Tryal

Uses

Tryal 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.

Tryal 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 Tryal works

Tryal 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

Tryal dosage

Dosage should be individualized. The initial dose should be low and then increased gradually, especially in patients over 60 years of age. Whether Tryal may best be given before or after meals should be determined by the way the patient reacts.

Idiopathic Parkinsonism: 1 mg of Tryalmay 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 Tryal 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. Tryal 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. Tryal 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.

Tryal 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.

Tryal Hypertension interaction

[Minor] Cardiovascular effects of anticholinergics may exacerbate hypertension.

Therapy with anticholinergic agents should be administered cautiously in patients with hypertension.

Tryal 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

Tryal Disease Interaction

Major: arrhythmias, autonomic neuropathy, GI obstruction, glaucoma, obstructive uropathy, tardive dyskinesia, infectious diarrheaModerate: psychosesMinor: hypertension, fever

Elimination Route

Tryal is absorbed from the gastrointestinal tract. Tryal reaches a C_max of 7.2 ng/mL, with a T_max 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

Tryal is contraindicated in patients with hypersensitivity in patients to trihexyphenidyl HCl or to any of the tablet or elixir ingredients. Tryal 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

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