DOC for drug (phenothiazine) induced parkinsonism:March 2013
**Core Concept**
Phenothiazine-induced parkinsonism is a type of drug-induced extrapyramidal side effect caused by blocking dopamine receptors in the basal ganglia. This leads to an imbalance in the dopaminergic and cholinergic systems, resulting in parkinsonian symptoms.
**Why the Correct Answer is Right**
The treatment for phenothiazine-induced parkinsonism typically involves the use of anticholinergic agents to counteract the excessive cholinergic activity. Trihexyphenidyl is a typical anticholinergic medication used to manage this condition. It works by blocking the action of acetylcholine at muscarinic receptors in the central nervous system, thereby reducing the cholinergic tone and alleviating parkinsonian symptoms.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because antihistamines, such as diphenhydramine, are not the primary treatment for phenothiazine-induced parkinsonism. While they may have some anticholinergic effects, they are not the preferred choice for managing this condition.
**Option B:** This option is incorrect because benzhexol (trihexyphenidyl) is the correct answer, not benzodiazepines. Benzodiazepines are not typically used to treat parkinsonism and may even exacerbate the condition.
**Option C:** This option is incorrect because amantadine is used to treat neuroleptic malignant syndrome (NMS), not phenothiazine-induced parkinsonism. While it has some dopaminergic effects, it is not the primary treatment for this condition.
**Option D:** This option is incorrect because amitriptyline is a tricyclic antidepressant and is not used to treat phenothiazine-induced parkinsonism. Its anticholinergic effects may even contribute to the development of parkinsonian symptoms.
**Clinical Pearl / High-Yield Fact**
In addition to anticholinergic agents, other treatment options for phenothiazine-induced parkinsonism include dose reduction or discontinuation of the offending medication, as well as the use of dopamine agonists or amantadine in some cases.
**Correct Answer: B. Benzhexol (Trihexyphenidyl)**