Clinical Pharmacology Unit, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK. Electronic address: m.j.brown@cai.cam.ac.uk. Institute of Cardiovascular Sciences, University College London, London, UK; National Institute for Health Research, University College London Hospitals Biomedical Research Centre, London, UK. Medicines Monitoring Unit, Medical Research Institute, University of Dundee, Dundee, Scotland, UK. Clinical Pharmacology Unit, University of Edinburgh, Centre for Cardiovascular Science, Queen's Medical Research Institute, Edinburgh, Scotland, UK. William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK. Cardiovascular Medicine & Diabetes, King's College London, London, UK. Robertson Centre for Biostatistics, University of Glasgow, Glasgow, Scotland, UK. BHF Glasgow Cardiovascular Research Centre, Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, Scotland, UK. International Centre for Circulatory Health, Imperial College London, London, UK. Clinical Pharmacology Unit, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK.