kapanol, MS Mono) may be opened, the pellets mixed with 10 – 20 mL of water or liquid feed, and given through a 16 or 20 gauge French gastrostomy tube, then rinsed through with more liquid to ensure all pellets are used. Do not crush pellets.

Patient advice

• Controlled release tablets (e.g. MS Contin®, Momex SR®) must be swallowed whole; do not crush or chew them.
• Controlled release capsules (Kapanol®, MS Mono®) may be opened, and the pellets sprinkled on soft food or mixed with 30 mL liquid. Take within 30 minutes for Kapanol® or 60 minutes for MS Mono®. Do not crush or chew pellets.
• Do not take morphine with alcohol as it may affect the release of morphine from the capsules and increase the likelihood of side effects.

Precautions

Renal

• Morphine’s active metabolites accumulate in renal impairment and have a longer half-life than morphine; may cause respiratory depression and delirium. Use an alternative opioid (or reduce dose if CrCl <50 mL/minute and use with caution).
• Avoid chronic use if CrCl <10 mL/minute, due to accumulation of active metabolites.

Hepatic

• Avoid use in severe hepatic impairment where it may cause excessive sedation.

Practice considerations

• Peak analgesia following a dose of morphine occurs within:

  • 60 minutes after oral liquid
  • 50–90 minutes after SC injection (30–60 minutes after IM)
  • 20 minutes after IV injection

• do not use controlled release products for acute pain management as slow onset and offset make rapid, safe titration impossible

• reassess the patient’s pain frequently and adjust morphine dose accordingly

• respiratory depression after intrathecal morphine may have a delayed onset and prolonged duration; continue monitoring for 18–24 hours after administration

Available products (a number of different brands are available; a few examples are given below)

Immediate release preparations

Ordine® liquid: 1, 2, 5, and 10 mg/mL

Sevredol® tablets: 10, 20 mg

Modified release preparations

Kapanol®: 10, 20, 50 and 100 mg (capsule containing sustained release pellets given every 12-24 hours)

MS Contin®: 5, 10, 15, 30, 60, 100, 200 mg (tablet for 12 hour delivery)

MS Mono® : 30, 60, 90, 120 mg (capsule for 24 hour delivery)