BECOM II Exam 5 > Lee - Pharmacokinetics > Flashcards

Lee - Pharmacokinetics Flashcards

(52 cards)

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1
Q

pharmacokinetics

A

what body does to drug

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2
Q

pharmacodynamics

A

what drug does to body

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3
Q

pharmacogenetics

A

influence of one gene on drug

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4
Q

pharmacogenomics

A

influence of entire genome on drug

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5
Q

what are 2 ways to get toxic effects?

A

drugs going to unintended targets or overdose of therapeutic drugs

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6
Q

spermeation

A

movement through or around cells which limit size

-drugs have to be of certain size and shape to be absorbed and bind to certain receptors

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7
Q

efficacy

A

effect of drugs

  • same effect b/w 2 drugs –> same efficacy
  • nothing to do with []
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8
Q

potency

A

amount of drug to get an effect

-least concentration –> most potent

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9
Q

what is the best type of drug to give?

A

one with least potency and takes a higher dose to have effect
-easier to manipulate and regulate

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10
Q

steps in pharmacokinetics

A
  1. absorption
  2. distribution
  3. metabolism
  4. excretion
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11
Q

absorption

A
  • polar molecules more easily absorbed (biotransformation in liver)
  • no rxn with receptor if bound to carrier
  • tight junctions (fast), lipophilic, facilitated or active transport, or endo/exocytosis (slow)
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12
Q

distribution

A

volume of distribution = amount of drug in body relative to [] in blood - measure space available to house the drug

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13
Q

metabolism

A

biotransformation by the liver - more polar and water soluble through conjugation to be excreted in urine

  • phase 1 and 2 enzymes
  • some drugs not metabolized
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14
Q

excretion

A
  • elimination - rate of removal from circulation

- clearance - body’s ability in removing drug

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15
Q

agonist

A

bind to same site as ligand to have same effect

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16
Q

antagonist

A
  • competitive - binding to same site to block ligand (no response)
  • non-competitive - bind to other site to elicit effect
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17
Q

allosteric activator vs. inhibitor

A
  • activator - bind to other receptor site increasing receptor response
  • inhibitor - bind to other site decreasing response
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18
Q

partial agonist

A

sometimes called antagonist

  • agonist on its own
  • antagonist in presence of other substrate
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19
Q

therapeutic index

A

Toxic/lethal does divided by effective dose

-bigger number –> better drug

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20
Q

tolerance

A

down regulating receptors after therapeutic effect takes place

  • decrease receptor –> decrease effect
  • may have to increase dose
  • protective response
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21
Q

barriers to absorption

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A
  • cell membrane - small (paracellular; lipophilic (diffuse); hydrophilic and charged (transporter)
  • capillaries - easier to get drugs across (larger pores)
  • blood/brain - protection; need transporter
  • placenta - only lipophilic drugs across
22
Q

1st pass metabolism

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A

oral –> GI –> hepatic portal vein –> metabolized by liver (protection)

  • occurs before interacting with receptor
  • can decrease availability in circulation and less reaches active site
  • skip by using another method besides oral
  • bioavailability good indication
  • proteins and lipids have high 1st pass - do not take orally
23
Q

bioavailability

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A

% of drug that ends up in circulation after 1st pass metabolism
-IV (most) > transdermal > IM and subQ > rectal > oral and inhalation

