Trihexyphenidyl Hydrochloride is an anticholinergic medication primarily used to manage symptoms associated with Parkinson's disease and extrapyramidal side effects induced by antipsychotic medications. It functions by inhibiting the action of acetylcholine, a neurotransmitter involved in muscle movement, thereby helping to restore the balance between dopamine and acetylcholine in the brain. This action alleviates symptoms such as tremors, rigidity, and bradykinesia (slowness of movement) in Parkinson's disease. Additionally, it is effective in controlling drug-induced extrapyramidal symptoms, including tardive dyskinesia and dystonia.