Effects of aspirin and a blood pressure medicine on the blood concentrations of allopurinol, a common treatment for gout

INTERVENTION: Healthy volunteers not taking any regular medication, including herbal medicines, will be will be treated in a randomised order with a single dose of allopurinol (control; 600 mg), and with allopurinol combined with a single dose of aspirin (100 mg), with a single dose of HCT (25 mg) and with the combination, aspirin and HCT. All drugs will be administered orally. Urine (3 x 2 h sequential collections) and blood samples (3 mid‐point blood samples) will be collected over 6 h. Blood and urine will be analysed for uric acid and plasma and urinary oxypurinol concentrations. There will be a washout period of 1 week between each treatment. CONDITION: Potential drug interaction(s) between low‐dose aspirin, hydrochlorothiazide (HCT) and allopurinol PRIMARY OUTCOME: To determine whether taking aspirin and HCT concomitantly with allopurinol will affect the pharmacokinetics of allopurinol as determined by oxypurinol clearance and/or the pharmacodynamic endpoint, the plasma and urinary concentrations of urate. SECONDARY OUTCOME: n/a INCLUSION CRITERIA: INCLUSION CRITERIA: 1) Male or female with Body Mass Index (BMI) between 20 and 30 kg/ m 2) Healthy, as determined by a medical examination, medical history and normal biochemical and haematological values.