All of the following drugs are commonly used in a management of Parkinsonism, EXCEPT:

DSSSB 13 August 2024

Pharmacology

Medium

Appeared in: DSSSB 13 August 2024

Explanation

The butyrophenone group of antipsychotics (e.g., haloperidol) are dopamine D2 receptor antagonists.
Parkinson's disease is caused by a deficiency of dopamine. Blocking the already limited dopamine activity would worsen the cardinal symptoms of tremor, rigidity, and bradykinesia.
These drugs are a well-known cause of drug-induced parkinsonism, a condition that mimics the symptoms of Parkinson's disease.
Therefore, they are contraindicated and are not used in the management of Parkinsonism.

Option A: Dopaminergic agents are the primary and most effective treatment for Parkinson's disease. They work by replenishing or mimicking dopamine in the brain.
Option B: Anticholinergic drugs are used in the management of Parkinson's disease, particularly to alleviate tremors. They work by correcting the imbalance between acetylcholine and dopamine.
Option D: Monoamine oxidase type B (MAO-B) inhibitors are a standard class of drugs used to treat Parkinson's. They prevent the breakdown of dopamine in the brain, increasing its availability.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pharmacological management of Parkinson's disease and contraindicated medications as background academic context rather than a clinical decision trigger.
A critical nursing responsibility is medication reconciliation and vigilance to prevent the administration of dopamine-blocking agents to patients with Parkinson's disease.
Common dopamine antagonists to watch for include typical antipsychotics (haloperidol) and certain antiemetics (metoclopramide, prochlorperazine), which can cause a rapid and severe worsening of motor symptoms.
What if? If a patient with Parkinson's disease develops psychosis that requires treatment, the appropriate action is to consult the physician about using an atypical antipsychotic with low dopamine D2 receptor affinity, such as quetiapine or clozapine, not a butyrophenone.

How to Approach the Question

First, identify the keyword "EXCEPT." This signals that you must find the option that does NOT fit with the others. Three options are used to treat Parkinsonism, and one is not.
Recall the fundamental pathophysiology of Parkinson's disease: a deficiency of dopamine in the brain.
Logically deduce that treatments will aim to increase dopamine levels or activity.
Evaluate each option based on this principle. Ask yourself, "Does this drug increase dopamine's effect or block it?"
Dopaminergic agents, anticholinergics (by rebalancing), and MAO-B inhibitors all effectively increase dopaminergic tone.
Recognize that antipsychotics in the butyrophenone class are dopamine blockers. This action is directly contrary to the therapeutic goal for Parkinson's, making it the correct answer.

Concept Tested & Keywords

Concept Tested: Pharmacological management of Parkinson's disease and contraindicated medications.
Stem keywords: Parkinsonism, management, drugs
Lead-in keywords: EXCEPT
Negative lead-in flag: This is a negative-lead question, asking for the option that is an exception.

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E6 Pharmacology Nursing Lilley 11e Part 1 p. 253-255

E6 Pharmacology Katzung 16e pp. 781-783, 793-795