Subjects will be screened for eligibility and if eligible will apply a buprenorphine patch (Day 1). The patch will be worn for 7 days during which time, safety assessments, pain scores, mucositis scores, PK sampling & vital signs will be assessed on each day. After patch removal subjects will continue with these assessments on a daily basis until Day 12. The subject will then be followed up for 10 days (to Day 22) to collect information on ongoing/new SAEs/AEs.