Week 2-Specific Opioid Agonists/Antagonists Flashcards
What type of pain is morphine more effective in relieving?
Continuous, dull pain is relieved by Morphine more effectively than is sharp, intermittent pain
Rank the following medications from lowest to highest potency: Morphine Merperidine Hydromorphine Methadone Fentanyl Sufentanil
Merperidine (0.1) Methadone and morphine (1) Hydromorphone (5-8) Fentanyl (100) Sufentanil (1000)
The effect of an opioid (as in peak effect) is proportional to the concentration at ______, not the plasma concentration.
the effect site
What effects drug onset?
Drug onset will depend on the effect being measured (e.g., incisional vs. postoperative pain, etc.), the opioid dose administered, and any pre-existing opioid concentrations.
What effects the absorption of a drug?
its lipid solubility and inversely on its polarity or degree of ionization
What is produced from morphine metabolism?
5-10% results in active metabolite: morphine-6-glucuronide (M6G)
What is elimination half life?
Elimination half-time is time necessary forplasmaconcentration of a drug to fall to 50% during the elimination phase
… is independent of the dose administered
Review opioid agonists. ``
Slide 62
What is context-sensitive half-time?
Context-sensitive half-time is time necessary for plasma concentration of a drug to fall to 50% aftera continuous infusion of a specific duration
What is effect site equalibration time?
Effect-site equilibration time is the half-time of equilibration between the drug concentration in plasma and the drug effect
Review peak effect slide.
Slide 73
What is codeine used for?
Used mainly for antitussive effects
What is the PK of codeine?
PRO-drug converted to Morphine (10%) in the liver
What impact does the liver have on codeine?
Limited first pass hepatic effect
What effect does liver failure and opioids have on one another?
Even though the liver is the metabolic organ primarily responsible for the biotransformation of most opioids, the degree of liver failure typically seen in perioperative patients is not severe enough to have a major impact on opioid pharmacokinetics
Alfentanil affected by _________.
CYP enzyme alterations
How is morphine metabolized?
Morphine 3-glucuronide and morphine 6-glucuronide are excreted via the kidney
What is important to know about meriperidine’s active metabolite, normeperidine?
excitatory CNS effects that can cause seizures
What is the relation between remifentanil and renal failure?
it is not impacted by renal failure
What is the relationship between morphine and gender?
- Evidence that Morphine is more potent in women than in men
- A lower concentration of morphine is required to produce comparable analgesia
- May be related to cyclic gonadal hormones
Fentanyl congeners are more potent in _________
older patients
What are the pharmokinetic differences associated with older patients?
decreases in clearance and Vd, in older patients
Pharmacodynamic differences are primarily responsible for _______________ in patients greater than 65 years of age
decreased dose requirements
What is an important factor influencing the clinical pharmacology of opioids?
Body weight
Morbidly obese patients require _________ doses than lean patients to achieve target concentrations
Higher
What is the response from partial agonists?
Bind to mu receptors, and activates it with a smaller shape change which leads to only a partial receptor response.