Case Report: Efficacy and Tolerability of Ketamine in Opioid-Refractory Cancer Pain

Therapeutic effects of 7- to 14-day subanesthetic ketamine infusions for chronic pain on standardized psychiatric measures

Background: We have previously shown that subanesthetic ketamine infusions effectively reduce refractory pain. However, the effects of ketamine infusions on comorbid conditions of depression and anxiety have not been explored in this patient population. Methods: We investigated the effects of ketamine on mood and anxiety in patients with refractory chronic pain treated with 7-14 days of subanesthetic continuous intravenous ketamine infusions, using well-validated clinical scales. Results: There was a significant 52% reduction in pain severity and 33% reduction in pain interference scores following ketamine treatment. Ketamine treatment also reduced scores on the depression module of the Patient Health Questionnaire (PHQ-9) by 28% and scores on the Generalised Anxiety and Depression Assessment (GAD-7) by 36%. Conclusion: Multiday subanesthetic ketamine infusions effectively reduce pain, anxiety and depression in patients with complex chronic pain.

Effectiveness of Low-Dose Ketamine Infusion in Opioid Refractory Cancer Pain: A Case Report

Most patients with advanced cancer experience debilitating pain, which significantly affects their quality of life and has both physical and psychological implications. Opioids have been the mainstay of treatment for chronic cancer pain, but some people develop serious adverse effects or may become refractory to opioid use. There is always a need and search for alternative non-opioid analgesics with an acceptable safety profile, and one such drug is ketamine. In this era of evolving analgesic therapeutics, ketamine has been noted to have favourable results. Ketamine, a phencyclidine analogue, is an N-methyl-D-aspartate antagonist (NMDA), and it has been shown to have an analgesic effect at sub-anaesthetic doses by blocking NMDA-induced pain sensitization and enhancing opioid receptor sensitization. This is a case report of a 46-year-old Indian female with recurrent metastatic adenocarcinoma endometrium (International Federation of Obstetrics and Gynecology (FIGO) Grade II) involving the vaginal vault, rectum, and adrenal glands, along with para-rectal, bilateral iliac, and retroperitoneal nodal metastases, in which ketamine infusion was used successfully to alleviate the pain that was initially not controlled with an incremental dose of opioids. The patient presented with progressive pain in the peri-anal region, rated 8/10 on the Numerical Pain Rating Scale (NRS), following which she was treated with escalating doses of intravenous (IV) fentanyl, but with little to no relief. In view of the patient's opioid-resistant pain, she was started on a low-dose ketamine IV infusion (50 mg in 50 ml of 0.9% NS) as "burst therapy," at infusion rates of 0.02 mg/kg/hr-0.08 mg/kg/hr, with adequate pain relief occurring at 0.08 mg/kg/hr. Literature suggests weight-based dosing of ketamine ranging from 0.06 mg/kg/hr to 0.8 mg/kg/hr was previously used to achieve satisfactory results. In this patient, even lower doses were effectively used to achieve optimum long-term analgesia, cause an upliftment in the patient's overall mood and quality of life, and cause a significant reduction in opioid usage. However, further research is required to assess the efficacy of ketamine at such doses and its effect on opioid consumption. This case report will promote further study regarding optimum IV ketamine dosing and administration in the management of opioid-refractory pain in cancer patients, especially in the Indian population.

Advancing Pharmacist Collaborative Care within Academic Health Systems

Introduction: The scope of pharmacy practice has evolved over the last few decades to focus on the optimization of medication therapy. Despite this positive impact, the lack of reimbursement remains a significant barrier to the implementation of innovative pharmacist practice models. Summary: We describe the successful development, implementation and outcomes of three types of pharmacist collaborative care models: (1) a pharmacist with physician oversight, (2) pharmacist–interprofessional teams and (3) physician–pharmacist teams. The outcome measurement of these pharmacist care models varied from the design phase to patient volume measurement and to comprehensive quality dashboards. All of these practice models have been successfully funded by affiliated health systems or grants. Conclusions: The expansion of pharmacist services delivered by clinical faculty has several benefits to affiliated health systems: (1) significant improvements in patient care quality, (2) access to experts in specialty areas, and (3) the dissemination of outcomes with national and international recognition, increasing the visibility of the health system.

An Update on the Basic and Clinical Science of Ketamine Analgesia

OBJECTIVE

In the context of the current opioid epidemic, there has been a renewed interest in the use of ketamine as an analgesic agent.

METHODS

We reviewed ketamine analgesia.

RESULTS

Ketamine is well-known as an antagonist for N-methyl-D-aspartate receptors. In addition, it can regulate the function of opioid receptors and sodium channels. Ketamine also increases signaling through α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors. These myriad of molecular and cellular mechanisms are responsible for a number of pharmacological functions including pain relief and mood regulation. Clinically, a number of studies have investigated the role of ketamine in the setting of acute and chronic pain, and there is evidence that ketamine can provide analgesia in a variety of pain syndromes.

