Introduction: Opicapone (OPC) is a well-established catechol-O-methyltransferase (COMT) inhibitor that is approved for the treatment of Parkinson's disease (PD) associated with L-DOPA / L-amino acid decarboxylase inhibitor (DDI) therapy allowing for prolonged activity due to a more continuous supply of L-DOPA in the brain. Thus, OPC decreases fluctuation in L-DOPA plasma levels and favours more constant central dopaminergic receptor stimulation, thus improving PD symptomatology. Areas covered: This review evaluates the preclinical development, pharmacology, pharmacokinetics and safety profile of OPC. Data were extracted from published preclinical and clinical studies published on PUBMED and SCOPUS (Search period: 2000-2019). Clinical and post-marketing data were also evaluated. Expert opinion: OPC is a third generation COMT inhibitor with a novel structure. It has an efficacy and tolerability superior to its predecessors, tolcapone (TOL) and entacapone (ENT). It also provides a safe and simplified drug regimen that allows neurologists to individually adjust the existing daily administration of L-DOPA. OPC is indicated as an adjunctive therapy to L-DOPA/DDI in patients with PD and end-of-dose motor fluctuations who cannot be stabilised on those combinations. Abbreviations: 3-OMD, 3-O-methyldopa; 6-OHDA, 6-hydroxydopamine; BG, basal ganglia; COMT, Catechol-O-methyltransferase; DDI, decarboxylase inhibitors; ENT, Entacapone; FDA, Food and Drug Administration; MPTP, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine; OPC, Opicapone; PD, Parkinson's disease; TOL, Tolcapone; GDNF, Glial cell-line-derived neurotrophic factor; NTN, neurturin; ICV, Intracerebroventricular; PDUFA, Prescription Drug User Fees Act; EMA, European Medicine Administration; AE, Adverse event BG, Basal ganglia. QD, once a day
