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nu 600 dynamics
Pharmacodynamics
| Question | Answer |
|---|---|
| What is pharmacodynamics? | The study of what the drug does to the body, and the relationship between drug concentration of effect that determines appropriate dosing between individuals |
| What drug was introduced before the receptor theory was accepted, and when? | In 1965 after the introduction of beta adrenergic antagonists (beta blockers) |
| Who are Langley and Ehrlich and what did they claim? | In the late 1800s-early 1900s they stated that drugs interact with materials in the body, but had no proof of receptors |
| What is the receptor theory? | Most drugs act on receptor targets in the body |
| What is an example of a drug that does not work on receptors? | Osmotic diuretics |
| What is the Lock and Key theory? | A receptor (lock) has a particularly shaped pocket for an appropriately shaped molecule (key) can interact |
| What is an allosteric site? | Another site on a receptor, other than the site which a particular ligand interacts |
| What is a receptor? | A protein structure |
| What is a ligand, and what does it mean? | Ligand means 'binding' in Latin. It is a complex biomolecule that initiates or completes a biological process, or signals a trigger. |
| True or False: A ligand may be an agonist or antagonist | True |
| A ligand that triggers a physiologic response is called a _______ for that receptor. | Agonist |
| The binding site on a receptor is governed by what two concepts? | Affinity and Intrinsic activity |
| What is affinity? | How well a particle (ligand) is drawn to and held at a receptor site |
| What is intrinsic activity? | The effect that the ligand has when it interacts with the receptor |
| True or false: Intrinsic activity is the same in each individual. | False. Intrinsic activity varies between individuals, therefore at similar plasma concentrations some patients show a therapeutic response, limited to no response, or a toxic response. |
| Why do receptors revolve over time? | To provide particular necessary bodily functions |
| What results from a high affinity and high intrinsic activity, but a small drug concentration? | Good results |
| High intrinsic activity but low affinity yields what type of response? | Poor |
| What happens when a drug has a high affinity but no intrinsic activity? | No response |
| What are 5 different receptor types? | Ligand-Gated Ion channels, Metabophores, G Protein coupled receptors (GPCR) AKA seven membrane domain receptors, Intracellular receptors, Transporters |
| Where are Ligand-Gated Ion Channels located? | Cell membrane |
| What is an example of the ligand-gated ion channel that remains open? | Inward rectifier potassium channel |
| What is the function of the inward rectifier potassium channel? | Ion conductance across membrane based on concentration and electrical gradients |
| What is an example of the ligand-gated ion channel that opens and closes in response to particular cellular voltage? | Sodium-potassium pump |
| True or False: The sodium-potassium pump is voltage gated | True |
| Neurotransmitter-activated ligand-gated in channels are abundant where? | CNS |
| What are examples of neurotransmitters in the CNS that activate the ligand-gated ion channels? | Acetylcholine, GABA, and serotonin |
| What is the main inhibitory neurotransmitter in the CNS? | GABA |
| What are metabophores and where are they located? | Receptors located in the transmembrane |
| Where are the binding site and enzymatic component of a metabophore located? | The binding site is located externally (outside of the cell) and the enzymatic component is internal |
| After a ligand binds to the external binding site of a metabophore, what occurs? | Internal protein modification that initiates metabolic conversions of intracellular compounds (metabolic process) |
| The metabolic conversion of GTP to cGMP (component of 2nd messenger system) occurs after what receptor is stimulated? | Metabophore |
| What are G protein coupled receptors and where are they located? | 7 transmembrane proteins that detect extracellular ligands and initiate intracellular response through series of changes |
| What is the most common receptor on the cell membrane? | G protein coupled receptors |
| In G protein coupled receptors what occurs after the ligand binds to the receptor? | The inactive G protein is activated by substituting GTP or GDP and then the G protein detaches and activates or inhibits macromolecules |
| Beta adrenergic agonist receptors activates adenylyl cyclase producing cAMP after what type of receptor is stimulated? | G protein coupled receptors |
| What is the primary intracellular 2nd messenger in the CNS? | cAMP |
| What diseases are involved in the malfunction of the GPCR? | Diabetes, allergies, depression, cardiovascular defects, and cancer |
| What type of receptor is a steroid receptor? | Intracellular receptor |
| Are steroids lipid soluble or water soluble? | Lipid soluble |
| How do steroids cross the cell membrane? | Passive diffusion |
| Once inside the cell, what do steroids bind to? | Inactive protein complex |
| When steroids bind to the inactive protein in the cell what occurs? | Protein complex becomes active and is transported to the nucleus of the cell where a Dimer with another receptor and binds to DNA to influence RNA |
| Why do steroids have a slow onset and longer duration? | Due to the lag time in protein synthesis |
| What are transporters? | Receptors that move large non lipid soluble molecules across the membrane |
| What are examples of transporter receptors? | Neurotransmitter re-uptake proteins (serotonin) |
| What is the dissociation constant of drugs? | The naturally occurring ligand/drug molecule's propensity to pull off the receptor site |
| How is the dissociation constant related to the affinity constant? | Inversely |
| What is the affinity constant? | The drug's attraction to a receptor site |
| What is the equation describing affinity and dissociation? | Ka= 1/Kd |
| What does high affinity mean for dissociation? | Low dissociation |
| What is Brownian motion? | Drug molecules move around receptor zones in a mixture of other molecules in random manner and it is only by chance that they bind with a receptor |
| What is the likelihood that a given compound will interact at the proper receptor site based on? | The concentration of the given compound near the receptor site |
| Once a drug dissociates, the receptor is available to bind with what? | Other molecules in the receptor zone |
