Guidelines provide direction for I.V. ketamine in pain management

Separate guidelines issued for patients with acute and chronic pain

In June, Regional Anesthesia and Acute Pain published the first consensus guidelines designed for managing I.V. ketamine infusions in patients with acute pain. Approved by the American Society of Regional Anesthesia and Pain Medicine (ASRA), the American Academy of Pain Medicine (AAPM), and the American Society of Anesthesiologists, this tool provided clinicians in acute care facilities with long sought-after direction for using ketamine to achieve safer and more effective pain control.

“Opioids have been the gold standard for the treatment of both acute and chronic pain for a long period of time,” said Jason Brady, PharmD, BCPS, emergency department clinical pharmacy manager at Maimonides Medical Center. “Unfortunately, the opioid crisis that we are facing in this country has forced us to rethink how we utilize opioids. With that being said, patients still experience pain for a variety of reasons. This means we must utilize a multimodal approach to treating pain.”

Issued alongside separate guidelines for use of I.V. ketamine infusions in chronic pain management, these recommendations answered six key questions in response to a series of previously unaddressed concerns about using I.V. ketamine to treat acute pain. They covered indications, contraindications, use of ketamine as an adjunct to opioid-based therapy, in patient-controlled analgesia (PCA), use of nonparenteral formulations, and evaluation of the optimal subanesthetic dosage range.

“In higher doses, ketamine allegedly acts by reserving central sensitization and enhancing the descending modulatory pathway in the presence of pain,” explained Mary Lynn McPherson, PharmD, MA, MDE, BCPS, CPE, professor and executive director of Advanced Post-Graduate Education in Palliative Care at the University of Maryland School of Pharmacy. At lower doses used to manage acute pain, ketamine acts as an antagonist at the N-methyl-D-aspartate receptor, although it also acts at many other receptors, such as the µ-opioid, muscarinic, monoaminergic, gammaaminobutyric receptors, and others.

Low-dose ketamine infusions were recommended for consideration in patients undergoing painful surgery and for opioid-dependent or opioid-tolerant patients undergoing surgery. Based on experience, the committee suggested considering ketamine in opioid-dependent or opioid-tolerant patients with acute or chronic sickle cell pain. For patients with sleep apnea, ketamine was noted as a potential adjunct to limit opioids.

The use of ketamine is limited by its relative contraindications, which include poorly controlled cardiovascular disease, some degrees of hepatic dysfunction, active psychosis, elevated intracranial or intraocular pressure, and pregnancy.

“My advice to pharmacists,” said Brady, “would be to become familiar with ketamine because it is being utilized to treat a variety of conditions, and I expect that more research will be conducted to identify other conditions, optimal dosing, and perhaps even start being used in conditions [in] which it has not been used previously.

For the full article, please visit www.pharmacytoday.org for the September 2018 issue of Pharmacy Today.