Opioid Narcotics Flashcards
In general, how do opioids cause their effect on the pre and post synaptic neurons and what does this result in?
Pre-> blunt Ca2+ influx into cells
Post-> drive K+ out of cells
Results in decrease glutamate release
What is unique to Buprenorphrine compared to fentanyl and morphine?
- partial agonist, where as the other two are full agonists
- more potent!!
What is the clinical utility of mu receptor agonists?
Analgesia (tissue injury=acute injury > nerve injury)
What are the common effects by Mu agonist stimulation?
Analgesia, CNS and respiratory depression, miosis, constipation.
What type of patients is the use of morphine contraindicated in and why?
Brain injury and emphysema patients. Morphine depresses respiration and decrease sensitivity to [CO2]
Name the six group 1 full agonists
Morphine, Methadone, Meperidine, Hydromorphone, Oxymorphone, Levorphanol
Name the three group 2 short-acting full agonists
Fentanyl, Sulfentanil, Remifentanyl
Name the two group 3 codeine-related agonists
Hydrocodone, oxycodone
What must a physician be aware of when switching a patient from a parenteral opioid to an oral form?
Bioavailability and Potency.
How is morphine metabolized?
- Strong first pass effect.
- Inactive metabolite–> Normophine by CYP3A4
- Active metabolite–> M-3 and M-6 Glucouronamide by UGT 1A1/ 2B7
- -> Hydromorphone by dehydrogenase enzyme
What are the characteristics of Methadone?
- Full Mu agonist
- Loner t1/2 (about 27 hours)
- Better oral absorption
- useful for withdrawal/ maintenance, detoxification.
- Can effect cardiac electrical conduction–> incrase QT interval.
What are the characteristics of Meperidine?
- Eye–> pupil dilation (difficult to detect abusers)
- Toxic metabolite Normeperidine accumulates and can cause seizure activity.
What are the characteristics of Sulfentanil?
- Short-acting full agonist
- binds all three opioid receptors
What are the characteristics of Remifentanyl?
- Very short acting
- Metabolized by plasma and tissue esterases.
- Used in OBGYN for birth
What are the characteristics of Fentanyl?
- Rapid onset and distribution (lipophilic)
- Short duration of action
- Transdermal and transmucosal administration
What are the characteristics of Codeine?
- Partial agonist
- reliable oral absorption
- analgesia for moderate pain
- anti-tussive- cough relief (Mu-independently)
What is the metabolism of codeine?
Codeine–> morphine via CYP2D6, active metabolite. Plus inactive norcodeine.
What must be considered when giving kids codeine?
-the possibility that they are ultra-fast metabolizers. This can lead to fatal respiratory depression.
What are the active metabolites of heroin and codeine?
Morphine
What is the active metabolite of oxycodone?
Oxymorphone
What is the active metabolite of meperidine?
Normeperidine, which is toxic.
What are the active metabolites of Hydromorphone, Oxymorphone, and Fentanyl?
There are none.
What opioids can be used in the GI tract as anti-diarrheals?
- Loperamide and Diphenyoxylate.
- Any opioid can be used but these have poor solubility and low risk for abuse.
What are the characteristics of Tramadol?
- Moderate Mu agonist
- Active metabolite is N-desmethyl
- Reliable oral absorption
- Inhibits catecholamine reuptake
- associated with seizures
