Trihexyphenidyl Hydrochloride

Indications

INDICATIONS AND USAGE Trihexyphenidyl 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.

Dosage and administration (summary)

DOSAGE AND ADMINISTRATION 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. 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 trihexyphenidyl tends to dry the mouth excessively, it may be better to take it before meals, unless it causes nausea.

Contraindications

CONTRAINDICATIONS Trihexyphenidyl is contraindicated in patients with hypersensitivity to trihexyphenidyl or to any of the other ingredients. Trihexyphenidyl is also contraindicated in patients with narrow angle glaucoma. Blindness after long-term use due to narrow angle glaucoma has been reported.

Warnings and precautions

WARNINGS Patients to be treated with trihexyphenidyl should have a gonioscope evaluation prior to initiation of therapy and close monitoring of intraocular pressures. The use of anticholinergic drugs may precipitate angle closure with an increase in intraocular pressure. If blurring of vision occurs during therapy, the possibility of narrow angle glaucoma should be considered. Blindness has been reported due to aggravation of narrow angle glaucoma. (See CONTRAINDICATIONS and ADVERSE REACTIONS ).

Pregnancy

Pregnancy Teratogenic Effects Pregnancy Category C Animal reproduction studies to evaluate teratogenic and embryotoxic potential have not been conducted with trihexyphenidyl. It is also not known whether trihexyphenidyl can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity.

Storage and supply

HOW SUPPLIED Trihexyphenidyl Hydrochloride Oral Solution, containing trihexyphenidyl hydrochloride 2 mg per 5 mL, is a clear, colorless lime-peppermint flavored liquid supplied in 473 mL (16 fl. oz) bottles, NDC 61748-054-16. Dispense in a tight, light-resistant container with a child-resistant closure. Store at 20° to 25°C (68° to 77°F) .

Source: Trihexyphenidyl Hydrochloride (Trihexyphenidyl Hydrochloride) — US FDA prescribing information, 2022-06-21, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.