Pronunciation: BENZ-troe-peen MEH-sih-LATE
- Tablets 0.5 mg
- Tablets 1 mg
- Tablets 2 mg
- Injection 1 mg/mL
Thought to act by competitively antagonizing acetylcholine receptors in corpus striatum to restore neuromuscular balance.
Indications and Usage
Treatment of all forms of parkinsonism; control of extrapyramidal disorders (except tardive dyskinesia) caused by neuroleptic drugs.
Angle-closure glaucoma; myasthenia gravis; pyloric or duodenal obstruction; stenosing peptic ulcer; prostatic hypertrophy or bladder neck obstructions; megacolon; tardive dyskinesia; children under 3 yr of age.
Dosage and AdministrationParkinsonism
PO 1 to 2 mg/day; range, 0.5 to 6 mg. Individualize dosage.Idiopathic Parkinsonism
PO Initially 0.5 to 1 mg at bedtime; 4 to 6 mg/day may be required.Postencephalitic Parkinsonism
PO 2 mg/day in 1 or more doses; some patients may require initial dose of 0.5 mg.Drug-Induced Extrapyramidal Disorders
1 to 4 mg every day or twice daily.Acute Dystonic Reactions
PO / IM / IV Initial dose is IM / IV 1 to 2 mg; then PO 1 to 2 mg twice daily.
Store in a dry place in tightly closed, light-resistant container.
May increase anticholinergic effects.Digoxin
May increase digoxin serum levels, especially with slow-dissolution oral digoxin tablets.Haloperidol
May worsen schizophrenic symptoms; may decrease haloperidol serum levels; tardive dyskinesia may develop.Phenothiazines
May decrease action of phenothiazines. May increase incidence of anticholinergic effects.
Laboratory Test Interactions
None well documented.
Toxic psychosis including confusion, disorientation, memory impairment, visual hallucinations; exacerbation of pre-existing psychosis; nervousness; depression; finger numbness.
Blurred vision; dilated pupils; narrow-angle glaucoma.
Paralytic ileus; constipation; nausea; vomiting; dry mouth.
Urinary retention; dysuria.
Heat stroke; hyperthermia; fever; weakness; inability to move particular muscle groups.
Category C .
Safety and efficacy not established
Patients above 60 yr of age may have increased side effects; dosage reduction and observation may be needed.
Special Risk Patients
Use with caution in patients with glaucoma, prostatic hypertrophy, epilepsy, cardiac arrhythmias, hypertension, hypotension, tendency toward urinary retention, liver or kidney disorders, obstructive disease of GI or GU tract, tachycardia or those who are taking other drugs with anticholinergic activity.
Fatal hyperthermia has occurred. Use with caution during hot weather.
Narrow-angle glaucoma may occur.
May aggravate tardive dyskinesia.
Circulatory collapse, cardiac arrest, respiratory depression, CNS depression or stimulation, shock, coma, stupor, seizures, convulsions, ataxia, anxiety, incoherence, hyperactivity, foul-smelling breath, decreased bowel sounds, dilated and sluggish pupils.
- Explain that full effectiveness of drug may not occur for 2 to 3 days after initiation of drug therapy. Explain that doses will be tapered gradually before stopping.
- Advise patient that increasing fluid intake will help decrease dry mouth and constipation.
- Instruct patient to take sips of water frequently, suck on ice chips or sugarless hard candy, or chew sugarless gum if dry mouth occurs.
- Warn patient to pay particular attention to dental hygiene because of problems associated with decreased salivation.
- Tell patient that stool softeners may be used if constipation occurs.
- Warn patient to drink plenty of fluids and take precautions against hyperthermia in hot weather.
- Tell patient that vision may be blurry during the first 2 to 3 wk of treatment.
- Advise patient that wearing sunglasses outdoors will help to minimize photophobia.
- Instruct patient that drug may cause drowsiness and to use caution while driving or performing other tasks requiring mental alertness.
- Advise patient to avoid intake of alcoholic beverages or other CNS depressants.
- Instruct patient to obtain periodic eye examinations during long-term treatment to monitor for glaucoma.
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