Clinical data | |
---|---|
Trade names | Artane, Parkin, Pacitane, Hexymer |
AHFS/Drugs.com | Monograph |
MedlinePlus | a682160 |
License data | |
Pregnancy category |
|
Routes of administration | Oral, as tablet or elixir |
ATC code | |
Legal status | |
Legal status | |
Pharmacokinetic data | |
Elimination half-life | 3.3-4.1 hours |
Identifiers | |
| |
CAS Number | |
PubChem CID | |
IUPHAR/BPS | |
DrugBank | |
ChemSpider | |
UNII | |
KEGG | |
ChEMBL | |
CompTox Dashboard (EPA) | |
ECHA InfoCard | 100.005.105 |
Chemical and physical data | |
Formula | C20H31NO |
Molar mass | 301.474 g·mol−1 |
3D model (JSmol) | |
| |
| |
(verify) |
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]
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.[ medical citation needed ]
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'. It has also been prescribed for essential tremor and akathisia. [6] [7]
Contraindications include according to the Therapeutic Goods Administration Australia from 2022: [8]
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. [9] People who are older or who have psychiatric conditions may become confused or develop delirium. Side effects include but are not limited to: [10]
Trihexyphenidyl is a pregnancy category C drug. It is advised to only use with caution if benefits outweigh risks. [12]
This section needs more reliable medical references for verification or relies too heavily on primary sources .(May 2017) |
Trihexyphenidyl (THP) 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. Trihexyphenidyl mimics an atropine intoxication with mydriasis, dryness of mucous membranes, red face, atonic states of bowels and bladder, and hyperthermia in high doses. Central consequences are agitation, confusion, and hallucinations. An untreated overdose may be fatal, particularly in children. Premortal signs are respiratory depression 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. The vital functions should be monitored and stabilized. It may be necessary to treat hyperthermia with cooling blankets. Clinical case reports have repeatedly shown overdose of trihexyphenidyl alongside other substances.
This section needs more reliable medical references for verification or relies too heavily on primary sources .(May 2017) |
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 [13] and possibly the dopamine receptor.[ which? ] [14] 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. [15] 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. [16] [17]
Trihexyphenidyl has been clinically relevant in trials pertaining to Parkinson's disease since 1949. [18]
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. [19]
The neurologist Oliver Sacks reported using the drug recreationally in the 1960s. [20] 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 [21] — have been compared in his book Hallucinations .
During the 1970s, trihexyphenidyl (trade name Parkan) was the most popular recreationally used prescription drug in Hungary. [22]
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. [23] 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. [24]
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. [25]
Trihexyphenidyl has a chiral center and two enantiomers. Medications are racemates. [26]
Enantiomers | |
---|---|
CAS number: 40520-25-0 | CAS number: 40520-24-9 |
Equivocal preliminary results from small studies exist for:
Trifluoperazine, marketed under the brand name Stelazine among others, is a typical antipsychotic primarily used to treat schizophrenia. It may also be used short term in those with generalized anxiety disorder but is less preferred to benzodiazepines. It is of the phenothiazine chemical class. It was approved for medical use in the United States in 1959.
Chlorpromazine (CPZ), marketed under the brand names Thorazine and Largactil among others, is an antipsychotic medication. It is primarily used to treat psychotic disorders such as schizophrenia. Other uses include the treatment of bipolar disorder, severe behavioral problems in children including those with attention deficit hyperactivity disorder, nausea and vomiting, anxiety before surgery, and hiccups that do not improve following other measures. It can be given orally, by intramuscular injection, or intravenously.
Haloperidol, sold under the brand name Haldol among others, is a typical antipsychotic medication. Haloperidol is used in the treatment of schizophrenia, tics in Tourette syndrome, mania in bipolar disorder, delirium, agitation, acute psychosis, and hallucinations from alcohol withdrawal. It may be used by mouth or injection into a muscle or a vein. Haloperidol typically works within 30 to 60 minutes. A long-acting formulation may be used as an injection every four weeks by people with schizophrenia or related illnesses, who either forget or refuse to take the medication by mouth.
Typical antipsychotics are a class of antipsychotic drugs first developed in the 1950s and used to treat psychosis. Typical antipsychotics may also be used for the treatment of acute mania, agitation, and other conditions. The first typical antipsychotics to come into medical use were the phenothiazines, namely chlorpromazine which was discovered serendipitously. Another prominent grouping of antipsychotics are the butyrophenones, an example of which is haloperidol. The newer, second-generation antipsychotics, also known as atypical antipsychotics, have largely supplanted the use of typical antipsychotics as first-line agents due to the higher risk of movement disorders in the latter.
Quetiapine, sold under the brand name Seroquel among others, is an atypical antipsychotic medication used for the treatment of schizophrenia, bipolar disorder, and major depressive disorder. Despite being widely used as a sleep aid due to its sedating effect, the benefits of such use may not outweigh its undesirable side effects. It is taken orally.
Ziprasidone, sold under the brand name Geodon among others, is an atypical antipsychotic used to treat schizophrenia and bipolar disorder. It may be used by mouth and by injection into a muscle (IM). The IM form may be used for acute agitation in people with schizophrenia.
