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Pharm SJSM > Block 1 Drug metabolism/elimination/clinical pharmacokinetics > Flashcards

Block 1 Drug metabolism/elimination/clinical pharmacokinetics Flashcards

1
Q

Describe what pharmacodynamics studies

A

Drug concentration & it’s effect

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2
Q

Describe Pharmacokinetics

A

Drug concentration & time

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3
Q

Describe the purpose of phase 1 reactions

A

Aka microsomal metabolism:

Turns lipophilic into a polar/hydrophilic metabolite via c-P450 (liver) via one of the following reactions:
- Oxidation*
- Reduction
- Hydrolysis

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4
Q

Describe the purpose of phase 2 reactions

A

Involves conjugating a drug into a polar metabolite (inactive) via one of these reactions:
- Glucuronidation*
- Acetylation
- Sulfation
- Methylation

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5
Q

Drug make up:

Describe the properties of lipophilic drugs

A
  1. Usually non-polar they can cross lipid membranes via passive diffusion (BBB, placenta etc)
  2. Mostly excreted via liver
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6
Q

Drug make up:

Describe the properties of hydrophilic drugs

A
  1. Usually Polar they need facilitated diffusion to pass lipid membranes
  2. Mostly excreted via liver
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7
Q

Drug make up:

Describe the properties of Amphiphilic drugs

A

have both lipo/hydro-philic properties

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8
Q

How does Vd change for the elderly?

  • In hydrophilic drugs
A

Hydrophilic drugs = The elderly tend to have less total body water therefor they tend to have lower Vd

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9
Q

How does Vd change for the elderly?

  • In acidic drugs
A

Acidic drugs = The elderly have less albumin therefor drugs can’t bind or stay in plasma (high Vd)

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10
Q

How does Vd change for the elderly?

  • In lipophilic drugs
A

The elderly tend to have more body fat therefor Higher Vd

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11
Q

Drug metabolism:

Describe what zero order kinetics are

A
  • When the metabolism/elimination rate stays constant (independent of plasma concentration of the drug at steady state)
  • It’s capacity limited meaning the drug can become over saturated (toxicity)
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12
Q

Types of conjugation:

What are the drugs metabolized via phase II Acetylation?

A

Sulfonamide
Hydralazine
INH
Procainamide & Penicillamine
Dapsone
“SHIPD”

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13
Q

Gastric patients have an increased _____ phase metabolism

A

Phase II metabolism

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14
Q

Drug half-life:

Describe what the:
1. rate of elimination
2. Drug examples

A
  1. The rate of elimination is constant meaning it can become over saturated
  2. “It takes zero PHEN-TAS-E”
    - Phenytoin
    - Aspirin
    - Ethanol
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15
Q

Describe the features of 1st order kinetics

A

The rate of metabolism is directly proportional to the drug’s plasma concentration (meaning it’s dependent on the elimination)

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16
Q

What’s the equation for Vd?

A

Vd =
Q (conc of drug in body)
/
C (conc of drug in plasma)

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17
Q

Intravascular drugs have _____ Vd

A

Low Vd because they are large + charged molecules with a high binding affinity to plasma proteins

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18
Q

ECM drugs have a _____ Vd

A

Medium Vd because they are small but hydrophilic

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19
Q

Tissue/fat drugs have a ____ Vd

A

High Vd because they are small + lipophilic & have a higher binding affinity for tissue proteins

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20
Q

What is the equation for the half life of a drug (t1/2)

A

t1/2 = (0.7 * Vd) / CL in first order eliminations

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21
Q

How many half lives does it take a drug to reach steady state when infused at a constant rate?

A

4-5 t1/2’s

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22
Q

Describe what steady state is

A

When the rate of a drugs elimination is equal to its rate of administration

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23
Q

What’s the key equation for CL?

A

CL = 0.7 * (Vd / t1/2)

OR

CL = Dosage rate / Plasma concentration

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24
Q

What’s the equation for the loading dose (also what is the loading dose)?

