Week 10 - Rec and Perform Drugs - Analgesics - Opioids Flashcards
Define Narcotic analgesics
old term for opioids
ability to induce sleep
Define Opioid
-substance that elicits morphine like effects
-can be blocked by antagonists
Eg. morphine, heroin, codeine
Define Opiate
compounds found in the opium poppy
Define Opium
- juice extract from poppy flower
- principal active ingredient
What are the effects of Morphine?
- Analgesia, Euphoria, Sedation
- Respiratory depression, cough suppression
- Nausea and Vomiting
- Pupillary constriction (overdose)
- Reduced GIT motility
- Bronchoconstriction and hypertension from histamine release
What are the mechanisms of the analgesic action of morphine?
Pain relief without loss of consciousness
- raise pain threshold at spinal cord level
- alter brains perception of pain
Still aware of pain presense, but not unpleasent
What are the 3 main opioid receptor subtypes?
μ (mu)
δ (delta)
κ (kappa)
What are the effects and side effects of the μ (mu) opioid receptor subtype?
- most of the opioid analgesic effects
- respiratory depression, euphoria, sedation and dependence
What are the effects of the δ (delta) opioid receptor subtype?
more important in periphery (analgesia)
What are the effects of the κ (kappa) opioid receptor subtype?
- analgesia at the spinal level
- sedation and dysphoria
- do not produce dependence
What is the Opioid receptor-transduction mechanisms?
- linked to G-proteins
- inhibit AC and cAMP
- facilitate K+ channels and inhibit Ca++ channels
Where in the spinal site do opiods actions occur?
-block transmission of pain message in the midbrain
Which receptors have effects on the presynaptic terminal and what are they?
keppa, delta and mu reduce Ca influx transmitter release
Which receptors have effects on the postynaptic terminal and what are they?
-mu increase K conductance
What are the pharmacokinetics of Morphine?
- IV, IM or slow release tablets
- GIT absorption slow, erratic and substantial first pass liver metabolism
- metabolite more potent analgesic
