The analgesic efficacy, tolerability, safety and pharmacokinetics of a sublingual wafer formulation of ketamine in burns patients undergoing painful dressing changes

INTERVENTION: Each patient will be dosed on two occasions, dressing change one and two, with a single dose of two 25mg racemic ketamine wafers or a single dose of two placebo wafers sublingually. The two treatment occasions will be separated by a minimum wash out period of 24 hours. The sequence of the two treatments will be randomly assigned. CONDITION: Burns PRIMARY OUTCOME: Primary outcome is Numerical rating scale (NSR) for pain intensity. SECONDARY OUTCOME: Burn specific pain anxiety scale (BSPAS) To assess adverse events for safety. Examples include: an unfavourable and uintended sign such as an abnormal laboratory finding, symptom or disease temporally associated with the use of the iinvestigational product. To assess incidence of use of rescue medication in participants To assess safety using laboratory investigations (biochemistry, haematology and urinalysis). To assess safety using pulse oximetry To assess safety using vital signs including systolic and diastolic blood pressure, pulse rate and pulse oximetry, body temperature and respiratory rate. To assess time to rescue analgesia To determine participant's treatment preference To evaluate participant's assessment of treatment on a 5‐point Likert Scale (poor, fair, good, very good and excellent). To evaluate the pharmacokinetics of ketamine using blood samples INCLUSION CRITERIA: 1) Adult burn patients aged 18‐65 years requiring at least two anticipated dressing changes of likely duration at least 20 minutes and anticipated to be sufficiently painful that procedural analgesia is clinically indicated. 2) Good general health without clinically significant renal, hepatic, cardiac or respiratory disease, as determined by the Investigator. 3) Agree to and be capable of understanding and signing an Informed Consent Form.