A

Loading dose = CP * Vd / F (bioavail)

Loading dose is the amount of drug needed to cause an initial therapeutic effect (typically administered in ER situations to stabilize

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25
Q

In renal & liver disease (hypoalbuminemia) how are loading & maintenance doses effected?

A

Loading dose is unaffected
&
Maintenace dose decreases

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26
Q

What is the equation for Maintenace dose?

A

Maintenance dose = CP * CL * t (dosage int) / F

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27
Q

Lipophilic drugs are metabolized via one of two phases:

Phase 1 is primarily CYP450 dependent & involves which reactions and produces what kind of metabolites?

A

Reactions:
Hydroxylation
Oxidation
Reduction

Metabolites:
slightly polar

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28
Q

Lipophilic drugs are metabolized via one of two phases:

Phase 2 involves which reactions and produces what kind of metabolites?

A

Reactions:
Methylation
Acetylation
Glucuronidation
Sulfation

Metabolites:
Very polar (except acetylation)

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29
Q

In phase 2 metabolism, all reactions products are very polar except for acetylation. Which drugs are metabolized in this phase via acetylation?

A

Sulfonamides
Hydralazine
INH
Procainamide
Dapsone

“SHIPD”

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30
Q

Efficacy describes the what?

A

The max effect a drug can cause (aka the Vmax)

31
Q

Potency describes the what?

A

The amount of drug that is needed to cause an effect (EC50)

32
Q

What type of receptor binding is this, describe it

A

Competitive antagonist:

Decreased potency
unchanged efficacy

Can be overcome with lots of agonists

33
Q

Diazepam + Flumazenil on GABA receptors = decreased potency describes flumazenil as what type of binding receptor?

A

competitive antagonist

34
Q

What type of receptor binding is this, describe it

A

Decreased Efficacy
Unchanged potency

It can’t be overcome by more agonists

35
Q

Norepi + phenoxybenzamine on alpha receptors = decreased efficacy describes phenoxybenzamine as what type of binding receptor?

A

Non-competitive antagonist

36
Q

What type of receptor binding is this, describe it

A

Decreased efficacy
Unchanged potency

It acts on the same site as the full agonist

37
Q

Morphine + buprenorphine at mew opiod receptors = decreased efficacy & independent potency depending on the drugs

A

Partial agonist

37
Q

Effects of drugs:

When the effect of A & B together is equal to their individual effects

A

Additive effect

37
Q

Aspirin + acetaminophen administered together is an example of what type of drug effect?

A

Additive effect

37
Q

Effects of drugs:

When drug A is needed to get the full effect of Drug B

A

Permissive effect

37
Q

Drug effect:

When the effect of drug A & drug B together is greater than their individual effects

A

Synergistic effect

37
Q

Clopidogrel increases the effect of aspirin administered together, describes what kind of drug effect?

A

Synergistic effect

38
Q

When the effects of drugs A & B together are grater but drug B doesn’t actually have a therapeutic effect, this describes what type of drug effect?

A

Potentiation effect

39
Q

Carbidopa only blocks the enzyme that metabolizes levodopa but this increases levodopa’s effect, this describes what type of drug effect?

A

potentiation effect

40
Q

When the effect of drugs A & B together is LESS than their individual effects, describes which type of drug effect?

A

Antagonistic effect

41
Q

Ethanol is used as an antidote to decrease the effect of methanol toxicity, describes what type of drug effect?

A

Antagonistic effect

42
Q

Repeated use of a drug causes it to have less of an effect (sensitization), describes what kind of drug effect?

