Trihexyphenidyl
Trihexyphenidyl Uses, Dosage, Side Effects, Food Interaction and all others data.
Trihexyphenidyl is a selective M1 muscarinic acetylcholine receptor antagonist. It is able to discriminate between the M1 (cortical or neuronal) and the peripheral muscarinic subtypes (cardiac and glandular). Trihexyphenidyl partially blocks cholinergic activity in the CNS, which is responsible for the symptoms of Parkinson's disease. It is also thought to increase the availability of dopamine, a brain chemical that is critical in the initiation and smooth control of voluntary muscle movement.
Trihexyphenidyl is an antimuscarinic indicated as an adjunct in the treatment of parkinsonism or as a treatment for drug-induced extrapyramidal symptoms. It has a long duration of action as it does not need to be given every day. It has a wide therapeutic window, with acute toxicity being non fatal in doses as high as 300 mg. Patients should have their iridocorneal angle examined before and intraocular pressure monitored during therapy. Patients should be counselled regarding the risk of anhidrosis and hyperthermia.
| Trade Name | Trihexyphenidyl |
| Availability | Prescription only |
| Generic | Trihexyphenidyl |
| Trihexyphenidyl Other Names | Trihexifenidilo, Trihexyphenidyl, Trihexyphénidyle, Trihexyphenidylum |
| Related Drugs | Gocovri, Rytary, Sinemet, Sinemet CR, baclofen, diphenhydramine, Benadryl, ropinirole, pramipexole, benztropine |
| Weight | 2mg/5ml, 2mg, 5mg |
| Type | Oral Solution, Oral Elixir, Oral Tablet, Tablet |
| Formula | C20H31NO |
| Weight | Average: 301.4662 Monoisotopic: 301.240564619 |
| Protein binding | Data regarding the extent of trihexyphenidyl protein binding in plasma are not readily available. Trihexyphenidyl is 36.13-41.92% bound to albumin under controlled conditions in a dialysis bag. |
| Groups | Approved |
| Therapeutic Class | Antiparkinson drugs |
| Manufacturer | Genus Pharmaceuticals, Harsen, Indofarma, Holi Farma, Mersifarma Trimaku Mercusana, Pyridam Farma |
| Available Country | United Kingdom, Canada, United States, Indonesia |
| Last Updated: | September 19, 2023 at 7:00 am |
Uses
Trihexyphenidyl Hydrochloride is used for an adjunct treatment of all forms of parkinsonism (postencephalitic, arteriosclerotic & idiopathic). Additionally, it is used for the control of extrapyramidal disorders caused by central nervous system drugs such as dibenzoxazepines, phenothiazines, thioxanthenes & butyrophenones.
Trihexyphenidyl is also used to associated treatment for these conditions: Extrapyramidal disorder, Extrapyramidal symptoms caused by butyrophenones, Extrapyramidal symptoms caused by dibenzoxazepines, Extrapyramidal symptoms caused by phenothiazines, Extrapyramidal symptoms caused by thioxanthenes, Idiopathic Parkinson's Disease, Parkinsonism post encephalitic, Arteriosclerotic Parkinsonism
How Trihexyphenidyl works
Trihexyphenidyl is a non-selective muscarinic acetylcholine receptor antagonist but binds with higher affinity to the M1 subtype. In vivo studies have shown that trihexyphenidyl demonstrates higher affinity for central muscarinic receptors located in the cerebral cortex and lower affinity for those located peripherally. Other studies suggest that trihexyphenidyl may modify nicotinic acetylcholine receptor neurotransmission, leading indirectly to enhanced dopamine release in the striatum. Although the anticholinergic has proven to be useful in the treatment of symptoms associated with Parkinson’s disease or other movement disorders, its mechanism of action has yet to be fully elucidated.
Dosage
Trihexyphenidyl dosage
Dosage should be individualized. The initial dose should be low and then increased gradually, especially in patients over 60 years of age. Whether Trihexyphenidyl may best be given before or after meals should be determined by the way the patient reacts.
Idiopathic Parkinsonism: 1 mg of Trihexyphenidylmay be administered the first day. The dose may then be increased by 2 mg increments at intervals of three to five days.
Drug-Induced Parkinsonism: Commence therapy with a single 1 mg dose increase the total daily dosage to 5-15 mg range if the extrapyramidal manifestations are not controlled.
Concomitant Use with Levodopa: When Trihexyphenidyl is used concomitantly with levodopa, the usual dose is 3-6 mg daily.
