Welcome to the MedLibrary.org Wikipedia Supplement on Trihexyphenidyl -- Please Click to Return to Front Page

Trihexyphenidyl
Systematic (IUPAC) name
1-cyclohexyl-1-phenyl-3-(1-piperidyl)propan-1-ol
Identifiers
CAS number	144-11-6
ATC code	N04AA01
PubChem	5572
DrugBank	APRD00070
Chemical data
Formula	C20H31NO
Mol. mass	301.466 g/mol
Pharmacokinetic data
Bioavailability	?
Metabolism	?
Half life	3.3-4.1 hours
Excretion	?
Therapeutic considerations
Pregnancy cat.	C US
Legal status	Rx-Only (US)
Routes	Oral, as tablet or elixir

Trihexyphenidyl, also known as Benzhexol, (sold under the brandnames Aparkan and Artane) is an antiparkinsonian drug of the antimuscarinic class. Chemically, it is a tertiary amine with alcohol, phenyl, and cyclohexyl moieties. It has been in clinical usage for decades. The drug is available as the hydrochloride salt.

Contents 1 Pharmacology 2 Pharmacokinetics 3 Established uses 4 Therapeutic prospects 5 Investigational uses 6 Contraindications and cautions 7 Pregnancy and lactation 8 Side-effects 9 Interactions 10 Dosage 11 Overdose 12 Brand names and dose forms 13 External links

Pharmacology

The exact mechanism of action in parkinsonian syndromes is not precisely understood, but it is known that trihexyphenidyl blocks efferent impulses in parasympathetically innervated structures like smooth muscles (spasmolytic activity), salivary glands, and eyes (mydriasis). In higher doses direct central inhibition of cerebral motor centers may contribute. In very high doses central toxicity as seen in atropine overdose is noted.

Pharmacokinetics

Trihexyphenidyl is rapidly absorbed from the GI-Tract. The onset of action is within 1 hour after oral dosing. The peak activity is noted after 2 to 3 hours. The duration of action of one single dose is 6 to 12 hours in a dose dependent manner. It is excreted in the urine, probably as unchanged drug. More precise data in animals and humans have so far not been determined.

Established uses

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 Morbus Parkinson and symptomatic problems caused by antipsychotic treatment.

Therapeutic prospects

The drug hao is not able to cure Morbus Parkinson, but may provide substantial alleviation of symptoms. An estimated 50 to 75% of patients with M. Parkinson 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'.

Investigational uses

Equivocal preleminary results from small studies exist for:

• Other Dyskinesias
• Huntington's Chorea
• Spasmodic Torticollis
• Dystonia

Trihexyphenidyl does not improve cerebral palsy and hemiplegia.

Contraindications and cautions

See Biperiden.

• Patients under 18 yrs. of age should not be treated due to a lack of clinical experience.

• Trihexyphenidyl has been reported as a drug of abuse, and while this is uncommon it may be prudent to be cautious in prescribing this drug to patients with a history of drug addiction. The drug has euphoriant and aphrodisiac properties and is smoked, insufflated, swallowed, or dissolved under the tongue and has enhanced activity when injected. Some users report a rush in the genital area when used in such a way as to deliver the dose very quickly and for this and other reasons Artane® and similar drugs are referred to by some as Sexy Trihexy, Tri-Sexual, T. Hex, and Octane.

• Patients should allow a period to adjust to the dose when first adjusting to trihexyphenidyl and when the dose has been increased or added to a regimen with other drugs because acute somnolence and accumulated fatigue can make in particularly dangerous to opeate an automobile, heavy machinery or that containing hot liquids &c.

Pregnancy and lactation

The safe use of Trihexyphenidyl during pregnancy and lactation has so far not been assured.

Side-effects

See Biperiden. Tolerance may develop during therapy which requires dose adjustments.

Interactions

See Biperiden.

Dosage

• Morbus Parkinson : One mg is given on the first day. Increments are usually 2mg every 3 days until 6 to 10mg are reached. In postencephalitic cases up to 15 mg might be necessary, but then excessive dryness of mouth or nausea could be a problem. To increase tolerability Trihexyphenidyl may be given in 3 divided doses.

• Extrapyramidal side effects : Usually, 5 to 15 mg daily are needed in 2 or 3 divided doses. Some patients, however, are successfully treated with as little as 1 mg daily.

Overdose

See Biperiden.

Brand names and dose forms

• Artane : elixir 2mg/5ml, tabletts 2mg and 5mg
• Generics (e.g. Cypress, URL, Watson, West-Ward) : elixir and/or tabletts
• Pacitane "http://www.wyethindia.com/products/pacitane.asp?prodid=7"

External links

• AHFS online database
• http://www.mentalhealth.com/drug/p30-t04.html

v • d • e Anticholinergics Nicotinic antagonists Ganglionic Mecamylamine - Trimethaphan - Hexamethonium Neuromuscular Non-depolarising Curare Alkaloids: Alcuronium - Dimethyltubocurarine - Tubocurarine Quaternary ammonium compounds: Atracurium - Cisatracurium - Doxacurium chloride - Fazadinium bromide - Gallamine - Hexafluronium - Metocurine - Mivacurium chloride - Pancuronium - Pipecuronium bromide - Rocuronium bromide,Vecuronium Depolarising Choline Derivatives: Suxamethonium - Succinylcholine Muscarinic antagonists Atropine - Scopolamine - Ipratropium - Tropicamide - Cyclopentolate - Benztropine - Dicycloverine - Tolterodine - Oxybutynin - Pirenzepine - Biperiden - Trihexyphenidyl - M1 (Pirenzepine) - M3 (Tiotropium, Darifenacin) Presynaptic acetylcholine synthesis (Hemicholinium-3) - acetylcholine release (Botulinum toxin) Other acetylcholinesterase reactivators (Pralidoxime, Obidoxime) note: in PNS, ganglionic blocker can have direct antinicotinic action at preganglionic terminal, but simulate indirect antimuscarinic activities at postganglionic terminal

v • d • e Anti-parkinson drugs: anticholinergic agents (primarily antimuscarinic) (N04A) Tertiary amines Trihexyphenidyl - Biperiden - Metixene - Procyclidine - Profenamine - Dexetimide - Phenglutarimide - Mazaticol - Bornaprine - Tropatepine Ethers chemically close to antihistamines Etanautine - Orphenadrine Ethers of tropine or tropine derivatives Benztropine - Etybenzatropine

Wikipedia content modification information:

• This page was last modified on 17 August 2008, at 02:32.

Wikipedia Authorship and Review

Wikipedia content provided here is not reviewed directly by MedLibrary.org. Wikipedia content is authored by an open community of volunteers and is not produced by or in any way affiliated with MedLibrary.org.

Wikipedia Usage Guidelines

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article on "Trihexyphenidyl".

The URL for this specific entry is:

• http://medlibrary.org/medwiki/Trihexyphenidyl

All Wikipedia text is available under the terms of the GNU Free Documentation License. (See Copyrights for details). Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc.