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(SEE BOXED WARNING) Because of the risk of potentially fatal, acute fulminant liver failure, TASMAR (tolcapone) should ordinarily be used in patients with Parkinson's disease on l-dopa/carbidopa who are experiencing symptom fluctuations and are not responding satisfactorily to or are not appropriate candidates for other adjunctive therapies (see INDICATIONS and DOSAGE AND ADMINISTRATION sections).

Because of the risk of liver injury and because TASMAR, when it is effective, provides an observable symptomatic benefit, the patient who fails to show substantial clinical benefit within 3 weeks of initiation of treatment, should be withdrawn from TASMAR.

TASMAR therapy should not be initiated if the patient exhibits clinical evidence of liver disease or two SGPT/ALT or SGOT/AST values greater than the upper limit of normal. Patients with severe dyskinesia or dystonia should be treated with caution (see PRECAUTIONS: Rhabdomyolysis).

Patients who develop evidence of hepatocellular injury while on TASMAR and are withdrawn from the drug for any reason may be at increased risk for liver injury if TASMAR is reintroduced. Accordingly, such patients should not ordinarily be considered for retreatment.

In controlled Phase 3 trials, increases to more than 3 times the upper limit of normal in ALT or AST occurred in approximately 1% of patients at 100 mg tid and 3% of patients at 200 mg tid. Females were more likely than males to have an increase in liver enzymes (approximately 5% vs 2%). Approximately one third of patients with elevated enzymes had diarrhea. Increases to more than 8 times the upper limit of normal in liver enzymes occurred in 0.3% at 100 mg tid and 0.7% at 200 mg tid. Elevated enzymes led to discontinuation in 0.3% and 1.7% of patients treated with 100 mg tid and 200 mg tid, respectively. Elevations usually occurred within 6 weeks to 6 months of starting treatment. In about half the cases with elevated liver enzymes, enzyme levels returned to baseline values within 1 to 3 months while patients continued TASMAR treatment. When treatment was discontinued, enzymes generally declined within 2 to 3 weeks but in some cases took as long as 1 to 2 months to return to normal.

Monoamine oxidase (MAO) and COMT are the two major enzyme systems involved in the metabolism of catecholamines. It is theoretically possible, therefore, that the combination of TASMAR and a non-selective MAO inhibitor (e.g., phenelzine and tranylcypromine) would result in inhibition of the majority of the pathways responsible for normal catecholamine metabolism. For this reason, patients should ordinarily not be treated concomitantly with TASMAR and a non-selective MAO inhibitor.

Tolcapone can be taken concomitantly with a selective MAO-B inhibitor (e.g., selegiline).

Falling Asleep During Activities of Daily Living and Somnolence

Tolcapone (TASMAR) increases plasma levels of levodopa in patients taking concomitant carbidopa levodopa products [see DOSAGE AND ADMINISTRATION]. Patients taking carbidopa levodopa products alone or with other dopaminergic medications have reported suddenly falling asleep without prior warning of sleepiness while engaged in activities of daily living (includes the operation of motor vehicles). Some of these episodes resulted in automobile accidents. Although many of these patients reported somnolence while on TASMAR, some did perceive that they had no warning signs, such as excessive drowsiness, and believed that they were alert immediately prior to the event. Some patients reported these events one year after the initiation of treatment.

The risk for somnolence was increased with TASMAR treatment (TASMAR 100 mg18 %, 200 mg-14 %, vs placebo-13 %) compared to placebo treatment. In clinical trials, discontinuation due to somnolence occurred in 1 % of patients treated with 200 mg TASMAR and 0 % of patients treated with 100 mg TASMAR or placebo. Falling asleep while engaged in activities of daily living usually occurs in patients experiencing preexisting somnolence, although some patients may not give such a history. For this reason, prescribers should continually reassess patients for drowsiness or sleepiness especially since some of the events occur well after the start of treatment. Prescribers should be aware that patients may not acknowledge drowsiness or sleepiness until directly questioned about drowsiness or sleepiness during specific activities. Patients who have already experienced somnolence or an episode of sudden sleep onset should not participate in these activities during treatment with TASMAR.

