Trihexyphenidyl Explained

Watchedfields:changed
Verifiedrevid:470614772
Iupac Name:(RS)-1-Cyclohexyl-1-phenyl-3-(1-piperidyl)propan-1-ol
Tradename:Artane, Parkin, Pacitane, Hexymer
Dailymedid:Trihexyphenidyl
Pregnancy Au:B1
Legal Br:B1
Legal Br Comment:[1]
Legal Us:Rx-Only
Routes Of Administration:Oral, as tablet or elixir
Elimination Half-Life:3.3-4.1 hours
Iuphar Ligand:7315
Cas Number:144-11-6
Atc Prefix:N04
Atc Suffix:AA01
Pubchem:5572
Drugbank:DB00376
Chemspiderid:5371
Unii:6RC5V8B7PO
Kegg:D08638
Chembl:1490
C:20
H:31
N:1
O:1
Smiles:OC(c1ccccc1)(CCN2CCCCC2)C3CCCCC3
Stdinchi:1S/C20H31NO/c22-20(18-10-4-1-5-11-18,19-12-6-2-7-13-19)14-17-21-15-8-3-9-16-21/h1,4-5,10-11,19,22H,2-3,6-9,12-17H2
Stdinchikey:HWHLPVGTWGOCJO-UHFFFAOYSA-N

Trihexyphenidyl (THP, benzhexol, trihex, marketed as Artane and others) is an antispasmodic drug used to treat stiffness, tremors, spasms, and poor muscle control. It is an agent of the antimuscarinic class and is often used in management of Parkinson's disease. It was approved by the FDA for the treatment of Parkinson's in the US in 2003.[2] [3]

It is on the World Health Organization's List of Essential Medicines.[4]

Medical uses

Trihexyphenidyl is used for the symptomatic treatment of Parkinson's disease in mono and combination therapy.[5] 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. 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 50–75% of people with Parkinson's disease will react positively and experience a 20–30% symptomatic improvement. To increase therapeutic activity, trihexyphenidyl is often given concomitantly with levodopa or other antimuscarinic or antihistaminic (e.g. diphenhydramine) agents. Combination therapy with dopamine agonists such as cabergoline is also possible. This is often termed a 'multidimensional approach'.

Trihexyphenidyl has also been prescribed for essential tremor and akathisia.[6] [7]

In pediatrics, it has been used for children with dystonia due to cerebral palsy,[8] [9] [10] and to control drooling.[11]

In organophosphate poisoning, trihexyphenidyl is a more effective antidote than atropine to counteract the cholinergic crisis, seizures, and neuropathology.[12]

Equivocal preliminary results from small studies exist for other dyskinesias, Huntington's chorea, Spasmodic torticollis.

Contraindications

Contraindications include according to the Therapeutic Goods Administration Australia from 2022:[13]

Adverse effects

Dose-dependent side effects are frequent, but typically lessen over time as the body adapts to the medication. All of the following symptoms considered, Artane has been shown to dramatically and consistently improve neurologic defects in people aged 16–86 over the course of five years.[14] People who are older or who have psychiatric conditions may become confused or develop delirium. Side effects include but are not limited to:[15]

Trihexyphenidyl is a pregnancy category C drug. It is advised to only use with caution if benefits outweigh risks.[17]

Overdose

Trihexyphenidyl and other antiparkinsonian drugs are known to be substances of abuse. This is true both in abusers of other substances and in chronic schizophrenics, the latter being infrequent abusers of other drugs.[18]

Overdose mimics an atropine intoxication with dryness of mucous membranes, red face, bowel and bladder paralysis, and hyperthermia in high doses. Central nervous system consequences are agitation, confusion, and hallucinations. An untreated overdose may be fatal, particularly in children. Premortal signs are respiratory depression, arrhythmia and cardiac arrest.

A specific antagonist is physostigmine, which combines a peripheral and a central action.

Carbachol can be used to treat atonic bowel and bladder. It may be necessary to treat hyperthermia with cooling blankets.

A case report of 24 hour long arrhythmia was treated with verapamil.[19]

Excessive myoclonus can be complicated by rhabdomyolysis; in one case risk was increased due to concomitant use of risperidone.[20]

Interactions

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. It binds to the M1 muscarinic receptor[21] and possibly the dopamine receptor.[22] Trihexyphenidyl is rapidly absorbed from the gastrointestinal tract. The onset of action is within 1 hour after oral dosing. The peak activity is noted after 2 to 3 hours.[23] 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.[24] [25]

History

Trihexyphenidyl has been clinically relevant in trials pertaining to Parkinson's disease since 1949.[26]

In the US, the FDA approved Artane, or its generic form Trihexyphenidyl HCL, only on June 25, 2003 for the clinical use of all types of parkinsonism.[27]

Society and culture

Recreational use

The neurologist Oliver Sacks reported using the drug recreationally in the 1960s. He recalled taking "a large dose" knowing full well the drug was intended for people with Parkinson's. More recounts of Dr. Sacks' experiences including experimentation with mescaline, psilocybin, LSD, and probably DMT[28] have been compared in his book Hallucinations.

During the 1970s, trihexyphenidyl (trade name Parkan) was the most popular recreationally used prescription drug in Hungary.[29]

In a 2008 news report, trihexyphenidyl was seen to be used for recreational purposes among Iraqi soldiers and police, among other prescription drugs. The report states that the drugs were taken to relieve combat stress reaction.[30] Although that may be the case for some, others used Artane as a substitute or more intense version of LSD. This was especially prevalent in the 1960s, according to a report in "The New Yorker". Similarly to those in Iraqi forces, some of the appeal was that the individual may retain partial control while under the influence.[31]

Chemistry

Trihexyphenidyl can be synthesized in two ways, one linear and one convergent synthesis.

In the first way, the initial 2-(1-piperidino)propiophenone is synthesized in turn by the aminomethylation of acetophenone using paraformaldehyde and piperidine in a Mannich reaction. In the second step the 2-(1-piperidino)propiophenone is reacted with cyclohexylmagnesium bromide in a Grignard reaction.[32]

Stereochemistry

Trihexyphenidyl has a chiral center and two enantiomers. Medications are racemates.[33]

See also

Notes and References

  1. Web site: Anvisa . Brazilian Health Regulatory Agency . 2023-03-31 . RDC Nº 784 - Listas de Substâncias Entorpecentes, Psicotrópicas, Precursoras e Outras sob Controle Especial . Collegiate Board Resolution No. 784 - Lists of Narcotic, Psychotropic, Precursor, and Other Substances under Special Control. live . https://web.archive.org/web/20230803143925/https://www.in.gov.br/en/web/dou/-/resolucao-rdc-n-784-de-31-de-marco-de-2023-474904992 . 2023-08-03 . 2023-08-16 . . pt-BR . 2023-04-04.
  2. Web site: TGA eBS - Product and Consumer Medicine Information Licence. 2020-08-20. www.ebs.tga.gov.au.
  3. Web site: U.S. Food and Drug Administration . 2003-05-25. New Drug Application Approval Notice. 2020-08-20.
  4. Book: ((World Health Organization)) . World Health Organization model list of essential medicines: 22nd list (2021) . 2021 . 10665/345533 . World Health Organization . World Health Organization . Geneva . WHO/MHP/HPS/EML/2021.02 . free .
  5. Harris MK, Shneyder N, Borazanci A, Korniychuk E, Kelley RE, Minagar A . Movement disorders . The Medical Clinics of North America . 93 . 2 . 371–88, viii . March 2009 . 19272514 . 10.1016/j.mcna.2008.09.002 . Common Neurologic Disorders .
  6. Inada T . [Drug-Induced Akathisia] . Brain and Nerve = Shinkei Kenkyu No Shinpo . 69 . 12 . 1417–1424 . December 2017 . 29282345 . 10.11477/mf.1416200927 .
  7. Duma SR, Fung VS . Drug-induced movement disorders . Australian Prescriber . 42 . 2 . 56–61 . April 2019 . 31048939 . 6478951 . 10.18773/austprescr.2019.014 .
  8. Ben-Pazi H . Trihexyphenidyl improves motor function in children with dystonic cerebral palsy: a retrospective analysis . Journal of Child Neurology . 26 . 7 . 810–816 . July 2011 . 21498790 . 10.1177/0883073810392582 .
  9. Sanger TD, Bastian A, Brunstrom J, Damiano D, Delgado M, Dure L, Gaebler-Spira D, Hoon A, Mink JW, Sherman-Levine S, Welty LJ . Prospective open-label clinical trial of trihexyphenidyl in children with secondary dystonia due to cerebral palsy . Journal of Child Neurology . 22 . 5 . 530–7 . May 2007 . 17690057 . 10.1177/0883073807302601 . 73087776 .
  10. Book: Tarnopolsky M, Alshahoumi R . "Complex I Deficiency . Saneto R, Parikh S, Cohen BH . Mitochondrial Case Studies: Underlying Mechanisms and Diagnosis. . Academic Press . November 2015 . 257–64 . 978-0-12-801149-2 .
  11. Reid SM, Westbury C, Guzys AT, Reddihough DS . Anticholinergic medications for reducing drooling in children with developmental disability . Developmental Medicine and Child Neurology . 62 . 3 . 346–353 . March 2020 . 31495925 . 10.1111/dmcn.14350 . 11343/286392 . free .
