Tolcapone

INDICATIONS: Tolcapone tablets is indicated as an adjunct to levodopa and carbidopa for the treatment of the signs and symptoms of idiopathic Parkinson's disease. Because of the risk of potentially fatal, acute fulminant liver failure, Tolcapone tablets 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. Because of the risk of liver injury and because Tolcapone tablets, 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the patient who fails to show substantial clinical benefit within 3 weeks of initiation of treatment, should be withdrawn from Tolcapone tablets. The effectiveness of Tolcapone tablets was demonstrated in randomized controlled trials in patients receiving concomitant levodopa therapy with carbidopa or another aromatic amino acid decarboxylase inhibitor who experienced end of dose wearing-off phenomena as well as in patients who did not experience such phenomena (see CLINICAL PHARMACOLOGY: Clinical Studies ).

DOSAGE AND ADMINISTRATION: Because of the risk of potentially fatal, acute fulminant liver failure, Tolcapone tablets 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 TOLCAPONE TABLETS 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THE PATIENT WHO FAILS TO SHOW SUBSTANTIAL CLINICAL BENEFIT WITHIN 3 WEEKS OF INITIATION OF TREATMENT, SHOULD BE WITHDRAWN FROM TOLCAPONE TABLETS. Tolcapone tablets 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 Patients who develop evidence of hepatocellular injury while on Tolcapone tablets and are withdrawn from the drug for any reason may be at increased risk for liver injury if Tolcapone tablets is reintroduced. These patients should not ordinarily be considered for retreatment with Tolcapone tablets. Only prescribe Tolcapone tablets for patients taking concomitant carbidopa levodopa therapy. The initial dose of Tolcapone tablets is always 100 mg three times per day. The recommended daily dose of Tolcapone tablets is also 100 mg tid. In clinical trials, elevations in ALT occurred more frequently at the dose of 200 mg tid. While it is unknown whether the risk of acute fulminant liver failure is increased at the 200-mg dose, it would be prudent to use 200 mg only if the anticipated incremental clinical benefit is justified (see BOXED WARNING , WARNINGS , and PRECAUTIONS: Laboratory Tests ). If a patient fails to show the expected incremental benefit on the 200-mg dose after a total of 3 weeks of treatment (regardless of dose), Tolcapone tablets should be discontinued. In clinical trials, the first dose of the day of Tolcapone tablets was always taken together with the first dose of the day of levodopa/carbidopa, and the subsequent doses of Tolcapone tablets were given approximately 6 and 12 hours later. In clinical trials, the majority of patients required a decrease in their daily levodopa dose if their daily dose of levodopa was >600 mg or if patients had moderate or severe dyskinesias before beginning treatment. To optimize an individual patient's response, reductions in daily levodopa dose may be necessary. In clinical trials, the average reduction in daily levodopa dose was about 30% in those patients requiring a levodopa dose reduction. (Greater than 70% of patients with levodopa doses above 600 mg daily required such a reduction.) Tolcapone tablets can be combined with both the immediate and sustained release formulations of levodopa/carbidopa. Tolcapone tablets may be taken with or without food (see CLINICAL PHARMACOLOGY ). Patients With Impaired Hepatic Function: Tolcapone tablets therapy should not be initiated in any patient with liver disease or two SGPT/ALT or SGOT/AST values greater than the upper limit of normal. (see BOXED WARNING , WARNINGS , and CLINICAL PHARMACOLOGY ). Patients With Impaired Renal Function: No dose adjustment of Tolcapone tablets is recommended for patients with mild to moderate renal impairment. However, patients with severe renal impairment should be treated with caution. The safety of tolcapone has not been examined in subjects who had creatinine clearance less than 25 mL/min (see CLINICAL PHARMACOLOGY ). Withdrawing Patients From Tolcapone Tablets: As with any dopaminergic drug, withdrawal or abrupt reduction in the Tolcapone tablets dose may lead to emergence of signs and symptoms of Parkinson's disease or Hyperpyrexia and Confusion, a syndrome complex resembling the neuroleptic malignant syndrome (see PRECAUTIONS: Events Reported …

