Efficacy and tolerability of entacapone as adjunctive therapy to levodopa in patients with Parkinson's disease and end-of-dose deterioration in daily medical practice: an open, multicenter study

Abstract

Entacapone is a potent, reversible and orally active inhibitor of catechol-O-methyltransferase. This open multicenter study evaluated the efficacy, safety and tolerability of entacapone as adjunct therapy to levodopa/dopa decarboxylase inhibitor (> or = 3 daily doses) in patients with idiopathic Parkinson's disease and end-of-dose motor fluctuations. The 8-week study included 489 patients under conditions of typical daily medical practice. Patients were treated with a 200-mg fixed dose of entacapone administered with each scheduled dose of levodopa to a maximum of 10 doses per day. Other antiparkinsonian medication should have been stable for at least 1 month. The primary efficacy criteria were: (1) Part II (activities of daily living, ADL) of the Unified Parkinson's Disease Rating Scale (UPDRS), (2) the reduction of 'off' time during the daily waking period as assessed by the percentage of patients improving by at least one category at Item 39 of Part IV of the UPDRS. Secondary outcome measures included: (1) the investigator's global assessment of change, (2) quality of life (QoL) was assessed using the Parkinson's Disease Questionnaire (PDQ-39). Adverse events, vital signs and liver enzymes were monitored at weeks 2 and 8. The baseline mean score for ADL was 10.5 (+/-7.04), which decreased to 8.5 (+/-6.37) at the end of the study (p < 0.0001). Compared to baseline, 40.8% of patients experienced a reduction in 'off' time during the waking period; this improvement was highly significant (p < 0.0001). A reduction in the daily dose of levodopa was observed in 35.8% of patients (mean decrease 209 +/- 149 mg). QoL was improved by a mean of 10% in all categories of the PDQ-39 (p < 0.001), except social support and cognition. This improvement was statistically significant (p < 0.001). The dyskinesia score (UPDRS Item 32) was decreased significantly from 2.3 to 2.1 from baseline to end of study (p < 0.001), although 52.7% of patients reported levodopa-induced dyskinesia as an adverse event. There was no case of increased liver enzymes. The study results confirm that the excellent risk/benefit ratio seen in phase III controlled studies can be seen in daily neurological practice. Moreover, the study suggests that the benefits of entacapone are associated with a significant improvement in QoL.