A Study to Assess the Effect of Verinurad on the Electric Activity of the Heart

This study will be conducted as a single-centre, randomised, placebo-controlled, double-blind, 3-period, crossover study to assess the effect on the QTcF interval of a single oral dose of verinurad 24 mg extended release (ER8) formulation (therapeutic exposure) or verinurad 40 mg immediate release (IR) formulation (supra-therapeutic exposure), each in combination with allopurinol 300 mg, compared to placebo in healthy subjects. There are 3 study treatments: * Treatment A: Verinurad 24 mg ER8 formulation co-administered with 300 mg allopurinol * Treatment B: Verinurad 40 mg IR formulation co-administered with 300 mg allopurinol * Treatment C: Matched placebos for both verinurad and allopurinol All subjects will receive a single dose of all 3 treatments (A, B, and C) in a cross-over design with wash-out periods of at least 7 days between each study dose administration. Subjects will be randomised to the treatment sequence (ABC, BCA, CAB, etc.) using William's Latin square. The treatments will be administered in a double-blind manner after an overnight fast of at least 10 hours. The study will comprise the following periods (visits): * Screening Period of maximum 28 days (Visit 1); * Three treatment periods of 3 days each, during which subjects will be resident at the study centre from the morning of the day before administration of the study dose until discharge 2 days after study dose administration (Visits 2 to 4); * Wash-out periods of at least 7 days between each study dose administration; * Final visit within 7 to 10 days after the last study dose administration (Visit 5). Each subject will be involved in the study for approximately 53 days and have 5 study visits.