BENZTROPINE MESYLATE
| BENZTROPINE MESYLATE (benz'troe-peen) Apo-Benztropine  , Cogentin, PMS Benztropine Classifications: anticholinergic; antiparkinson agent; Therapeutic: antiparkinson agent Prototype: Levodopa Pregnancy Category: C |
Availability
0.5 mg, 1 mg, 2 mg tablets; 1 mg/mL ampules
Action
Synthetic centrally acting anticholinergic (antimuscarinic) agent. Acts by diminishing excess cholinergic effect associated with dopamine deficiency.
Therapeutic Effect
Suppresses tremor and rigidity; does not alleviate tardive dyskinesia.
Uses
Symptomatic treatment of all forms of parkinsonism (arteriosclerotic, idiopathic, postencephalitic) and to relieve extrapyramidal symptoms associated with neuroleptic drugs, e.g., haloperidol (Haldol), phenothiazines, thiothixene (Navane), acute dystonia. Commonly used as supplement with trihexyphenidyl, carbidopa, or levodopa therapy.
Contraindications
Narrow angle glaucoma; myasthenia gravis; obstructive diseases of GU and GI tracts; tendency to tachycardia; tardive dyskinesia, children <3 y; pregnancy (category C).
Cautious Use
Older children, older adults or debilitated patients, patients with poor mental outlook, mental disorders; tachycardia; autonomic neuropathy; enlarged prostate; hypertension; history of renal or hepatic disease, lactation.
Route & Dosage
| Parkinsonism Adult: PO 0.5–1 mg/d, may gradually increase as needed up to 6 mg/d IM/IV 1–2 mg/d Extrapyramidal Reactions Adult: PO 1–2 mg b.i.d. IM/IV 1–4 mg 1–2 times daily as needed Child (>3 y): PO/IM/IV 1–2 mg/d Acute Dystonia Adult: IV 1–2 mg daily |
Administration
Oral- Give immediately after meals or with food to prevent gastric irritation. Tablet can be crushed and sprinkled on or mixed with food.
- Initiate and withdraw drug therapy gradually; effects are cumulative.
- Store in tightly covered, light-resistant container at 15°–30° C (59°–86° F) unless otherwise directed.
Intravenous
PREPARE: Direct: Give undiluted. ADMINISTER: Direct: Give 1 mg or a fraction thereof over 1 min. |
Adverse Effects (≥1%)
CNS: Sedation, drowsiness, dizziness, paresthesias; agitation, irritability, restlessness, nervousness, insomnia, hallucinations, delirium, mental confusion, toxic psychosis, muscular weakness, ataxia, inability to move certain muscle groups. CV: Palpitation, tachycardia, flushing. Special Senses: Blurred vision, mydriasis, photophobia. GI: Nausea, vomiting, constipation, dry mouth, distention, paralytic ileus. Urogenital: Dysuria.Interactions
Drug: Alcohol, cns depressants have additive sedation and depressant effects; amantadine, tricyclic antidepressants, mao inhibitors, phenothiazines, procainamide, quinidine have additive anticholinergic effects and cause confusion, hallucinations, paralytic ileus.Pharmacokinetics
Onset: 15 min IM/IV; 1 h PO. Duration: 6–10 h.Nursing Implications
Assessment & Drug Effects
- Assess therapeutic effectiveness. Clinical improvement may not be evident for 2–3 d after oral drug is started.
- Monitor I&O ratio and pattern. Advise patient to report difficulty in urination or infrequent voiding. Dosage reduction may be indicated.
- Closely monitor for appearance of S&S of onset of paralytic ileus including intermittent constipation, abdominal pain, diminution of bowel sounds on auscultation, and distention.
- Monitor for and report muscle weakness or inability to move certain muscle groups. Dosage reduction may be needed.
- Supervise ambulation and use bed side rails as necessary.
- Report immediately S&S of CNS depression or stimulation. These usually require interruption of drug therapy.
Patient & Family Education
- Do not drive or engage in potentially hazardous activities until response to drug is known. Seek help walking as necessary.
- Avoid alcohol and other CNS depressants because they may cause additive drowsiness. Do not take OTC cold, cough, or hay fever remedies unless approved by physician.
- Sugarless gum, hard candy, and rinsing mouth with tepid water will help dry mouth.
- Avoid doing manual labor or strenuous exercise in hot weather; diminished sweating may require dose adjustments because of possibility of heat stroke. This condition is most apt to occur in the older adults.
Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; 
Prototype drug