Topical and peripheral ketamine as an analgesic

Area of Science:

• Pharmacology
• Pain Management
• Neurology

Background:

• Ketamine in subanesthetic doses provides systemic analgesia for chronic pain, primarily via N-methyl-D-aspartate receptor blockade.
• Peripheral N-methyl-D-aspartate receptors on sensory nerves suggest potential for localized ketamine applications.
• Ketamine possesses diverse pharmacological actions, including ion channel and transporter modulation, and anti-inflammatory effects.

Purpose of the Study:

• To explore the efficacy of peripheral and topical ketamine applications for pain management.
• To investigate ketamine's effectiveness in various pain conditions, including neuropathic and postoperative pain.
• To assess the impact of different administration routes and combinations on ketamine's analgesic properties.

Main Methods:

• Review of experimental trials involving volunteers and complex regional pain syndrome subjects.
• Analysis of case reports and controlled trials on topical ketamine, alone and in combination therapies.
• Evaluation of oral ketamine administration in postoperative settings.

Main Results:

• Localized ketamine injections showed limited alterations in sensory thresholds.
• Topical ketamine alone had unconfirmed analgesic effects in controlled neuropathic pain trials.
• Combinations of topical ketamine demonstrated variable pain relief (40-75% response rates in retrospective analyses).
• Oral ketamine yielded significant analgesia for oral/throat pain in postoperative patients.

Conclusions:

• Peripheral and topical ketamine applications show promise but require optimized formulations and patient selection.
• Oral ketamine is effective for specific postoperative pain scenarios.
• Future trials should consider patient and disease factors to maximize topical ketamine efficacy.