Tolcapone

A to Z Drug Facts

 Action The exact mechanism of action is unknown. Inhibits catechol-O-methyl transferase (COMT) thus blocking the degradation of catechols including dopamine and levodopa. This may lead to more sustained levels of dopamine and consequently a more prolonged antiparkinson's effect.

 Indications As an adjunct to levodopa/carbidopa for the management of signs and symptoms of Parkinson's disease.

 Contraindications Hypersensitivity to the drug or its ingredients; patients with liver disease; patients who were withdrawn from tolcapone because of evidence of tolcapone-induced hepatocellular injury; patients with a history of non-traumatic rhabdomyolysis or hyperpyrexia and confusion possibly related to medication.

 Route/Dosage

ADULTS: PO 100 or 200 mg tid. The maximum recommended dose is 600 mg/day.

 Interactions None well documented.

 Lab Test Interferences None well documented.

 Adverse Reactions

CV: Orthostatic complaints; syncope; chest pain; hypotension; hest discomfort. CNS: Sleep disorder; excessive dreaming; somnolence; confusion; dizziness; eadache; hallucination; dyskinesia; dystonia; fatigue; balance loss; hyperkinesia; aresthesia; hypokinesia; agitation; irritability; mental deficiency; hyperactivity; anic reaction; euphoria; hypertonia. EENT: Xerostomia; cataract; eye inflammation. HEPA: Severe hepatocellular injury, including fulminant liver failure resulting in death. GI: Nausea; diarrhea; vomiting; constipation; abdominal pain; dyspepsia; flatulence. GU: Urinary tract infection; urine discoloration; micturition disorder; uterine tumor. RESP: Upper respiratory tract infection; dyspena; sinus congestion. DERM: Dermal bleeding; skin tumor; alopecia. OTHER: Muscle cramps; anorexia; falling; increased sweating; rhabdomyolysis; tiffness; arthritis; neck pain; influenza; burning; malaise; fever.

 Precautions

Pregnancy: Category C. Lactation: Undetermined. Children: Safety and efficacy not established. Diarrhea: Most common reason for stopping therapy. Follow up all cases with appropriate work-up, including occult blood. Dosage reduction: Decrease levodopa dosage appropriately when used concurrently. Hepatic enzyme abnormalities: Discontinue therapy if liver enzyme elevations are ³ 5 times the upper limit of normal or if jaundice occurs. Monitor liver enzymes monthly during the first 3 months of therapy and every 6 weeks for the next 3 months. Hepatic impairment: Do not initiate treatment in patients who have 2 ALT or AST values greater than the upper limit of normal or any other evidence of hepatocellular dysfunction. Do not initiate therapy in patient with liver disease. Monoamine oxidase (MAO) inhibitors: Avoid concurrent use of MAO inhibitors. Administration of MAO inhibitors may result in inhibition of the majority of pathways for catecholamine metabolism.

 Administration/Storage

• May be given without regard to meals.
• Store at room temperature.

 Assessment/Interventions

• Obtain patient history, including drug history, and any known allergies.
• Do not use tolcapone until there has been a complete discussion of the risks and the patients has provided written informed consent.
• Perform complete baseline assessment of parkinsonian signs and symptoms before instituting therapy.
• Monitor liver enzymes.
• Check for occult blood in stool if diarrhea occurs.
• Assist with ambulation during initial phase of therapy because of dizziness due to hypotension.
• Offer support to patient and family because relief of parkinsonian symptoms may take several weeks to months after therapy is initiated.
• Conduct appropriate tests to exclude the presence of liver disease before strating treatment with tolcapone. Determine baseline levels of ALT and AST and every 2 weeks for the first year of therapy, every 4 weeks for the next 6 months, and every 8 weeks thereafter.

 Patient/Family Education

• Provide patient information pamphlet.
• Instruct patient to take drug only as prescribed.
• Inform patient that postural hypotension with or without symptoms (g, dizziness, syncope) may occur and caution patients against rising rapidly after sitting or lying down.
• Inform patient that nausea may occur.
• Advise patient of the possibility of an increase in dyskinesia and dystonia.
• Instruct patient to notify their physician if they become pregnant or intend to become pregnant during therapy.
• Advise patient to notify their physician if they intend to breastfeed an infant.
• Advise patients about the need for self-monitoring for classical signs of liver disease (eg, clay-colored stools, jaundice) and nonspecific ones (eg, fatigue, appetite loss, lethargy).
• Inform patient of the clinical signs and symptoms that suggest the onset of hepatic injury (persistent nausea, fatigue, lethargy, anorexia, jaundice, dark urine, pruritus, and right upper quandrant tenderness).

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Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts