Low Dose Ketamine as an Analgesic Adjuvant in Difficult Pain Syndromes

Abstract

Ketamine is a non-competitive N-methyl D-aspartate (NMDA) receptor antagonist with analgesic and dissociative anesthetic properties. Low dose or sub-anesthetic doses of ketamine have been used effectively as either a primary analgesic or analgesic adjuvant in a variety of pain syndromes. In this paper, three patients with difficult to treat, predominantly neuropathic pain syndromes will be described. Their pain syndromes were initially managed successfully with the addition of low dose parenteral ketamine as an analgesic adjuvant. The strategy of concurrently starting ketamine at a low dose, i.e., 40-60 mg over 24 hours, with a benzodiazepine proved effective in preventing psychotomimetic side effects. An unavoidable shortage of ketamine prompted a literature search, which suggested that the equianalgesic dose of oral ketamine could be lower than the parenteral dose. Subsequently the patients were converted to oral ketamine at doses 30 to 40% of the previous parenteral dose. Their pain syndromes remained controlled on the lower dose of oral ketamine with remarkably few side effects. The implications of this warrant further discussion and study.

Daily Oral Ketamine for the Treatment of Depression and Anxiety in Patients Receiving Hospice Care: A 28-Day Open-Label Proof-of-Concept Trial

“…50 Significant literature supports its safe use in hospice patients for other symptoms, including pain. 36,37,40,41,[51][52][53][54][55][56] Presented are data from a 28-day, open-label, proof-ofconcept trial of daily oral ketamine administration with the objectives of evaluating and assessing the tolerability, potential efficacy, and time to potential efficacy in the treatment of depression and anxiety in patients receiving hospice care.…”

Oral Ketamine for the Rapid Treatment of Depression and Anxiety in Patients Receiving Hospice Care

“…22 Significant literature supports its safe use in hospice patients for other symptoms, including pain. [23][24][25][26][27][28][29][30][31][32] The cases presented here involved subjects in an on-going open label study that is approved by both the Institute for Palliative Medicine Institutional Review Board and the University of California, San Diego Human Research Protection Program.…”

Intravenous Therapies in the Management of Neuropathic Pain: A Review on the Use of Ketamine and Lidocaine in Chronic Pain Management

“…This is mostly in contrast with others who recommend lower conversion rates. Fitzgibbon and others started with a lower dose which was approximately one-third of the parenteral ketamine dose (Fitzgibbon, 2002). Most agree that a conversion factor of 15% is appropriate (Soto, 2011).…”