benztropine

Benztropine is a medication used as an adjunct therapy for the treatment of all forms of Parkinson’s disease, a neurological disorder caused by degeneration of brain cells that affects movement and balance.

Benztropine is also used to control drug-induced extrapyramidal symptoms, movement disorders that result from antipsychotic therapy.

Benztropine is an anticholinergic agent that works by reducing the activity of acetylcholine, a substance (neurotransmitter) that nerve terminals release to make muscles contract. Benztropine binds to protein molecules known as muscarinic receptors in neuromuscular junctions, and prevents acetylcholine from stimulating them and making the muscle contract. This helps reduce muscle stiffness and provides symptomatic relief in both Parkinson’s and drug-induced extrapyramidal symptoms.

Benztropine cannot be used for tardive dyskinesia, a type of movement disorder that occurs from prolonged antipsychotic therapy. In addition, benztropine also binds to histamine receptors and inhibits the activity of histamine, the substance that mediates inflammation, however, this property is not of therapeutic value in Parkinson’s or extrapyramidal symptoms.

• Do not use benztropine:
  • In patients with hypersensitivity to any of its components
  • To treat pediatric patients younger than 3 years of age
  • In pregnant patients, because safety is not established
• Do not use for the treatment of tardive dyskinesia, benztropine does not alleviate symptoms and in some instances, may aggravate them.
• Use with caution in pediatric patients above 3 years.
• Benztropine may cause anticholinergic effects such as constipation, dry mouth, blurred vision, urinary retention and painful urination (dysuria).
• Benztropine prevents sweating, which can elevate body temperature and lead to hyperthermia, especially during exercise or hot weather. Consider lowering the dose to prevent impairment of heat regulation by sweating in a hot environment.
• High doses may cause confusion, hallucinations and worsening of symptoms or toxic psychosis in psychiatric patients being treated with neuroleptic drugs. Exercise caution.
• Benztropine may cause weakness and inability to move particular muscle groups, especially with large doses. Adjust dosage if required.
• Use with caution and monitor effects in patients with the following conditions:
  • Rapid heart rate (tachycardia)
  • Gastrointestinal obstruction
  • Enlarged prostate (prostatic hyperplasia) and urinary stricture
• Benztropine may cause glaucoma, an eye disorder that damages the optic nerve, monitor the patient. Use with caution in simple glaucoma and avoid use in angle-closure glaucoma.
• Initiate at lower doses for elderly patients above 65 years of age and increase only if needed, while monitoring adverse effects.
• Benztropine may suppress central nervous system and impair mental and physical abilities to perform hazardous tasks. Advise patients appropriately.

Common side effects of benztropine include:

• Rapid heart rate (tachycardia)
• Confusion
• Disorientation
• Depression
• Memory impairment
• Nervousness
• Visual hallucinations
• Worsening of psychotic symptoms
• Toxic psychosis
• Lethargy
• Numbness of fingers
• Absence of sweating (anhidrosis)
• High body temperature (hyperthermia)
• Heatstroke
• Blurred vision
• Dilation of pupils (mydriasis)
• Nausea
• Vomiting
• Dry mouth (xerostomia)
• Constipation
• Paralysis of intestinal muscles (paralytic ileus)
• Urinary retention
• Painful urination (dysuria)
• Skin rash

Call your doctor immediately if you experience any of the following symptoms or serious side effects while using this drug:

• Serious heart symptoms include fast or pounding heartbeats, fluttering in your chest, shortness of breath, and sudden dizziness;
• Severe headache, confusion, slurred speech, severe weakness, vomiting, loss of coordination, feeling unsteady;
• Severe nervous system reaction with very stiff muscles, high fever, sweating, confusion, fast or uneven heartbeats, tremors, and feeling like you might pass out; or
• Serious eye symptoms include blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights.

This is not a complete list of all side effects or adverse reactions that may occur from the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may also report side effects or health problems to the FDA at 1-800-FDA-1088.