| How is the rate of drug binding to receptors increased? | By increasing the concentration of the drugs near the receptor |
| What is drug binding to a receptors based on? | Chemical make up of drug (negative drugs are attracted to positive receptors), concentration of drug, ligand's shape compared to receptor's shape |
| What is the maximum pharmacodynamic response point? | The point at which the critical number of receptors are occupied and the body is unable to produce a greater physiologic response even with increased drug doses |
| Are all receptor site occupied at the maximum pharmacodynamic response point? | They do not have to be |
| With increased drug dosages, is a graph plotting physiologic response linear or logarithmic? | Logarithmic |
| What is an agonist? | A ligand or drug that binds with a receptor and produces/mimics a desired physiologic effect |
| What is an example of an agonist and what receptors does it act on? | Dopamine and it acts on D1-D4 |
| True or False: Exogenous agonists usually decrease normal agonistic stimulation | False. Exogenous agonist drugs usually increase normal agonist stimulation |
| What is a partial agonist? | A ligand or drug that produces less than the primary endogenous agonist |
| True or false: Exogenous partial agonist drugs have high affinity but lower intrinsic activity than endogenous agents | True |
| What is an example of a partial agonist and where does it act? | Buprenorphine and it acts on the mu receptor |
| WHat is a super agonist? | It produces more of an effect than endogenous agents |
| What is an example of a super agonist? | Fentanyl (100x more potent than morphine) |
| What is a physiologic agonist? | Compounds that produce same bodily effect but through a different receptor system and mechanism |
| What is a coagonist? | Requires multiple compounds to produce desired effect |
| What is an antagonist? | Blocks or decreases normal physiologic response at receptor zone |
| What are examples of antagonists and where do they work? | Labetalol (mixed alpha and beta receptors) Esmalol (Beta 1 specific receptors: cardiac) |
| What is competitive antagonism/blocking? | Antagonists occupy same site as agonist but with little to no intrinsic activity |
| Is competitive antagonism reversible or irreversible? | Reversible |
| What is competitive antagonism based on? | Law of mass action: the greater number of antagonists, the higher the likelihood that the receptor will be occupied by an antagonist and not an agonist |
| What is law of mass action? | The greater number of molecules of an agent, the more likely that it will bind to the receptor over another molecule |
| Does the use of competitive antagonists causes a shift to the right or left of the agonist dose-response curve with no change in maximal response? | Right |
| How is competitive antagonism overcome? | With increased agonists (based on law of mass action) |
| What is a nonspecific agonist? | A drug that works on all receptors in a family and is not selective |
| What is an example of a nonselective beta agonist? | Isuprel |
| What is a selective agonist? | Agonist that works on one specific receptor zone |
| What is an example of a selective beta 2 agonist? | Albuterol |
| Are NMBAs competitive or noncompetitive antagonists? | Competitive |
| How do NMBAs work? | Competitive antagonism at nicotinic Ach receptor at neural junction and blocks acetylcholine |
| How are NMBAs reversed? | Neostigmine (an anticholinesterase) forms reversible complex with acetylcholinesterase allowing acetylcholine to accumulate in the synaptic cleft |
| Is neostigmine a form of competitive or noncompetitive antagonism? | Competitive |
| How many acetylcholine molecules can anti-cholinesterase hydrolyze in 1 minute? | 300,000 |
| What is the first type of noncompetitive antagonism? | Antagonist binds to receptor irreversible and the receptor is no longer available to the agonist. The agonists are not able to bind to enough receptors to produce maximal response. |
| What is the second type of noncompetitive antagonism? | Antagonist binds to allosteric site and causes changes to the receptor so the agonist can no longer bind to it. Increasing agonists will not cause effect. Receptor can return to normal |
| What is up regulation? | When the amount of available agonists decrease to a certain point, and receptors are increased to “find” the agonist |
| What happens after up regulation? | The cell is hypersensitive and exposure to the agonist can lead to cell injury or death |
| What is down regulation? | After excessive stimulation of receptors via agonists, the body decreases the number of available receptors in the zone |
| What is succinylcholine not used after 72 hours following an SCI? | Up regulation: the cell is hypersensitive to acetylcholine |
| Why are certain drugs (beta blockers) tapered and not abruptly discontinued? | Down regulation: the body needs to adjust available receptors |
| What is tachyphylaxis? | A rapidly decreasing response to a drug following initial administration |
| What drug is an example of tachyphylaxis? | Ephedrine |
| What is physical tolerance? | Administered agent cases down regulation and increased dosages are required to elicit same effect |
| What is stereochemistry? | Study of how molecules are structured in the three dimensions |
| What is the purpose of structure-activity relationships? | They link the action of drugs to the chemical structure and facilitate the design of more pharmacologically desirable drugs |
| What is a chiral molecule? | A molecule that has a center of three dimensional asymmetry |
| What is the structural basis of enantiomerism? | Chirality |
| What is an enantiomer? | Two mirror images of one another but opposite and cannot be superimposed |
| True or false: Both pairs of an enantiomer are therapeutically active. | False, one of the pairs in therapeutically active |
| How are enantiomers distinguished? | By which direction they rotate polarized light |
| What is the origin of the term optical isomer? | Because of their characteristic to rotate light |
| Enantiomers that rotate light to the right or clockwise or given what symbol? | rectus (R-) or dextrarotary (d+) |
| Enantiomers that rotate light counterclockwise or to the left are given what symbol? | Sinister (S+) or levorotary (l-) |
| What is a racemic mixture? | A solution with 50:50 of two enantiomers |
| Do racemic mixtures rotate light? | No, they cancel each other out |
Created by:
rbf007
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