Pharm - Pharmacokinetics/-dynamics (Receptor binding & Therapeutic measures) Flashcards
Pg. 241-242 in First Aid 2014 Sections include: -Efficacy vs. potency -Receptor binding -Therapeutic index
Define Efficacy.
Maximal effect a drug can produce.
What are 4 examples of high-efficacy drug classes?
High-efficacy drug classes are (1) analgesic (pain) medications (2) antibiotics (3) antihistamines (4) decongestants
Contrast partial and full agonists in terms of efficacy.
Partial agonists have less efficacy than full agonists
Define Potency.
Amount of drug needed for a given effect
What is the relationship between potency and affinity for receptor?
Increase potency, Increase affinity for receptor
What are 3 examples of highly potent drug classes?
Highly potent drug classes include (1) chemotherapeutic (cancer) drugs (2) antihypertensive (blood pressure) drugs (3) lipid-lowering (cholesterol) drugs
Draw graphs demonstrating Drug X having greater efficacy and being more potent than Drug Y, but Drug Y being able to reach Drug X’s effect with greater dosage.
See p. 241 in First Aid 2014 for graphs
Draw a graph depicting the effect of a competitive antagonist on agonist dose and percent maximal effect.
See p. 242 in First Aid 2014 for graph on left
Draw a graph depicting the effect of a noncompetitive antagonist on agonist dose and percent maximal effect.
See p. 242 in First Aid 2014 for middle graph
Draw a graph depicting the dose and maximal effect of full versus partial agonist.
See p. 242 in First Aid 2014 for graph on right
What is the effect of a competitive antagonist? Can it be overcome?
Shifts curve to right (decreasing potency), no change in efficacy. Can be overcome by increasing the concentration of agonist substrate.
What is the effect of a noncompetitive antagonist? Can it be overcome? What other type of antagonist shares these properties?
Shifts curve down (decreasing efficacy). Cannot be overcome by the increased agonist substrate concentration; Irreversible competitive antagonist
How do partial agonists contrast with full agonist? What kind of variable is potency?
Acts at same site as full agonists, but with lower maximal effect (decreased efficacy); Potency is an independent variable
What is an example of competitive antagonist, and on what receptor does it act?
Diazepam + Flumazenil (competitive antagonist) on GABA receptor
What is an example of noncompetitive antagonist, and on what receptor does it act?
Glutamate + Ketamine (noncompetitive antagonist) on NMDA receptors
What is an example of irreversible competitive antagonist, and on what receptor does it act?
Norepinephrine + Phenoxybenzamine (irreversible competitive antagonist) on alpha-receptors
What is an example of full versus partial agonist, and on what receptor does it act?
Morphine vs. Buprenorphine (partial agonist) at opioid mu-receptors.
What is the clinical use of therapeutic index?
Measurement of drug safety
What is the equation for therapeutic index?
TD 50 / ED 50 = median toxic dose / median effective dose; Think: “TITE: Therapeutic index = TD 50 / ED 50”
What is the therapeutic window?
Therapeutic window - measure of clinical drug effectiveness for a patient
Do safer drugs have lower or higher TI values?
Safer drugs have higher TI values
What are 4 examples of drugs with low TI values?
Examples of drugs with low TI values include (1) digoxin (2) lithium (3) theophylline (4) warfarin
What often replaces TD 50 in animal studies?
LD 50 (lethal median dose) often replaces TD 50 in animal studies.
Draw a graph of (x-axis: log (drug concentration), y-axis: % of patients responding), depicting and labeling the following: (1) efficacy (2) therapeutic index (3) therapeutic window (4) toxicity (5) ED 50 = median effective dose (6) TD 50 = median toxic dose.
See p. 242 in First Aid 2014 for graph at bottom of page