A

Tachyphylactic effect

43
Q

Describe what redistribution means for drugs

A

this describes the fast acting & terminating effects of very lipid soluble drugs on the BBB & Heart

44
Q

Thiopentone sodium & Propofol are examples of drugs that undergo ________

A

Redistribution

45
Q

Describe zero order kinetics

A

drug elimination is capacity limited meaning it can become over saturated (the graph won’t be linear)

46
Q

Zero order drugs include (4)

A

Phenytoin
Ethyl alcohol
Theophylline
Aspirin

47
Q

List the CYP450 Inducers

A

St. Johns wort
Phenytoin
Phenobarbitone
Modafinil
Nevirapine
Rifampin
Griseofulvin
Carbamazepine
Chronic alcohol

48
Q

St. Johns wort
Phenytoin
Phenobarbitone
Modafinil
Nevirapine
Rifampin
Griseofulvin
Carbamazepine
Chronic alcohol

Are all examples of CYP450

A

Inducers

49
Q

St. Johns wort
Phenytoin
Phenobarbitone

are examples of

A

CYP450 Inducers

50
Q

Modafinil
Nevirapine
Rifampin

Are examples of

A

CYP450 Inducers

51
Q

Griseofulvin
Carbamazepine
Chronic alcohol

Are examples of

A

Cyp450 Inducers

52
Q

List the CYP450 Inhibitors

A

Sodium Valproate
Isoniazid (INH)
Cimetidine
Ketoconazole
Fluconazole
Acute Alcohol
Chloramphenicol
Erythromycin
Sulfonamides
Ciprofloxacin
Omeprazole
Amiodarone
Ritonavir
Grapefruit juice

53
Q

Sodium Valproate
Isoniazid (INH)
Cimetidine
Ketoconazole
Fluconazole
Acute Alcohol
Chloramphenicol
Erythromycin
Sulfonamides
Ciprofloxacin
Omeprazole
Amiodarone
Ritonavir
Grapefruit juice

Are all examples of

A

CYP450 Inhibitors

SICK FACES COme when I AM Really drinking GF juice

54
Q

Sodium Valproate
Isoniazid (INH)
Cimetidine

Are examples of

A

CYP450 Inhibitors

55
Q

Ketoconazole
Fluconazole
Acute Alcohol

Are examples of

A

CYP450 Inhibitors

56
Q

Chloramphenicol
Erythromycin
Sulfonamides

Are examples of

A

CYP450 Inhibitors

57
Q

Ciprofloxacin
Omeprazole
Amiodarone

Are examples of

A

CYP450 Inhibitors

58
Q

Ritonavir
Grapefruit juice

Are examples of

A

CYP450 Inhibitors

59
Q

List the substrates of CYP450

A

Theophylline
OCP’s
Anti-Epileptics
Warfarin

60
Q

Theophylline
OCP’s
Anti-Epileptics
Warfarin

Describes what

A

CYP450

61
Q

Theophylline
OCP’s

Describes what

A

CYP450 substrate

62
Q

Anti-Epileptics
Warfarin

Describes what

A

CYP450 Substrates

63
Q

Describe the actions of an agonist

A

they bind & mimics a substance in our body (i.e morphine)

Affinity & Efficacy = 1

64
Q

Describe an antagonist

A

a drug that blocks receptors of a substance preventing its effect. i.e Naxolone

65
Q

Describe an inverse agonist

A

When a drug binds a receptor but produces the opposite effect that the endogenous substance was supposed to (vasocontraction instead of vasodilation)

66
Q

flumazenil binds to the same receptors as benzodiazepines (drugs that reduce anxiety) but instead of calming the brain, it produces an opposite effect and increases anxiety levels

This describes a ______

A

Inverse agonist

67
Q

Describe a partial agonist

A

When a drug is only partly as effective as a full agonist. But it acts as a competitive antagonist when there is a full agonist around

Affinity = 1
Efficacy < 1

68
Q

buprenorphine, which is used to treat opioid addiction. It has both agonist and antagonist properties and binds to opioid receptors in the brain, producing some opioid-like effects but not as strongly as full agonists like heroin

This describes ______

A

Partial agonist that can act as a competitive inhibitor to heroin

69
Q
A

Pharm SJSM (23 decks)

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