Aripiprazole, sold under the brand names Abilify and Aristada, among others, is an atypical antipsychotic. It is primarily used in the treatment of schizophrenia and bipolar disorder; other uses include as an add-on treatment in major depressive disorder and obsessive compulsive disorder (OCD), tic disorders, and irritability associated with autism. Aripiprazole is taken by mouth or via injection into a muscle. A Cochrane review found low-quality evidence of effectiveness in treating schizophrenia.
Amoxapine, sold under the brand name Asendin among others, is a tricyclic antidepressant (TCA). It is the N-demethylated metabolite of loxapine. Amoxapine first received marketing approval in the United States in 1980, approximately 10 to 20 years after most of the other TCAs were introduced in the United States.
Cabergoline, sold under the brand name Dostinex among others, is a dopaminergic medication used in the treatment of high prolactin levels, prolactinomas, Parkinson's disease, and for other indications. It is taken by mouth.
Amisulpride is an antiemetic and antipsychotic medication used at lower doses intravenously to prevent and treat postoperative nausea and vomiting; and at higher doses by mouth to treat schizophrenia and acute psychotic episodes. It is sold under the brand names Barhemsys and Solian, Socian, Deniban and others. At very low doses it is also used to treat dysthymia.
Flupentixol (INN), also known as flupenthixol, marketed under brand names such as Depixol and Fluanxol is a typical antipsychotic drug of the thioxanthene class. It was introduced in 1965 by Lundbeck. In addition to single drug preparations, it is also available as flupentixol/melitracen—a combination product containing both melitracen and flupentixol . Flupentixol is not approved for use in the United States. It is, however, approved for use in the UK, Australia, Canada, Russian Federation, South Africa, New Zealand, Philippines, Iran, Germany, and various other countries.
Biperiden, sold under the brand name Akineton among others, is a medication used to treat Parkinson disease, certain drug-induced movement disorders and Touret Syndrome. It is not recommended for tardive dyskinesias. It is taken by mouth, injection into a vein, or muscle.
Extrapyramidal symptoms (EPS) are symptoms that are archetypically associated with the extrapyramidal system of the brain's cerebral cortex. When such symptoms are caused by medications or other drugs, they are also known as extrapyramidal side effects (EPSE). The symptoms can be acute (short-term) or chronic (long-term). They include movement dysfunction such as dystonia, akathisia, parkinsonism characteristic symptoms such as rigidity, bradykinesia, tremor, and tardive dyskinesia. Extrapyramidal symptoms are a reason why subjects drop out of clinical trials of antipsychotics; of the 213 (14.6%) subjects that dropped out of one of the largest clinical trials of antipsychotics, 58 (27.2%) of those discontinuations were due to EPS.
Rasagiline is an irreversible inhibitor of monoamine oxidase-B used as a monotherapy to treat symptoms in early Parkinson's disease or as an adjunct therapy in more advanced cases.
Zuclopenthixol, also known as zuclopentixol, is a medication used to treat schizophrenia and other psychoses. It is classed, pharmacologically, as a typical antipsychotic. Chemically it is a thioxanthene. It is the cis-isomer of clopenthixol. Clopenthixol was introduced in 1961, while zuclopenthixol was introduced in 1978.
Safinamide is a drug used as an add-on treatment for Parkinson's disease with "off" episodes; it has multiple modes of action, including the inhibition of monoamine oxidase B.
Pimavanserin, sold under the brand name Nuplazid, is an atypical antipsychotic which is approved for the treatment of Parkinson's disease psychosis and is also being studied for the treatment of Alzheimer's disease psychosis, schizophrenia, agitation, and major depressive disorder. Unlike other antipsychotics, pimavanserin is not a dopamine receptor antagonist.
Perampanel, sold under the brand name Fycompa, is an anti-epileptic medication developed by Eisai Co. that is used in addition to other drugs to treat partial seizures and generalized tonic-clonic seizures for people older than twelve years. It was first approved in 2012, and as of 2016, its optimal role in the treatment of epilepsy relative to other drugs was not clear. It was the first antiepileptic drug in the class of selective non-competitive antagonist of AMPA receptors.
Cariprazine, sold under the brand names Vraylar,Reagila and Symvenu among others, is an atypical antipsychotic originated by Gedeon Richter, which is used in the treatment of schizophrenia, bipolar mania, bipolar depression, and major depressive disorder. It acts primarily as a D3 and D2 receptor partial agonist, with a preference for the D3 receptor. Cariprazine is also a partial agonist at the serotonin 5-HT1A receptor and acts as an antagonist at 5-HT2B and 5-HT2A receptors, with high selectivity for the D3 receptor. It is taken by mouth.
Brexpiprazole, sold under the brand name Rexulti among others, is a medication used for the treatment of major depressive disorder, schizophrenia, and agitation associated with dementia due to Alzheimer's disease. It is an atypical antipsychotic.
This article incorporates public domain material from Toxnet:Trihexyphenidyl. United States Department of Health and Human Services . Retrieved 8 May 2017.