Trihexyphen Uses

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What is Trihexyphen?

Trihexyphen alters unusual nerve impulses and relaxes stiff muscles.

Trihexyphen is used to treat the stiffness, tremors, spasms, and poor muscle control of Parkinson's disease. It is also used to treat and prevent the same muscular conditions when they are caused by drugs such as chlorpromazine (Thorazine), fluphenazine (Prolixin), perphenazine (Trilafon), haloperidol (Haldol), thiothixene (Navane), and others.

Trihexyphen may also be used for purposes other than those listed in this medication guide.

Trihexyphen indications

An indication is a term used for the list of condition or symptom or illness for which the medicine is prescribed or used by the patient. For example, acetaminophen or paracetamol is used for fever by the patient, or the doctor prescribes it for a headache or body pains. Now fever, headache and body pains are the indications of paracetamol. A patient should be aware of the indications of medications used for common conditions because they can be taken over the counter in the pharmacy meaning without prescription by the Physician.

Trihexyphen (Trihexyphen) is indicated as an adjunct in the treatment of all forms of parkinsonism (postencephalitic, 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.

How should I use Trihexyphen?

Use Trihexyphen as directed by your doctor. Check the label on the medicine for exact dosing instructions.

Ask your health care provider any questions you may have about how to use Trihexyphen.

Uses of Trihexyphen in details

There are specific as well as general uses of a drug or medicine. A medicine can be used to prevent a disease, treat a disease over a period or cure a disease. It can also be used to treat the particular symptom of the disease. The drug use depends on the form the patient takes it. It may be more useful in injection form or sometimes in tablet form. The drug can be used for a single troubling symptom or a life-threatening condition. While some medications can be stopped after few days, some drugs need to be continued for prolonged period to get the benefit from it.

Trihexyphen is used to treat symptoms of Parkinson’s disease (a type of nerve disease that causes movement disorder characterized by slowness of movements, muscle stiffness, uncontrolled shaking and poor balance and co-ordination) and drug-induced extra pyramidal symptoms (movement disorders similar to symptoms of Parkinson’s disease) except tardive dyskinesia (involuntary movement of face and jaw). It is often given along with levodopa (anti-Parkinson drug).

Trihexyphen description

A histamine H1 antagonist with low sedative action but frequent gastrointestinal irritation. It is used to treat asthma; HAY fever; urticaria; and rhinitis; and also in veterinary applications. Trihexyphen is administered by various routes, including topically.

Trihexyphen dosage

Dosage should be individualized. The initial dose should be low and then increased gradually, especially in patients over 60 years of age. Whether Trihexyphen® (Trihexyphen HCl) may best be given before or after meals should be determined by the way the patient reacts. Postencephalitic patients, who are usually more prone to excessive salivation, may prefer to take it after meals and may, in addition, require small amounts of atropine which, under such circumstances, is sometimes an effective adjuvant. If Trihexyphen (Trihexyphen) tends to dry the mouth excessively, it may be better to take it before meals, unless it causes nausea. If taken after meals, the thirst sometimes induced can be allayed by mint candies, chewing gum or water.

Abrupt withdrawal of treatment for parkinsonism may result in acute exacerbation of parkinsonism symptoms; therefore, abrupt withdrawal should be avoided.

Abrupt withdrawal of treatment may result in neuroleptic malignant syndrome (NMS)

Idiopathic Parkinsonism

As initial therapy for parkinsonism, 1 mg of Trihexyphen (Trihexyphen) in tablet or elixir form may be administered the first day. The dose may then be increased by 2 mg increments at intervals of three to five days, until a total of 6 to 10 mg is given daily. The total daily dose will depend upon what is found to be the optimal level. Many patients derive maximum benefit from this daily total of 6 to 10 mg, but some patients, chiefly those in the postencephalitic group, may require a total daily dose of 12 to 15 mg.

Drug-Induced Parkinsonism

The size and frequency of the Trihexyphen (Trihexyphen) dose needed to control extrapyramidal reactions to commonly employed tranquilizers, notably the phenothiazines, thioxanthenes, and butyrophenones, must be determined empirically. The total daily dosage usually ranges between 5 and 15 mg although, in some cases, these reactions have been satisfactorily controlled with as little as 1 mg daily. It may be advisable to commence therapy with a single 1 mg dose. If the extrapyramidal manifestations are not controlled in a few hours, the subsequent doses may be progressively increased until satisfactory control is achieved. Satisfactory control may sometimes be more rapidly achieved by temporarily reducing the dosage of the tranquilizer when instituting Trihexyphen (Trihexyphen) therapy and then adjusting the dosage of both drugs until the desired ataractic effect is retained without onset of extrapyramidal reactions.