Before initiating treatment with TASMAR, advise patients about the potential to develop drowsiness and ask specifically about factors that may increase the risk for somnolence with TASMAR such as the use of concomitant sedating medications and the presence of sleep disorders. Consider discontinuing TASMAR in patients who report significant daytime sleepiness or episodes of falling asleep during activities that require active participation (e.g., conversations, eating, etc.). If treatment with TASMAR continues, patients should be advised not to drive and to avoid other potentially dangerous activities that might result in harm if patients become somnolent. There is insufficient information to establish that dose reduction will eliminate episodes of falling asleep while engaged in activities of daily living.



Dopaminergic therapy in Parkinson's disease patients has been associated with orthostatic hypotension. Tolcapone enhances levodopa bioavailability and, therefore, may increase the occurrence of orthostatic hypotension. In TASMAR clinical trials, orthostatic hypotension was documented at least once in 8%, 14% and 13% of the patients treated with placebo, 100 mg and 200 mg TASMAR tid, respectively. A total of 2%, 5% and 4% of the patients treated with placebo, 100 mg and 200 mg TASMAR tid, respectively, reported orthostatic symptoms at some time during their treatment and also had at least one episode of orthostatic hypotension documented (however, the episode of orthostatic symptoms itself was invariably not accompanied by vital sign measurements). Patients with orthostasis at baseline were more likely than patients without symptoms to have orthostatic hypotension during the study, irrespective of treatment group. In addition, the effect was greater in tolcapone-treated patients than in placebo-treated patients. Baseline treatment with dopamine agonists or selegiline did not appear to increase the likelihood of experiencing orthostatic hypotension when treated with TASMAR. Approximately 0.7% of the patients treated with TASMAR (5% of patients who were documented to have had at least one episode of orthostatic hypotension) eventually withdrew from treatment due to adverse events presumably related to hypotension.

In controlled Phase 3 trials, approximately 5%, 4% and 3% of tolcapone 200 mg tid, 100 mg tid and placebo patients, respectively, reported at least one episode of syncope. Reports of syncope were generally more frequent in patients in all three treatment groups who had an episode of documented hypotension (although the episodes of syncope, obtained by history, were themselves not documented with vital sign measurement) compared to patients who did not have any episodes of documented hypotension.


In clinical trials, diarrhea developed in approximately 8%, 16% and 18% of patients treated with placebo, 100 mg and 200 mg TASMAR tid, respectively. While diarrhea was generally regarded as mild to moderate in severity, approximately 3% to 4% of patients on tolcapone had diarrhea which was regarded as severe. Diarrhea was the adverse event which most commonly led to discontinuation, with approximately 1%, 5% and 6% of patients treated with placebo, 100 mg and 200 mg TASMAR tid, respectively, withdrawing from the trials prematurely. Discontinuing TASMAR for diarrhea was related to the severity of the symptom. Diarrhea resulted in withdrawal in approximately 8%, 40% and 70% of patients with mild, moderate and severe diarrhea, respectively. Although diarrhea generally resolved after discontinuation of TASMAR, it led to hospitalization in 0.3%, 0.7% and 1.7% of patients in the placebo, 100 mg and 200 mg TASMAR tid groups.

Typically, diarrhea presents 6 to 12 weeks after tolcapone is started, but it may appear as early as 2 weeks and as late as many months after the initiation of treatment. Clinical trial data suggested that diarrhea associated with tolcapone use may sometimes be associated with anorexia (decreased appetite).

No consistent description of tolcapone-induced diarrhea has been derived from clinical trial data, and the mechanism of action is currently unknown.

It is recommended that all cases of persistent diarrhea should be followed up with an appropriate work-up (including occult blood samples).

