Principles of Drug Action Flashcards
Drug dosage, absorption, distribution, metabolism, and elimination refers to:
A) pharmacodynamics
B) pharmacokinetics
pharmacokinetics
Concentration of drug at site of action, therapeutic effects, and side effects refer to:
A) pharmacodynamics
B) pharmacokinetics
A) pharmacodynamics
Drug indications means getting which of the following?
right drug
right space
right concentration
right period of time
right drug
Distribution/mechanism means getting which of the following?
right drug
right space
right concentration
right period of time
right space
Mechanism/metabolism means getting which of the following?
right drug
right space
right concentration
right period of time
right concentration
Pharmacokinetics means getting which of the following?
right drug
right space
right concentration
right period of time
right period of time
Some consequences of poor drug therapy: (5)
- No therapeutic benefit
- Side effects
- Poor compliance
- Drug interactions
- Drug resistance
Dose-response curve
___-axis represents drug response as % maximal response.
___-axis represents dose amount.
y
x
This dose response curve is better to evaluate/compare drug effects over the typical large concentration (or dose) ranges used in pharmacology:
arithmetic scale or semi-logarithmic scale?
semi-logarithmic
EC50 is the effective ______ to produce 50% of maximal response–a measure of potency.
concentration
Since we often do not know the concentration of free drug in the body, we can use the effective ____ of drug producing 50% of maximal response, known as ____ to compare the potencies of 2 or more drugs.
DOSE
ED50
Note: The units of ED50 is in units of DOSE!
Potency refers to the _______ necessary to achieve the desired effect.
dose
Definitions:
- IC50
- TD50
- LD50
- inhibitory concentration
- toxic dose
- lethal dose
The level of effect a drug elicits is _____.
efficacy
Efficacy is synonymous with response
The amount or concentration of drug responsible for a response is _____.
potency
Potency is synonymous with dose.
What is the rank order of efficacy of the 3 drugs?
bumetanide and furosemide are more efficacious than metolzaone
What is the rank order of potency for the 3 drugs?
metolazone and bumetanide are equally more potent than furosemide
Measure of equal ED50 or EC50 of drugs.
Don’t care about maximal effect!
Which drug is more potent, morphine or aspirin? Why?
Which drug is more effective? Why?
Morphine is more potent because ED50 falls at a much lower dose than aspirin.
Morphine is more effective because the response curve is much greater than aspirin.
Caution on exam: Which is better? Depends!
Most side effects of drugs are ______ based.
mechanism
ON EXAM:
Most side effects are mechanism based due to: (4)
- therapeutic mechanism of action
- off-target mechanism of action
- interaction/interference with other drugs
- Often, but not always, dose-dependent
_______ Index quantifies side-effects to evaluate drug safety.
Therapeutic
Therapeutic index = ____/_____
or _____/_____.
The larger the ratio, the safer the drug.
TD50/ED50
LD50/ED50
Therapeutic index can be any _____ drug effect, and the denominator can be any ______ outcome.
adverse
therapeutic
Drugs can act directly or indirectly on: (4)
- receptors
- channels
- transporters
- enzymes
Mechanisms of drug action: (6)
- Act competitively or irreversibly
- Mimic or antagonize endogenous substances
- Classic: e.g, drugs affecting autonomic nervous system
- Emerging: Biologics
- Drugs and drug target can be pleiotropic (affect many systems) or very specific
- Can impair key point(s) in a metabolic chain to collapse the whole
- Toxicity is usually mechanism-based and is rarely idiosyncratic
- Metabolism both creates (pro-drugs) and destroys
Some drugs work by unconventional mechanisms of action: (6)
- disrupters of structural proteins
- enzyme drugs (thrombolytics)
- covalently link to macromolecules
- chemically react with small molecules (antacids)
- others (vaccines, vitamins, osmotics)
- drugs that bind free molecules or atoms
What drug is used to treat HIV-1 infection?
- Name:
- Pharacodynamics:
- Pharmacokinetics:
- Other:
- Name: Emtriva, or emtricitabine
- Pharacodynamics:cytosine analog reverse transcriptase inhibitor
- Pharmacokinetics:high bioavailability, once daily, low protein binding (means low drug interaction)
- Other: Activity against HBV
