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Flashcards in Pharmacokinetics 2 Deck (87)
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1
Q

Pharmacokinetics of Risperidone?

A

First-pass hepatic metabolism to 9-hydroxyrisperidone.

2
Q

What enzyme forms active metabolite of Risperidone?

A

CYP 2D6 catalyzes hydroxylation

3
Q

Protein binding of Risperidone?

A

90%

4
Q

Protein binding of Risperidone metabolite?

A

77%

5
Q

What is the major metabolite of Risperidone?

A

Paliperidone

6
Q

Receptor effects of Paliperidone?

A

5HT2 receptor blocker

Partially blocks D2 receptors

7
Q

Absorption of Paliperidone?

A

Gradual water absorption delivers drug molecules slowly

8
Q

Half life of Quetiapine?

A

6-12 hours

9
Q

Dosing of Quetiapine?

A

Multiple daily dosing is required, but with longer duration once daily dosing is sufficient.

10
Q

Active metabolite of Aripriprazole?

A

Dihydroaripiprazole

11
Q

Half-life of Aripriprazole?

A

75 hours

12
Q

Half-life of Dihydroaripiprazole?

A

94 hours

13
Q

When is steady state conc of Aripriprazole reached?

A

14 days

14
Q

What metabolizes Aripriprazole?

A

CYP 3A4

CYP 2D6

15
Q

Protein binding of Aripripraozle?

A

99%

16
Q

Which atypical antipsychotics can be given as depots?

A

Aripiprazole
Palpiperidone
Risperidone microspheres
Olanzapine

17
Q

Oral dose tapering needed for Aripiprazole depot?

A

2 weeks oral dose tapering

18
Q

Oral tapering needed for Paliperidone depot?

A

Does not need oral tapering

19
Q

How often is Paliperidone depot given?

A

Once a month

20
Q

How is paliperidone depot excreted?

A

Renal

21
Q

How does Risperidone microsphere depot work?

A

Releases active drug at therapeutic levels 3 weeks after injection

22
Q

How should long-acting risperidone depot be supplemented?

A

With oral risperidone for 3 weeks

23
Q

What is olanzapine depot composed of?

A

Olanzapine and pamoic acid

24
Q

Half-life of olanzapine depot?

A

30 days

25
Q

When is steady state of olanzapine depot reached?

A

12 weeks

26
Q

Oral supplementation of olanzapine depot?

A

None required

27
Q

Which depots need to be refridgerated?

A

Risperidone microspheres - granular

28
Q

Why is oral antipsychotic medication required with some depots?

A

As the depots show delayed as well as prolonged release.

29
Q

Name some anti-dementia drugs

A
Tacrina
Donepezil
Rivastigmine
Galantamine
Memantine
30
Q

What metabolizes Tacrine?

A

CYP 1A2 hepatic enzymes

31
Q

Half life of Tacrine?

A

Short

Poor absorption

32
Q

Oral bioavailability of Donepezil?

A

100%

Linear pharmakokinetics

33
Q

How long does it take for Donepezil to reach steady state?

A

2 weeks

34
Q

Half life of Donepezil?

A

70 hours

35
Q

Plasma protein binding of Donepezil?

A

Extensively plasma protein bound

36
Q

What metabolizes Donepezil?

A

CYP 2D6 and 3A4 hepatic enzymes

37
Q

What is oral bioavailability of Rivastigmine?

A

40% up to dose of 3mg after which this increases non-linearly.

38
Q

Half life of Rivastigmine?

A

1.5 hours

39
Q

Metabolism of Rivastigmine?

A

Hydrolysis by cholinesterase

Minimal hepatic involvement

40
Q

Excretion of Rivastigmine?

A

Urine as sulfate of decarbamylated metabolite

41
Q

Oral bioavailability of galantamine?

A

90%

42
Q

Plasma protein binding of Galantamine?

A

Low - 18%

43
Q

Metabolism of Galantamine?

A

CYP2D6

CYP3A4

44
Q

Excretion of Galantamine?

A

One-third is excreted unchanged in urine

45
Q

Plasma protein binding of Memantine?

