Despite a paucity of data, pain management clinics are administering topical gel mixtures that have included ketamine, tricyclics, calcium channel blockers and baclofen. Internet blogs have already identified this gel mixture as a way to "get high". This is one of those google searches you have to do on your own.
References
1: Lynch ME, Clark AJ, Sawynok J, Sullivan MJ. Topical 2% amitriptyline and 1% ketamine in neuropathic pain syndromes: a randomized, double-blind, placebo-controlled trial. Anesthesiology. 2005 Jul;103(1):140-6. 2: Lynch ME, Clark AJ, Sawynok J. A pilot study examining topical amitriptyline, ketamine, and a combination of both in the treatment of neuropathic pain. Clin J Pain. 2003 Sep-Oct;19(5):323-8. 3: Uzaraga I, Gerbis B, Holwerda E, Gillis D, Wai E. Topical amitriptyline, ketamine, and lidocaine in neuropathic pain caused by radiation skin reaction: a pilot study. Support Care Cancer. 2012 Jul;20(7):1515-24.