Hallucinations / Psychotic Like Behavior

In clinical trials, hallucinations developed in approximately 5% of patients treated with placebo, compared to 8% and 10% of patients treated with 100 mg or 200 mg three times per day, respectively. Hallucinations led to drug discontinuation and premature withdrawal from clinical trials in 0.3% of patients treated with placebo, compared to 1.4% and 1.0% of patients treated with TASMAR 100 mg or 200 mg TASMAR three times per day, respectively. Hallucinations led to hospitalization in 0.0% of patients in the placebo group, compared to 1.7% and 0.0% of patients treated with 100 mg or 200 mg TASMAR three times per day, respectively.

In general, hallucinations present shortly after the initiation of therapy with tolcapone (typically within the first 2 weeks). Clinical trial data suggest that hallucinations associated with tolcapone use may be responsive to levodopa dose reduction. Patients whose hallucinations resolved had a mean levodopa dose reduction of 175 mg to 200 mg (20% to 25%) after the onset of the hallucinations. Hallucinations were commonly accompanied by confusion and to a lesser extent sleep disorder (insomnia) and excessive dreaming. The incidence of hallucination may be increased in elderly patients over 75 years treated with TASMAR [see Geriatric use].

Post-marketing reports indicate that patients may experience new or worsening mental status and behavioral changes, which may be severe, including psychotic-like behavior during TASMAR treatment or after starting or increasing the dose of TASMAR. Other drugs prescribed to improve the symptoms of Parkinson's disease may have similar effects on thinking and behavior. This abnormal thinking and behavior may present with one or more symptoms, including paranoid ideation, delusions, hallucinations, confusion, psychotic-like behavior, disorientation, aggressive behavior, agitation, and delirium.

Ordinarily, patients with a major psychotic disorder should not be treated with TASMAR because of the risk of exacerbating psychosis. In addition, certain medications used to treat psychosis may exacerbate the symptoms of Parkinson's disease and may decrease the effectiveness of TASMAR.


TASMAR may potentiate the dopaminergic side effects of levodopa and may cause and/or exacerbate preexisting dyskinesia. Although decreasing the dose of levodopa may ameliorate this side effect, many patients in controlled trials continued to experience frequent dyskinesias despite a reduction in their dose of levodopa. Dyskinesia was the most common adverse reaction observed in controlled trials and developed in approximately 20% of patients treated with placebo, compared to 42% and 51% of patients treated with TASMAR 100 mg or 200 mg three times daily, respectively. The rates of withdrawal for dyskinesia were 0.0% in the placebo group, compared to 0.3% and 1.0% in the groups receiving TASMAR 100 mg or 200 mg three times a day, respectively.

Impulse Control / Compulsive Behaviors

Reports suggest that patients may experience an intense urge to gamble, increased sexual urges, intense urges to spend money, binge eating, and/or other intense urges, and the inability to control these urges. These reports are associated with patients taking TASMAR in conjunction with carbidopa/levodopa, as well as other medications that increase central dopaminergic tone and that are used to treat patients with Parkinson's disease. In some cases, although not all, these urges were reported to have stopped when the dose was reduced or the medication was discontinued. Because patients may not recognize these behaviors as abnormal, it is important for prescribers to specifically ask patients or their caregivers about the development of new or increased gambling urges, sexual urges, uncontrolled spending or other urges while being treated with TASMAR. Physicians should consider dose reduction or stopping the medication if a patient develops such urges while taking TASMAR [see PATIENT INFORMATION].


Cases of severe rhabdomyolysis, with one case of multi-organ system failure rapidly progressing to death, have been reported. The complicated nature of these cases makes it impossible to determine what role, if any, TASMAR played in their pathogenesis. Severe prolonged motor activity including dyskinesia may account for rhabdomyolysis. Some cases, however, included fever, alteration of consciousness and muscular rigidity. It is possible, therefore, that the rhabdomyolysis may be a result of the syndrome described in Hyperpyrexia and Confusion (see PRECAUTIONS: Events Reported With Dopaminergic Therapy).

