Oral Ketamine for Chronic Pain: Towards an Evidence-Based Dosing Regimen

Area of Science:

• Pharmacology and Pain Management
• Clinical Therapeutics

Background:

• The opioid crisis necessitates alternative oral analgesics, with ketamine emerging as a relevant option for chronic pain.
• Heterogeneity in dosing regimens across clinical trials and reviews of oral ketamine complicates clinical application.
• This review addresses gaps in understanding oral ketamine dosing and adverse events for chronic pain management.

Purpose of the Study:

• To identify and analyze dosing regimens and adverse events reported in the literature for oral ketamine in chronic pain.
• To evaluate the potential of oral ketamine as an alternative analgesic in the context of the opioid crisis.

Main Methods:

• Comprehensive literature search of MEDLINE, EMBASE, and PUBMED (January 1965 - July 2022) for studies on oral ketamine's analgesic effects.
• Inclusion criteria focused on studies using 0.5 mg/kg BID-QID or equivalent dosing for benefit-risk analysis.
• Quantitative analysis was limited to 5 studies due to inconsistencies in dosing and study design among 1539 reviewed articles.

Main Results:

• Mean pain scores decreased from 7.72/10 at baseline to 3.2/10 after 30-90 days of treatment.
• A significant correlation (R-squared=0.76) was observed between average pain scores and treatment duration.
• Oral ketamine demonstrated potential efficacy comparable to opioids for managing hyperalgesia and allodynia.

Conclusions:

• Oral ketamine is a viable option for managing chronic pain, including conditions like allodynia and hyperalgesia.
• A specific regimen of 0.5 mg/kg oral ketamine, administered three times daily for 7-90 days, shows efficacy with an acceptable safety profile.
• Standardized, evidence-based dosing protocols for oral ketamine are needed for clinical practice and future research in multimodal pain management.