Prodigy Pharmacokinetics Flashcards
Which is the single most important enzyme, accounting for 40-45 percent of all mediated drug metabolism?
CYP3A4
After intravenous administration of fentanyl, there is an initial rapid increase in plasma concentration of the drug followed by a rapid decline in plasma administration. This initial, rapid decline is due primarily to
redistribution to highly-perfused organs
Once injected, the plasma concentration of an opioid such as fentanyl _______
rises rapidly.
Shortly after this initial rise, the plasma concentration rapidly
decreases as the drug is distributed into the highly perfused organs such as the brain, liver, and kidneys. A second, slower decrease in the plasma concentration occurs as the drug distributes into the less well-perfused tissues such as the muscles and adipose tissue.
A protein binds to a cell membrane receptor, causing it to open and allow the passage of substances into the cell. This is an example of a
ligand-gated receptor
A ligand-gated receptor is triggered by the
binding of a chemical to the receptor. When this occurs, the receptor’s shape alters causing the channel to open. This allows the passage of specific substances through the channel.
Which drug exhibits the classic drug-drug interaction associated with serotonin syndrome when combined with MAOIs?
Meperidine
The classic drug interaction associated with serotonin syndrome is the combination of meperidine with.
MAOIs
Phenylpiperidines including (4) associated with interactions with MAOI and serotonin
fentanyl, methadone, and tramadol and methylene blue have also been associated.
The term that describes the amount of drug within the body as a whole compared to the amount of the drug in the bloodstream is the
The volume of distribution is a number that describes the amount of drug in the body compared to how much is actually in the bloodstream.
Vd: It is calculated as
Vd = Amount of drug in body/Plasma concentation of the drug. It actually describes an apparent volume.
If a large amount of a drug has been administered and only a small amount of the drug appears in the plasma, the drug is said to have a ____Vd
have a large volume of distribution.
What term refers to the dose of a drug required to produce a given effect in 50 percent of subjects
Potency (ED 50)
The only process that does not involve the cytochrome P450 pathway is
Hydrolysis
Cytochrome P450 enzymes are involved in
oxidation, reduction, and conjugation reactions.
The only metabolic pathway in which CYP 450 they are not present is
hydrolysis, which typically occurs outside of the liver.
Drugs such as(4) undergo hydrolysis.
remifentanil, esmolol, succinylcholine, and ester local anesthetics
Which of the following measurements predicts the time it takes for 50% of a drug to be eliminated from the central compartment when a continuous infusion is discontinued?
Context sensitive half time
The steady-state plasma concentration corresponds to the
steady concentration at the site of action and is determined by a concentration-response curve
Which term refers to the theoretical volume of blood from which a drug is completely and irreversibly removed in a unit of time?
Elimination clearance
The most important factor determining the rate of diffusion of a drug across a membrane is
Concentration gradient accross the membrane
What is hepatic enzyme induction?
If liver enzymes are exposed to particular compounds or drugs over a period of time, they will increase their activity, resulting in an increased ability to metabolize the drugs.
A chemical that can bind with a protein to form a new complex is a
Ligand
The primary function of phase II conjugation reactions are to make the molecule more
Water-soluble
Remifentanil exhibits a _____ volume of distribution than fentanyl due to a(n) _____ clearance.
smaller, increased
Drugs such as fentanyl that are
highly lipophilic and exhibit low protein-binding exhibit a high volume of distribution.
Opioids such as remifentanil and alfentanil exhibit a
smaller volume of distribution due to increased protein binding and a faster clearance
Most drug metabolism is performed by microsomal enzymes in the smooth endoplasmic reticulum of the
Liver cells
The vessel-poor group is comprised of bone, ligament, and cartilage, accounts for
20% of the body mass, and receives a negligible amount (0%) of the cardiac output.
The vessel-poor group is comprised of
bone, ligament, and cartilage, accounts for
The muscle group is comprised of muscle and skin. It accounts for______% body mass and receives ___% of the Cardiac output
50% of the body mass and receives 19% of the cardiac output.
Vessel RICH GROUP It comprises ____%of the body mass but receives 75% of the cardiac output.
10%
The maximum duration that a single transdermal medication patch would be effective is about____days? Why?
7 days; Because the skin sloughs and regenerates about every 7 days, the maximum duration for a single transdermal application is about 7 days.
A drug is being administered by continuous infusion, and its plasma concentration is now constant. The drug is said to be in
Steady state
Ideally, a medication used for a transdermal application has (weigh)
a molecular weight less than 1000 daltons
Ideally, a medication used for a transdermal application has (ph and lipid solubility)
pH between 5-9 in an aqueous solution
Ideally, a medication used for a transdermal application has (daily requirements)
less than 10 mg
Hepatic clearance is the product of the hepatic blood flow and the drug’s
hepatic extraction ratio
Which of the following is a Phase II reaction?
conjugation and synthesis reactions.
Which anesthetic intervention is typically avoided in patients undergoing a large hepatic resection?
Epidural catheter placement
Even if the preoperative coagulation studies were normal, patients undergoing liver resection can exhibit an
abnormal INR and platelet count postoperatively.The effect peaks on postop day 1 or 2 and typically resolves by about 5 days postop. Because of the alteration in coagulation studies, many practitioners avoid epidural catheter placement.
The diffusion of a drug across a membrane from an area of higher concentration to an area of lower concentration without the expenditure of energy is
Passive transport
Erythromycin administration in patients taking theophylline can lead to
theophylline toxicity. erythromycin can inhibit the metabolism of theophylline and potentially lead to theophylline toxicity.
What is pharmacokinetics?
Pharmacokinetics, or what the body does to the drug can be remembered with the ADME mnemonic, which stands for absorption, distribution, metabolism, and excretion of the drug.
In opioids with a small volume of distribution, the termination of the analgesic effect is primarily due to
Clearance of the drug
Determining the safety margin of a drug requires that you know data about the effective dose of the drug and
the Lethal dose
Select two inducers of hepatic drug metabolism.
Rifampin
Phenytoin
Name some inducers of CYP450
carbamazepine, ethanol, glucocorticoids, phenobarbital, phenytoin, rifampin, St. John’s Wort, and tamoxifen.
What determines the duration of action of an irreversible antagonist?
Receptor regeneration
When you administer a bolus dose of a drug intravenously, which tissue would have an increase in the tissue concentration of the drug first?
Liver
The plasma half-life of a drug is inversely proportional to its
rate of clearance
The percent of a drug that the liver can clear as it passes through it is referred to as the
hepatic extraction ratio
Which of the following terms refers to compounds that bind to receptors without producing any changes in cellular function?
Antagonists
Which drug or drug class is an inhibitor of hepatic drug metabolism?
azole antifungal drugs, cimetidine, disulfiram, grapefruit juice, macrolide antibiotics, protease inhibitors, quinidine, SSRIs.
One of the advantages of transdermal medication over other routes is that it
provides a more consistent plasma concentratio
transdermal site A common side effect
can be rash or erythema at the application site.
Hepatic enzyme induction will result in a reduction in the ____ of a drug.
half-life
Which of the following medication administration routes can undergo first-pass hepatic metabolism?
oral / rectal
In opioids with a high volume of distribution, the decrease in plasma concentration and termination of the analgesic effect is due primarily to
Redistribution
Which Phase 1 reaction is characterized by reactions that remove electrons from a molecule?
Oxidation
Select two common treatments for moderate to severe serotonin syndrome.
Chlorpromazine
Cyproheptadine
