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27 Cards in this Set
- Front
- Back
What is Pharmacokinetics? |
What the body does to the drug, Think ADME: Adsorption Distribution Metabolism Excretion |
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What is pK? |
The pH at which half of the molecules are ionised. |
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The four main types of proteins drugs act on... |
Enzymes Receptors Transporters Ion channels |
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What is Pharmacodynamics? |
The effect of Drug on Body. allows us to compare effectiveness of drugs. determine appropriate dose for patient. |
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What does an Antagonist do? |
Activates receptor |
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What does an Antagonist do? |
Inhibits receptor |
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Describe allosteric action of a drug on an ion channel... eg. Benzodiazipines on a GABA(A) receptor. |
Benzodiazipan will enhance the binding of GABA by changing shape of binding site and therefore affinity. |
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What are the four main types of Receptors? |
Ligand Gated Ion channels G Protein coupled receptor Tyrosine Kinase link receptor Intracellular receptor |
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Two types of Ion channels? |
Ligand gated (think ACh) Voltaged Gated (think Ca2+ ion channels at terminal ends) |
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Describe the functions of these three types of G protein receptors, Gs, Gi, Gq |
Gs- Stimulates Adenyl cyclase Gi - Inhibits Adenyl cyclase Gq - Activates Phospholipase C |
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Which of the follow is an example of a Gs receptor? Alpha 1, Alpha 2, Beta1/2 |
Beta 1/2 are both examples of Gs receptors as they stimulate adenyl cyclase, activating Ca2+ channels, flooding the cell with calcium ions |
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What kind of G protein receptor is Alpha 1? |
Alpha 1 is a Gq receptor as it actives the enzyme Phospholipase C. |
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What kind of G protein receptor is Alpha 2? |
Alpha 2 is a Gi receptor as it inhibits the active of Adenyl cyclase. It is a type of autoreceptor. eg. post-ganglion, sympathetic neurones, where its activation will inhibit the release of neurotransmitters (Ca2+ cannot enter cell and allow fusing of vesicles into synaptic cleft) |
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There Two major classes of intracellular receptors, Class I and Class II. Where is Class I located? |
The Cyotplasm. These receptors form Heterodimers, and their ligands are endocrines(eg steroids and lipophilic hormones which can cross the celle membrane easily) |
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Where are Class II intracellular receptors located? |
The Nucleus. Also form Heterodimers, Ligands tend to be Lipids. |
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List the following Drug targets in order of their speed in eliciting a response, from fastest to slowest: Nuclear receptor Ligand-gated ion Channels Tyrosine Kinase-linked receptor G-protein coupled receptors |
Ligand-gated Ion channels (milliseconds) G-protein coupled receptors (seconds) Tyrosine kinase-link receptor (minutes) Nuclear receptors (Hours) |
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What are the axis of a Dose response Curve? |
X-axis: Agonist concentration Y-axis: % response |
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What are the two types of Dose response Curves? |
Graded, and Quantal - Allow Potency and Efficacy to be determined |
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Describe Graded Dose-response curves... |
-The response of a particular system eg isolated piece of smooth muscle -Produced by plotting Pharmacological response against Log dose -Graded response eg half of all receptors are inhibited |
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What Parameter can be determined from a Graded dose response curve? |
The maximal response |
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Describe Quantal dose-response curves... |
- Gives a specificed response in a certain Population -All-or-Nothing response, either an animal/individual in a population will response or they will not. - Produced by plotting % Responding against log dose |
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What is the difference between Potency and Efficacy? |
Potency: How well a drug can BIND to a receptor (in order to elicit a response) Efficacy: Describes the ability of an agonist to ACTIVATE a receptor. ie. efficacy is the maximal effect a drug can produce, an agonist with a high efficacy will be a Full Agonist, while a drug with a lower efficacy will be a Partial Agonist. |
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What does Kd represent? |
Kd = the dissociation constant of a particular drug. (think of it as how likely a ligand will dissociate from receptor) -can be used to identify an unknown receptor -can be used to quatitively compare the affinity of different drugs on the same receptor. -There is an inverse relationship between Kd and affinity i.e a lower Kd indicates a tighter ligand-receptor interaction and therefore a higher affinity. |
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How is Kd found? |
Kd is the value at which 50% of drug is bound to the receptor, therefore when 50% are bound at a lower concentration there will be a higher affinity, as Less drug is needed to bind 50% of receptors. |
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Why does Higher affinity not always mean a high Efficacy? *remember efficacy is the ability of a drug to activate a receptor ie full agonists have high affinity, partial have low affinity* |
A drug may have a high affinity for a receptor but it could infact be an antagonist for example which would inhibit the receptor instead. similarly perhaps the drug has a high affinity but it binds else where on the receptor and not the area which would activate it. |
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Summary of Efficacy, affinity and response curves. |
- % Binding against log agonist response curve can be used to calculate Kd (the conc at which 50% of receptors are bound). This will tell us about the affinity of the drug but not necessarily the efficacy. - To see efficacy we need a graded dose response curve with % response of tissue against log concentration of drug/dose. we can see maximum response here and at what concentration, determine if full/partial agonist or possibly antagonist. |
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What exactly is Potency and how can we calculate it? |
*potency is how well a drug can bind to a receptor in order to elicit a response. it depends on affinity, efficacy, receptor density, and efficiency of the intrinsic stimulus response mechanism* - It is the amount of drug needed to produce a given effect -calculated as 50% of tMax i.e the lower the EC50 (50% tMax) the higher the potency as a lower concentration is required to cause a response. must be determined from graded-dose response curves. |