Renal Impairment

No dosage adjustment is needed in patients with mild to moderate renal impairment, however, patients with severe renal impairment should be treated with caution (see CLINICAL PHARMACOLOGY: Pharmacokinetics of Tolcapone and DOSAGE AND ADMINISTRATION).

Renal Toxicity

When rats were dosed daily for 1 or 2 years (exposures 6 times the human exposure or greater) there was a high incidence of proximal tubule cell damage consisting of degeneration, single cell necrosis, hyperplasia, karyocytomegaly and atypical nuclei. These effects were not associated with changes in clinical chemistry parameters, and there is no established method for monitoring for the possible occurrence of these lesions in humans. Although it has been speculated that these toxicities may occur as the result of a species-specific mechanism, experiments that would confirm the theory have not been conducted.

Hepatic Impairment

Because of the risk of liver injury, TASMAR therapy should not be initiated in any patient with liver disease. For similar reasons, treatment should not be initiated in patients who have two SGPT/ALT or SGOT/AST values greater than the upper limit of normal (see BOXED WARNING) or any other evidence of hepatocellular dysfunction.


The rates of hematuria in placebo-controlled trials were approximately 2%, 4% and 5% in placebo, 100 mg and 200 mg TASMAR tid, respectively. The etiology of the increase with TASMAR has not always been explained (for example, by urinary tract infection or warfarin therapy). In placebo-controlled trials in the United States (N=593) rates of microscopically confirmed hematuria were approximately 3%, 2% and 2% in placebo, 100 mg and 200 mg TASMAR tid, respectively.

Events Reported With Dopaminergic Therapy

The events listed below are known to be associated with the use of drugs that increase dopaminergic activity, although they are most often associated with the use of direct dopamine agonists. While cases of Hyperpyrexia and Confusion have been reported in association with tolcapone withdrawal (see paragraph below), the expected incidence of fibrotic complications is so low that even if tolcapone caused these complications at rates similar to those attributable to other dopaminergic therapies, it is unlikely that even a single example would have been detected in a cohort of the size exposed to tolcapone.

Hyperpyrexia and Confusion

In clinical trials, four cases of a symptom complex resembling the neuroleptic malignant syndrome (characterized by elevated temperature, muscular rigidity, and altered consciousness), similar to that reported in association with the rapid dose reduction or withdrawal of other dopaminergic drugs, have been reported in association with the abrupt withdrawal or lowering of the dose of tolcapone. In 3 of these cases, CPK was elevated as well. One patient died, and the other 3 patients recovered over periods of approximately 2, 4 and 6 weeks. Rare cases of this symptom complex have been reported during marketed use. It is difficult to determine if TASMAR played a role in the pathogenesis of these events because these patients received several concomitant medications affecting the central nervous system such as monoaminergic (i.e., MAO-I, tricyclic and selective serotonin reuptake inhibitors) and anticholinergic agents.

Fibrotic Complications

Cases of retroperitoneal fibrosis, pulmonary infiltrates, pleural effusion, and pleural thickening have been reported in some patients treated with ergot derived dopaminergic agents. While these complications may resolve when the drug is discontinued, complete resolution does not always occur. Although these adverse events are believed to be related to the ergoline structure of these compounds, whether other, nonergot derived drugs (e.g., tolcapone) that increase dopaminergic activity can cause them is unknown.

Three cases of pleural effusion, one with pulmonary fibrosis, occurred during clinical trials. These patients were also on concomitant dopamine agonists (pergolide or bromocriptine) and had a prior history of cardiac disease or pulmonary pathology (nonmalignant lung lesion).


Epidemiological studies have shown that patients with Parkinson's disease have a higher risk (2- to approximately 6-fold higher) of developing melanoma than the general population. Whether the increased risk observed was due to Parkinson's disease or other factors, such as drugs used to treat Parkinson's disease, is unclear.

For the reasons stated above, patients and providers are advised to monitor for melanomas frequently and on a regular basis when using TASMAR for any indication. Ideally, periodic skin examination should be performed by appropriately qualified individuals (e.g., dermatologists).

