Codeine
- OralCodeineWeakly agonises all opioid receptors
Up to 10% of the population lack the enzyme required to convert codeine (weak) to morphine (potent) – in these cohorts codeine has nearly no effect
Mechanism of Action
- Acts on opioid receptors (δ, κ and µ) and nociceptin orphanin FQ (NOF) receptors on neuronal cell membranes within the thalamus, diencephalon, midbrain and medulla, resulting in reduced neurotransmitter release.
Clinical Use
- Indications
- Acute and chronic pain
- Adverse Effects
- Nausea / vomiting
- Constipation
- Sedation
- Respiratory depression
- Diaphoresis
- Delirium
- Hypersensitivity – bronchospasm, urticaria
- Bradycardia
- Tolerance
- Dependence
- Hypogonadism