Medwiki

Morphine

Trade name(s): Sevredol tablets, m-Eslon SR capsules, RA-Morph liquid, Wockhardt morphine liquid, Oramorph liquid Drug Class: Opioid Analgesic

Pharmacological action: Full opioid agonist. Binds to mu opiate receptors in the brain spinal cord and other tissues resulting in inhibition of ascending pain pathways. It also acts on organs with smooth muscle (GI tract and bladder etc).

Reduced breathlessness and respiratory effort by reducing ventilatory drive in hypoxic and hypercapnic states. Sedating effect may also reduce anxiety associated with breathlessness. Cough suppression stems from action against the cough centre in the medulla.

Pharmacokinetics:

  • Absorption Injection
  • IM Peak analgesic action 30 to 60 minutes after injection.
  • SC Peak analgesic action 50-90 mins after injection.
  • IV Peak analgesic action 20 mins after infusion.

Tablet (sevredol) The onset of action of SEVREDOL tablets is about 15-30 minutes after oral administration. The duration of action is 3-4 hours.

  • Distribution 35% protein bound and distributed throughout body however favours functional (parenchymal) tissues.

  • Metabolism: Conjugated with glucuronic acid to morphine 3-glucuronic acid and morphine-6-glucuronic acid. M6G is pharmocologically active with a higher half life compared to morphine.

  • Excretion Half life is approx 1.5-2 hours (MEDSURGE injection datasheet) and 90% of the dose is recovered in urine within 24 hours. 7-10% of dose is in faeces after bile excretion.

Indications: asterisks is unapproved indications acute pain, chronic pain, pain in palliative care, intrapartum analgesia, premedication, MI, acute pulmonary oedema, intractable cough, intractable cough in palliative care, dyspnoea in palliative care

Contraindications: Raised intracranial pressure, acute head injury, comatose patients, risk od paralytic ileus, use of monoamine oxidase inhibitor (MAOI) within 14 days

Oramorph had 10% alcohol as preservative

Precautions: Impaired respiratory function, neurological disorders, obstructive bowel disorders etc.

Also warn patients about driving (see what to tell patients.

Adverse reactions: Constipation, dysphoria, dizziness, euphoria, sedation, hyperhidrosis, nausea, vomiting.

Interactions: Eluxadoline (increased risk of constipation, Naltrexone (Predicted to reduce opioid efficacy), Benzodiazepines in general,

Dosing/Current guidelines: Dose dependant on route of admin and disease state:

Acute pain Oral, immediate release

  • Adults: start with 5-10 mg every 4 hours, adjust to response. SC or IM
  • Adults: start with 5–10 mg every 4 hours, adjust to response. IV
  • Adult, start with 5 mg injected at 1-2mg per min every 4 hours adjusted to response. usual range is 2.5 to 15 mg. Elderly reduce dose.

Chronic pain (including palliative care) Oral, immediate release

  • Adults: start with 5-10 mg every 4 hours adjust to response.

Premedication IM and SC

  • Up to 10 mg 60-90 mins before operation.

Myocardial infarction

  • Adults: start with 5-10 mg injected at 1-2mg per min every 4 hours adjusted to response. Elderly reduce dose to 2.5-5mg .

Acute pulmonary oedema

  • Adults: start with 5-10 mg injected at 1-2mg per min.

Intractable cough Oral, immediate release;

  • Adults: start with 5-10 mg every 4 hours adjust to response.

Intractable cough in palliative care opioid naive patients Oral, immediate release

  • Adults: start with 2.5-5 mg every 4-6 hours adjust to response Oral, modified release
  • Adults: 10mg twice daily

switching from codeine Oral, immediate release

  • Adults; 5-10 mg every 4-6 hours when required adjust to response Oral modified release 10-20mg twice daily adjust according to response

Opiate accustomed patients Breakthrough pain dose. if this does not relieve cough further doses are of no benefit.

Dyspnoea in Pallicare Opioid naive patients Oral, immediate release and SC injection

  • Initially 2.5-5mg every 4 hoyrs when required adjust according to response (usual dose is 10-20 mg every 24 hr)

Patients already regularly taking medication Increase regular opioid dose by 25-50% and give in divided doses every 4 hours if required titrate to response

Monitoring:

Overdose: Main danger with overdose is respiratory depression and eventual hypoxia.

Treatment: Establish airway through intubation and assisted breathing. Naloxone is a specific antidote to respiratory depression Recommended adult dose for the treatment of opiate respiratory depression is 0.4-2 mg intravenously every 2-3 mins, with assisted respiration. Children 0.01mg/kg is recommended for 2-3 doses.

Naloxone is shorter action duration compared to morphine and so monitoring for lowering levels of consciousness is important.

Naloxone can affect opioid-addicted patients in a potentially harmful way as it could lead to abrupt withdrawal syndrome.

Pregnancy: associated with foetal CNS defects in rodent studies. Not advised to give.

What to tell patients:

  • This medicine can cause sleepiness, dizziness, and impair concentration. Do not drive or perform skilled tasks. if you feel sleepy or until you know how this medicine impairs you, especially when you first start treatment. Be aware that the effect can continue into the following day, and that alcohol and other substances can make impairment worse. It is illegal to drive while impaired.
  • This medicine can be dangerous if you have taken alcohol or other medicines that can make you sleepy, if you exceed your recommended dose, or if you are particularly sensitive to its effects. Stop treatment and seek medical attention if you experience excessive sleepiness, difficulty waking, confusion, or shallow breathing. Let your healthcare professional know as soon as possible if you have an accident with a head injury.
  • This medicine may be addictive with prolonged use. Talk to your healthcare professional if you feel the medicine is no longer working for you, or before you change your dose.
  • Tell your healthcare professional if you have low blood pressure, or have ever had a seizure.
  • Oral, modified (slow) release preparations only: swallow this medicine whole. Do not chew or crush.
  • Oral liquid: be aware that morphine oral liquid is available in different strengths, and these may have the same colour and flavour. Always read the label on the medicine container and do not rely on the colour, smell, or flavour to determine contents. If you are unsure, check the correct volume to measure with your pharmacist or healthcare provider; it is recommended that a syringe is used to measure the dose.

Subsidy: Some forms are subsidised and some arent Capsule (m-Eslon), tablet (Sevredol), injection(Medsurge), and oral liquid (Wockhardt, oramorph, RAmorph) are all subsidised. every thing else is not.

Comments/Observations/notes:

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