It is sometimes possible to maintain the patient on a reduced Trihexyphen (Trihexyphen) dosage after the reactions have remained under control for several days. Instances have been reported in which these reactions have remained in remission for long periods after Trihexyphen (Trihexyphen) therapy was discontinued.

Concomitant Use with Levodopa

When Trihexyphen (Trihexyphen) is used concomitantly with levodopa, the usual dose of each may need to be reduced. Careful adjustment is necessary, depending on side effects and degree of symptom control. An Trihexyphen (Trihexyphen) dosage of 3 to 6 mg daily, in divided doses, is usually adequate.

Concomitant Use with Other Parasympathetic Inhibitors

Trihexyphen (Trihexyphen) may be substituted, in whole or in part, for other parasympathetic inhibitors. The usual technique is partial substitution initially, with progressive reduction in the other medication as the dose of Trihexyphen HCl is increased.

Trihexyphen (Trihexyphen) TABLETS and ELIXIR - The total daily intake of Trihexyphen (Trihexyphen) tablets or elixir is tolerated best if divided into 3 doses and taken at mealtimes. High doses ( > 10 mg daily) may be divided into 4 parts, with 3 doses administered at mealtimes and the fourth at bedtime.

How supplied

Trihexyphen® (Trihexyphen HCl) Tablets are available as follows:

2 mg - round, flat, scored, white tablets; engraved “Trihexyphen (Trihexyphen) ” above “2” on one side and “LL” above “A11” below the score on the other side, supplied as follows:

NDC 0005-4434-23 - Bottle of 100

NDC 0005-4434-34 - Bottle of 1000

5 mg - round, flat, scored, white tablets; engraved “Trihexyphen (Trihexyphen) ” above “5” on one side and “LL” above “A12” below the score on the other side, supplied as follows:

NDC 0005-4436-23 - Bottle of 100

NDC 0005-4436-34 - Bottle of 1000

Store at controlled room temperature 20° to 25°C (68° to 77°F).

Dispense in tight containers as defined in the USP.


Trihexyphen (Trihexyphen) is available in Elixir as follows:

2 mg/5 mL - NDC 0005-4440-65 - Bottle of 16 fl oz

Store at controlled room temperature 20° to 25°C (68° to 77°F).


Dispense in tight containers as defined in the USP.

Lederle Pharmaceutical Division of American Cyanamid Company, Pearl River, NY 10965. Rev 03/03.

Trihexyphen interactions

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What other drugs will affect Trihexyphen?


Cannabinoids, barbiturates, opiates, and alcohol may have additive effects with PMS Trihexyphen, and thus, an abuse potential exists.

Concurrent use of alcohol or other CNS depressants with PMS Trihexyphen may cause increased sedative effects.

Monoamine oxidase inhibitors and tricyclic antidepressants possessing significant anticholinergic activity may intensify the anticholinergic effects of antidyskinetic agents because of the secondary anticholinergic activities of these medications

Prophylactic administration of anticholinergic agents, such as Trihexyphen, as a prevention of drug-induced parkinsonism during neuroleptic therapy is not recommended. There may be an increased risk for the development of tardive dyskinesia during concomitant administration of anticholinergics and neuroleptics.

The usual dose of either Trihexyphen or levodopa may need to be reduced during concomitant therapy, since concomitant administration may increase drug-induced involuntary movements

Nursing Mothers It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when PMS Trihexyphen is administered to a nursing woman. As with other anticholinergics, Trihexyphen may cause suppression of lactation. Therefore, Trihexyphen should only be used if the expected benefit to the mother outweighs the potential risk to the infant

Pediatric Use Safety and effectiveness in pediatric patients have not been established.

Trihexyphen side effects

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What are the possible side effects of Trihexyphen?


Minor side effects, such as dryness of the mouth, blurred vision, dizziness, mild nausea or nervousness, will be experienced by 30 to 50 percent of all patients. These sensations, however, are much less troublesome with Trihexyphen (Trihexyphen) than with belladonna alkaloids and are usually less disturbing than unallenated parkinsonism. Such reactions tend to become less pronounced, and even to disappear, as treatment continues. Even before these reactions have remitted spontaneously, they may often be controlled by careful adjustment of dosage form, amount of drug, or interval between doses.

Isolated instances of suppurative parotitis secondary to excessive dryness of the mouth, skin rashes, dilatation of the colon, paralytic ileus, and certain psychiatric manifestations such as delusions, hallucinations, and paranoia, all of which may occur with any of the atropine-like drugs, have been reported rarely with Trihexyphen® (Trihexyphen)

Potential side effects associated with the use of any atropine-like drugs, including Trihexyphen (Trihexyphen), include cognitive dysfunctions, including confusion and memory impairment; constipation, drowsiness, urinary hesitancy or retention, tachycardia, dilation of the pupil, increased intraocular pressure, choreiform movements, weakness, vomiting, and headache. Exacerbation of parkinsonism with abrupt treatment withdrawal has been reported. Neuroleptic malignant syndrome with abrupt treatment withdrawal has been reported.