Side Effects
Minor side effects such as dryness of the mouth, blurring of vision, dizziness, mild nausea or nervousness. Patients with arteriosclerosis or with a history of idiosyncrasy to other drugs may exhibit reactions of mental confusion, agitation, disturbed behavior, or nausea and vomiting. Potential side effects are constipation, drowsiness, urinary hesitancy or retention, pupil dilation, increased intraocular tension, vomiting and headache.
Toxicity
Symptoms of overdose include mydriasis, dryness of mucous membranes, red face, atonic states of bowels and bladder, and hyperthermia in high doses. Trihexyphenidyl causes agitation, confusion, and hallucinations due to its effects on the central nervous system. Untreated overdose may result in death, especially in children. Respiratory depression and cardiac arrest may be seen as premortal signs.
Patients experiencing an overdose of trihexyphenidyl may experience dry mouth, anhidrosis, mydriasis, nausea, vomiting, tachycardia, hyperpyrexia, reduced gastrointestinal motility, urinary hesitancy or retention, rash, hyperthermia, confusion, restlessness, agitation, poor coordination, paranoia, psychosis, delirium, hallucinations, coma, respiratory failure, circulatory failure, and death. Patients should be treated with symptomatic and supportive care which may include airway maintenance and the use of physostigmine.
Precaution
Patients with cardiac, liver, or kidney disorders, or with hypertensioon, should closely be monitored. Since trihexyphenidyl has parasympatholytic activity, it should be used with caution in patients with glaucoma, obstructive disease of the gastrointestinal or genitourinary tracts, and in elderly males with possible prostatic hypertrophy. Trihexyphenidyl is not recommended for use in patients with tardive dyskinesia unless they have concomitant Parkinson’s disease. Abrupt withdrawal of treatment for parkinsonism may result in acute exacerbation of parkinsonism symptoms; therefore, abrupt withdrawal should be avoided.
Interaction
Cannabinoids, barbiturates, opiates, and alcohol may have additive effects with trihexyphenidyl, and thus, an abuse potential exists. Concurrent use of alcohol or other CNS depressants with trihexyphenidyl may cause increased sedative effects. It may be contraindicated in patients taking monoamine oxidase inhibitors & tricycllic antidepressants.
Food Interaction
- Take with or without food. Taking with food may minimize stomach upset. May take before meals to mitigate dry mouth or may take after meals to reduce excess salivation.
Trihexyphenidyl Alcohol interaction
[Moderate] GENERALLY AVOID:
Use of anticholinergic agents with alcohol may result in sufficient impairment of attention so as to render driving and operating machinery more hazardous.
In addition, the potential for abuse may be increased with the combination.
The mechanism of interaction is not established but may involve additive depressant effects on the central nervous system.
No effect of oral propantheline or atropine on blood alcohol levels was observed in healthy volunteers when administered before ingestion of a standard ethanol load.
However, one study found impairment of attention in subjects given atropine 0.5 mg or glycopyrrolate 1 mg in combination with alcohol.
Alcohol should generally be avoided during therapy with anticholinergic agents.
Patients should be counseled to avoid activities requiring mental alertness until they know how these agents affect them.
Trihexyphenidyl Hypertension interaction
[Minor] Cardiovascular effects of anticholinergics may exacerbate hypertension.
Therapy with anticholinergic agents should be administered cautiously in patients with hypertension.
Trihexyphenidyl Drug Interaction
Moderate: aripiprazole, rasagiline, diphenhydramine, duloxetine, ziprasidone, clonazepam, lurasidone, escitalopram, pregabalin, quetiapine, alprazolamMinor: acetaminophen, acetaminophenUnknown: aspirin, omega-3 polyunsaturated fatty acids, polyethylene glycol 3350, esomeprazole, cyanocobalamin, ascorbic acid, cholecalciferol
Trihexyphenidyl Disease Interaction
Major: arrhythmias, autonomic neuropathy, GI obstruction, glaucoma, obstructive uropathy, tardive dyskinesia, infectious diarrheaModerate: psychosesMinor: hypertension, fever
Elimination Route
Trihexyphenidyl is absorbed from the gastrointestinal tract. Trihexyphenidyl reaches a Cmax of 7.2 ng/mL, with a Tmax of 1.3 hours, and an AUC of 201 ng*h/mL.
Half Life
The mean elimination half life of trihexyphenidyl is 3.2 ± 0.3 hours.
