Trihexyphenidyl [Benzhexol]

Trihexyphenidyl is indicated for all forms of Parkinson’s disease including idiopathic and drug-induced. Trihexyphenidyl is prescribed as adjunctive pharmacotherapy with other antiparkinsonian drugs. Maximal therapeutic benefit from trihexyphenidyl pharmacotherapy is in the range of 20 percent to 30 percent improvement among 50 percent to 75 percent of patients. Trihexyphenidyl usually is prescribed as adjunctive pharmacotherapy with other antiparkinsonian drugs. When adjunctive trihexyphenidyl pharmacotherapy is prescribed with levodopa pharmacotherapy, it may be necessary to reduce the dosage of each drug according to individual patient response. Patients who are receiving adjunctive trihexyphenidyl pharmacotherapy require a gonioscope evaluation and close monitoring of intraocular pressure at regular intervals. Collaboration with the patient’s ophthalmologist is indicated. The exact mechanism of trihexyphenidyl’s antiparkinsonian action has not yet been fully determined. It appears to act by the following mechanisms: the blockade of cholinergic receptors in the basal ganglia, which, in turn, blocks efferent nerve impulses; and the central inhibition of cerebral motor centers.