Dosing and uses of Comtan (entacapone)
Adult dosage forms and strengths
tablet
- 200mg
Parkinson Disease
200 mg PO with each dose of levodopa/carbidopa
Not to exceed 1600 mg/day
See also combo with levodopa/carbidopa
Renal Impairment
Dose adjustment not necessary
Hepatic Impairment
Safety and efficacy not established
Pediatric dosage forms and strengths
Not recommended
Geriatric dosage forms and strengths
Parkinson disease
200 mg PO with each dose of levodopa/carbidopa
Not to exceed 1600 mg/day
See also combo with levodopa/carbidopa
Comtan (entacapone) adverse (side) effects
>10%
Dyskinesia (25%)
Nausea (14%)
Diarrhea (10%)
Hyperkinesia (10%)
Urine discoloration (10%)
1-10%
Hypokinesia (9%)
Dizziness (8%)
Abdominal pain (8%)
Fatigue (6%)
Constipation (6%)
Back pain (4%)
Vomiting (4%)
Dry mouth (3%)
Dyspnea (3%)
Increased sweating (2%)
Back pain (2%)
Anxiety (2%)
Somnolence (2%)
Dyspepsia (2%)
Flatulence (2%)
Purpura (2%)
Asthenia (2%)
Hallucinations (1-4%)
Taste perversion (1%)
Agitation (1%)
Gastritis (1%)
Bacterial infection (1%)
Frequency not defined
Insomnia
Postural hypotension
Confusion
Dopaminergic side affects due to increased dopamine levels
Rare: rhabdomyolysis, retroperitoneal fibrosis
Warnings
Contraindications
Hypersensitivity
Cautions
Use only in combo with levodopa/carbidopa
Increases plasma levodopa levels, which may result in suddenly falling asleep without prior warning of sleepiness while engaged in activities of daily living; adjust levodopa dose
Less hepatotoxic than tolcapone
May be linked to higher melanoma risk in patients with Parkinson Disease
Diarrhea may occur and be associated with weight loss, dehydration, and hypokalemia; if severe, may be a sign of drug-induced microscopic colitis
Dyskinesia incidence 25% compared with 15% for placebo
Dopaminergic therapy in patients with Parkinson disease has been associated with hypotension, orthostatic hypotension, syncope, increased heart rates, possible arrhythmias, and excessive changes in blood pressure
Hallucinations and psychotic-like behavior reported with dopaminergic therapy
Rhabdomyolysis, hyperpyrexia, and confusion reported
Impulse control/compulsive behaviors: Risk of uncontrollable sexual, gambling or other urges
Pregnancy and lactation
Pregnancy category: C
Lactation: excretion in milk unknown; use with caution
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Comtan (entacapone)
Mechanism of action
Reversible catechol-O-methyltransferase (COMT) inhibitor that prolongs half life of levodopa in Parkinsonian patients, reducing motor fluctuations
Pharmacokinetics
Peak Plasma Time: 1 hr
Concentration: 1.2 mcg/mL
Excretion: Feces (90); urine (10%)
Bioavailability: 35%
Protein Bound: 98%
Vd: 20 L
Half-life elimination: 0.4-0.7 hr (B-phase); 2.4 hr (Y-phase)
Metabolism: Hepatic glucuronidation
Total body clearance: 850 mL/min
