Pharmacokinetics and dynamics Flashcards

1
Q

Michaelis-Menten Kinetics

A

Velocity on Y-axis, [S] on X-axis

Km, Vmax are found on this

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2
Q

Km

A

inversely related to the affinity of the enzyme for the substrate

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3
Q

Vmax

A

directly proportional to the enzyme concentration

half of Vmax is how you find Km on the X-axis

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4
Q

Lineweaver-Burk Plot

A

Plotted line crossed the Y-axis
1/V on Y axis; 1/[S] on X-axis
1/(Vmax) is when plotted line touches Y-axis
1/-Km on X-axis

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5
Q

Pharmacokinetics

A

The effects of the body on the drug

Absorption, Distribution, Metabolism, Excretion

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6
Q

Pharmacodynamics

A

The effects of the drug on the body

includes concepts of receptor binding, drug efficacy, drug potency and toxicity

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7
Q

Bioavailability (F)

A

Fraction of administered drug that reaches systemic circulation unchanged

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8
Q

Bioavailability for IV dose

A

F = 100%

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9
Q

Volume of Distribution (Vd)

A

(amt drug in body)/([plasma drug])

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10
Q

Vd for large/charged molecules; plasma protein bound

A

Low Vd, in blood compartment

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11
Q

Vd for small hydrophilic molecules

A

Medium Vd, in ECF

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12
Q

Vd for small lipophilic molecules, esp if bound to tissue protein

A

High Vd, in all tissues including fat

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13
Q

Half lives to reach steady state

A

need 4-5 t1/2

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14
Q

Eqtn for T1/2

A

(0.639*Vd)/(CL)

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15
Q

Clearance

A

CL = (rate of elimination of drug)/([plasma drug])

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16
Q

Zero Order Elimination

A

Plasma concentratino decreases linearly with time
Constant amount of drug eliminated per unit time
Phenytoin, Ethanol, Aspirin

17
Q

First Order Elimination

A

Rate of elimination is directly proportional to drug concentration

18
Q

Weak Acid Drugs

A

Phenobarbital, Methotrexate, Aspirin

Trap in basic environments so tx overdose with bicarbonate

19
Q

Weak Base Drugs

A

Amphetamines

Trap in acidic environments so tx overdose with ammonium chloride

20
Q

Phase I drug metabolism

A

Reduction, Oxidation, Hydrolysis with cyto P450

Geriatrics lose phase I first

21
Q

Phase II drug metabolism

A

Conjugation (Glucuronidation, Acetylation, Sulfation)

yields very polar, inactive metabolites

22
Q

Slow acetylators

A

Great S/E from drugs because decreased rate of metabolism

23
Q

Efficacy

A

Maximal Effect a drug can produce

24
Q

Partial Agonists

A

less efficacy than full agonists

25
Potency
Amount of drug needed for a given effect
26
Competitive Antagonist
shifts curve to right (decreases potency), no change in efficacy. Can be overcome by increase conc of agonist
27
Noncompetitive Antagonist
Shifts curve down to decrease efficacy. | Cannot be overcome with increase agonist substrate
28
Irreversible competitive antagonist
Shifts curve down to decrease efficacy. | Cannot be overcome with increase agonist substrate
29
Partial Agonist
Acts on same site as full agonist but with lower efficacy. Potency is variable.
30
Therapeutic Index
Measurement of Drug Safety | between ED50 and TD50 on graph or = TD50/ED50
31
High Therapeutic Index
safer drug
32
Low therapeutic Index
more dangerous drug
33
LD50
median lethal dose
34
TD50
median toxic dose
35
Therapeutic Window
measure of clinical drug effectiveness
36
ED
effective dose