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Biomedical Lab III > Lab 9 > Flashcards

Lab 9 Flashcards

1
Q

The effect that a drug has on a person may be different than expected.
Give 3 reasons why this is the case

A

the drug may interact with:

-another drug
-food/beverage/supplement
-disease states

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2
Q

name the 3 types of drug interactions

A

drug-drug
drug-food
drig-disease

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3
Q

true or false

the effects of drug interactions are usually unwanted and sometimes harmful

A

true

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4
Q

give an example of how the effects of drug interactions are usually unwanted

A

they may increase or decrease the actions of one or more drugs which results in side effects or failed treatment

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5
Q

individually, drugs can produce effects that are dependent on the _______

A

dose

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6
Q

the dose of the drug influences the ___ as well as the ____ of the response

A

nature as well as the magnitude of the response

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7
Q

how can the dose-response relationship be plotted

A

log dose (x axis) vs response (y axis)

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8
Q

how can the potency of a drug be described

A

by calculating ED 50 – dose required to produce an effect in 50% of the population

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9
Q

interactions between medications are generally categorized into ____ main categories:

A

2:
pharmacokinetic interactions
pharmacodynamic interactions

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10
Q

explain the difference between pharmacokinetic and pharmacodynamic drug-drug interactions

A

pharmacokinetic interactions – one of the drugs influences the ADME of the other or each other. this affects the concentrations at the receptor site/site of action

pharmacodynamic interactions –
drugs influence each other’s effects directly at the receptor level or the site of action

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11
Q

what is polytherapy

A

the administration of several drugs to a patient

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12
Q

what increases the risk of clinically important drug interactions?

A

polytherapy, - it increases the complexity of therapeutic management due to increased risk of interactions

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13
Q

true or false

all drug interactions are harmful

A

false - some are beneficial.

like the drug-food interaction:

a high fat diet taken with ketoconazole improves absorption

drug-drug interaction of probenecid and ampicillin increases ampicillin concentration in the plasma and thus INCREASES ampicillin effectiveness

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14
Q

many interactions have negative effects such as….

A

-ADR (adverse drug reactions)
-reduce the clinical efficacy
-increase the toxicity

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15
Q

______ interactions are generally evaluated during drug discovery

A

pharmacodynamic

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16
Q

clinically significant drug interactions are related to the _______- of the drugs

A

pharmacokinetics

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17
Q

pharmacokinetics describes what

A

the time course of the drug concentration in the body (normally in blood/plasma)

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18
Q

______ describes the time course of the drug concentration in the body (normally in the blood or plasma)

A

pharmacokinetics

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19
Q

how can the concurrent use of 2 drugs alter absorption

A

can influence:

-solubility
-complexation
-intestinal flora
-GI motility

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20
Q

drugs need to be ______ before they can pass through the cell membrane

A

solubilized

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21
Q

is ketoconazole a weak acid or weak base?
what kind of environment is needed for its dissolution?

A

weal base

needs an acidic environment for dissolution

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22
Q

what happens when ketoconazole is administered with H2 blockers like cimetidine?

A

this can increase the pH and thus decrease the solubility through non ionization and decreased absorption

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23
Q

what can improve absorption of ketoconazole?
what can reduce absorption?

A

high fat content in food bc ketoconazole is a hydrophobic drug

reduce - concurrent use of H2 blockers

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24
Q

what can reduce the absorption of tetracyclines?

A

cationic antacids form a complex with tetracycline and reduce its absorption

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25
Q

how can warfarin’s activity be increased?

A

antibiotics decrease bacteria flora in the large intestines. this leads to a reduction in vitamin K — increasing warfarin’s activity

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26
Q

what drug can reduce the absorption of acetaminophen and how?

A

metoclopramide increases the upper GI motility which thus reduces the absorption of acetaminophen

27
Q

how can distribution be affected?

A

by the concurrent use of other agents that compete for protein binding

-many drugs are transported with some of their molecules in free form and the rest bound to plasma proteins – reversibly.

only the unbound molecules are free and pharmacologically active

1 drug may compete with the other and displace it from the sites it already is occupying (depending on the relative concentrations and affinities for the binding site)

28
Q

give a specific example of 2 drugs that compete with the same binding sites and thus distribution is affected

A

warfarin and phenylbutazone

29
Q

drug are often eliminated by…..

A

metabolism and/or excretion into the urine or bile

30
Q

the liver is the major site of metabolism.

metabolism mostly occurs through either…..

A

enzyme induction or inhibition

31
Q

what is enzyme induction?
what is enzyme inhibition?

A

enzyme induction is when the rate of metabolism INCREASES so the drug gets eliminated faster. thus, you will need a larger dose to get the same effect

enzyme inhibition is when the normal rate of metabolism is slowed – so the drug begins to accumulate in the body.

