Flashcards in 20 Opioids II Deck (17):
The benchmark opioid is _What component of pain does it mainly affect?What type of antagonist is it?
- Morphine- The motivational affective component of pain - It is not an antagonist. It is an AGONIST at the mu receptor
Where in the CNS does morphine mainly function?
Largely in the brain
Urinary retention, sedation, euphoria, respiratory depression, and miosis are all side effects of opioids. True or false?
- True or false: At neutral pH, majority of morphine is in the uncharged state. - What pharmacokinetic variable is affected by this?
- False. At neutral, approx 80% of morphine is charged. - Slow absorption across the membrane
- Why does morphine have a slow onset of action (3)? - Approximately for how long (hours) does a single does exert its actions?
- Slow onset because of 1) low lipid solubility, 2) slow entry into brain, also 3) charged at neutral pH - Approx. 4 hrs, onset of action at 15 mins
- What is the chemical moiety added to morphine during its metabolism? - Where does this addition occur? - What is the active metabolite (proportion)? - The inactive metabolite (proportion)?
- Glucuronide (Glucuronidation)- In Liver - Active - M-6-glucuronide (5-10%), - Inactive - M-3-glucuronide (75-85%)
What is the half life of morphine?
Which is more important consideration for the activity of morphine; liver disease or kidney disease? Why?
- Kidney disease. M-6-glucuronide is excreted by the kidney. If damaged, elevated plasma levels and prolonged drug action - Unless severe, liver disease has no effect on morphine pharmacokinetics
True or false: Opioid Analgesia does not vary much from patient to patient.
False - it is very variable (Pharmacodynamic variability)
What are the continuous release and slow release forms of morphine? What are they used for (2)?
- MS contin and Morphine SR- Chronic pain syndromes, cancer pain
How should an IV dose of morphine to altered to achieve the same PO dose? Why?
- 3-5 fold increase- Reduced bioavailability orally
What type of morphine can be administered directly into the spinal cord? What type of spinal cord administration should it be used for acute pain? Chronic pain?
- Morphine, preservative free- Acute pain - intrathecally or epidurally - Chronic - intrathecally
Among the major morphine side effects, which 2 are generally reduced with spinal administration compared to oral administration?
What is a PCA? What is the advantage?
Patient controlled anesthesiaAllows patient to determine how much opioid they receive by allowing them to admin. small doses
How does M-6_glucuronide compare to morphine with regards to potency?
It is 10X more potent than morphine
What transporters in the kidney eliminate morphine?
Organic ion transporters