Active Recall Part III
General Principles
Q: What are the three primary properties of an ideal drug?
A: Effectiveness, Safety, Selectivity
Q: Which property is most important?
A: Effectiveness
Q: What does selectivity mean?
A: Producing the desired response while minimizing effects on other tissues.
Q: Name four additional desirable characteristics of an ideal drug.
A: Predictability, Reversible action, Ease of administration, Freedom from interactions (also low cost, chemical stability).
Q: What is the therapeutic objective of drug therapy?
A: Maximum benefit with minimal harm.
Pharmacokinetics (ADME)
Q: What does ADME stand for?
A: Absorption, Distribution, Metabolism (Biotransformation), Excretion
Q: What is pharmacokinetics?
A: What the body does to the drug.
Absorption
Q: What is absorption?
A: Movement of a drug from its administration site into the bloodstream.
Q: What is bioavailability?
A: Fraction of administered dose reaching systemic circulation.
Q: Which route has 100% bioavailability?
A: IV administration.
Q: What factors affect absorption?
A: Blood flow, route, formulation, gastric motility, food.
Q: What is first-pass effect?
A: Drug metabolism in the liver before reaching systemic circulation.
Q: Which route is most affected by first-pass metabolism?
A: Oral (PO).
Distribution
Q: What is distribution?
A: Movement of drug from bloodstream into tissues.
Q: What factors affect distribution?
A: Blood flow, capillary permeability, protein binding.
Q: Which protein binds many medications?
A: Albumin.
Q: Which drug form is active?
A: Free (unbound) drug.
Q: What happens when albumin levels decrease?
A: Increased free drug and increased toxicity risk.
Biotransformation (Metabolism)
Q: What is biotransformation?
A: Metabolism of drugs, primarily in the liver.
Q: Why does metabolism occur?
A: To convert drugs into forms easier to excrete.
Q: Which organ is most responsible for metabolism?
A: Liver.
Excretion
Q: What is excretion?
A: Removal of drugs from the body.
Q: Which organ is most important for excretion?
A: Kidneys.
Q: What two kidney factors affect excretion?
A: Renal blood flow and GFR.
Q: What happens when kidney function declines?
A: Drug accumulation and toxicity risk increase.
Factors Affecting Pharmacokinetics
Q: Why are elderly patients at higher risk for drug toxicity?
A: Reduced renal function, decreased albumin, increased body fat.
Q: How does increased body fat affect fat-soluble drugs?
A: Drugs remain in the body longer.
Q: Why are pediatric patients different?
A: Organ systems are immature and drug handling differs.
Q: How can disease states affect pharmacokinetics?
A: Liver disease decreases metabolism; kidney disease decreases excretion.
Q: What is P-glycoprotein?
A: A transporter protein that pumps drugs out of cells and protects organs.
Pharmacodynamics
Q: What is pharmacodynamics?
A: What the drug does to the body.
Q: What determines a drug's effects?
A: Drug-receptor interactions and other mechanisms.
Q: What is affinity?
A: Strength of attraction between a drug and receptor.
Q: High affinity means what?
A: Strong receptor binding.
Theories of Drug Action
Q: What is a drug-receptor interaction?
A: Drug binds to receptor and changes cell activity.
Q: What is a drug-enzyme interaction?
A: Drug alters enzyme activity.
Q: What is a nonspecific drug interaction?
A: Drug acts without binding a receptor.
Drug Response Relationships
Plasma Drug Levels
Q: What is the minimum effective concentration (MEC)?
A: Lowest concentration that produces a therapeutic effect.
Q: What is the therapeutic range?
A: Drug concentration between MEC and toxic level.
Q: What is a toxic level?
A: Concentration at which adverse effects become likely.
Q: What is a peak level?
A: Highest drug concentration in the bloodstream.
Q: Why are peak levels monitored?
A: To prevent toxicity.
Biologic Half-Life
Q: What is half-life?
A: Time required for plasma drug concentration to decrease by 50%.
Q: If 100 mg remains in the body and the half-life passes, how much remains?
A: 50 mg.
Q: After a second half-life?
A: 25 mg.
Q: Why is half-life important?
A: Helps determine dosing intervals.
Steady State
Q: What is steady state?
A: Drug administration equals drug elimination.
Q: When does steady state occur?
A: Usually after approximately 4–5 half-lives.
Q: Why is steady state important?
A: Predictable therapeutic drug levels are achieved.
Potency and Efficacy
Q: What is potency?
A: Amount of drug needed to produce an effect.
Q: What is efficacy?
A: Maximum effect a drug can produce.
Q: Which is more important clinically?
A: Efficacy.
Q: Can a drug be potent but have low efficacy?
A: Yes.
Memory Tip:
Potency = How much?
Efficacy = How well?
Drug Responses
Therapeutic Response
Q: What is a therapeutic response?
A: Desired beneficial effect of a drug.
Predictable Adverse Responses
Q: What are side effects?
A: Secondary effects occurring at normal doses.
Q: What are toxic effects?
A: Harmful effects caused by excessive drug levels.
Q: What are cumulative effects?
A: Effects caused by drug accumulation.
Unpredictable Responses
Q: What is an allergic reaction?
A: Immune-mediated response to a drug.
Q: What is an anaphylactic reaction?
A: Severe, life-threatening allergic response.
Q: What is an idiosyncratic response?
A: Unusual or unexpected drug reaction.
Iatrogenic Response
Q: What is an iatrogenic disease?
A: Disease caused unintentionally by medical treatment.
Black Box Warning
Q: What is a Black Box Warning?
A: FDA's strongest warning for serious risks.
Q: Why are Black Box Warnings important?
A: They identify potentially life-threatening adverse effects.
Drug Interactions
Additive Effect
Q: What is an additive effect?
A: Combined effect equals sum of individual effects.
Memory:
1 + 1 = 2
Synergism
Q: What is synergism?
A: Combined effect is greater than expected.
Memory:
1 + 1 = 3
Potentiation
Q: What is potentiation?
A: One drug with little/no effect increases another drug's effect.
Memory:
0 + 1 = 3
Antagonism
Q: What is antagonism?
A: One drug reduces or blocks another drug's effect.
Memory:
1 + 1 = 0
Rapid Fire NCLEX Review
Q: ADME stands for?
A: Absorption, Distribution, Metabolism, Excretion
Q: What does pharmacokinetics study?
A: What the body does to the drug.
Q: What does pharmacodynamics study?
A: What the drug does to the body.
Q: Which route has 100% bioavailability?
A: IV
Q: Which organ performs most drug metabolism?
A: Liver
Q: Which organ performs most drug excretion?
A: Kidneys
Q: What is the active form of a drug?
A: Free drug
Q: What is half-life?
A: Time for drug concentration to decrease by 50%.
Q: When is steady state reached?
A: About 4–5 half-lives.
Q: Difference between potency and efficacy?
A: Potency = amount needed; efficacy = maximum effect.
Q: FDA's strongest warning?
A: Black Box Warning.
Q: 1+1=3 interaction?
A: Synergism.
Q: 0+1=3 interaction?
A: Potentiation.
Q: 1+1=0 interaction?
A: Antagonism.