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Pharmacology III > Parkinson's & Alzheimer's Drugs > Flashcards

Parkinson's & Alzheimer's Drugs Flashcards

1
Q

L-Dopa (Levodopa; Dopar®; Larodopa®) - MoA

A 
- Increase DA levels
 “Replacement” Therapy
 L-3,4-dihydroxyphenylalanine
 Dopamine does not cross BBB
 L-Dopareadily crosses BBB and  is converted into DA 
    in the neuron
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2
Q

L-Dopa (Levodopa; Dopar®; Larodopa®) - Uses

A

 Improvement of PD symptoms for 3-4 yrs;
bradykinesia
 Not all patients respond well to (or can tolerate) l-
dopa(~33%)
 Effectiveness of l-dopa will go down over time
 Does not affect progression; DA neurons continue to
degenerate
 As l-dopa loses effectiveness, other drugs are added
 Not effective in drug-induced Parkinsonism

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3
Q

L-Dopa (Levodopa; Dopar®; Larodopa®) - Pharmacokinetics

A

 Orally administered; absorption is delayed by food,
amino acids
 Short half-life; taken 3-4 times/day
 Need high doses; only 1-3% gets into CNS

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4
Q

L-Dopa/Carbidopa (Sinemet) - MoA

A

 L-dopa is converted to dopamine in the periphery
 Carbidopa inhibits dopa-decarboxylase, but doesn’t
cross BBB
 Conversion of l-dopa to DA is inhibited in periphery
but not in brain
 Decreases the dose of l-dopa needed
 Decreases peripheral effects; nausea

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5
Q

L-Dopa/Carbidopa (Sinemet) - Side Effects

A

 Tend to increase as disease progresses
 Peripheral effects decreased with carbidopa
 GI: nausea/emesis
• divided doses will help decrease GI effects
• avoid antiemetics that block DA D2 receptors
(Prochlorperazine)
 Cardiovascular: postural hypotension, arrhythmias,
hypertension
 Dyskinesias develop with time; more common with l-
dopa/carbidopa combination; treat by reducing l-dopa
 Behavioral: Depression, anxiety, agitation, sleep
problems
• psychosis possible; treat with atypical
antipsychotics
 Drug holiday

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6
Q

L-dopa Drug Interactions

A

 MAO-AI’s – may cause hypertensive crisis
 Pyridoxine (Vitamin B6) – increases peripheral
metabolism of l-dopa, thus decreases effectiveness

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7
Q

L-dopa Contraindications

A

 Psychosis
 Closed angle glaucoma – increases intraocular
pressure
 Cardiac disease
 Active peptic ulcers – can increase GI bleeding
 Malignant melanoma –l-dopa is precursor of
melanin
 L-dopa toxicity?

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8
Q

MAOI inhibitors (MAOIs) - MoA

A

Inhibit DA metabolism

  • Selegiline (Deprenyl®)
  • Rasagiline (Azilect®)
  • Safinaminde (Xadago®)

Inhibit MAO-B in CNS and reduces striatal metabolism
of DA
 Does not affect peripheral metabolism of DA by
MAO-A
 May inhibit progression of PD by decreasing free
radicals produced during DA metabolism

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9
Q

Adverse effects of MAO-BIs

A

 Insomnia – Amphetamine “like” metabolites; taken
morning and noon to decrease likelihood
 Severe hypertension if combined with other MAOIs
(phenelzine)
 Will increase the side effects of L-dopa in late stages
of disease
 Do NOT combine with meperidine–can lead to
stupor, rigidity, agitation, hyperthermia, possible
serotonin syndrome
 Serotonin syndrome possible if combined with TCAs
or SSRIs

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10
Q

COMT Inhibitors - MoA

A

 Catachol-O-methyl transferase (COMT) metabolizes
DA and l-dopa
 Inhibit DA and l-dopa metabolism

  • Tolcapone (Tasmar®)
  • Entacapone (Comtan®)
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11
Q

Tolcapone (Tasmar®)

A
  • inhibits COMT in CNS and periphery
    • Prolongs action of DA in CNS
    • Increases pool of l-dopa for transport into the brain
    • Has been associated with death from hepatic failure
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12
Q

Entacapone (Comtan®)

A
  • inhibits COMT in periphery only

• Increases pool of l-dopa for transport into the brain

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13
Q

COMT Inhibitors - Side Effects

A 
dyskinesia
confusion
nausea
hypotension
abdominal pain
sleep disturbances
orange color in urine
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14
Q

DA Receptor Agonists - MoA

A
  • Stimulate DA receptors
     Act directly on receptors; primarily DA D2
     Because these drugs act directly on receptors, they
    will continue to be effective as the disease
    progresses
     Role in first-line therapy for PD
     Used in combination with L-dopa during “on-off”
    periods
     Lower incidence of response fluctuations and
    dyskinesias
  • Bromocriptine (Parlodel®)
  • Ropinirole (Requip®)
  • Pramipexole (Mirapex®)
  • Rotigotine (Neupro®)
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15
Q

Bromocriptine (Parlodel®)

A

 Ergot derivatives – Can cause vasospasms,
Erythromelalgia
 Mutation in DDC; cannot synthesize DA, treated with
bromocriptine

