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Questions and Answers
What type of antagonism occurs when two drugs bind to different receptors, stimulating opposite functions?
What determines the duration of action of an irreversible antagonist?
What is the term for the combined effect of two drugs being greater than the sum of their individual effects?
What is the result of continued stimulation of receptors with agonists?
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What is the therapeutic index?
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What is the primary factor that influences the ability of a drug to cross cell membranes?
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What happens to basic drugs when they enter a more basic environment than their pKa?
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What is the term for the enhancement of the action of one drug by another that has no detectable action of its own?
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What happens to acidic drugs when they enter a more basic environment than their pKa?
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What is the term for the phenomenon where the action of one drug is opposed by another?
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What is the primary factor that determines the degree of ionization of an agent as it crosses a membrane?
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What is the term for the uptake of a drug across tissues and its movement into the bloodstream?
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According to Fick's law, what is the rate of diffusion across a specific membrane dependent on?
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What is the fraction of the administered drug that actually reaches the systemic circulation?
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What happens to Lidocaine when it crosses the placenta?
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What is the term for a drug becoming trapped in a specific area because of its increased ionization?
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What is pharmacokinetics concerned with?
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What is the term for the ability of a drug to produce a desired response?
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What is the term for the amount of drug needed to produce an effect in 50% of the population?
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What type of receptor binding is irreversible?
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What is the term for the dosage range that provides safe therapy?
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What is the term for a drug that binds to a receptor and blocks its function?
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What is the term for the attraction of a drug to the receptor site?
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What is the term for the rapid decrease in response to a given dose of a drug?
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What is the most common site of receptor binding?
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What can be assumed if a drug name contains 'sodium', 'calcium', or 'magnesium'?
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What type of ion does a weak base typically unite with?
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If a drug name contains 'chloride' or 'sulfate', what can be assumed about the drug?
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What is the percentage of the ionized form of a weak acid with a pKa of 4 at a moving into a solution with a pH of 11?
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What is the percentage of the ionized form of a weak acid with a pKa of 10 entering a solution with a pH of 9.5?
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A basic drug with a pKa of 7.4 is given IV. What is the percentage of the drug in the ionized form?
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What is the relationship between the pKa of a drug and the pH of the environment in which it is administered?
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What is the primary route that a drug takes after being absorbed from the GI tract?
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What happens to an oral drug that is extensively metabolized by the liver?
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What is the purpose of compartment models in pharmacokinetics?
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What is the central compartment composed of?
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What is the primary factor that determines the volume of distribution of a drug?
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What is the normal volume of distribution for a 70kg adult?
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What does a high volume of distribution indicate about a drug?
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What is the formula for calculating the volume of distribution of a drug?
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Study Notes
Pharmacokinetics/Pharmacodynamics
- Pharmacokinetics: What the body does to the drug (Absorption, Distribution, Metabolism, Excretion)
- Pharmacodynamics: What the drug does to the body (MOA, effects, potency, etc.)
Receptors
- Protein or other substance binding to an endogenous chemical or drug (ligand)
- Reversible vs. Irreversible binding (Aspirin irreversibly binds to platelet receptor)
- Affinity: attraction of drug to the receptor site
- Potency: amount of drug needed to produce effect
- Efficacy (intrinsic activity): ability of drug to produce desired response
- Tolerance: increased amount of drug needed to produce a given response
- Tachyphylaxis: acute tolerance/rapid decrease in response to a given dose (e.g., nitroglycerine)
Terminology
- ED50: effective dose in 50% of population, ED99: effective dose in 99% of population
- TD50: toxic dose in 50% of population, LD50: lethal dose in 50% of population
- Ceiling Effect: dose beyond which no effect is seen, after which unwanted effects are seen
- Therapeutic window/index: dosage range that provides safe therapy
Receptor Binding
- Bonds with a receptor fall into categories of strength: Van der Waals, hydrophobic, hydrogen, ionic, and covalent
- Most common site of receptor is in the cell membrane
- Occupancy theory: magnitude of drug's effect is proportional to number of receptors occupied
- Square receptor concept: relationship between number of receptors bound and response is nonlinear
Antagonism
- Competitive antagonism: agonist and antagonist have affinity for the same receptor
- Physiological antagonism: two agonist drugs binding to different receptors that stimulate opposite functions
- Chemical antagonism: drugs action is blocked, but no receptor is involved
Drug Interaction Terminology
- Addition: combined effect of two drugs with the same mechanism produces an effect equal to that expected
- Synergism: combined effect of two drugs is greater than the sum of individual effects
- Potentiation: enhancement of action of one drug by another that has no detectable action of its own
- Antagonism: action of one drug opposes another
Up & Down Regulation
- Continued stimulation of receptors with agonists generally results in desensitization/down-regulation
- Continued administration of an antagonist results in up-regulation as a response to chronic blockade
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Description
Learn about the basics of pharmacology, including pharmacokinetics, pharmacodynamics, and relevant terminology. Understand how the body interacts with drugs and how drugs affect the body.
