Topical administration of ketamine was shown to cause a reduction in allodynia in a double-blind placebo controlled study and peripheral administration of ketamine has antinociceptive efficacy similar to that of systemic administration which is likely mediated by NMDA antagonism (7). Ketamine may also potentiate the effects of other systemic opioid analgesics and may reverse opiate tolerance to some degree. Also, given that topical administration of opiates has a local effect, topical ketamine may produce a local tolerance reversal. Ketamine also has modest anti-inflammatory properties which could provide beneficial effects in mucositis pain relief. (8)