Benztropine

benztropine (benz-troe-peen)
Apo-Benztropine, Cogentin

Classification
Therapeutic: antiparkinson agents
Pharmacologic: anticholinergics
Pregnancy Category C

Indications
Adjunctive treatment of all forms of Parkinson’s disease, including drug-induced extrapyramidal effects and acute dystonic reactions.

Action
Blocks cholinergic activity in the CNS, which is partially responsible for the symptoms of Parkinson’s disease.
Restores the natural balance of neurotransmitters in the CNS.
Therapeutic Effects: Reduction of rigidity and tremors.

Pharmacokinetics
Absorption: Well absorbed following PO and IM administration.
Distribution: Unknown.
Metabolism and Excretion: Unknown.
Half-life: Unknown.
TIME/ACTION PROFILE (antidyskinetic activity)

ROUTE    ONSET         PEAK        DURATION
PO       1–2 hr        several     days 24 hr
IM,IV    within min    unknown     24 hr

Contraindications/Precautions
Contraindicated in: Hypersensitivity; Children
<3 yr; Angle-closure glaucoma; Tardive dyskinesia.
Use Cautiously in: Prostatic hyperplasia; Seizure disorders; Cardiac arrhythmias;
OB, Lactation: Safety not established; Geri:increase risk of adverse reactions.
Adverse Reactions/Side Effects
CNS: confusion, depression, dizziness, hallucinations, headache, sedation, weakness. EENT: blurred vision, dry eyes, mydriasis.
CV: arrhythmias, hypotension, palpitations, tachycardia.
GI: constipation, dry mouth, ileus, nausea. GU: hesitancy, urinary retention.
Misc: decreased sweating.

Interactions
Drug-Drug: Additive anticholinergic effects with drugs sharing anticholinergic properties,
such as antihistamines, phenothiazines, quinidine, disopyramide, and tricyclic antidepressants.
Counteracts the cholinergic effects of bethanechol.
Antacids and antidiarrheals may decrease absorption.
Drug-Natural Products:increase anticholinergic effect with angel’s trumpet, jimson weed, and scopolia.

Route/Dosage
Parkinsonism PO (Adults): 1–2 mg/day in 1–2 divided doses (range 0.5–6 mg/day).
Acute Dystonic Reactions IM, IV (Adults): 1–2 mg, then 1–2 mg PO twice daily.
Drug-Induced Extrapyramidal Reactions PO, IM, IV (Adults): 1–4 mg given once or twice daily (1–2 mg 2–3 times daily may also be used PO).

Availability (generic available)
Tablets: 0.5 mg, 1 mg, 2 mg. Injection: 1 mg/ mL.

NURSING IMPLICATIONS
Assessment
● Assess parkinsonian and extrapyramidal symptoms (restlessness or desire to keep moving, rigidity, tremors, pill rolling, masklike face, shuffling gait, muscle spasms, twisting motions, difficulty speaking or swallowing, loss of balance control) before and throughout therapy.
● Assess bowel function daily. Monitor for constipation, abdominal pain, distention, or absence of bowel sounds.
● Monitor intake and output ratios and assess patient for urinary retention (dysuria, distended abdomen, infrequent voiding of small amounts, overflow incontinence).
● Patients with mental illness are at risk of developing exaggerated symptoms of their disorder during early therapy with benztropine. Withhold drug and notify physician or other health care professional if significant behavioral changes occur.
● IM/IV: Monitor pulse and blood pressure closely and maintain bedrest for 1 hr after administration. Advise patients to change positions slowly to minimize orthostatic hypotension.
Potential Nursing Diagnoses Impaired physical mobility (Indications) Risk for injury (Indications)

Implementation
● PO: Administer with food or immediately after meals to minimize gastric irritation. May be crushed and administered with food if patient has difficulty swallowing.
● IM: Parenteral route is used only for dystonic reactions.

IV Administration
● Direct IV: IV route is rarely used because onset is same as with IM route. Rate: Administer at a rate of 1 mg over 1 min.
● Syringe Compatibility: metoclopramide, perphenazine.
● Y-Site Compatibility: fluconazole, tacrolimus. Patient/Family Teaching
● Encourage patient to take benztropine as directed. Take missed doses as soon as possible, up to 2 hr before the next dose. Taper gradually when discontinuing or a withdrawal reaction may occur (anxiety, tachycardia, insomnia, return of parkinsonian or extrapyramidal symptoms).
● May cause drowsiness or dizziness. Advise patient to avoid driving or other activities that require alertness until response to the drug is known.
● Instruct patient that frequent rinsing of mouth, good oral hygiene, and sugarless gum or candy may decrease dry mouth. Patient should notify health care professional if dryness persists (saliva substitutes may be used). Also, notify the dentist if dryness interferes with use of dentures.
● Caution patient to change positions slowly to minimize orthostatic hypotension.
● Instruct patient to notify health care professional if difficulty with urination, constipation, abdominal discomfort, rapid or pounding heartbeat, confusion, eye pain, or rash occurs.
● Advise patient to confer with health care professional before taking OTC medications, especially cold remedies, or drinking alcoholic beverages.
● Caution patient that this medication decreases perspiration. Overheating may occur during hot weather. Patient should notify health care professional if unable to remain indoors in an air-conditioned environment during hot weather.
● Advise patient to avoid taking antacids or antidiarrheals within 1–2 hr of this medication.
● Emphasize the importance of routine follow-up exams.

Evaluation/Desired Outcomes
● Decrease in tremors and rigidity and an improvement in gait and balance. Therapeutic effects are usually seen 2–3 days after the initiation of therapy.

Posted in: ANTICHOLINERGICS