Exam 3 Flashcards
What does ADME stand for?
Absorption, Distribution, Metabolism, and Excretion
What are the three primary means to quantify drug effect?
Onset, duration and intensity
What goes on 1, 2, and 3?
1: Intensity
2: Duration
3. Onset
What happens onset, intensity and duration on the red line in comparison to the black?
Onset: same, intensity: decreases, duration: increases
Two reasons why less than 100% of a dose may reach the site of action
Degradation and excretion
The study of the absorption, distribution, biotransformation, and elimination of xenobiotics
pharmacokinetics
The study of the molecular, biochemical, and physiological effects of xenobiotics and their mechanisms of actions
pharmacodynamics
The fate of a drug after it has entered the systemic circulation
drug disposition
What three aspects make up pharmacotherapeutics?
pathophysiology, pharmacodynamics, and pharmacokinetics
What was the greatest reason why drugs failed in Phase I of clinical trials in 1991? What was the %? What changed to lower the percentage (and what’s the %s value)?
Biggest reason: pharmacokinetics/bioavailability (40%)
Development of improved preclinical ADME greatly reduced drug attrition due to poor PK/bioavailability (<10%)
What route of administration has the most rapid onset? Slowest?
Fastest: IV slowest: smoked
What are the four routes of administration?
ingestion, inhalation, dermal, and parenteral
A reduction in the extent of absorption will impact which of the three measures of pharmacologic effect: onset, intensity, and/or duration?
Intensity
A reduction in the speed of entry into the systemic circulation will impact which of the three measures of pharmacologic effect: onset, intensity, and/or duration?
Onset
Barriers and blood flow can impact both the speed and extent of ________ of a drug in the body
distribution
Of the four consequences of metabolism, what process is used for active to inactive metabolites?
phenobarbital -hydroxylation-> Hydroxyphenobarbital
Of the four consequences of metabolism, what process is used for active to active metabolites
Procainamide -acetylation-> N-acetylprocainamide
Of the four consequences of metabolism, what process is used for inactive to active metabolites
Codeine -demethylation-> morphine
Of the four consequences of metabolism, what process is used for active to reactive metabolites
Acetaminophen -> reactive metabolite
A ______ in the extent of absorption will reduce the peak drug conc. and the time the drug conc. remains above the minimally effective conc.
reduction
A reduction in the speed of entry into the systemic circulation will (inc/dec) the time it takes for the drug conc. to reach the minimally effective conc. Which part of the curve will be most impacted?
increase; the onset
What barrier can significantly reduce the amount of drug that enters the site of action?
tissue
The graph below shows the conc vs time curve for two formulations of a bupropion. Compared to “Budeprion XL” (green), the maximal intensity of the pharmacologic effect for “Wellbutrin XL (red)” would be expected to occur:
a. later
b. sooner
c. at the same time
a. later
What percent of drug currently fail in clinical trials due to problems with the ADME of the compounds?
A. ~40%
B. <10%
C. 25%
B. <10%
Which route of admin. would be expected to produce the most rapid onset of pharmacologic effect?
a. oral
b. dermal
c. subcutaneous
d. intravenous
e. intramuscular
d. intravenous
Morphine is a metabolite of codeine and this metabolite is responsible for the analgesic effect when codeine is admind. In a patent who has a genetic defect such that they cannot metabolize codeine, the magnitude of pain relief would be expected to be (incr/decr/same) compared to normal pateints?
decreased
Which route of admin. avoids the need to cross a biological membrane in order to reach the systemic circulation?
intravenous
Which route of admin. avoids the need to cross a biological membrane in order to reach the CNS?
None
What impact would a drug that speeds up stomach emptying (metoclopramide) have on the time to peak conc for acetaminophen?
The peak drug conc would be higher
In Fick’s equation, if the diffusion rate increases, what happens to the concentration?
Increases directly
For a drug which undergoes passive diffusion, the rate of transport across the membrane should (incr/decr/same) as the concentration increases
increase
What site in the GI tract is where most drug absorption occurs? Why?
Small intestine: covered in folds of Kercking with villi containing microvilli. This increases the surface area and transit time (~3-5hrs)
The passive movement of drug through lipid membranes
transcellular diffusion
The passive movement of drugs between cells via tight junctions.
paracellular diffusion
A carrier-mediated process that involves a transport protein which moves drug with a conc. gradient
facilitated diffusion
A carrier-mediated process that requires energy.
active transport
What types of transport are passive? Carrier-mediated?
Passive: transcellular and paracellular
Carrier-mediated: facilitated and active
Which transports are driven or move with a concentration gradient?
A. Transcellular
B. Facilitated
C. Paracellular
D. Active Transport
trans and para driven and facilitated moved
In a base solution, which pKa(><=)pH is favorable? Acid?
Base: pKa<pH favorable
Acid: pKa>pH favorable
T or F: Gastrointestinal transit time does NOT influence the extent and rate of drug absorption
False