Pharmacology 2: Pharmacologic Management of Parkinsonism

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Questions and Answers

What are the main signs of Parkinsonism?

Rigidity of skeletal muscles, akinesia (or bradykinesia), flat facies, and tremor at rest (mnemonic RAFT).

What is the essential feature required for a diagnosis of Parkinson's disease?

Bradykinesia

What is the pathogenesis of parkinsonism related to?

Impaired degradation of proteins, intracellular protein accumulation and aggregation, oxidative stress, mitochondrial damage, inflammatory cascades, and apoptosis.

What factors are protective against Parkinson's disease?

Cigarette smoking, coffee, anti-inflammatory drug use, and high serum uric acid levels Signup and view all the answers

What occupations are associated with an increased incidence of Parkinson's disease?

Teaching, health care, or farming Signup and view all the answers

What is the effect of lead or manganese exposure on the incidence of Parkinson's disease?

It increases the incidence of the disease Signup and view all the answers

What is the effect of vitamin D deficiency on the incidence of Parkinson's disease?

It increases the incidence of the disease Signup and view all the answers

Is Parkinson's disease curable?

No, it is incurable, but pharmacologic treatment may relieve motor symptoms and improve the quality of life. Signup and view all the answers

What type of drugs exacerbate tardive dyskinesias that result from prolonged use of antipsychotic drugs?

Agents Signup and view all the answers

What type of drugs can alleviate physiologic and essential tremor?

β-blocking drugs Signup and view all the answers

What is the preferred β-blocker to use in patients with concomitant pulmonary disease?

Metoprolol Signup and view all the answers

What type of drugs are sometimes used to treat essential tremor?

Antiepileptic drugs Signup and view all the answers

What is the primary neurotransmitter imbalance in Huntington's disease?

GABA functions are diminished and dopaminergic functions are enhanced Signup and view all the answers

What type of drugs are often used to treat Huntington's disease?

Amine-depleting drugs and dopamine receptor antagonists Signup and view all the answers

What type of drugs are often effective in treating Tourette's syndrome?

Dopamine D2 receptor blockers Signup and view all the answers

What is the preferred drug to use in patients with Tourette's syndrome?

Haloperidol Signup and view all the answers

What type of therapy are dopamine agonists used as?

add on therapy to levodopa/carpidopa Signup and view all the answers

What is the typical response of patients who don't respond to levodopa/carpidopa when treated with dopamine agonists?

disappointing result Signup and view all the answers

What type of agonist is bromocriptine at dopamine D2 receptors?

partial agonist Signup and view all the answers

What are some common adverse effects of bromocriptine?

anorexia, nausea and vomiting, dyskinesias, and postural hypotension Signup and view all the answers

What is the receptor subtype that pramipexole has high affinity for?

dopamine D3 receptor Signup and view all the answers

In what situations is pramipexole effective?

as mono therapy in mild parkinsonism and together with levodopa in more advanced disease Signup and view all the answers

What are some common adverse effects of pramipexole?

anorexia, nausea and vomiting, postural hypotension, and dyskinesias Signup and view all the answers

What is a rare but significant adverse effect of pramipexole?

an uncontrollable tendency to fall asleep Signup and view all the answers

Study Notes

Parkinsonism

Parkinsonism is a common movement disorder characterized by dysfunction in the basal ganglia and associated brain structures.
Signs include rigidity of skeletal muscles, akinesia (or bradykinesia), flat facies, and tremor at rest (mnemonic RAFT).

Facts about Parkinson's Disease

Parkinsonism can occur for a variety of reasons, but is usually idiopathic (Parkinson's disease or paralysis agitans).
Bradykinesia should be present before a diagnosis of Parkinson's disease is made.
Focal dystonic features may be present.
Cognitive decline occurs in many patients as the disease advances.
The disease is incurable, generally progressive, and leads to increasing disability with time, but pharmacologic treatment may relieve motor symptoms and improve the quality of life for many years.

Pathogenesis of Parkinsonism

Pathogenesis seems to relate to a combination of impaired protein degradation, intracellular protein accumulation and aggregation, oxidative stress, mitochondrial damage, inflammatory cascades, and apoptosis.
Epidemiologic studies reveal that cigarette smoking, coffee, anti-inflammatory drug use, and high serum uric acid levels are protective, whereas the incidence of the disease is increased in those working in teaching, health care, or farming, and in those with lead or manganese exposure or with vitamin D deficiency.

Drug Therapy of Other Movement Disorders

A. Tremor

Physiologic and essential tremor are clinically similar conditions characterized by postural tremor.
Conditions may be accentuated by anxiety, fatigue, and certain drugs, including β-adrenergic blockers, tricyclic antidepressants, and lithium.
β-blockers, including propranolol, may alleviate symptoms.
Metoprolol, a β1-selective antagonist, is also effective, and its use is preferred in patients with concomitant pulmonary disease.
Antiepileptic drugs, including gabapentin and topiramate, as well as intramuscular injection of botulinum toxin, have also been used to treat essential tremor.

B. Huntington's Disease and Tourette's Syndrome

Huntington's disease is an inherited disorder resulting from a brain neurotransmitter imbalance, with diminished GABA functions and enhanced dopaminergic functions.
Pharmacologic attempts to enhance brain GABA and acetylcholine activities have not been successful in patients with this disease.
Drug therapy usually involves the use of amine-depleting drugs (e.g., reserpine, tetrabenazine) and dopamine receptor antagonists (e.g., haloperidol, perphenazine).
Tourette's syndrome is a disorder of unknown cause that frequently responds to haloperidol and other dopamine D2 receptor blockers, including pimozide.

Dopamine Agonists

1. Bromocriptine

Bromocriptine is an ergot alkaloid that acts as a partial agonist at dopamine D2 receptors in the brain.
The drug increases the functional activity of dopamine neurotransmitter pathways, including those involved in extrapyramidal functions.
Common adverse effects include anorexia, nausea and vomiting, dyskinesias, and postural hypotension.
Behavioral effects, including confusion, hallucinations, and delusions, occur more commonly with bromocriptine than with newer dopamine agonists.

2. Pramipexole

Pramipexole is a non-ergot dopamine receptor agonist with high affinity for the dopamine D3 receptor.
It is effective as monotherapy in mild parkinsonism and can be used together with levodopa in more advanced disease.
Adverse effects include anorexia, nausea and vomiting, postural hypotension, and dyskinesias.
Mental disturbances, including confusion, delusions, hallucinations, and impulsivity, are more common with pramipexole than with levodopa.

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Description

This quiz covers the pharmacologic management of Parkinsonism, a common movement disorder characterized by dysfunction in the basal ganglia and associated brain structures.