A

45%

46
Q

Half life of Memantine?

A

60-80 hours

47
Q

Excretion of Memantine?

A

Half excreted unchanged in urine

Half undergoes hepatic conversion to inactive metabolites

48
Q

What reduces clearance of mematine?

A

Drugs that alkalinize urine such as carbonic anhydrase inhibitors

49
Q

Absorption of Methylphenidate?

A

Absorbed well orally

50
Q

When does Methylphenidate reach peak plasma levels?

A

1-2 hours

51
Q

Half-life of Methylphenidate?

A

2-3 hours

52
Q

When does Modafinil reach peak plasma?

A

2-4 hours

53
Q

Half life of Modafinil?

A

15 hours

54
Q

Half life of Atomoxetine?

A

5 hours

55
Q

What metabolizes Atomoxetine?

A

CYP 2D6

56
Q

Impact of SSRIs on Atomoxetine?

A

SSRIs may raise Atomoxetine levels

57
Q

Which benzos are long-acting?

A

Diazepam
Chlordiazepoxide
Clonazepam
Flurazepam

58
Q

When can toxicity of long-acting benzos be evident?

A

1-2 weeks

59
Q

Which benzos are intermediate or short-acting?

A

Lorazepam
Oxazepam
Temazepam
Alprazolam

60
Q

Clinical effect of intermediate/short-acting benzos?

A

Severe withdrawl phenomenon but lesser risk of daytime imapirment and daytime sedation.
Rebound insomnia and anterograde amnesia more often seen in shorter half-life.

61
Q

Half-life of Lorazepam?

A

15 hours

62
Q

Half-life of Temazepam?

A

10 hours

63
Q

Whch benzo has a very short duration of action?

A

Triazolam

64
Q

What is Triazolam often used in?

A

Anaesthesia

65
Q

Oral bioavailability of Diazepam?

A

Nearly 100%

66
Q

When is peak plasma conc of diazepam reached?

A

15-90 minutes after oral administration

Second peak 6-12 hours due to enterohepatic recirculation

67
Q

How is diazepam distributed

A

Widely as highly lipophilic (CSF conc equals plasma conc)

68
Q

How much of diazepam is plasma binding?

A

95-99%

69
Q

Elimination half life of Diazepam?

A

30 hours

70
Q

How long does it take diazepam to reach steady state?

A

5-6 days

71
Q

Metabolism of Diazepam?

A

In liver with 3 active metabolites.

72
Q

What are the three active metabolites of diazepam?

A

Nordiazepam/desmethyldiazepam
Oxazepam
Temazepam

73
Q

What is the principal metabolite of Diazepam?

A

Desmethyldiazepam - could accumulate due to long half-life

74
Q

Which z-hypnotics are quickly absorbed when given orally?

A

Zolpidem
Zaleplon
Eszopiclone

75
Q

Impact of food on quickly-absorped z-hypnotics?

A

Food can delay absorption for up to an hour

76
Q

Accummulation of quickly-absorbed z-hypnotics?

A

None - no active metabolites

77
Q

Give e.g. of z-hypnotics?

A

Zopcilone/Eszopiclone
Zaleplon
Zolpidem

78
Q

Onset of Zopiclone?

A

45 mins

79
Q

Half-life of Zopiclone?

A

4-5 hours

80
Q

How does zopcilone work?

A

Benzo receptor selective for alpha 1 subunit

81
Q

What is eszopiclone?

A

Enantiaomer - only z-hypnotic indicated for sleep maintenance therapy

82
Q

Onset of Zaleplon?

A

Within 30 mins

83
Q

Half-life of Zaleplon?

A

1-2 hours

84
Q

Effect of Zaleplon?

A

Shorter half life and quick onset makes it suitable for sleep initation problems.

85
Q

Onset of Zolpidem?

A

Within 30 mins

86
Q

Half life of Zolpidem?

A

1-4 hours

87
Q

Effect of Zolpidem?

A

Short half-lif and onset mades it suitable for sleep initation problems.
Less hangover effect.