Brand name: Cogentin
Drug class: Anticholinergic Agents
VA class: AU350
CAS number: 132-17-2

Medically reviewed by Drugs.com on Feb 7, 2025. Written by ASHP.

Introduction

Antimuscarinic antiparkinsonian agent.^{157 200 201}

Uses for Benztropine

Parkinsonian Syndrome

Symptomatic management of all forms of parkinsonian syndrome, including idiopathic parkinson disease and parkinsonism resulting from encephalitis (postencephalitic parkinsonism).^{200 201 c}

Has been used as monotherapy or adjunctive therapy in the treatment of parkinson disease.^{123 157 158}

Levodopa is currently the most effective drug for relieving motor symptoms of parkinson disease; however, long-term use associated with motor complications.^{101 115 123 157} To avoid these complications, may initiate treatment with other antiparkinsonian agents first and postpone use of levodopa.^{115 123 157} Some clinicians state that anticholinergic agents (e.g., trihexyphenidyl, benztropine) may be particularly useful for initial therapy in patients <60 years of age with resting tremors as their only or most prominent symptom.^{115 123}

Although main use of anticholinergic agents in parkinson disease is to control tremors, evidence of a benefit largely anecdotal.^{123 157 158}

Drug-induced Extrapyramidal Reactions

Control of extrapyramidal symptoms (EPS) induced by antipsychotic agents (e.g., phenothiazines).^{200 201}

Anticholinergic agents (e.g., benztropine, trihexyphenidyl) are used traditionally to restore acetylcholine and dopamine imbalance in patients with antipsychotic-induced EPS; however, evidence supporting a benefit is lacking or inconsistent and the drugs are associated with a variety of adverse effects.^{160 161 162}

In general, use cautiously and for minimum duration necessary to control EPS.^{160 162}

Benztropine does not alleviate symptoms of tardive dyskinesia, and in some instances may aggravate them.^{200 201 c} Use not recommended.^{200 201 c}

Benztropine Dosage and Administration

Administration

Administer orally or by IM injection.^{200 201}

Also may be given IV.²⁰⁰ Because onset of effect is similar with IV and IM route, manufacturer states there usually is no need to administer IV and does not provide specific instructions for IV administration.²⁰⁰

Oral Administration

Administer as a single dose at bedtime or in divided doses 2–4 times daily.²⁰¹

IM Administration

Reserve for patients who cannot take oral medication or for emergency situations (e.g., acute dystonia).^{200 201 c}

Dosage

Available as benztropine mesylate; dosage is expressed in terms of the salt.^{200 201}

Adjust dosage carefully according to individual requirements and response.^{200 201} Initiate with low dosage and increase gradually to minimum effective dosage.^{200 201}

Dosing guidelines are the same for oral and IM administration; oral administration preferred whenever possible.²⁰⁰

Pediatric Patients

Manufacturers make no specific dosage recommendations for children ≥3 years of age.^{200 201} (See Pediatric Use under Cautions.)

Adults

Parkinsonian Syndrome

May require periodic dosage adjustments to maintain optimum symptomatic relief in patients receiving concomitant levodopa-carbidopa therapy.^{200 201}

If used to replace or supplement other antiparkinsonian drugs, change should be gradual, with dosage of previous medication reduced as benztropine dosage is increased.^{200 201}

Avoid abrupt discontinuance of concomitantly administered antiparkinsonian drugs.^{200 201}

Idiopathic Parkinsonian Syndrome

Oral

Initially, 0.5–1 mg as a single daily dose at bedtime.²⁰¹ Dosage may be increased by 0.5-mg increments at 5- or 6-day intervals based on response and tolerability up to a maximum of 6 mg daily.²⁰¹

Usual dosage: 1–2 mg daily (range: 0.5–6 mg daily).²⁰¹

IM

Initially, 0.5–1 mg as a single dose at bedtime.²⁰⁰ Dosage may be increased by 0.5-mg increments at 5- or 6-day intervals based on response and tolerability up to a maximum of 6 mg daily.²⁰⁰

Usual dosage: 1–2 mg daily (range: 0.5–6 mg daily).²⁰⁰

For emergency situations, 1–2 mg normally will provide quick relief; repeat dose if parkinsonian symptoms return.²⁰⁰

Postencephalitic Parkinsonian Syndrome

Oral

Initially, 2 mg daily, given in 1 or more divided doses.²⁰¹ In highly sensitive patients, may give a single 0.5 mg-dose at bedtime.²⁰¹ Dosage may be increased by 0.5-mg increments at 5- to 6-day intervals up to a maximum of 6 mg daily.²⁰¹

Usual dosage: 1–2 mg daily (range: 0.5–6 mg daily).²⁰¹

IM

Initially, 2 mg daily, given in 1 or more divided doses.²⁰⁰ In highly sensitive patients, may give a single 0.5 mg-dose at bedtime. Dosage may be increased by 0.5-mg increments at 5- or 6-day intervals up to a maximum of 6 mg daily.²⁰⁰

Usual dosage: 1–2 mg daily (range: 0.5–6 mg daily).²⁰⁰

For emergency situations, 1–2 mg normally will provide quick relief; repeat dose if parkinsonian symptoms return.²⁰⁰

Drug-Induced Extrapyramidal Reactions

Oral

1–4 mg once or twice daily.^{160 201}

For EPS that develops shortly after initiation of antipsychotic therapy, 1–2 mg 2 or 3 times daily usually provides relief within 1 or 2 days.²⁰¹ Evaluate need for continued therapy after 1–2 weeks.²⁰¹

