Adult Dosing
Trihexyphenidyl in Idiopathic Parkinsonism
- First day: 1 mg PO daily
- Titrated dose: May increase by 2 mg PO q3-5 days, until 6-10 mg/day divided tid
- In postencephalitic group: 12-15 mg/day divided qid
- Max: 15 mg/day
Trihexyphenidyl HCl in Drug-Induced Parkinsonism
- Starting dose: 1 mg PO daily, if not relieved in a few hours, increase until adequate response
- Usual dose 5-15 mg PO in divided doses
- Max: 15 mg/day
Concomitant Use of Trihexyphenidyl with Levodopa
- 3-6 mg PO in divided doses
- Carefully adjust the doses depending on side effects and degree of symptom control
Concomitant Use of Trihexyphenidyl with Other Parasympathetic Inhibitors
- Initially partially substitute the other parasympathetic inhibitors, with progressive reduction in the other medication as the dose of trihexyphenidyl is increased
Notes:
- To be administered after meals in patients prone to excessive salivation, if trihexyphenidyl tends to dry the mouth excessively, administer before meal
- Administer high doses (>10 mg daily) in 4 divided doses, with 3 doses administered at mealtimes and the fourth at bedtime
Pediatric Dosing
- Safety and effectiveness in pediatric patients have not been established
[Outline]
- As trihexyphenidyl has atropine-like properties, when used indefinitely, patients should be subjected to constant and careful long-term observation to avoid allergic and other untoward reactions
- Strict dosage regulation is required in geriatric patients (>60 yrs), as they frequently develop increased sensitivity to parasympatholytic activity of trihexyphenidyl
- Perform gonioscope evaluation and closely monitor the intraocular pressures at regular periodic intervals of patients treated with trihexyphenidyl
- Trihexyphenidyl should be administered with caution and under close observation in patients with cardiac, liver, or kidney disorders, or with hypertension
- Tardive dyskinesia has been reported with long-term therapy of antipsychotic drugs or after the drugs has been discontinued. Antiparkinsonism agents do not alleviate the symptoms of tardive dyskinesia, and in some instances may aggravate them
- Neuroleptic malignant syndrome with dose reduction or discontinuation is possible
Cautions: Use cautiously in
- Renal impairment
- Hepatic impairment
- Cardiac disorder
- Hypertension
- Glaucoma
- GI obstructive disease
- Genitourinary tracts obstructive disease
- Prostatic hypertrophy
- Geriatric patients
Pregnancy Category:C
Breastfeeding: Safety unknown. As per limited data no adverse effect was seen in breastfed infants after the maternal doses of trihexyphenidyl up to 4 mg daily together with haloperidol. Single dose is not likely to interfere with breastfeeding, but long term use might reduce milk production or milk letdown. Observe the sign of decreased lactation (e.g., insatiety, poor weight gain) during long term use. This information is based upon LactMed database (available at http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?LACT last accessed 22 March 2011.
US Trade Name(s)
US Availability
trihexyphenidyl (generic)
- TABS: 2, 5 mg
- SOLN: 2 mg/5 mL
Canadian Trade Name(s)
Canadian Availability
trihexyphenidyl (generic)
- TABS: 2, 5 mg
- SOLN: 0.4 mg/mL
UK Trade Name(s)
UK Availability
Broflex
Australian Trade Name(s)
Australian Availability
[Outline]
Pricing data from www.DrugStore.com in U.S.A.
- Trihexyphenidyl HCl 0.4 MG/ML ELIX [Bottle] (PHARMACEUTICAL ASSOCIATES)
473 ml = $30.99
1419 ml = $79.97 - Trihexyphenidyl HCl 2 MG TABS [Bottle] (WATSON LABS)
90 mg = $22.99
180 mg = $39.97
Warning: This pricing information is subject to change at the sole discretion of DS Pharmacy. For the most current and up-to-date pricing information, please visit drugstore.com.