Yes: Tablet

Anticholinergic Agent; Anti-Parkinson's Agent (Anticholinergic)

Adjunctive treatment of Parkinson's disease; treatment of drug-induced extrapyramidal effects

C

Hypersensitivity to trihexyphenidyl or any component; patients with narrow-angle glaucoma; pyloric or duodenal obstruction, stenosing peptic ulcers; bladder neck obstructions; achalasia; myasthenia gravis

Use with caution in hot weather or during exercise. Elderly patients require strict dosage regulation. Use with caution in patients with tachycardia, cardiac arrhythmias, hypertension, hypotension, prostatic hypertrophy or any tendency toward urinary retention, liver or kidney disorders, and obstructive disease of the GI or GU tract. May exacerbate mental symptoms when used to treat extrapyramidal reactions. When given in large doses or to susceptible patients, may cause weakness. Does not improve symptoms of tardive dyskinesias.

Cardiovascular: Tachycardia

Central nervous system: Confusion, agitation, euphoria, drowsiness, headache, dizziness, nervousness, delusions, hallucinations, paranoia

Dermatologic: Dry skin, increased sensitivity to light, rash

Gastrointestinal: Constipation, xerostomia, dry throat, ileus, nausea, vomiting, parotitis

Genitourinary: Urinary retention

Neuromuscular & skeletal: Weakness

Ocular: Blurred vision, mydriasis, increase in intraocular pressure, glaucoma

Respiratory: Dry nose

Miscellaneous: Diaphoresis (decreased)

Symptoms of overdose include blurred vision, urinary retention, tachycardia

Anticholinergic toxicity is caused by strong binding of the drug to cholinergic receptors. Anticholinesterase inhibitors reduce acetylcholinesterase; for anticholinergic overdose with severe life-threatening symptoms, physostigmine 1-2 mg (0.5 mg or 0.02 mg/kg for children) S.C. or I.V., slowly may be given to reverse these effects

Decreased effect: May increase gastric degradation of levodopa and decrease the amount of levodopa absorbed by delaying gastric emptying; the opposite may be true for digoxin

Therapeutic effects of cholinergic agents (tacrine, donepezil) and neuroleptics may be antagonized

Increased toxicity: Central and/or peripheral anticholinergic syndrome can occur when administered with amantadine, rimantadine, narcotic analgesics, phenothiazines and other antipsychotics (especially with high anticholinergic activity), tricyclic antidepressants, quinidine and some other antiarrhythmics, and antihistamines

Exerts a direct inhibitory effect on the parasympathetic nervous system. It also has a relaxing effect on smooth musculature; exerted both directly on the muscle itself and indirectly through parasympathetic nervous system (inhibitory effect)

Peak effect: Within 1 hour

Half-life: 3.3-4.1 hours

Time to peak serum concentration: Within 1-1.5 hours

Elimination: Primarily in urine

Adults: Oral: Initial: 1-2 mg/day, increase by 2 mg increments at intervals of 3-5 days; usual dose: 5-15 mg/day in 3-4 divided doses

Alcohol: Additive CNS effect, avoid use

IOP monitoring and gonioscopic evaluations should be performed periodically

No information available to require special precautions

>10% of patients experience significant dry mouth; normal salivary flow will resume with cessation of drug therapy. Prolonged xerostomia may contribute to development of caries, periodontal disease, oral candidiasis and discomfort

Take exactly as directed; with meals if GI upset occurs, before meals if dry mouth occurs, after eating if drooling or if nausea occurs. Take at the same time each day. Maintain adequate hydration (2-3 L/day of fluids unless instructed to restrict fluid intake); void before taking medication. Do not use alcohol and all prescription or OTC sedatives or CNS depressants without consulting prescriber. You may experience drowsiness, confusion, or vision changes (use caution when driving, climbing stairs, or engaging in tasks requiring alertness until response to drug is known); increased susceptibility to heat stroke, decreased perspiration (use caution in hot weather - maintain adequate fluids and reduce exercise activity); constipation (increased exercise, fluids, or dietary fruit and fiber may help); dry skin or nasal passages (consult prescriber for appropriate relief). Report unresolved constipation, chest pain or palpitations, difficulty breathing, CNS changes (hallucination, loss of memory, nervousness, etc), painful or difficult urination, increased muscle spasticity or rigidity, skin rash, or significant worsening of condition. Pregnancy/breast-feeding precautions: Inform prescriber if you are or intend to be pregnant. Consult prescriber if breast-feeding.

Tolerated best if given in 3 daily doses and with food; high doses may be divided into 4 doses, at meal times and at bedtime; patients may be switched to sustained-action capsules when stabilized on conventional dosage forms

Capsule, as hydrochloride, sustained release: 5 mg

Elixir, as hydrochloride: 2 mg/5 mL (480 mL)

Tablet, as hydrochloride: 2 mg, 5 mg

Feinberg M, "The Problems of Anticholinergic Adverse Effects in Older Patients," Drugs Aging, 1993, 3(4):335-48.