IM

1–4 mg once or twice daily.^{160 200}

For EPS that develops shortly after initiation of antipsychotic therapy, 1–2 mg 2 or 3 times daily usually provides relief within 1 or 2 days.²⁰⁰ Evaluate need for continued therapy after 1–2 weeks.²⁰⁰

Acute Dystonia

IM followed by Oral

1–2 mg, as a single IM dose, followed by 1–2 mg orally twice daily to prevent recurrence.^{200 201}

Prescribing Limits

Adults

Parkinsonian Syndrome

Oral

Maximum 6 mg daily.²⁰¹

IM

Maximum 6 mg daily.²⁰⁰

Special Populations

Hepatic Impairment

No specific dosage recommendations at this time.^{200 201}

Renal Impairment

No specific dosage recommendations at this time.^{200 201}

Geriatric Patients

Geriatric patients generally cannot tolerate high dosages of the drug; select dosage with caution, starting at low end of dosing range and increasing only as needed.^{200 201} (See Geriatric Use under Cautions.)

Low Body Weight

Patients with less than average body weight generally cannot tolerate high dosages of the drug.^{200 201}

Cautions for Benztropine

Contraindications

• Known hypersensitivity to benztropine or any ingredient in the formulation.^{200 201}

• Children <3 years of age.^{200 201}

Warnings/Precautions

Warnings

Pregnancy

Safe use during pregnancy has not been established.^{200 201}

Cognitive/Physical Impairment

Risk of impaired mental alertness or physical coordination required for performing hazardous tasks (e.g., driving or operating machinery).^{200 201}

Drug Interactions

Concomitant use with phenothiazines or tricyclic antidepressants associated with potentially fatal paralytic ileus, hyperthermia, or heat stoke.^{200 201} Advise patients to promptly notify clinicians if adverse GI effects, fever, or heat intolerance occur if used concomitantly with these drugs or other drugs with anticholinergic or antidopaminergic (e.g., haloperidol) effects.^{200 201} (See Interactions.)

Anhidrosis

Possibly severe anhidrosis and fatal hyperthermia.^{200 201} Use with caution in hot weather, particularly when given concomitantly with other anticholinergic drugs to chronically ill or alcoholic patients, those who have CNS disease, and those engaged in manual labor.^{200 201} Decrease dosages as needed to maintain ability to perspire.^{200 201}

General Precautions

Adequate Patient Monitoring

Has cumulative effects; continue to monitor patients, particularly those with tendency toward tachycardia or with prostatic hypertrophy.^{200 201}

Musculoskeletal Effects

Possible complaints of weakness and inability to move particular muscle groups, particularly at large dosages; adjust dosage as required.^{200 201}

CNS Effects

Possible mental confusion and excitement, particularly with large dosages or in susceptible patients.^{200 201} Visual hallucinations also possible.^{200 201} (See Dosage under Dosage and Administration.)

Risk of intensification of mental symptoms or precipitation of toxic psychosis in patients with mental disorders receiving phenothiazines, especially at beginning of therapy or during dosage adjustment; monitor closely.^{200 201} (See Specific Drugs under Interactions.)

Tardive Dyskinesia

Not recommended for use in patients with tardive dyskinesia.^{200 201} (See Drug-induced Extrapyramidal Reactions under Uses.)

Renal Effects

Possible dysuria or urinary retention.^{200 201}

Glaucoma

Consider risks of glaucoma.^{200 201} Probably should not be used in patients with angle-closure glaucoma.^{200 201 e}

Specific Populations

Pregnancy

Safe use during pregnancy not established.^{200 201}

Geriatric Use

Possibility exists of greater sensitivity to the drug in some geriatric individuals.^{200 201} Careful dosage selection necessary.^{200 201} Some experts state to avoid use in geriatric patients because of unfavorable balance of benefits and risks compared with alternative treatments.^{157 159}

Pediatric Use

Safety and efficacy not established in children <3 years of age.^{200 201} (See Cautions: Contraindications.)

Use with caution in children >3 years of age because of adverse anticholinergic effects.^{200 201}

Common Adverse Effects

Dry mouth, blurred vision, mydriasis, nausea, nervousness, tachycardia, paralytic ileus, constipation.^{c e}

Drug Interactions

Specific Drugs

Stability

Storage

Oral

Tablets

20–25°C.²⁰¹

Parenteral

Injection

20–25°C.²⁰⁰

Compatibility

Drug Compatibility

For information on IV injection of benztropine, see Administration under Dosage and Administration.

Actions

• Possesses both anticholinergic and antihistaminic effects, although only the former have been established as therapeutically important in management of parkinsonism.^{200 201}

Advice to Patients

• Potential for drug to impair mental alertness or physical coordination; use caution when driving or operating machinery until effects on individual are known.^{200 201}

• Risk of hyperthermia.^{200 201}

• Importance of promptly notifying clinicians of adverse GI effects, fever, or heat intolerance, particularly if also receiving phenothiazines, haloperidol, or other drugs with anticholinergic or antidopaminergic activity.^{200 201}

• Importance of women informing their clinician if they are or plan to become pregnant or plan to breast-feed.^{200 201}

• Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs, as well as concomitant illnesses.^{200 201}

• Importance of informing patients of other important precautionary information.^{200 201} (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

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