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50 Cards in this Set
- Front
- Back
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What are the 4 types of drug interaction receptors?
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ligand ion channels
G protein coupled receptors tyrosine kinase intracellular nuclear receptors |
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G protein Gs mechanism
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activates adenylyl cylcase which actvates cAMP which activates protein kinase A and that phophorylates proteins
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g protein Gi mechanism
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Gi inhibits adenylyl cyclase thereby inhibiting cAMP
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g protein Gq mechanism
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Gq activates phospholipase C which activates PIP2 which makes DAG and IP3. DAG activates protein kinase C which increases Ca.
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intracellular nuclear receptors are kept inactive by what?
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chaperone proteins like heat shock proteins (HSP-90)
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what are the 4 ways drugs work?
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interaction with receptors
alteration of the activity of the enzymes antimetabolite action nonspecific chemical or physical interactions |
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whats ED 50?
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is the dose that produces the half maximal response - when the drug produces its first noticeable effects
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what are partial agonists
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they occupy recptors but cannot elicit a maximal response. such drugs have an intrinsic activity less than 1
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how do reversible competitive antagonists shift the dose response curve?
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shift curve to the right and increase ED 50 but maximal response can be obtained at higher doses
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do noncompetative antagonists change the ED 50?
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No!
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what is the potency of a drug dependent on?
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the affinity for the receptor. lower ED 50 value is more potent
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what is therapeutic index
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relates desired effect with undesired toxicity= TD50/ED50
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in quantal dose response curve what is ED 50?
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the dose of the drug that produces the response in half the populations
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usually absorption increases as lipid solubility...
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increases
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ionized or unionized cross membranes?
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unionized
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henderson hasselbach for weak acid
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pH=pK+log (A-)/ HA
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henderson hasselbach equation for weak base
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pH=pK+log (B)/(BH+)
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pK=pH...what does that mean
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50% is unionized and 50% is ionized
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is facillitated diffusion active transport?
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No! it doesnt not used energy but it is down the concentration gradient through carriers
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what is first pass effect?
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after being absorbed from small intestine drugs must go to liver and may be inactivated by liver enzymes before getting to general circulation
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decreased emptying time means what for absorption?
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decreased absoprtion
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what kind of parenteral administrations are there?
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IV, IM, sub q
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how do drugs enter in IM and sub q?
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through capillaris and pores between endothelial cells
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is first pass bypassed in sublingual
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yes!
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distribution of the drug depends on what?
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blood flow
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volume of distribution equation?
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Vd= amount of drug administered/ initial plasma concentration
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thiopental is know for what?
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redistribution ( to low blood flow areas like fat)
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what is first order elimination
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constant fraction of drug is eliminated per unit time.
= constant (clearance) X drug plasma conc |
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what is zero order kinetics
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constant amount of drug is eliminated per unit time- saturated elimination. doesntr depend on plasma concentration
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what is zero order kinetics
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constant amount of drug is eliminated per unit time- saturated elimination. doesntr depend on plasma concentration
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rate of elimination of an organ=
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CL organ X (drug) plasma perfusing organ
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where is the major site for biotransformation
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liver
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phase I reactions
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involve enzyme- catalyzed biotransformation of the drug without any conjugations. ex- oxidations, reductions, hydrolysis. gives drug functional group for phase II
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phase II reactions (synthetic)
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conugation reactions- involve enzyme catalyzed combination of a drug with endogenous substance. require functional group- active center- for conjugations
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largest cyp450 enzyme family?
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cyp3A
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rifampin- inducer or inhibitor
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inducer
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st johns wort
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inducer
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cimetidine
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inhibitor
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glucoronyl transferases are associted with which phase reactions?
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phase II
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rifampin and indomethacin are eliminated how?
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in poopy
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renal clearance =
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U X (V/P)
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one compartment model= what graph
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linear
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one compartment model= what drug elimination?
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first order
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two compartment = what graph
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logarithmic
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half life is ___ to elimination rate constant
___ to volume distribution and __ to clearance |
inversely related to elimination rate constant (k) and clearance
and related to volume disribution |
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95% of drug will be eliminated from body in what time?
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first 5 half lives
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when will steady state be reached in multidose kinetics?
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5 half lives
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maintenance dose =
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desired drug concentration X clearance
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loading dose is needed why?/when?
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when therapeutic concentraion must be achieved rapidly and you cant wait 5 half lives
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loading dose=
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desired drug conc plasma X Vd
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