WARNINGS: (see BOXED WARNING ) Because of the risk of potentially fatal, acute fulminant liver failure, Tolcapone tablets 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 Tolcapone tablets, 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 Tolcapone tablets. Tolcapone tablets 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 Tolcapone tablets and are withdrawn from the drug for any reason may be at increased risk for liver injury if Tolcapone tablets 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 Tolcapone tablets 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 Tolcapone tablets 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 Tolcapone tablets 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 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 Tolcapone tablets, 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 Tolcapone tablets treatment (Tolcapone tablets 100 mg-18%, 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 Tolcapone tablets and 0% of patients tre…

CONTRAINDICATIONS: Tolcapone tablets are contraindicated in patients with liver disease, in patients who were withdrawn from Tolcapone tablets because of evidence of Tolcapone tablets-induced hepatocellular injury or who have demonstrated hypersensitivity to the drug or its ingredients. Tolcapone tablets is also contraindicated in patients with a history of nontraumatic rhabdomyolysis or hyperpyrexia and confusion possibly related to medication (see PRECAUTIONS: Events Reported With Dopaminergic Therapy ).

Drug Interactions: See PRECAUTIONS: Drug Interactions . Drug Interactions: Protein Binding: Although tolcapone is highly protein bound, in vitro studies have shown that tolcapone at a concentration of 50 mcg/mL did not displace other highly protein-bound drugs from their binding sites at therapeutic concentrations. The experiments included warfarin (0.5 to 7.2 mcg/mL), phenytoin (4.0 to 38.7 mcg/mL), tolbutamide (24.5 to 96.1 mcg/mL) and digitoxin (9.0 to 27.0 mcg/mL). Drugs Metabolized by Catechol-O-Methyltransferase (COMT): Tolcapone may influence the pharmacokinetics of drugs metabolized by COMT. However, no effects were seen on the pharmacokinetics of the COMT substrate carbidopa. The effect of tolcapone on the pharmacokinetics of other drugs of this class such as α-methyldopa, dobutamine, apomorphine, and isoproterenol has not been evaluated. A dose reduction of such compounds should be considered when they are co-administered with tolcapone. Effect of Tolcapone on the Metabolism of Other Drugs: In vitro experiments have been performed to assess the potential of tolcapone to interact with isoenzymes of cytochrome P450 (CYP). No relevant interactions with substrates for CYP 2A6 (warfarin), CYP 1A2 (caffeine), CYP 3A4 (midazolam, terfenadine, cyclosporine), CYP 2C19 (S-mephenytoin) and CYP 2D6 (desipramine) were observed in vitro. The absence of an interaction with desipramine, a drug metabolized by cytochrome P450 2D6, was also confirmed in an in vivo study where tolcapone did not change the pharmacokinetics of desipramine. Due to its affinity to cytochrome P450 2C9 in vitro, tolcapone may interfere with drugs, whose clearance is dependent on this metabolic pathway, such as tolbutamide and warfarin. However, in an in vivo interaction study, tolcapone did not change the pharmacokinetics of tolbutamide. Therefore, clinically relevant interactions involving cytochrome P450 2C9 appear unlikely. Similarly, tolcapone did not affect the pharmacokinetics of desipramine, a drug metabolized by cytochrome P450 2D6, indicating that interactions with drugs metabolized by that enzyme are unlikely. Since clinical information is limited regarding the combination of warfarin and tolcapone, coagulation parameters should be monitored when these two drugs are co-administered. Drugs That Increase Catecholamines: Tolcapone did not influence the effect of ephedrine, an indirect sympathomimetic, on hemodynamic parameters or plasma catecholamine levels, either at rest or during exercise. Since tolcapone did not alter the tolerability of ephedrine, these drugs can be co-administered. When Tolcapone tablets was given together with levodopa/carbidopa and desipramine, there was no significant change in blood pressure, pulse rate and plasma concentrations of desipramine. Overall, the frequency of adverse events increased slightly. These adverse events were predictable based on the known adverse reactions to each of the three drugs individually. Therefore, caution should be exercised when desipramine is administered to Parkinson's disease patients being treated with Tolcapone tablets and levodopa/carbidopa. In clinical trials, patients receiving Tolcapone tablets/levodopa preparations reported a similar adverse event profile independent of whether or not they were also concomitantly administered selegiline (a selective MAO-B inhibitor).