The occurrence of angle-closure glaucoma in patients receiving Trihexyphen HCl has been reported (blindness has been reported in some cases). Paradoxical sinus bradycardia, dry skin, and cycloplegia have been reported.

In addition to adverse events seen in adults, the following adverse events have been reported in the literature in pediatric patients: hyperkinesia, psychosis, forgetfulness, weight loss, restlessness, chorea, and sleep alterations.

Drug Abuse And Dependence

Although Trihexyphen (Trihexyphen) is not classified as a controlled substance, the possibility of abuse should be borne in mind due to its stimulant and euphoriant properties.

Trihexyphen contraindications

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What is the most important information I should know about Trihexyphen?

Dose-dependent side effects are frequent. Particularly geriatric patients may react with confusional states or develop delirium.

* CNS : Drowsiness, vertigo, headache, and dizziness are frequent. With high doses nervousness, agitation, anxiety, delirium, and confusion are noted. Trihexyphen may be abused due to a short acting mood-elevating and euphoriant effect. The normal sleep architecture may be altered (REM sleep depression). Trihexyphen may lower the seizure-threshold.

* Peripheral side effects : Blurred vision, dry mouth, impaired sweating, abdominal discomfort, and obstipation are frequent. Tachycardia may be noted. Allergic skin reactions may occur.

Parenteral use may cause orthostatic hypotension.

* Eyes : Trihexyphen causes mydriasis with or without photophobia. It may precipitate narrow angle glaucoma.

* Tolerance may develop during therapy which requires dose adjustments.

Active ingredient matches for Trihexyphen:


Unit description / dosage (Manufacturer)Price, USD
Tablet; Oral; Trihexyphenidyl Hydrochloride 2 mg
Tablet; Oral; Trihexyphenidyl Hydrochloride 5 mg

List of Trihexyphen substitutes (brand and generic names):

Elixir; Oral; Trihexyphenidyl Hydrochloride 2 mg / 5 ml
Tablet; Oral; Trihexyphenidyl Hydrochloride 2 mg
Tablet; Oral; Trihexyphenidyl Hydrochloride 5 mg
Trihexyphenidyl HCl 5 mg tablet$ 0.37
Trihexyphenidyl 5 mg tablet$ 0.36
Trihexyphenidyl HCl 2 mg tablet$ 0.26
Trihexyphenidyl 2 mg tablet$ 0.18
Apo-Trihex 5 mg Tablet$ 0.07
Apo-Trihex 2 mg Tablet$ 0.04
Trihexyphenidyl tablet 2 mg (Aa Pharma Inc (Canada))
Trihexyphenidyl tablet 5 mg (Aa Pharma Inc (Canada))
Trihexyphenidyl Pharmedic 2 mg x 5 Blister x 20 Tablet
TRIMLIN TABLET 1 strip / 10 tablets each (Stadchem Of India)$ 0.21
Triphen 2mg TAB / 10 (Sun Pharmaceutical Industries Ltd.)$ 0.05
2 mg x 10's (Sun Pharmaceutical Industries Ltd.)$ 0.05
Triphen 2 mg Tablet (Sun Pharmaceutical Industries Ltd.)$ 0.02
TRIPHEN 2 MG TABLET 1 strip / 10 tablets each (Sun Pharmaceutical Industries Ltd.)$ 0.24
TRIPHEN tab 2 mg x 10's (Sun Pharmaceutical Industries Ltd.)$ 0.21
Triphen 2mg Tablet (Sun Pharmaceutical Industries Ltd.)$ 0.02
TRIRISS tab 2 mg x 10's (Curis)
TRIXYL 2MG TABLET 1 strip / 10 tablets each (A N Pharmacia)$ 0.25
TRYAL 2 MG TABLET 1 strip / 10 tablets each (Health Plan)$ 0.22
TRYAL 2 MG TABLET 1 strip / 10 tablets each (Mankind Pharma Ltd)$ 0.25
TRYHP 2MG TABLET 1 strip / 10 tablets each (Sigmund Promedica)$ 0.23
TRYHP 5MG TABLET 1 strip / 10 tablets each (Sigmund Promedica)$ 0.33
Tryhp 5mg Tablet (Sigmund Promedica)$ 0.03


  1. PubChem. "trihexyphenidyl". (accessed September 17, 2018).
  2. DrugBank. "trihexyphenidyl". (accessed September 17, 2018).
  3. DTP/NCI. "trihexyphenidyl: The NCI Development Therapeutics Program (DTP) provides services and resources to the academic and private-sector research communities worldwide to facilitate the discovery and development of new cancer therapeutic agents.". (accessed September 17, 2018).


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Information checked by Dr. Sachin Kumar, MD Pharmacology

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