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Clinical Pharmacology > Pharmacokinetics and Pharmacodynamics > Flashcards

Pharmacokinetics and Pharmacodynamics Flashcards

1
Q

what is the therapeutic window

A

range of concentrations of the drug in the plasma to allow it to have its desired effect

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2
Q

what is the bioavaliabilty of a drug

A

the fraction of the drug administered which reaches circulation

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3
Q

what factors affect the bioavaliabilty of a drug

A

first pass metabolism, age, food, vomiting, malabsorption

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4
Q

what is first pass metabolism

A

where a drug can be metabolised before it reaches systemic circulation

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5
Q

where does first pass metabolism occur

A

gut lumen, gut wall and liver

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6
Q

what is the bioavaliabilty for a drug given by IV

A

100% as it reaches the blood immediately

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7
Q

how does protein binding affect the distribution of a drug

A

if drugs bind to plasma proteins then they are not active so cant have therapeutic effects

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8
Q

what is the volume of distribution

A

how far through the body compartments a drug will dissolve

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9
Q

how does the Vd change with weight

A

in patients with larger weights the Vd increases as the drug can travel through the fat better - this means he drug has less of an effect as theres a lower drug plasma concentration

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10
Q

what is the equation for Vd

A

Vd = Dose/immediate plasma concentration

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11
Q

what is the equation for bioavalibilty

A

AUCoral/AUCiv

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12
Q

which group of enzymes carry out the first stage of metabolism

A

CYP4500 enzymes

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13
Q

what do CYP4500 enzymes do

A

cause oxidation, reduction, hydrolysis in order to change the ionic charge of the drug

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14
Q

what does Phase II enzymes do

A

conjugate the drug e.g. with sulphate or glutathione to increase its solubility

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15
Q

what are pro-drugs

A

drugs which must be metabolised in order to become activated

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16
Q

what factors affect metabolism

A

hepatic disease, age, alcohol, smoking

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17
Q

what are the routes for drug elimination

A

kidney elimination, salvia, breast milk, sweat, bile

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18
Q

what 3 processes in the kidney affect elimination

A

glomerular filtration, passive tubular reabsorption and active tubular secretion

19
Q

what happens to clearance if the GFR is decreased

A

clearance decreases

20
Q

what happens to the half life if the GFR Is decreased

A

half life increases because less of the drug is cleared

21
Q

what are first order kinetics

A

where the rate of clearance is proportional to the drug level

22
Q

what are zero order kinetics

A

where the rate of elimination is constant

23
Q

what is the hat life of a drug

A

amount of the it take for the concentration of a drug to half

24
Q

what is the equation for half life

A

t1/2 = 0.7 x Vd/Cl

25
Q

how does hepatic disease affect clearance

A

less metabolism can occur

26
Q

how does cardiac disease affect clearance

A

less perfusion to kidneys and liver

27
Q

what is a loading dose

A

where a higher concentration of a drug is given first in a repeated prescription in order to reach a steady state quicker

28
Q

true or false - a loading dose is used in drugs with a low half life

A

false - its for drugs with a high half life

29
Q

what is the equation for loading dose

A

loading dose = Vd x target drug concentration

30
Q

what is tornado de pointes

A

where interactions between drugs leads to a slower conduction of the heart giving a prolonged QT internal

31
Q

what is digoxin used to treat

A

AF with heart failure

32
Q

why is a loading dose needed with digoxin

A

the drug has a long half life, however patient with AF need immediate treatment so you cant wait days to reach the steady state of the drug

33
Q

what are the different types of antagonist

A

competitive (reversible and irreversible) and non-competitive

34
Q

what is the therapeutic index

A

the relationship between the concentration of the drug causing adverse and desirable effects

35
Q

what is the equation for the therapeutic index

A

toxic dose/effective dose

36
Q

what is the affinity of a drug

A

how well a drug binds to a receptor

37
Q

what does a low Kd say about the affinity of a drug

A

high affinity

38
Q

what is the efficacy of a drug

A

the ability of a drug to produce a response

39
Q

what is the potency of a drug

A

the dose required to give 50% response. same as EC50. the more potent a drug the better a response it can give at lower concentrations

40
Q

what is intrinsic efficacy

A

the ability to bind to a receptor and cause a response.

41
Q

what does the potency of a drug depend on

A

affinity and efficacy

42
Q

what is Bmax

A

drug concentration when all receptors are bound

43
Q

what is Emax

A

drug concentration giving 100% response

Clinical Pharmacology (18 decks)

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