Long-Term Safety and Efficacy of Sub-Lingual Ketamine Trouches / Lozenges in Chronic Non-Malignant Pain Management
Chronic non-malignant pain is a disabling condition that results in a reduction in function and quality of life when inadequately managed. Sub-lingual ketamine has been shown to be efficacious for use in chronic pain. Despite its use for decades in chronic non-malignant pain, there is no published long-term data on safety, side effects or adverse drug reactions. We present a retrospective review of twenty-nine patients (n=29) from a metropolitan tertiary pain service who have been receiving sub-lingual ketamine trouches / lozenges between the period of 2012-2019. There was a wide range of dosages used from 25-600mg in divided doses. The duration of treatment ranged from 2-89 months. There was no association with either the dosage or duration of treatment and frequency of side effects. There was an overall reduction in the use of opioids, gabapentinoids or benzodiazepines in 59% of patients with 39% having a complete cessation of an analgesic agent. Side effects were reported in 24%, but only 7% discontinued the treatment due to the side effect (drowsiness). There were no reports of renal impairment, cystitis or hepatotoxicity. This retrospective case-series has demonstrated that sub-lingual ketamine is a safe and effective analgesic agent to use in chronic non-malignant pain management. It is indicated in a variety of chronic pain conditions and has an excellent safety profile, with no association between the frequency in side effects and duration of therapy or total daily dosages. The study has also shown that the safe dose may be higher than the previous consensus.