Pharmacokinetics 2 Flashcards

1
Q

Pharmacokinetics of Risperidone?

A

First-pass hepatic metabolism to 9-hydroxyrisperidone.

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2
Q

What enzyme forms active metabolite of Risperidone?

A

CYP 2D6 catalyzes hydroxylation

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3
Q

Protein binding of Risperidone?

A

90%

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4
Q

Protein binding of Risperidone metabolite?

A

77%

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5
Q

What is the major metabolite of Risperidone?

A

Paliperidone

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6
Q

Receptor effects of Paliperidone?

A

5HT2 receptor blocker

Partially blocks D2 receptors

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7
Q

Absorption of Paliperidone?

A

Gradual water absorption delivers drug molecules slowly

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8
Q

Half life of Quetiapine?

A

6-12 hours

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9
Q

Dosing of Quetiapine?

A

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

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10
Q

Active metabolite of Aripriprazole?

A

Dihydroaripiprazole

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11
Q

Half-life of Aripriprazole?

A

75 hours

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12
Q

Half-life of Dihydroaripiprazole?

A

94 hours

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13
Q

When is steady state conc of Aripriprazole reached?

A

14 days

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14
Q

What metabolizes Aripriprazole?

A

CYP 3A4

CYP 2D6

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15
Q

Protein binding of Aripripraozle?

A

99%

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16
Q

Which atypical antipsychotics can be given as depots?

A

Aripiprazole
Palpiperidone
Risperidone microspheres
Olanzapine

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17
Q

Oral dose tapering needed for Aripiprazole depot?

A

2 weeks oral dose tapering

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18
Q

Oral tapering needed for Paliperidone depot?

A

Does not need oral tapering

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19
Q

How often is Paliperidone depot given?

A

Once a month

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20
Q

How is paliperidone depot excreted?

A

Renal

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21
Q

How does Risperidone microsphere depot work?

A

Releases active drug at therapeutic levels 3 weeks after injection

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22
Q

How should long-acting risperidone depot be supplemented?

A

With oral risperidone for 3 weeks

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23
Q

What is olanzapine depot composed of?

A

Olanzapine and pamoic acid

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24
Q

Half-life of olanzapine depot?

A

30 days

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25
When is steady state of olanzapine depot reached?
12 weeks
26
Oral supplementation of olanzapine depot?
None required
27
Which depots need to be refridgerated?
Risperidone microspheres - granular
28
Why is oral antipsychotic medication required with some depots?
As the depots show delayed as well as prolonged release.
29
Name some anti-dementia drugs
``` Tacrina Donepezil Rivastigmine Galantamine Memantine ```
30
What metabolizes Tacrine?
CYP 1A2 hepatic enzymes
31
Half life of Tacrine?
Short | Poor absorption
32
Oral bioavailability of Donepezil?
100% | Linear pharmakokinetics
33
How long does it take for Donepezil to reach steady state?
2 weeks
34
Half life of Donepezil?
70 hours
35
Plasma protein binding of Donepezil?
Extensively plasma protein bound
36
What metabolizes Donepezil?
CYP 2D6 and 3A4 hepatic enzymes
37
What is oral bioavailability of Rivastigmine?
40% up to dose of 3mg after which this increases non-linearly.
38
Half life of Rivastigmine?
1.5 hours
39
Metabolism of Rivastigmine?
Hydrolysis by cholinesterase | Minimal hepatic involvement
40
Excretion of Rivastigmine?
Urine as sulfate of decarbamylated metabolite
41
Oral bioavailability of galantamine?
90%
42
Plasma protein binding of Galantamine?
Low - 18%
43
Metabolism of Galantamine?
CYP2D6 | CYP3A4
44
Excretion of Galantamine?
One-third is excreted unchanged in urine
45
Plasma protein binding of Memantine?
45%
46
Half life of Memantine?
60-80 hours
47
Excretion of Memantine?
Half excreted unchanged in urine | Half undergoes hepatic conversion to inactive metabolites
48
What reduces clearance of mematine?
Drugs that alkalinize urine such as carbonic anhydrase inhibitors
49
Absorption of Methylphenidate?
Absorbed well orally
50
When does Methylphenidate reach peak plasma levels?
1-2 hours
51
Half-life of Methylphenidate?
2-3 hours
52
When does Modafinil reach peak plasma?
2-4 hours
53
Half life of Modafinil?
15 hours
54
Half life of Atomoxetine?
5 hours
55
What metabolizes Atomoxetine?
CYP 2D6
56
Impact of SSRIs on Atomoxetine?
SSRIs may raise Atomoxetine levels
57
Which benzos are long-acting?
Diazepam Chlordiazepoxide Clonazepam Flurazepam
58
When can toxicity of long-acting benzos be evident?
1-2 weeks
59
Which benzos are intermediate or short-acting?
Lorazepam Oxazepam Temazepam Alprazolam
60
Clinical effect of intermediate/short-acting benzos?
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
Half-life of Lorazepam?
15 hours
62
Half-life of Temazepam?
10 hours
63
Whch benzo has a very short duration of action?
Triazolam
64
What is Triazolam often used in?
Anaesthesia
65
Oral bioavailability of Diazepam?
Nearly 100%
66
When is peak plasma conc of diazepam reached?
15-90 minutes after oral administration | Second peak 6-12 hours due to enterohepatic recirculation
67
How is diazepam distributed
Widely as highly lipophilic (CSF conc equals plasma conc)
68
How much of diazepam is plasma binding?
95-99%
69
Elimination half life of Diazepam?
30 hours
70
How long does it take diazepam to reach steady state?
5-6 days
71
Metabolism of Diazepam?
In liver with 3 active metabolites.
72
What are the three active metabolites of diazepam?
Nordiazepam/desmethyldiazepam Oxazepam Temazepam
73
What is the principal metabolite of Diazepam?
Desmethyldiazepam - could accumulate due to long half-life
74
Which z-hypnotics are quickly absorbed when given orally?
Zolpidem Zaleplon Eszopiclone
75
Impact of food on quickly-absorped z-hypnotics?
Food can delay absorption for up to an hour
76
Accummulation of quickly-absorbed z-hypnotics?
None - no active metabolites
77
Give e.g. of z-hypnotics?
Zopcilone/Eszopiclone Zaleplon Zolpidem
78
Onset of Zopiclone?
45 mins
79
Half-life of Zopiclone?
4-5 hours
80
How does zopcilone work?
Benzo receptor selective for alpha 1 subunit
81
What is eszopiclone?
Enantiaomer - only z-hypnotic indicated for sleep maintenance therapy
82
Onset of Zaleplon?
Within 30 mins
83
Half-life of Zaleplon?
1-2 hours
84
Effect of Zaleplon?
Shorter half life and quick onset makes it suitable for sleep initation problems.
85
Onset of Zolpidem?
Within 30 mins
86
Half life of Zolpidem?
1-4 hours
87
Effect of Zolpidem?
Short half-lif and onset mades it suitable for sleep initation problems. Less hangover effect.