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35 Cards in this Set
- Front
- Back
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Pharmacology |
- study of biochemical and physiological effects of chemicals and their mechanism of action - focus on what drug does to the body |
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How do drugs work? |
- interact with molecules of organism - macromolecules are most often the target - interaction between drug and target alters function of target - end result is change in physiology |
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Drug target examples |
- most often proteins - DNA (anti-cancer drugs) - not always macromolecules (drugs that change pH, osmotic pressure) |
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Drug receptors |
- common targets for drug action - proteins that mediate cellular signaling for endogenous regulatory chemicals (neurotransmitters, hormones) |
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Drug receptor history |
- late 1800s: hypothetical constructs to explain actions of endogenous chemicals - 1970s: strong biochemical evidence for their existence - 1980s: isolation provided final proof - now hundreds have been proven to exist |
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Agonist |
- produces a response at molecular, cellular, or tissue level - bind to and ACTIVATE their receptor - focus on molecular actions- not on whole body |
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Full agonist |
- drug produces maximal response for that tissue or system |
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Partial agonist |
- does not produce maximal response (less than maximal response) - not necessarily half response, just lower |
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Inverse agonist |
- produces opposite response of agonist |
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Dose response curves |
- x-axis: LOG drug concentration - y-axis: response - at 0 drug concentration response is not always at 0 because there is often a base level of response (heart rate) |
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Antagonist |
- blocks the response to an agonist - does not inhibit receptor - does not do anything by itself- must have agonist present |
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Neutral antagonist |
- can be competitive or noncompetitive |
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Negative antagonist |
- reduces response in absence of agonist - equivalent to an inverse agonist |
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Drug-receptor interaction types |
- covalent- strongest - ionic - hydrogen - hydrophobic- weakest |
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Drug-receptor interactions |
- drugs have diverse 3D structures and can bind at multiple points with receptors - covalent bonds uncommon, only occur with non-competitve antagonists, irreversible - ionic, hydrogen, hydrophobic: most common, all reversible |
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Affinity |
- tendency of drug to bind to a particular receptor - often used to compare with other drugs - qualitative |
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Drug/ Pharmacological Efficacy |
- ability to produce biochemical response based on number of receptors bound - sometimes corresponds to clinical efficacy |
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Clinical Efficacy |
- ability to produce a therapeutic response - may be due to efficacy of drug at molecular level but not always |
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Epinephrine |
- increases blood pressure for patients with low blood pressure - extremely high clinical efficacy |
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Antihistamines |
- allergic rxn causes release of histamine in body - histamine is an agonist - antihistamine is a neutral antagonist - has 0 pharmacological efficacy, good clinical efficacy |
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Receptors |
- have binding sites, not all binding sites are receptors - fundamental properties: molecular recognition, signal transduction- due to separate domains on receptor but they are linked |
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Molecular recognition |
- bind to the drug |
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Signal transduction |
- message propagation - signal transferred from drug to receptor |
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Kd theory |
- index of drug affinity- strength/tendency of drug binding to receptor - drug specific property, used for classification - depends only on drug and receptor- not on tissue or number of receptors - 1 drug can have multiple Kd values if it can bind to more than 1 receptor |
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Equilibrium binding equation |
Bound = Bmax[L] / [L] + Kd - Bound: how much of receptor is bound - Bmax: constant for max # of receptors - [L]: ligand/drug concentration - Kd: constant for drug affinity |
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Kd math |
= [drug] at 1/2 Bmax - affinity inversely related to Kd - high Kd = lower affinity - low Kd = higher affinity |
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Linear plot |
- x-axis: ligand concentration - y-axis: ligand binding - difficult to evaluate Kd - must estimate Bmax |
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Semi-log plot |
- x-axis: log ligand concentration - y-axis: ligand binding - sigmoidal (S-shaped) - symmetric around Kd - can see binding at high and low concentration - easier to estimate Bmax and Kd |
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Scatchard plot |
- x-axis: Bound - y-axis: Bound/Free ligand - slope = -1/Kd - x-intercept = Bmax - derived from algebraic rearrangement of binding equation |
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Comparing drug affinities |
- used for defining drug selectivity - used for classifying drugs |
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Comparing drug affinity with linear plot |
- can tell Kd different - difficult to estimate how big difference is |
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Comparing drug affinity with semilog plot |
- clearly can tell Kd different - if Kd is left, has higher affinity - if Kd is right, has lower affinity |
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Comparing drug affinity with scatchard plot |
- clearly can tell sloped are different - steeper slope = lower Kd = higher affinity - shallow slope = higher Kd = lower affinity |
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Comparing receptor density |
- Bmax different - not often done for comparing 2 drugs - more important for comparing effect of disease or experimental treatment on binding ofsingle drug |
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Pharmacokinetics |
- study of what the body does to the drug - absorption - distribution - metabolism - elimination |
