Male or female. Female patients to be post menopausal (defined as 12 months of spontaneous amenorrhoea or 6 months spontaneous amenorrhoea with FSH levels greater than 40mIU/ml), surgically sterilised (post hysterectomy and/or oophorectomy). Male patients with female partners that have child bearing potential must use adequate contraception (condoms +/-spermicidal gel/foam) throughout the duration of the trial period.