Opiods Part 1 Flashcards
An unpleasant sensory & emotional experience assc. w/ actual or potential damage is
Pain
3 classif. Of pain
Severity, duration, source
Nociceptors
- free nerve endings
- threshold must be reached before signal trigger
Pain pathway (6 steps)
1) injury
2) dorsal root ganglia
3) spinal cord
4) ascending path
5) brain
6) descending path
2 sites that opioids act on
- brain
- spinal cord
When was morphine first recommended for Tx of colic, cought, and analgesia in horses
1930
Difference between opiates and opioids
- opiates: “natural”; derived from poppy seeds
- opioids: can be natural, semi-synthetic, or synthetic
Why are opioids sometimes called narcotics?
- they can prod. Sedation and sleep
3 types of opioid receptors
- Mu
- Kappa
- Delta
Mu receptors
- target endorphins
- located in brain, spinal cord, and peripheral sensory neurons
Kappa receptors
- target dynorphins
- located in brain, spinal cord, and peripheral sensory neurons
Delta receptors
- target encephalin receptors
- located in brain & peripheral sensory neurons
Main intended effect for opiate receptors (all 3 receptors)
Spinal & supraspinal analgesia
Opioid MOA facts
- bind to spinal & supraspinal receptors
- all 3 receptors are G protein coupled receptors
MOA of opioids
- inhibit adenyl cyclase
- activate K+ channels-> hyperpolarization of resting membrane potential
- inhibition of excitatory NT release (ACh, glutamic acid, dopamine, substance p, serotonin)
4 pharmacological effects of opioids
- analgesic
- respiratory
- cardiovasc.
- GI
Analgesic effects of opioids
- decrease pain transm. In spinal cord & brain
Resp. effects of opioids
- resp. depression due to reduced neuron sensitivity in brain to CO2
- assc. w/ MOP receptor
Cardiovasc. effects of opioids
- usually spared @ therapeutic doses
- especially seen in horses
GI effets of opioids
- antidiarrheal & constipation
- emetic
- assc. w/ MOP & KOP receptors
6 therapeutic uses of opioids
- analgesia
- sedation
- calming & euphoria
- diarrhea, decreased GI motility
- antitussive (anti-cough)
- induction & anesthesia maint.
