Trihexyphenidyl

Trihexyphenidyl is a prescription medication used to treat Parkinson's Disease and Drug-induced Extrapyramidal Symptoms.

• Trihexyphenidyl is available under the following different brand names: Artane, Trihex

Adult dosage

Tablets

• 2mg
• 5mg

Elixir

• 0.4mg/mL

Parkinson Disease

Adult dosage

• Initial: 1 mg orally first day, then increase by 2 mg every 3-5 days until dose reaches 6-10 mg/day
• Maintenance: 5-15 mg/day orally divided every 6-8 hours
• Use SR product once stabilized on regular release product; when used with levodopa, generally use 3-6 mg/day in divided doses

Drug-induced Extrapyramidal Symptoms

Adult dosage

• 1 mg/day orally initially; increase as necessary to maintenance range of 5-15 mg/day orally divided every 6-8 hours

Dosage Considerations – Should be Given as Follows: 

• See “Dosages”.

Common side effects of Trihexyphenidyl include:

• blurred vision, 
• dry mouth, 
• constipation, 
• decreased urination, 
• dizziness, 
• drowsiness, 
• weakness, 
• nausea, 
• vomiting, 
• headache, 
• restlessness, and 
• nervousness

Serious side effects of Trihexyphenidyl include:

• hives, 
• difficult breathing, 
• swelling in the face or throat, 
• blurred vision, 
• tunnel vision, 
• eye pain, 
• seeing halos around lights, 
• hot and dry skin, 
• no sweating even after feeling hot, 
• rapid or jerky repetitive involuntary movement, 
• severe constipation, 
• painful or difficult urination, 
• unusual thoughts or behavior, 
• confusion, 
• memory problems, 
• very stiff (rigid) muscles, 
• high fever, 
• sweating, 
• confusion, 
• fast or uneven heartbeats, 
• tremors, and
• lightheadedness

Rare side effects of Trihexyphenidyl include:

• none 

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first

• Trihexyphenidyl has severe interactions with no other drugs.
• Trihexyphenidyl has serious interactions with the following drugs:
  • glucagon
  • glucagon intranasal
  • glycopyrronium tosylate topical 
  • revefenacin
  • secretin
  • umeclidinium bromide/vilanterol inhaled
• Trihexyphenidyl has moderate interactions with at least 69 other drugs.
• Trihexyphenidyl has minor interactions with the following drug:
  • levodopa 

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this drug, tell your doctor or pharmacist of all the drugs you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist. Check with your physician if you have health questions or concerns.

Contraindications

• Hypersensitivity 
• Angle-closure glaucoma

Effects of drug abuse

• None

Short-Term Effects

• See “What Are Side Effects Associated with Using Trihexyphenidyl?”

Long-Term Effects

• See “What Are Side Effects Associated with Using Trihexyphenidyl?”

Cautions

• Exacerbation of parkinsonism, neuroleptic malignant syndrome, and withdrawal symptoms associated with therapy discontinuation or dose reduction; the drug should be withdrawn gradually
• Perform gonioscope evaluation before initiating treatment; monitor intraocular pressure closely at regular periodic intervals
• Therapy may impair memory and exacerbate cognitive deficits in the elderly; may also cause delirium, hallucinations, and confusion when administered at high doses
• Use extreme caution and monitor closely patients with liver, cardiac, kidney disorders, prostatic hyperplasia (urinary stricture), or hypertension
• The drug has atropine-like properties; use with caution in patients with glaucoma, obstructive disease of the gastrointestinal or genitourinary tracts, and in elderly males with prostatic hypertrophy
• Geriatric patients (over 60 years of age) develop increased sensitivity to parasympathetic drugs; may precipitate incipient glaucoma in these patients
• Not for use in patients with tardive dyskinesia unless it exists concomitantly with Parkinson disease; therapy may potentially exacerbate symptoms of tardive dyskinesia
• May cause hyperthermia that can be fatal and anhidrosis; use with caution during exercise or hot weather, especially if administered concomitantly with anticholinergic agents to patients with CNS disease, alcoholics, or persons in a hot environment doing manual labor

Pregnancy and Lactation

• Use with caution if the benefits outweigh the risks during pregnancy. 
• Lactation: no data; may inhibit lactation.