Morphine

General

A potent opioid analgesic.

The "gold standard" of pain relief.

High potential for tolerance and addiction.

Mimics natural 'pain relief' chemicals - endorphins and cephalins

Action

Morphine is a phenanthrenephenanthrene opioid receptor agonist – its main effect is binding to and activating the μ-opioid receptors in the central nervous system.

Blocks calcium and potassium flux via GPCRs and protein kinase cascade.

Binds very strongly.

Antitussive.

Blocks peristalsis - therefore anti-diarrhoea

Administration

Can be taken orally, rectally, subcutaneously, intravenously, intrathecally or epidurally.

Pharmacokinetics

Extensive first-pass metabolism by liver (only 40 - 50 % of an oral dose reaches CNS).

Elimination half-life 120 mins.

Structure