Laboratory Tests

Although a program of frequent laboratory monitoring for evidence of hepatocellular injury is deemed essential, it is not clear that periodic monitoring of liver enzymes will prevent the occurrence of fulminant liver failure. However, it is generally believed that early detection of drug-induced hepatic injury along with immediate withdrawal of the suspect drug enhances the likelihood for recovery. Accordingly, the following liver monitoring program is recommended.

Before starting treatment with TASMAR, the physician should conduct appropriate tests to exclude the presence of liver disease. In patients determined to be appropriate candidates for treatment with TASMAR, serum glutamic-pyruvic transaminase (SGPT/ALT) and serum glutamic-oxaloacetic transaminase (SGOT/AST) levels should be determined at baseline and periodically (i.e. every 2 to 4 weeks) for the first 6 months of therapy. After the first six months, periodic monitoring is recommended at intervals deemed clinically relevant. Although more frequent monitoring increases the chances of early detection, the precise schedule for monitoring is a matter of clinical judgment.

If the dose is increased to 200 mg tid (see DOSAGE AND ADMINISTRATION section), liver enzyme monitoring should take place before increasing the dose and then be conducted every 2 to 4 weeks for the following 6 months of therapy. After six months, periodic monitoring is recommended at intervals deemed clinically relevant.

Discontinue TASMAR if SGPT/ALT or SGOT/AST levels exceed 2 times the upper limit of normal or if clinical signs and symptoms suggest the onset of hepatic dysfunction (e.g., persistent nausea, fatigue, lethargy, anorexia, jaundice, dark urine, pruritus, and right upper quadrant tenderness).

Special Populations

TASMAR therapy should not be initiated if the patient exhibits clinical evidence of active liver disease or two SGPT/ALT or SGOT/AST values greater than the upper limit of normal. Patients with severe dyskinesia or dystonia should be treated with caution (see PRECAUTIONS: Rhabdomyolysis). Patients with severe renal impairment should be treated with caution (see INDICATIONS, DOSAGE AND ADMINISTRATION, BOXED WARNING and WARNINGS).

Carcinogenesis, Mutagenesis and Impairment of Fertility


Carcinogenicity studies in which tolcapone was administered in the diet were conducted in mice and rats. Mice were treated for 80 (female) or 95 (male) weeks with doses of 100, 300 and 800 mg/kg/day, equivalent to 0.8, 1.6 and 4 times human exposure (AUC = 80 ug·hr/mL) at the recommended daily clinical dose of 600 mg. Rats were treated for 104 weeks with doses of 50, 250 and 450 mg/kg/day. Tolcapone exposures were 1, 6.3 and 13 times the human exposure in male rats and 1.7, 11.8 and 26.4 times the human exposure in female rats. There was an increased incidence of uterine adenocarcinomas in female rats at exposure equivalent to 26.4 times the human exposure. There was evidence of renal tubular injury and renal tubular tumor formation in rats. A low incidence of renal tubular cell adenomas occurred in middle- and high-dose female rats; tubular cell carcinomas occurred in middle- and high-dose male and high-dose female rats, with a statistically significant increase in high-dose males. Exposures were equivalent to 6.3 (males) or 11.8 (females) times the human exposure or greater; no renal tumors were observed at exposures of 1 (males) or 1.7 (females) times the human exposure. Minimal-to-marked damage to the renal tubules, consisting of proximal tubule cell degeneration, single cell necrosis, hyperplasia and karyocytomegaly, occurred at the doses associated with renal tumors. Renal tubule damage, characterized by proximal tubule cell degeneration and the presence of atypical nuclei, as well as one adenocarcinoma in a high-dose male, were observed in a 1-year study in rats receiving doses of tolcapone of 150 and 450 mg/kg/day. These histopathological changes suggest the possibility that renal tumor formation might be secondary to chronic cell damage and sustained repair, but this relationship has not been established, and the relevance of these findings to humans is not known. There was no evidence of carcinogenic effects in the long-term mouse study. The carcinogenic potential of tolcapone in combination with levodopa/carbidopa has not been examined.