DISCUSSION

In this review, we examined basic mechanisms of ketamine and its current clinical use and potential novel use in pain management.

[Drug management of cancer-related peripheral neuropathic pain: A systematic review of the literature]

The objective of the present systematic literature review was to provide an update on medical treatment of neuropathic pain in cancer patients. The number of cancer patients is steadily increasing. Pain is frequent in cancer patients. Few studies have focused on medical treatment of pain, and especially of neuropathic pain, in current or former cancer patients. The present systematic review of all studies published between December 2012 and August 2018 was intended to estimate the scale of this lack. In all, 27 articles were identified on a systematic PubMed search and from the authors' personal knowledge, confirming that scant data have been published. The heterogeneity of cancer patients, of cancer, and of pain go some way toward explaining this scarcity. Guidelines, founded mainly on results from non-cancer patients, recommend tricyclic antidepressants and antiepileptic drugs; local treatments have the advantage of good systemic tolerance. Larger-scale studies taking account of the etiology of neuropathic pain, its characteristics (strictly neuropathic or mixed) and patient characteristics (awaiting treatment, under treatment, recent or non-recent survivor, or in terminal phase) along the care pathway are needed to improve knowledge. The results of the present literature analysis can help future research.

Case Report: Utility of Ketamine, Lidocaine, and Mexiletine as Nonopioid Adjuvants in Complex Cancer-Associated Pain

Ketamine, lidocaine, and mexiletine are potential nonopioid adjuvant medications for the use of refractory cancer-related pain, particularly when opioids are demonstrating limited objective benefit. This is a case report of a single patient admitted to a large academic medical center in the United States. The patient is a 43-year-old woman with a history of Crohn's disease complicated by rectal squamous cell carcinoma and complex, progressive, and intractable pelvic and rectal pain. Over the course of hospitalization, her pain demonstrated limited opioid responsiveness despite marked fluctuations of her oral morphine equivalent doses. She also demonstrates variable responsiveness to ketamine. Lidocaine continuous infusion ultimately proves beneficial, and she is discharged after conversion to oral mexiletine. An overview of the hospital system's protocols for ketamine and lidocaine continuous infusions for pain and considerations for transitioning to mexiletine from lidocaine infusion are included.

Ketamine: 50 Years of Modulating the Mind

Ketamine was introduced into clinical practice in the 1960s and continues to be both clinically useful and scientifically fascinating. With considerably diverse molecular targets and neurophysiological properties, ketamine’s effects on the central nervous system remain incompletely understood. Investigators have leveraged the unique characteristics of ketamine to explore the invariant, fundamental mechanisms of anesthetic action. Emerging evidence indicates that ketamine-mediated anesthesia may occur via disruption of corticocortical information transfer in a frontal-to-parietal (“top down”) distribution. This proposed mechanism of general anesthesia has since been demonstrated with anesthetics in other pharmacological classes as well. Ketamine remains invaluable to the fields of anesthesiology and critical care medicine, in large part due to its ability to maintain cardiorespiratory stability while providing effective sedation and analgesia. Furthermore, there may be an emerging role for ketamine in treatment of refractory depression and Post-Traumatic Stress Disorder. In this article, we review the history of ketamine, its pharmacology, putative mechanisms of action and current clinical applications.

The Role of NMDARs Ligands on Antinociceptive Effects of Pregabalin in the Tail Flick Test

Background:

Pregabalin as a new anticonvulsant has been used in different pain treatments.

Objectives:

The aim of this study was to investigate the role of N-methyl-D-aspartate (NMDA) ligands in antinociceptive effect of pregabalin in mice using tail flick.

Materials and Methods:

NMDA (15 and 30 mg/kg) as an agonist or MK801 (0.02 and 0.05 mg/kg) as an antagonist were injected intraperitoneally either alone or 15 minutes before antinociceptive dose of pregabalin (100 mg/kg). Then the latency times and %MPE were measured in the tail flick assay during 75 minutes.

Results:

NMDA and MK801 had no effects alone. NMDA pretreatment significantly decreased the latency times of pregabalin till 75^th minutes. In NMDA pretreated groups, %MPE₃₀ unlike %MPE₇₅ decreased significantly compared to those of pregabalin. MK801 delayed the latency times in pretreated groups, but %MPE₃₀ and %MPE₇₅ did not change significantly compared to pregabalin alone.

Conclusions:

Our findings support the role of NMDARs in pregabalin antinociception, because the NMDAR agonist, unlike the antagonist, decreased the antinociceptive effect of pregabalin, even if tail flick is not an adequate pain assessment method in this regard.