Elimination Route
Data regarding the route of elimination of trihexyphenidyl are not readily available. However, it is likely eliminated predominantly in the urine.
Pregnancy & Breastfeeding use
Pregnancy Category C. It is not known whether the drug is excreted in human milk and therefore trihexyphenidyl should only be used if the expected benefit to the mother outweighs the potential risk to the infant.
Contraindication
Trihexyphenidyl is contraindicated in patients with hypersensitivity in patients to trihexyphenidyl HCl or to any of the tablet or elixir ingredients. Trihexyphenidyl is also contraindicated in patients with narrow angle glaucoma. Blindness after long-term use due to narrow angle glaucoma has been reported.
Acute Overdose
Overdosage with trihexyphenidyl produces typical central symptoms of atropine intoxication ( the central anticholinergic syndrome). Signs & symptoms are: dilated and sluggish pupils, warm, dry skin, facial flushing, decreased secretions of mouth, pharynx, nose and bronchi, foul smelling breath, tachycardia etc. Neuropsychiatric signs such as delirium, disorientation, anxiety, hallucinations etc. The condition can progress to stupor, coma, paralysis, cardiac, respiratory arrest and death.
Innovators Monograph
You find simplified version here Trihexyphenidyl
Trihexyphenidyl contains Trihexyphenidyl see full prescribing information from innovator Trihexyphenidyl Monograph, Trihexyphenidyl MSDS, Trihexyphenidyl FDA label
FAQ
What is Trihexyphenidyl used for?
Trihexyphenidyl is used along with other medications to treat the symptoms of Parkinson's disease (PD; a disorder of the nervous system that causes difficulties with movement, muscle control, and balance) and to control extrapyramidal symptoms (tremor, slurred speech) caused by certain medications.
How safe is Trihexyphenidyl?
talk to your doctor about the risks and benefits of taking Trihexyphenidyl if you are 65 years of age or older. Older adults should not usually take Trihexyphenidyl because it is not as safe or effective as other medications that can be used to treat the same condition.
What are the common side effects of Trihexyphenidyl?
Trihexyphenidyl may cause side effects.
- dizziness or blurred vision.
- dry mouth.
- upset stomach.
- vomiting.
- constipation.
- headache.
- difficulty urinating.
What does Trihexyphenidyl do to the brain?
Trihexyphenidyl helps control Parkinson's type symptoms by blocking the receptors that acetylcholine acts on and thus reducing acetylcholine activity. This helps restore the balance of acetylcholine and dopamine in the brain.
Does Trihexyphenidyl cause memory loss?
It has been shown to cause more confusion and memory loss in older people.
Is Trihexyphenidyl safe during pregnancy?
Trihexyphenidyl should not be used during pregnancy unless clearly necessary.
Is Trihexyphenidyl safe during breastfeeding?
Long-term use of Trihexyphenidyl might reduce milk production or milk letdown, but a single dose is not likely to interfere with breastfeeding.During long-term use, observe for signs of decreased lactation.
Can I take alcohol with Trihexyphenidyl?
It is recommended that people taking Trihexyphenidyl should not drink alcohol. This is because both antimuscarinics and alcohol can cause confusion and drowsiness.
When should Trihexyphenidyl be given?
Take this medication by mouth, usually 3 to 4 times a day with meals and at bedtime, or as directed by your doctor. Your doctor may start you at a low dose and increase your dose slowly to find the best dose for you.
How long does Trihexyphenidyl stay in my system?
The mean elimination half life of Trihexyphenidyl is 3.2 ± 0.3 hours.
Is Trihexyphenidyl taken with food?
You may take this medicine before or after food, although it is usually taken with meals.
How much Trihexyphenidyl should I take?
The dose is usually not more than 15 mg per day, given in divided doses 3 or 4 times per day.
Who should not take Trihexyphenidyl?
Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.
What happens if I miss a dose?
Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.
What happen if I overdose on Trihexyphenidyl?
Seek emergency medical attention or call the Poison Help line.
Overdose symptoms may include severe drowsiness, fever, dilated pupils, feeling hot, paleness in your face, dry skin and mouth, hallucinations, paranoia, agitation, seizure, or numbness in or around your mouth, nose, or throat.
What happens when I stop taking Trihexyphenidyl?
If you are also taking other medications. Sudden stoppage can cause symptoms of Parkinson's disease to return.
Is Trihexyphenidyl a narcotic?
Trihexyphenidyl is not classified as a controlled substance, the possibility of abuse should be borne in mind due to its stimulant and euphoriant properties.