Tolcapone was clastogenic in the in vitro mouse lymphoma/thymidine kinase assay in the presence of metabolic activation. Tolcapone was not mutagenic in the Ames test, the in vitro V79/HPRT gene mutation assay, or the unscheduled DNA synthesis assay. It was not clastogenic in an in vitro chromosomal aberration assay in cultured human lymphocytes, or in an in vivo micronucleus assay in mice.

Impairment of Fertility

Tolcapone did not affect fertility and general reproductive performance in rats at doses up to 300 mg/kg/day (5.7 times the human dose on a mg/m² basis).


Pregnancy Category C

Tolcapone, when administered alone during organogenesis, was not teratogenic at doses of up to 300 mg/kg/day in rats or up to 400 mg/kg/day in rabbits (5.7 times and 15 times the recommended daily clinical dose of 600 mg, on a mg/m² basis, respectively). In rabbits, however, an increased rate of abortion occurred at a dose of 100 mg/kg/day (3.7 times the daily clinical dose on a mg/m² basis) or greater. Evidence of maternal toxicity (decreased weight gain, death) was observed at 300 mg/kg in rats and 400 mg/kg in rabbits. When tolcapone was administered to female rats during the last part of gestation and throughout lactation, decreased litter size and impaired growth and learning performance in female pups were observed at a dose of 250/150 mg/kg/day (dose reduced from 250 to 150 mg/kg/day during late gestation due to high rate of maternal mortality; equivalent to 4.8/2.9 times the clinical dose on a mg/m² basis).

Tolcapone is always given concomitantly with levodopa/carbidopa, which is known to cause visceral and skeletal malformations in rabbits. The combination of tolcapone (100 mg/kg/day) with levodopa/carbidopa (80/20 mg/kg/day) produced an increased incidence of fetal malformations (primarily external and skeletal digit defects) compared to levodopa/carbidopa alone when pregnant rabbits were treated throughout organogenesis. Plasma exposures to tolcapone (based on AUC) were 0.5 times the expected human exposure, and plasma exposures to levodopa were 6 times higher than those in humans under therapeutic conditions. In a combination embryo-fetal development study in rats, fetal body weights were reduced by the combination of tolcapone (10, 30 and 50 mg/kg/day) and levodopa/carbidopa (120/30 mg/kg/day) and by levodopa/carbidopa alone. Tolcapone exposures were 0.5 times expected human exposure or greater: levodopa exposures were 21 times the expected human exposure or greater. The high dose of 50 mg/kg/day of tolcapone given alone was not associated with reduced fetal body weight (plasma exposures of 1.4 times the expected human exposure).

There is no experience from clinical studies regarding the use of TASMAR in pregnant women. Therefore, TASMAR should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Nursing Women

In animal studies, tolcapone was excreted into maternal rat milk.

It is not known whether tolcapone is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when tolcapone is administered to a nursing woman.

Pediatric Use

There is no identified potential use of tolcapone in pediatric patients.

Geriatric Use

Parkinson's disease is primarily an affliction of the elderly. Consequently, the mean age of patients in tolcapone clinical trials was 60 to 65 years. To investigate safety as it relates to advancing age, three subgroups were identified: less than 65 years, 65 to 75 years, and greater than 75 years. There were generally no consistent age-related trends in safety parameters. However, patients greater than 75 years of age may be more likely to develop hallucinations than patients less than 75 years of age, while patients over 75 may be less likely to develop dystonia (see PRECAUTIONS: Hallucinations/Psychotic Like Behavior). In tolcapone clinical trials, measures of therapeutic efficacy (effects on “Off” time, levodopa dose, and effects on Activities of Daily Living) were not affected by age (see CLINICAL PHARMACOLOGY: Clinical studies). Tolcapone pharmacokinetics have not been found to be affected by age (see CLINICAL PHARMACOLOGY: Special Populations).

Last reviewed on RxList: 5/24/2013
This monograph has been modified to include the generic and brand name in many instances.


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