Opiods Flashcards
Where are opioid receptors located
The GI,CNS and spine and urinary bladder
What are the three opioids receptors called
μ (mu), κ (kappa), and δ (delta) They are all members of the G-protein-coupled receptor family.μ (mu) is the primay opiod receptor
What is the purpose of opioids
They are used namely to relive pain and mimic the action of endogenous peptide neurotransmitters (for example, endorphins, enkephalins, and dynorphins).
What is the mechanism of Morphine (Opiods)
Opiods causes hyperpolarisation of nerve cells and inhibit, inhibitory neurotransmitter GABA. This allows
glutamate, dopamine, serotonin and norepinephrine to be released. Norepinephrine and Serotonin release takes place in pain processing regions of the brain like the thalamus, brainstem, and spinal cord, resulting in a decreased sensitivity to pain.
When dopamine release takes place in reward pathway regions like the ventral tegmental area, nucleus accumbens, and prefrontal cortex, the result is a calming sensation that feels really good.
Morphine acts mainly on the K receptor
What are the full drug agonist response opioids
These drugs bind to opioids receptors and causes a complete inhibition of GABA release
What drugs are full agonist
morphine, -partially absorbed in the GI
fentanyl,- lipophilic, rapid onset and short duration, used for anesthesia, cardiac surgery ( Alfentanil, remifentanil, sufentanil) These drugs are related to fentanyl
Side effects for full agonist
Euphoria effect Sedation Anxiety Addiction Tolerance Drug interaction is rare Respiration depression Mitosis of eyes Depression of cough reflex Causes vomiting Constipation Bradycardia Hypotension Bronchoconstriction Vasodilation Prolongs labour Hormonal actions: increases antidiuretic hormone i.e. causes urinary retention
Define mixed agonist-antagonist opioids
partial agonist
These drugs stimulate one receptor such as mu but may block the other receptors. These effect of these drugs depends on if an individual have already been exposed to these drugs in the past, this mean that it will work. But for those who are drug addicts this drug may not work and these will show withdrawal symptoms
what are the mixed agonist-antagonist opioids
partial agonist
Buprenorphine- works on μ receptor
Nalbuphine
What are the other opiods
Tramadol- this binds to the μ receptor, The drug undergoes extensive metabolism via CYP450 2D6, leading to an active metabolite that has a much higher affinity for the μ receptor than the parent compound. In addition, it weakly inhibits reuptake of norepinephrine and serotonin. It is used to manage moderate to moderately severe pain.
Trimeperidine
What is an opioid antagonist
These drugs bind to the opioid receptor but they do not active a response.
However, in patients dependent on opioids, antagonists rapidly reverse the effect of agonists, such as morphine or any full μ-agonist, and precipitate the symptoms of opiate withdrawal.
List of opioids antagonist
Naloxone- works between within 30 seconds, it works on all 3 of the opioids receptors and has a high affinity for for μ than for κ receptors
Naltrexone- this has a longer duration in comparison to Naloxone it works up to 48 hours