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16
Q

Ropinirole (Requip®)

Pramipexole (Mirapex®)

A

 New DA agonists (D2; some agonist activity for D3)
 May cause sudden sleep during the day
 Both agents have a pro-longed release formulation
 Monotherapy in mild PD; soothing response to
l-dopa in late PD

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17
Q

Ropinirole

A
  • Relatively pure DA D2agonist

* DOC for restless leg syndrome (RLS)

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18
Q

Pramipexole

A

FDA warning on possible heart failure – Sept, 2012

19
Q

Rotigotine (Neupro®)

A

transdermal patch for PD and RLS

20
Q

Side Effects of DA Agonists

A

 GI: anorexia, nausea, vomiting (CTZ); minimized by
taking with meals
• constipation, dyspepsia, gastro-esophageal reflux,
bleeding of peptic ulcers
 Cardiovascular: postural hypotension (beginning of
treatment)
• Ergot derivatives - digital vasospasm; decrease dose
• cardiac arrhythmias: discontinue treatment
 Dyskinesia: similar to l-dopa; reduce dose of
dopaminergic drugs
 Mental Disturbances: confusion, hallucinations,
delusion
 Erythromelalgia: bromocriptine
 Prolactin – DA agonists will decrease release

21
Q

Amantadine (Symmetrel®) - MoA

A

Increase DA neurotransmission

 May increases release of DA; may also inhibit DA
reuptake

22
Q

Amantadine (Symmetrel®) - Uses

A

 Antiviral used for influenza

 Used to treat early or mild cases of PD

23
Q

Amantadine (Symmetrel®) - Side Effects

A

 Can cause livedo reticularis – reddish/blue spotting
of skin
 Restlessness, depression, irritability, insomnia,
agitation, confusion, hallucinations
 Peripheral edema, responds to diuretics
 Toxic psychosis and convulsions may occur with
overdose

24
Q

Anticholinergics

A

Benztropine (Cogentin®)
Trihexyphenidyl (Artane®)
Diphenhydramine (Benadryl) - anticholinergic effects

25
Q

Anticholinergics - MoA

A

 Muscarinic receptor antagonists; Restores DA/ACh

balance in striatum

26
Q

Anticholinergics - Uses

A

 Modest anti-Parkinson action
 Improves rigidity, tremor; little effect on bradykinesia
 Used in early & late stages; adjunct to DA therapy

27
Q

Anticholinergics - Side Effects

A

constipation, urinary retention, blurred vision, sedation, confusion; if discontinuing, do so gradually

28
Q

Anticholinergics - Drug Interactions

A

Tricyclic antidepressants or antihistamines will increase effects

29
Q

Pimavanserin (Nuplazid®) - MoA

A

Inverse agonist/antagonist for 5-HT receptors; does not affect dopaminergic, adrenergic, cholinergic, or histamine receptors

30
Q

Pimavanserin (Nuplazid®) - Uses

A

Atypical antipsychotic approved for treatment of psychosis and delusions/hallucinations associated with Parkinson’s

31
Q

Pimavanserin (Nuplazid®) - Side Effects

A

Gastrointestinal upset, prolonged QT interval

32
Q

Pimavanserin (Nuplazid®) - Pharmacokinetics

A

plasma 1/2 life of ~57 hrs

metabolized by CYP3A4

33
Q

Pimavanserin (Nuplazid®) - Contraindications

A

NOT approved for treatment of dementia associated with Alzheimer’s disease. Increases mortality

34
Q

Cholinesterase Inhibitors

A

Donepezil (Aricept®)
Rivastigmine (Exelon®)
Galantamine (Reminyl®)

35
Q

Cholinesterase Inhibitors - MoA

A

Inhibit metabolism of ACh; Increases the amount of ACh in the nerve terminal

36
Q

Cholinesterase Inhibitors - Pharmacokinetics

A

 Well absorbed and readily penetrate the CNS
 Metabolized by CYP450s
 Taken once/day

37
Q

Cholinesterase Inhibitors - Side Effects

A

GI; Nausea, vomiting, diarrhea, stomach cramps are

most common

38
Q

Cholinesterase Inhibitors - Uses

A

 Increases brain activity & improves cognitive
function
 May slow progression of the disease and delay
transition from mild cognitive impairment to AD

39
Q

Memantine (Namenda®) - MoA

A

 NMDA receptor antagonist (channel blocker)
 Blocks pathological activation of NMDA receptors
 Reduces excitotoxic effect of glutamate and slows
degeneration

40
Q

Memantine (Namenda®) - Uses

A

late stages of Alzheimer’s in combination with AChE-Is

41
Q

Memantine (Namenda®) - Pharmacokinetics

A

 Competes for renal tubular secretion
 Monitor dose in patients with renal impairment
 May increase side effects of l-dopa

42
Q

Memantine (Namenda®) - SIde Effects

A

agitation, insomnia, urinary incontinence, urinary tract infection, and diarrhea

43
Q

Memantine (Namenda®) - Contraindications

A

Contraindicated with meperidine, dextromethorphan

Pharmacology III (10 decks)

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