Week 8 - Analgesics Flashcards
What is the mechanism of action of opioids?
Act at the level of the spinal cord and the CNS
- decrease neurotransmitter release
- block post-synaptic receptors
- activate inhibitory pathways
What are the side effects of using opioids?
Dose related:
-N&V, constipation, drowsiness, hypotension, acute respiratory depression, sedation, dependency
What are the contraindications for opioids?
Acute respiratory depression
Acute alcoholism
Head injury
What do opioids interact with?
Alcohol - increased hypotensive and sedative effects
MAOI - increased CNS excitation/inhibition
SSRI/TCA - increased sedation
Carbamazepine - decreased plasma concentration of methadone
Cimetidine (ulcer healing) - inhibits opioids metabolism
Which receptors do opioids act as agonists on?
Opioid receptors
-u, k, delta receptors
What are most analgesic opioids?
U-receptor agonists
(CNS, spinal cord, peripheral sensory neurons, GI tract) - responsible for side effects as well
What does the k opioid receptor do?
CNS, spinal cord, peripheral sensory neurons
- sedation and dysphoria
- few side effects
- doesn’t contribute to dependence
What does the delta opioid receptor do?
Acts on the CNS and peripheral sensory neurons
-may contribute to analgesia
What are opioid antagonists and give some examples
- block the actions of opiates
- e.g. Naloxone and naltrexone
- treatment of heroin/morphine overdose
What are pure opioid agonists?
- typified by morphine like drugs
- have a high affinity for u receptors
- low affinity for delta and k receptors
What are partial opioid agonists and mixed opioid agonist-antagonists?
Partial agonists:
-nalorphine - mixed effects on u receptors
Mixed agonist-antagonists:
-pentamidine and cyclazocine
What can be used as analgesia?
- opioids
- NSAIDS
- paracetamol
- anti-epileptics
- anti-depressants
- corticosteroids
- anaesthetics