  12. Aracava Y, Albuquerque EX, Pereira EF . (R,S)-trihexyphenidyl, acting via a muscarinic receptor-independent mechanism, inhibits hippocampal glutamatergic and GABAergic synaptic transmissions: Potential relevance for treatment of organophosphorus intoxication . Neuropharmacology . 239 . 109684 . November 2023 . 37549771 . 10590273 . 10.1016/j.neuropharm.2023.109684 . November 15, 2024 .
  13. Web site: Therapeutic Goods Administration . July 2022 . TGA eBS - Product and Consumer Medicine Information Licence . 2024-02-12 . Australian Government .
  14. Doshay LJ, Constable K, Zier A . Five year follow-up of treatment with trihexyphenidyl (artane); outcome in four hundred eleven cases of paralysis agitans . Journal of the American Medical Association . 154 . 16 . 1334–6 . April 1954 . 13151847 . 10.1001/jama.1954.02940500014005 .
  15. Web site: nd . Trihexyphenidyl . Web MD . First Databank Inc.
  16. Web site: Trihexyphenidyl. Toxnet .
  17. Web site: trihexyphenidyl (Rx). Medscape.
  18. Chiappini S, Mosca A, Miuli A, Semeraro FM, Mancusi G, Santovito MC, Di Carlo F, Pettorruso M, Guirguis A, Corkery JM, Martinotti G, Schifano F, Di Giannantonio M . Misuse of Anticholinergic Medications: A Systematic Review . Biomedicines . 10 . 2 . 355 . February 2022 . 35203563 . 8962297 . 10.3390/biomedicines10020355 . free .
  19. Liao WB, Bullard MJ, Kuo CT, Hsiao CT, Chu PH, Chiang CW . Anticholinergic overdose induced torsade de pointes successfully treated with verapamil . Japanese Heart Journal . 37 . 6 . 925–931 . November 1996 . 9057687 . 10.1536/ihj.37.925 .
  20. Hsu YC, Yeh YW . Multidrug overdose-induced myoclonus complicated by rhabdomyolysis: possible role and mechanism of muscle toxicity of risperidone . Journal of Clinical Pharmacy and Therapeutics . 39 . 6 . 698–700 . December 2014 . 25203795 . 10.1111/jcpt.12205 . free .
  21. Giachetti A, Giraldo E, Ladinsky H, Montagna E . Binding and functional profiles of the selective M1 muscarinic receptor antagonists trihexyphenidyl and dicyclomine . British Journal of Pharmacology . 89 . 1 . 83–90 . September 1986 . 2432979 . 1917044 . 10.1111/j.1476-5381.1986.tb11123.x .
  22. Berke JD, Hyman SE . Addiction, dopamine, and the molecular mechanisms of memory . Neuron . 25 . 3 . 515–32 . March 2000 . 10774721 . 10.1016/S0896-6273(00)81056-9 . 14766533 . free .
  23. Web site: Trihexyphenidyl Hydrochloride. Drugs.com.
  24. Watson Laboratories Inc. trihexyphenidyl hydrochloride tablets, USP. prescribing information. Corona, CA; 2005 May.
  25. Book: AHFS drug information . McEvoy GK . Trihexyphenidyl . Bethesda, MD . American Society of Health-System Pharmacists . 2006 . 1256 .
  26. Doshay LJ, Constable K . Artane therapy for parkinsonism; a preliminary study of results in 117 cases . Journal of the American Medical Association . 140 . 17 . 1317–22 . August 1949 . 18137284 . 10.1001/jama.1949.02900520003002 .
  27. Web site: Katz R, Feeney J, Ressler T, David P . Approval Package for Application No. 6-773/36 . Access Data from the Food and Drug Association . FDA . 8 May 2017 .
  28. Book: Sacks O . Hallucinations . 2012 . Random House Inc. . Chapter 6 .
  29. Web site: Kábítószerek a szocializmusban . Drug use in socialist Hungary . Sándor B, József R, Zsófia TE . Múlt-kor. 19 November 2011 .
  30. Web site: Al-Husaini M, Goode E . Abuse of Prescription Drugs Rises Among Stressed Iraqi Soldiers . . 2008-12-20 .
  31. Sacks O . Altered States . The New Yorker . 20 August 2012 . Condé Nast . 7 May 2017 .
  32. Weiss MJ, O'Donoghue MD . Synthesis of Certain 3-Hydroxy-3-phenylpropylsulfonium Salts. Sulfonium Analogs of Artane (Trihexyphenidyl) and Pathilon (Tridihexethyl Iodide). . Journal of the American Chemical Society . September 1957 . 79 . 17 . 4771–6 . 10.1021/ja01574a048 .
  33. Book: Rote Liste Service GmbH (Hrsg.) . Rote Liste 2017 – Arzneimittelverzeichnis für Deutschland (einschließlich EU-Zulassungen und bestimmter Medizinprodukte) . Rote Liste Service GmbH . Frankfurt/Main . 2017 . 57 . 978-3-946057-10-9 . 224 .

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