Tablet

• 0.5 mg
• 1 mg
• 2 mg

Injectable Solution

• 1 mg/mL

Adults:

Parkinsonism

Postencephalitic parkinsonism

• 1-2 mg/day (range, 0.5-6 mg/day) orally, intravenously (IV) or intramuscularly (IM) at bedtime or divided every 6-12 hours; may consider lower dose or 0.5 mg at bedtime in highly sensitive patients; titrate dose in 0.5-mg increments every 5-6 days (range 0.5-6 mg daily); not to exceed 6 mg/day

Idiopathic parkinsonism

• 0.5-1 mg at bedtime initially; titrate dose in 0.5-mg increments every 5-6 days (range 0.5-6 mg daily; some patients may need 4-6 mg/day); not to exceed 6 mg/day

Drug-Induced Extrapyramidal Disorders

• 1-2 mg IV/IM/oral every 8-12 hours; titrate gradually at 0.5 mg increments at 5-6 day intervals based on response and tolerability; not to exceed 6 mg/day; reevaluate after 1-2 weeks; may reinitiate therapy if symptoms recur
• Acute dystonia: 1-2 mg IV, then 1-2 mg oral once or twice daily for 7-28 days to prevent recurrence

Geriatric:

Parkinsonism

• 0.5 mg orally once daily or every 12 hours; titrate dose in 0.5-mg increments every 5-6 days; not to exceed 4 mg/day

Dosing Considerations

• Nonanticholinergic antiparkinson agents should be considered first for treatment of Parkinson disease (Beers criteria)
• Not well tolerated in elderly, because of bowel, bladder, and CNS effects; avoid use if possible
• Should not be used as prophylaxis against extrapyramidal symptoms in elderly

Pediatric:

Drug-Induced Extrapyramidal Disorders

• Children below 3 years: Not recommended
• Children above 3 years: 0.02-0.05 mg/kg IV/IM/oral once daily or every 12 hours  
• Adolescents (off-label): 1-4 mg IV/IM/oral every day or every 12 hours

• Benztropine overdose causes central nervous system (CNS) depression preceded or followed by stimulation.
• Overdose symptoms include confusion, nervousness, worsening of symptoms or toxic psychosis in psychiatric patients being treated with neuroleptic drugs, hallucinations, muscle weakness, dry mouth, dilated pupils, blurred vision, nausea, vomiting, high temperature, allergic reactions, high heart rate and blood pressure, palpitations, delirium, coma, shock, convulsions, circulatory collapse and respiratory arrest.
• Treatment is symptomatic and supportive, including:
  • Physostigmine salicylate to reverse benztropine effects
  • A short-acting barbiturate for CNS stimulation, but with caution to avoid subsequent depression
  • Supportive measures for CNS depression
  • Respiratory support in case of respiratory depression
  • Intravenous fluids and medications for circulatory collapse

Inform your doctor of all medications you are currently taking, who can advise you on any possible drug interactions. Never begin taking, suddenly discontinue, or change the dosage of any medication without your doctor’s recommendation.

• Benztropine has no known severe interactions with other drugs.
• Serious interactions of benztropine include:
  • glucagon
  • glucagon intranasal
  • glycopyrronium tosylate topical
  • revefenacin
  • secretin
  • umeclidinium bromide/vilanterol inhaled
• Benztropine has moderate interactions with at least 70 different drugs.
• Mild Interactions of benztropine include:
  • desipramine
  • levodopa
  • trazodone

The drug interactions listed above are not all of the possible interactions or adverse effects. For more information on drug interactions, visit the RxList Drug Interaction Checker.

It is important to always tell your doctor, pharmacist, or health care provider of all prescription and over-the-counter medications you use, as well as the dosage for each, and keep a list of the information. Check with your doctor or health care provider if you have any questions about the medication.

• Safety of use in pregnancy is not established, avoid use.
• Two newborns developed intestinal muscle paralysis (paralytic ileus) that resolved rapidly, after exposure to a combination of benztropine and chlorpromazine during the second and third trimesters and the last 6 weeks of pregnancy, respectively.
• Anticholinergic medications may suppress lactation and it is not known if it is excreted in breast milk, avoid use.

• Take benztropine exactly as prescribed by your physician.
• Benztropine prevents sweating and may dangerously elevate body temperatures. Exercise caution in hot environments and during exercise.
• Benztropine may impair mental and physical ability, avoid engaging in hazardous tasks such as driving and operating heavy machinery.
• Store safely out of reach of children.
• In case of overdose, seek medical help immediately or contact Poison Control.