24
Q

large, polar, lipophilic drug

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A

do not take orally

  • take IV or IM
  • harder to be absorbed, 1st pass metabolism, more broken down
25
non polar, uncharged drugs
more easily absorbed - take orally
26
henderson-hasselbach equation
pH = pKa + log10 ([A]/[HA]) - uncharged molecules better absorbed than charged - more acidic --> more uncharged - more basic --> more charged - equal charged and uncharged when pH = pKa
27
ion trapping
- gastric juice (pH 2) --> convert to uncharged form --> better absorption - plasma (pH 7) --> reconvert to charged form --> ion trapping - ex. aspirin being absorbed in stomach - ex. methamphetamine in urine - can change pH of urine to excrete faster
28
drug bound to protein
cannot exit to peripheral tissues or bind to receptor - acts as reservoir - drug maintained in central compartment - liver damage --> less albumin --> more free drug and higher effect
29
lipophilic/fat soluble drugs
bypass 1st pass metabolism bc they enter lymphatic circulation then head to periphery 1st -end up in adipose tissue compartment
30
partition coefficient
ratio of solubility of a substance in water to a lipophilic, non-polar solvent - determine how hydrophilic/hydrophobic something is - larger number --> more hydrophobic
31
volume of distribution
measure of space in body to contain drug Vd = amount of drug/plasma [] -low # --> drug in central compartment -high # --> drug in peripheral compartment and has longer half life (not metabolized or excreted)
32
one vs. two compartment model
administer drug --> central --> peripheral --> metabolized and excreted by liver and kidneys in central increasing [] in peripheral (reservoir) --> drug reenters central to reach equilibrium
33
what is the goal of phase 1 and 2 rxns
make something more polar --> better excretion - CYP enzymes in liver (can activate or deactivate drug) - phase 1 = oxidize - phase 2 = conjugate
34
CYP enzymes
needed by phase 1 rxns - lipophilic, mainly in the ER membranes, Low specificity and react with a lot of molecules breaking them down - can inactivate a drug or activate a prodrug
35
phase 2 rxns
conjugation - not CYP dependent - make more water soluble than phase 1 - oxidative stress can decrease GSH levels
36
what can hydrolysis during phase 1 lead to?
toxicity of drug - best to excrete it before reaching phase 1
37
acetaminophen
broken down into metabolite --> excreted by GSH or other conjugators or go down toxic path - excess acetominophen --> induce CYP2E1 --> toxic pathway - EtOH also induces CYP2E1 --> immediate toxicity
38
CYP3A/4
metabolize 50% of drugs in phase 1
39
glucoronidation
metabolize 25% of drugs in phase 2
40
competitive inhibition of drugs
reduce metabolism when 2 drugs competing for the same site - prodrug not metabolized fast enough to have effect - real drug not broken down into inactive --> toxic - can be substrate and inhibitor at same time
41
inducers vs. inhibitors
inducers - increase CYP enzyme and metabolism -ex. rifampin, carbamazepine, ethanol inhibitors - downregurate CYP decreasing activity -ex. erythromycin, grapefruit, cimetidine
42
elimination vs. excretion
``` elimination = remove drug by excretion or or biotransformation (drug --> metabolite) excretion = removal of intact drug ```
43
ion trapping
pH changes across 2 different tissues that traps an ion in one of the tissues - weak acid - uncharged if pH below pKa --> can get across - weak base - charged if pH is above pKa --> cannot get across (trapped)
44
enterohepatic circulation
where lipophilic drugs end up - another compartment, not much enter circulation - reservoir for lipophilic drugs that can leak back into circulation causing effect
45
clearance
ability of organs to eliminate drug from the body | -region of body that is cleared of a drug
46
half life (t1/2)
time required to reduce the drug in the body by half during elimination
47
zero order rxn
- elimination rate CONSTANT - not dependent on drug [] - half life CHANGES - longer half-life with more drug - linear - ex. PEA (phenytoin, ethanol, aspirin)
48
1st order rxn
- elimination rate dependent on drug [] --> faster with more drug - half life CONSTANT - exponential - 95% of drug eliminated in 5 half lives
49
impact of infusion and bioavailability
- increase infusion rate --> increase [] - equal infusion but half bioavailability --> lower [] but longer duration - half infusion rate, same bioavailability --> decrease [] and duration
50
maintenance dose rate
plasma drug concentration x clearance x time divided by bioavailability -maintain dose in plasma - keep at equilibrium
51
loading dose
plasma drug concentration x Vd divided by bioavailability | -given to overcome lag period
52
half life equation
0.7 x Vd divided by CL
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