TOLCAPONE
(tol'ca-pone)
Tasmar
Classifications: autonomic nervous system agent; anticholinergic (parasympatholytic); catecholamine-o-methyltransferase (comt) inhibitor
Pregnancy Category: C

Availability

100 mg, 200 mg tablets

Actions

Selective inhibitor of catecholamine-O-methyltransferase (COMT). COMT is the enzyme responsible for metabolizing levodopa.

Therapeutic Effects

Concurrent administration of tolcapone and levodopa increases the amount of levodopa available to control Parkinson's disease by increasing dopaminergic brain stimulation.

Uses

Idiopathic Parkinson's disease as adjunct to levodopa/carbidopa.

Contraindications

Hypersensitivity to tolcapone; liver disease; pregnancy (category C).

Cautious Use

History of hypersensitivity to other COMT inhibitors (e.g., entacapone, nitecapone); lactation.

Route & Dosage

Parkinson's Disease
Adult: PO 100 mg t.i.d. (max: 200 mg t.i.d.)

Administration

Oral

Adverse Effects (1%)

Body as a Whole: Muscle cramps, orthostatic complaints, fatigue, falling, balance difficulties, hyperkinesia, stiffness, arthritis, hypokinesia. CNS: Dyskinesia, sleep disorder, dystonia, excessive dreaming, somnolence, confusion, dizziness, headache, hallucination, syncope, paresthesias. CV: Chest pain, hypotension. GI: Nausea, anorexia, diarrhea, vomiting, constipation, fulminant liver failure, severe hepatocellular injury, dry mouth, abdominal pain, dyspepsia, flatulence. Respiratory: URI, dyspnea, sinus congestion. Skin: Sweating. Urogenital: UTI, urine discoloration, micturition disorder.

Interactions

Drug: Will increase levodopa levels when taken simultaneously; cns depressants may cause additive sedation; do not give with non-selective maois (isocarboxazid, phenelzine, or tranylcypromine furazolidone, linezolid, procarbazine).

Pharmacokinetics

Absorption: Rapidly absorbed from GI tract, bioavailability 65%; food decreases bioavailability. Peak: 2 h. Distribution: >99% protein bound. Metabolism: Extensively metabolized by COMT and glucuronidation. Elimination: 60% excreted in urine, 40% in feces; clearance is reduced by 50% in patients with moderate cirrhotic liver disease. Half-Life: 2–3 h.

Nursing Implications

Assessment & Drug Effects

Patient & Family Education


Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug