Also Known As: Trihexyphenidyl, Artane, Apo-Trihex, Benzhexol
Trihexyphenidyl (Artane, Apo-Trihex), also known as benzhexol, is an antiparkinsonian agent of the antimuscarinic class. It has been in clinical usage for decades. The drug is available as the hydrochloride salt.
Trihexyphenidyl is used for the symptomatic treatment of Parkinson's disease in mono- and combination therapy. It is active in postencephalitic, arteriosclerotic, and idiopathic forms. The drug is also commonly used to treat extrapyramidal side effects occurring during antipsychotic treatment. It reduces the frequency and duration of oculogyric crises as well as of dyskinetic movements and spastic contractions. Excessive salivation may also respond. Trihexyphenidyl may improve psychotic depression and mental inertia frequently associated with Parkinson's disease and symptomatic problems caused by antipsychotic treatment.
The drug cannot cure Parkinson's disease, but may provide substantial alleviation of symptoms. An estimated 50 to 75% of patients with Parkinson's disease will react positively and experience a 20 to 30% symptomatic improvement. To increase therapeutic activity trihexyphenidyl is often given concomitantly with levodopa, other antimuscarinic or antihistaminic (e.g. diphenhydramine) agents. Combination treatment with dopaminergic agonists such as cabergoline is also possible. This is often termed a 'multidimensional approach'.
It has also been prescribed for Essential Tremors.
Equivocal preliminary results from small studies exist for:
- Other dyskinesias
- Huntington's chorea
- Spasmodic torticollis
Trihexyphenidyl does not improve cerebral palsy and hemiplegia.