Pregnancy: 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/m 2 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/m 2 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/m 2 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 Tolcapone tablets in pregnant women. Therefore, Tolcapone tablets 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 ).

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.

ADVERSE REACTIONS: Cases of severe hepatocellular injury, including fulminant liver failure resulting in death, have been reported in postmarketing use. As of May 2005, three cases of fatal fulminant hepatic failure have been reported from more than 40,000 patient years of worldwide use. This incidence may be 10- to 100-fold higher than the background incidence in the general population. All three cases were reported within the first six months of initiation of treatment with Tolcapone tablets. Analysis of the laboratory monitoring data in over 3,400 Tolcapone tablets-treated patients participating in clinical trials indicated that increases in SGPT/ALT or SGOT/AST, when present, generally occurred within the first 6 months of treatment with Tolcapone tablets. The imprecision of the estimated increase is due to uncertainties about the base rate and the actual number of cases occurring in association with Tolcapone tablets. The incidence of idiopathic potentially fatal fulminant hepatic failure (i.e., not due to viral hepatitis or alcohol) is low. One estimate, based upon transplant registry data, is approximately 3/1,000,000 patients per year in the United States. Whether this estimate is an appropriate basis for estimating the increased risk of liver failure among Tolcapone tablets users is uncertain. Tolcapone tablets users, for example, differ in age and general health status from candidates for liver transplantation. Similarly, underreporting of cases may lead to significant underestimation of the increased risk associated with the use of Tolcapone tablets. During the premarketing development of tolcapone, two distinct patient populations were studied, patients with end-of-dose wearing-off phenomena and patients with stable responses to levodopa therapy. All patients received concomitant treatment with levodopa preparations, however, and were similar in other clinical aspects. Adverse reactions are shown for these two populations combined. The most commonly observed adverse reactions in the double-blind, placebo-controlled trials (N=892), with a difference in incidence (Tolcapone tablets minus Placebo) of at least 5% or greater in the 100 mg or 200 mg Tolcapone tablets-treated groups compared to placebo, were dyskinesia, nausea, diarrhea, anorexia, sleep disorder, vomiting, urine discoloration, somnolence, hallucination, dystonia, and sweating. Approximately 16% of the 592 patients who participated in the double-blind, placebo-controlled trials discontinued treatment due to adverse reactions compared to 10% of the 298 patients who received placebo. Diarrhea was by far the most frequent cause of discontinuation (approximately 6% in tolcapone patients vs. 1% on placebo). Adverse Reaction Incidence in Controlled Clinical Studies: Table 4 lists treatment emergent adverse reactions that occurred in at least 1% of patients treated with tolcapone participating in the double-blind, placebo-controlled studies and were numerically more common in at least one of the tolcapone groups. In these studies, either tolcapone or placebo was added to levodopa/carbidopa (or benserazide). The prescriber should be aware that these figures cannot be used to predict the incidence of adverse reactions in the course of usual medical practice where patient characteristics and other factors differ from those that prevailed in the clinical studies. Similarly, the cited frequencies cannot be compared with figures obtained from other clinical investigations involving different treatments, uses, and investigators. However, the cited figures do provide the prescriber with some basis for estimating the relative contribution of drug and nondrug factors to the adverse reactions incidence rate in the population studied. Table 4. Summary of Patients With Adverse Reactions After Start of Trial Drug Administration (At Least 1% in Tolcapone Tablets Group and at Least One Tolcapone Tablets Dose Group Greater Than Placebo) Placebo Tolcapone tid 100 mg 200 mg N = 298…