Topical ketamine gel: possible role in treating neuropathic pain
Gammaitoni A, Gallagher RM, Welz-Bosna M.
Pain Medicine and Comprehensive Rehabilitation Center,
MCP Hahnemann School of Medicine Graduate Hospital,
Philadelphia, PA, USA.
Pain Med. 2000 Mar;1(1):97-100.


Neuropathic pain is often resistant to opioids, so other medication classes, such as tricyclic antidepressants, anticonvulsants, and local anesthetics, are often used. Central sensitization, or pain 'wind-up', may perpetuate chronic neuropathic pain even when ongoing peripheral sensory input is absent. Wind-up is thought to cause allodynia, hyperalgesia, and hyperpathia. Receptors such as NMDA, AMPA, and M-glu have recently been identified for their role in central sensitization or pain 'wind-up'. Ketamine has been proposed recently for neuropathic pain secondary to its NMDA receptor activity. The current application as a topical gel stems from the theory that ketamine has peripheral action at both opioid and Na+-K+ channels. This case study involved 5 patients from 25 to 70 years old (3 RSD, 1 lumbar radiculopathy, 1 post-herpetic neuralgia). Dose used was determined by site and surface area of involvement and ranged from 0.093 mg/kg to 9.33 mg/kg. All five patients reported significant pain relief at initial application and wished to continue treatment. The average numerical analogue scale (NAS) score preapplication was 8.8. The average 15 minutes post application NAS was 1.6. Patients reported alterations in temperature sensation, feelings of relaxation and decreased tension in the area of application, and pain relief. Reduction in numerical pain scores postapplication of ketamine gel ranged from 53-100% using a 1-10 numerical pain intensity scale. No significant side effects were reported. Ketamine Gel may provide clinicians with a new option in the battle against chronic neuropathic pain. Until further information is available and larger trials can be conducted, we can only recommend this type of therapy for refractory cases in which all primary and secondary options have been exhausted.

Beyond the K-hole
Ketamine and opiate withdrawal
Ketamine and the nucleus accumbens
Ketamine: medical and non-medical use
The role of ketamine in pain management
Ketamine and the glutaminergic hypothesis of schizophrenia
Low-dose ketamine as a fast-onset, long-acting antidepressant

and further reading

Future Opioids
BLTC Research
Utopian Surgery?
The Abolitionist Project
The Hedonistic Imperative
MDMA: Utopian Pharmacology
Dissociative Anaesthetics: Ketamine
The Good Drug Guide
The Responsible Parent's Guide
To Healthy Mood Boosters For All The Family