Tolcapone and Hepatotoxic Effects

Four patients with Parkinson disease have recently been described in whom severe hepatic dysfunction developed in association with tolcapone therapy. These reports led to the introduction of a "black box" warning and more intensive monitoring requirements in the United States. A review of these cases and all clinical trials indicates that liver dysfunction did not develop in any patient who had received monitoring of liver function according to the original prescribing information. Virtually all instances of liver enzyme abnormality and clinical liver dysfunction occurred within 6 months of initiating treatment. To assess the current role of tolcapone therapy in Parkinson disease, a panel of neurologists and hepatologists was convened. Consensus was reached with respect to the following: (1) Tolcapone is an effective agent in the treatment of patients with fluctuating Parkinson disease. (2) The risk of developing irreversible liver injury is negligible with appropriate monitoring. (3) It may be possible to reduce the frequency of monitoring after 6 months of treatment. (4) The requirement that tolcapone be withdrawn if liver enzymes are elevated above the upper limit of normal on a single occasion is unnecessarily restrictive. It was concluded that tolcapone, when used as an adjunct to levodopa, is an effective anti-parkinsonian agent and that less frequent monitoring after 6 months, with an action limit of 2 to 3 times the upper limit of normal, is sufficient to ensure safety in patients who are deriving benefit from the drug.