Trihexyphenidyl hydrochloride is a synthetic antispasmodic drug available in the following forms: Tablets, 2 mg and 5 mg.
This drug is indicated as an adjunct in the treatment of all forms of parkinsonism (post-encephalitic, arteriosclerotic, and idiopathic). It is often useful as adjuvant therapy when treating these forms of parkinsonism with levodopa. Additionally, it is indicated for the control of extrapyramidal disorders caused by central nervous system drugs such as the dibenzoxazepines, phenothiazines, thioxanthenes, and butyrophenones.
Published Studies Related to Trihexyphenidyl
Retrograde facilitation of verbal memory by trihexyphenidyl in healthy elderly with and without the APOE epsilon4 allele. [2010.07]
Retrograde facilitation (RF) of information learned prior to acute oral administration of trihexyphenidyl, a preferential muscarinic M1 receptor antagonist which impairs new learning, was studied in 24 healthy elderly subjects. The relationship between the RF induced by this anticholinergic drug and the APOE epsilon4 allele was also examined...
Retrograde facilitation of verbal memory by trihexyphenidyl in healthy elderly
with and without the APOE epsilon4 allele. 
Retrograde facilitation (RF) of information learned prior to acute oral
administration of trihexyphenidyl, a preferential muscarinic M1 receptor
antagonist which impairs new learning, was studied in 24 healthy elderly
subjects. The relationship between the RF induced by this anticholinergic drug
and the APOE epsilon4 allele was also examined...
Pilot study on trihexyphenidyl in the treatment of dystonia in children with cerebral palsy. [2009.02]
The aim of this study was to assess trihexyphenidyl in reducing overall dystonia, improving upper limb function, and achieving goals in children with dystonic cerebral palsy. A randomized, double-blinded, placebo-controlled, crossover trial was conducted with 16 participants at a tertiary children's hospital...
Clinical Trials Related to Trihexyphenidyl
Childhood Hypertonia of Central Origin: A Trial of Anticholinergic Treatment Effects [Completed]
This study is an open-label trial of trihexyphenidyl in children with upper extremity
dystonia due to cerebral palsy. It is hypothesized that trihexyphenidyl in doses up to
0. 75mg/kg/day would be well-tolerated and show significant changes on the Melbourne scale of
upper extremity function.
Neuroimaging of Dystonia [Recruiting]
Clinical Evaluation of Ropinirole PR/XR Tablets in Monotherapy for Parkinson's Disease (PD) [Not yet recruiting]
This study was designed to evaluate the pharmacokinetic profile, safety and efficacy in
Parkinson's Disease patients.
Dopamine Treatment in Children With Cerebral Palsy With Dystonia- A Double Blind Controlled Study [Recruiting]
Cerebral palsy (CP) is the main cause of childhood immobility and is defined as a non
progressive injury to the developing central nervous system in children younger than 3
years, resulting in neurological and musculoskeletal abnormalities. The main
pathophysiological causes are encephalopathy of prematurity (periventricular leukomalacia)
hypoxic ischemic encephalopathy. Infections, infracts and migration defects are other less
common causes of CP. The brain injury leads to functional motor impairment impacting on
daily activities commonly manifests as a movement disorder: pyramidal, leading to spasticity
and extra-pyramidal leading to dystonia and chorea. In most cases extensive brain injury
causes a mixed movement disorder. Dystonia is defined as involuntary muscle contractions
causing twisting and abnormal postures. While the neurological underpinnings of CP remain
unknown, a link between low dopamine and increased acetylcholine release has recently been
reported in dystonia. Dopamine is considered the first line of treatment in children with
dystonia and CP followed by anticholiergic treatment with trihexphenidyl. The recommendation
of dopaminergic treatment is based on need to rule out dopamine-responsive-dystonia, a rare
genetic disorder, and on single case study reporting improvement in CP. A double blind study
support or refute the use of dopamine treatment for dystonic CP was never reported. Working
In children with CP due to a clear underlying pathology, dopamine treatment will not improve
daily function. Methods: the investigators will perform a double blinded randomized
controlled crossover study. 50 children ages 4-18 years with a clear pathophysiological
cause for CP will be enrolled. Each child will receive dopamine and placebo treatment for 2
weeks with a 2 week washout interval. Participants will be randomized into 2 groups; one
will receive placebo followed by dopamine and the other vice versa. The primary outcome
measure, goal-attainment-scale, and secondary outcome functional measures (such as box and
blocks, 9 hole pegs, pronation/ supination, finger sequencing) will be assessed at the
beginning and end of each treatment as well as parent questionnaires regarding satisfaction
and side effects.
No functional improvement with dopamine treatment compared to placebo.
supplying sufficient data to support or refute the use of dopamine treatment for dystonic
Probable implications to Medicine:
this may lead to a change in medical treatment guidelines for children with CP.
Page last updated: 2013-02-10