2024 September Coffee Chat-Chat Slides

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Ketamine, primarily an N-methyl-D-aspartate/glutamate (NMDA) receptor blocker, inhibits excitatory effects by blocking the open NMDA channel, which plays a role in central sensitization, and is involved in complex pain, neuropathic pain, and tolerance (wind-up). Ketamine also interacts with opioid, nicotine, and muscarinic receptors.<br /><br />In terms of pharmacology, ketamine can be administered through various routes: oral, intranasal, transdermal, rectal, and subcutaneous. The oral route converts ketamine to Norketamine, which is less active. The onset of action for ketamine is 15-30 minutes, with a duration of up to 2 hours. It remains stable when mixed with Dexamethasone, Haldol, or metoclopramide, but caution is advised with CYP34A drugs.<br /><br />Adverse effects of ketamine are dose-dependent and include dissociation, nausea, sedation, delirium, and hallucinations, particularly with IV/IM administration. To minimize these effects, Ativan or Haldol is occasionally used. Long-term use can lead to neuropsychiatric, urinary, and hepatobiliary toxicity, and ketamine induces its own metabolism, leading to tolerance.<br /><br />Ketamine is used for pain management, though no large controlled trials unequivocally support its analgesic effect. Numerous case reports advocate its use for both cancer and non-cancer pain (e.g., neuropathy, ischemia, bone metastases, mucositis). It is also utilized in dressing changes combined with morphine, and topically for neuropathic pain and mucositis. Additionally, ketamine is considered for de-escalating high-dose opioid therapy.<br /><br />Dosing for ketamine typically starts at 10-25 mg orally three to four times daily, with up-titration by 10-25 mg as needed. For IV administration, the initial dose is 50 mg per day, with titration increments of 25-50 mg daily. If a patient's prognosis is limited to a few weeks, an attempt is made to wean them off the drug.<br /><br />Other novel palliative care medications discussed include Versed as an alternative to Ativan infusions, Propofol for palliative sedation and nausea, and Dexmedetomidine (Precedex), an alpha-2 receptor agonist for pain and anxiety.
Keywords
Ketamine
NMDA receptor
pain management
pharmacology
adverse effects
opioid therapy
neuropathic pain
dosing
palliative care
analgesic