Trihexyphenidyl

Brand Name: Artane

Description

Trihexyphenidyl is an anticholinergic agent used to treat Parkinson's disease. By improving muscle control and reducing stiffness, this medicine allows more normal movements of the body as the disease symptoms are reduced. It is also used to control severe reactions to certain medicines such as reserpine (e.g., Serpasil) (medicine to control high blood pressure) or phenothiazines, chlorprothixene (e.g., Taractan), thiothixene (e.g., Navane), loxapine (e.g., Loxitane), and haloperidol (e.g., Haldol) (medicines for nervous, mental, and emotional conditions). It may also be used to treat other conditions as determined by your doctor.

Pharmacology

Trihexyphenidyl is an anticholinergic antiparkinsonian agent. It produces an atropine-like blocking action of parasympathetic-innervated peripheral structures, including smooth muscle. It also exhibits a direct spasmolytic action and weak mydriatic, anti-sialogogue and cardiovagal blocking effects. In small doses, trihexyphenidyl depresses the CNS but larger doses cause cerebral excitement resembling the signs of atropine toxicity.

After oral administration, the onset of action occurs within 1 hour, peak effects last 2 to 3 hours and the duration of action is 6 to 12 hours.

Indications and Usage

The treatment of all forms of Parkinsonism as well as in the prevention or control of extrapyramidal disorders due to CNS drugs such as reserpine and the phenothiazines.

Contraindications

Patients hypersensitive to trihexyphenidyl should not be given the drug.

Warnings

Trihexyphenidyl 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 may cause anhidrosis.

Usage in Pregnancy

Safe use of trihexyphenidyl during pregnancy and lactation has not been established; therefore, when the drug is administered to pregnant patients, nursing mothers, or women of childbearing potential, the potential benefits must be weighed against the possible hazards.

Usage in Children: This drug is not recommended for use in children, since safety and effectiveness in the pediatric age group have not been established.

Precautions

Use extra care to reduce overheating during hot weather or exercise.

Closely observe patients with cardiac, liver, kidney or hypertensive disorders. Patients undergoing prolonged therapy should be subjected to careful periodic review to avoid unhealthy reactions.

Drug Interactions

BEFORE USING THIS MEDICINE: INFORM YOUR DOCTOR OR PHARMACIST of all prescription and over-the-counter medicine that you are taking. This includes medicine to treat mood disorders. Inform your doctor of any other medical conditions, allergies, pregnancy, or breast-feeding.

Adverse Reactions

Check with your doctor immediately if you experience a fast or pounding heartbeat, confusion, difficult or painful urination (especially in older men), eye pain, or rash. If you notice other effects not listed above, contact your doctor, nurse, or pharmacist.

Other less serious side effects, that may go away during treatment, include dry mouth, nausea, constipation, dizziness, lightheadedness, nervousness, drowsiness, increased sensitivity of eyes to light, or blurred vision, false sense of well-being (especially in the elderly or with high doses); headache; loss of memory (especially in the elderly); muscle cramps; nervousness; numbness or weakness in hands or feet; soreness of mouth and tongue; stomach upset or pain; unusual excitement (more common with large doses of trihexyphenidyl), false sense of well-being (especially in the elderly or with high doses); headache; loss of memory (especially in the elderly); muscle cramps; nervousness; numbness or weakness in hands or feet; soreness of mouth and tongue; stomach upset or pain; unusual excitement (more common with large doses of trihexyphenidyl) If they continue or are bothersome, check with your doctor.

Overdose

Symptoms: Clumsiness or unsteadiness; drowsiness (severe); dryness of mouth, nose, or throat (severe); fast heartbeat; hallucinations (seeing, hearing, or feeling things that are not there); mood or mental changes; seizures; shortness of breath or troubled breathing; trouble in sleeping; warmth, dryness, and flushing of skin.

Treatment

If you or someone you know may have used more than the recommended dose of this medicine, contact your local poison control center or emergency room immediately.

Treatment should be symptomatic and supportive. Give ipecac syrup and activated charcoal or perform gastric lavage if no contraindications exist.

Dosage

Do not exceed the recommended dosage or take this medicine for longer than prescribed. Do not stop taking this medicine without checking with your doctor.

Follow the directions for using this medicine provided by your doctor.
Take this medicine with meals or after finishing meals.
Store this medicine at room temperature, away from heat and light.
If you miss a dose of this medicine, take it as soon as possible. If it is within 2 hours of your next dose, skip the missed dose and go back to your regular dosing schedule. Do not take 2 doses at once.

Additional Information: Do not share this medicine with others for whom it was not prescribed. Do not use this medicine for other health conditions. Keep this medicine out of the reach of children.

Discontinuation: After you stop using this medicine, your body may need time to adjust. The length of time this takes depends on the amount of medicine you were using and how long you used it.

During this period of time check with your doctor if you notice any of the following side effects: Anxiety; difficulty in speaking or swallowing; dizziness or lightheadedness when getting up from a lying or sitting position; fast heartbeat; loss of balance control; mask-like face; muscle spasms, especially of face, neck, and back; restlessness or desire to keep moving; shuffling walk; stiffness of arms or legs; trembling and shaking of hands and fingers; trouble in sleeping; twisting movements of body.

IF YOU WILL BE USING THIS MEDICINE FOR AN EXTENDED PERIOD OF TIME, be sure to obtain necessary refills before your supply runs out.

Trihexyphenidyl is not recommended for children.

The dosage must be individualized according to the requirements of each patient. Treatment should be initiated at the lowest recommended dose and increased gradually with careful assessment of clinical response and any evidence of intolerance.

For extended-release oral dosage forms (extended-release capsules):

Usual Adult Dose: 5 mg after breakfast. Your doctor may add another 5 mg dose to be taken twelve hours later, depending on your condition.

For other oral dosage forms (elixir or tablets):

Usual Adult Dosage: To start, 1 to 2 mg a day. Your doctor may adjust your dose as needed; however, the dose is usually not more than 15 mg a day.

How Supplied

Extended-release capsules, Elixir and Tablets.

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The information in this monograph is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects. This information is generalized and is not intended as specific medical advice. If you have questions about the medicines you are taking or would like more information, check with your doctor, pharmacist, or nurse.