32
Q

phenobarbital + warfarin is an example of enzyme induction or inhibition?

A

induction

33
Q

give an example of 2 drugs that accumulate in the body due to enzyme inhibition

A

cimetidine + theophylline

34
Q

in excretion, the drug becomes…..

A

either ineffective or toxic and is excreted out of the body

35
Q

how can some drug interactions alter blood flow?

A

by increasing renal blood flow

by inhibiting active tubular secretion

altering tubular reabsorption

36
Q

give an example of a drug that alters excretion by increasing renal blood flow

A

hydralazine increases the rate of blood flow and thus increases the excretion of DIGOXIN

37
Q

give an example of a drug that alters excretion by inhibiting active tubular secretion

A

probenecid reduces the tubular secretion of pencillin and thus increases peniciilin serum levels

38
Q

give an example of a drug that alters excretion by altering tubular reabsorption

A

alkanalizing agents can increase the pH which DECREASES the ionization of amphetamines and REDUCES their excretion

39
Q

pharmacodynamics describes….

A

the time course of the drug effects (whether desired or undesired)

40
Q

most drug effects are mediated by what?

A

interaction with a specific receptor. follows the laws of drug-receptor interactions

41
Q

the amount of drug that is bound to the available receptors and the effect produced is dependent on what?

A

the concentration of the drug available at the site of the receptor

42
Q

what is required to accurately assess pharmacodynamic interactions?

A

a complex analysis of the various effects and genetic impact

43
Q

the mechanisms of pharmacodynamic interactions are divided into ___ groups:

A

3 groups:

-direct effect at receptor function
-interference with a biological or physiological control process
-increased or decreased pharamcological effect

44
Q

name the 5 methods to classify pharmacodynamic interactions based on their MECHANISM and MAGNITUDE of the effect change

A

-additive
-summation
-antagonism
-synergism
-potentiation

45
Q

explain what additive is

A

the combined effect of 2 drugs equal to the sum of the individual drugs

both drug responses occur via the SAME MECHANISM

2+2=4

46
Q

give an example of 2 drugs that exhibit the pharmacodynamic property of additive

A

aspirin and acetaminophen

47
Q

define summation

A

the combined effect of 2 drugs is equal to the sum of the originl drugs, BUT the drug responses occur via DIFFERENT mechanisms

2+2=4

48
Q

give an example of drugs that exhibit summation

A

beta blockers + calcium channel antagonists

49
Q

define the pharmacodynamic property of antagonism

A

the combined effect of 2 drugs is NULLIFIED by the other

occurs at the SAME RECEPTOR

1+1=0

50
Q

give an example of 2 drugs that exhibit antagonism

A

pilocarpine + atropine

51
Q

define synergism

A

when 2 drugs produce a larger response than the sum of their individual effects

2+2=10

52
Q

give an example of drugs that exhibit synergism

A

sulfonamides and trimethorpim are dihydrofolic acid reductase inhibitors

53
Q

define the pharmacodynamic property of potentiation

A

when a drug effect is increased by another drug that has no such effect

0+1 = 2

OR

0+10 = 25

54
Q

give an example of drugs that exhibit potentiation

A

diphenhydramine + opioids

diphenhydramine potentiates narcotic effects not is NOT an endogenous opioid analgesia

55
Q

drugs are generally classified based on….

A

their mechanism of action and/or their similarity in pharmacological effects

56
Q

what 2 drugs function on the GABA receptor?
explain the significance

A

ethanol and pentobarbital – GABA is a neurotransmitter that binds to GABA receptors to cause an inhibitory response (sedation)

concurrent use of barbiturates and ethanol may result in excessive CNS depression, which has moderate clinical significance

57
Q

name 3 barbiturates

A

pentobarbital
phenobarbital
thiopental

58
Q

explain the mechanism of ethanol

A

enhances inhibitory excitability neurotransmission via NMDA and GABAA receptor operated channels

binds to the allosteric site on the GABA A receptor and thus increases the frequency of GABA chloride channel openings.

59
Q

what primarily metabolizes ethanol?
what is the secondary?

A

primary = alcohol dehydrogenase

secondary = CYP2E1 to form acetaldehyde

60
Q

explain the mechanism of barbiturates at high concentrations and in low concentrations

A

in general - activate inhibitory GABA A receptors and inhibit AMPA/kainate receptors

at low conc - act as positive allosteric modulators of GABA A

at high conc - activate GABA A receptors to increase the average open duration of the channel without altering the ion conductance or opening frequency

61
Q

true or false

barbiturates decrease hepatic CYP450 metabolism of drugs

A

FALSE – increase

62
Q

true or false

barbiturates competitively inhibot the metabolism of some drugs

A

true

63
Q
A

Biomedical Lab III (10 decks)

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