Prospective audit of short-term concurrent ketamine, opioid and anti-inflammatory (‘triple-agent’) therapy for episodes of acute on chronic pain

Should Subanesthetic Ketamine be Considered When Managing Opioid Refractory Cancer Pain?

In the cancer pain setting, ketamine has been typically employed as a co-analgesic for opioid refractory and neuropathic pain. One controversial topic is whether subanesthetic ketamine be considered when managing opioid refractory cancer pain. In this "Controversies in Palliative Care" article, three clinicians independently answer this question. Specifically, each clinician provides a synopsis of the key studies that inform their thought processes, share practical advice on their clinical approach, and highlight the opportunities for future research. Three independent clinicians reported a divergence of opinion regarding the usefulness of subanesthetic ketamine for managing opioid refractory cancer pain. All investigators acknowledged the lack of high-quality trials. All agreed on the need for adequately powered trials, the development of standardized methodology, and the exploration of any patient sub-populations that may benefit from ketamine for cancer related pain.

Low-Dose Ketamine Infusion as Adjuvant Therapy during an Acute Pain Crisis in Pediatric Patients

Recent studies in pediatric patients have suggested that ketamine, an N-methyl-D-aspartate receptor (NMDA) antagonist, given at sub-anesthetic doses can effectively decrease pain scores, provide analgesic effects, and in some cases, reduce opioid requirements. Our study aims to assess impact of low-dose ketamine on reducing pain scores and total opioid requirements during an acute pain crisis in pediatric patients. From November 2016 to December 2018, eight patients between the ages of 2 and 17 years admitted to the pediatric intensive care unit (PICU) were treated with LDK infusions to manage severe, opioid-refractory, acute pain crises. Subjective pain scores and total morphine milligram equivalent (MME) intake before, during, and after ketamine infusion were collected through a structured chart review. Overall, the addition of ketamine appeared to reduce subjective pain scores and opioid requirements. Two patients were in palliative care and expired shortly after ketamine was started and two patients were discharged within 48 hours of LDK infusion cessation. Ketamine seemed to reduce heart rate and had no appreciable effect on respiratory rate, blood pressure, or oxygen saturation. Hallucination was reported in one patient which resolved upon dose reduction. LDK infusion could be considered as an adjuvant therapy to optimize pain control in pediatric patients experiencing acute pain crises. Further investigation with a larger patient population is warranted to establish the effects of LDK on pain improvement and reducing total opioid requirements.

Design, synthesis and biological evaluation of novel analgesic agents targeting both cyclooxygenase and TRPV1

Multitarget-directed ligands might offer certain advantages over traditional single-target drugs and/or drug combinations. In the present study, a series of novel analgesic agents targeting both cyclooxygenase and TRPV1 were prepared and evaluated in an effort to optimize properties of previously described lead compounds from piperazine, ethanediamine cores. These compounds were evaluated for antagonism of hTRPV1 activation by capsaicin and the ability to inhibit Ovine COX-1 and human recombinant COX-2 in vitro. The favorable potentials of these test compounds were further characterized in preliminary analgesic and side-effects tests in vivo. On the basis of comprehensive evaluations, compound 8d which showed strong TRPV1 antagonistic activity, middle COX-2 inhibition, weak ulcerogenic action and had no hyperthermia side-effect was considered as a safe candidate for the further development of analgesic drugs.

Daily subcutaneous parecoxib injection for cancer pain: an open label pilot study

BACKGROUND

Nonsteroidal anti-inflammatory analgesics (NSAIDs) are useful in cancer pain but the specific use of subcutaneous parecoxib has not been previously reported.

OBJECTIVE

This pilot study aimed to establish the efficacy and side effect profile of short-term sequential single daily dose subcutaneous parecoxib sodium in patients with severe cancer bone pain.

METHODS

Nineteen hospitalized patients with advanced cancer and uncontrolled malignant bone pain (9 males, 10 females) received 24 courses of one, two, or three days sequential therapy with 'off-label' daily subcutaneous parecoxib. All patients were receiving opioid therapy; the median baseline daily oral equivalent dose (OED) of morphine was 180 mg. Pain was assessed at baseline, 24 hours, 48 hours, and 72 hours. Pain scores as assessed on an 11-point numeric pain rating scale (NPRS), any side effects including subcutaneous site reactions, as well as patient satisfaction rating with analgesia were recorded. A clinically significant decrease in pain scores was defined as a reduction of two or more points on the NPRS.

RESULTS

Median pain score of all patient treatments decreased from 7 to 4.5 at 24 hours (p<0.001) and 4.0 at 48 hours. A response was seen in 17 (71%) of the 24 treatments at 24 hours. There was no difference between median negative change in pain scores in 19 (79%) treatments where pain was either strongly movement related, or in 22 (94%) treatments where local bone tenderness was more pronounced. No major side effects were observed during treatment. One patient died from pulmonary embolism after cessation of concurrent prophylactic low molecular weight heparin prior to staging liver biopsy. Subcutaneous site reactions occurred in 2 (8%) treatments and were mild and self limiting.

CONCLUSIONS

Short-term daily subcutaneous parecoxib injection was effective for malignant bone pain when added to existing analgesic therapy and was well tolerated. Further research is warranted into the short-term use of parecoxib in hospitalized patients with intractable malignant bone pain.

Analgesic effects of ketamine infusion therapy in korean patients with neuropathic pain: A 2-week, open-label, uncontrolled study

BACKGROUND

The overexcitation of the N-methyl-D-aspartate receptor complex appears to play a critical role in the development of neuropathic pain, and ketamine acts as an antagonist to that receptor. Some publications have reported on the prominent relief of neuropathic pain with intravenous or subcutaneous ketamine infusions or a single-dose intravenous ketamine injection despite adverse effects.

OBJECTIVES

The primary objective of this study was to determine the analgesic effect of intravenous ketamine infusion therapy for neuropathic pain refractory to conventional treatments. Secondary objectives included identifying the variables related to the analgesic effect and the pain descriptors susceptible to ketamine infusion.

METHODS

This 2-week, open-label, uncontrolled study was conducted in Korean patients with neuropathic pain recruited from the Samsung Seoul Hospital (Seoul, Republic of Korea) outpatient pain management unit. Patients were required to have a pain severity score >5 (visual analog scale [VAS], where 0 = no pain and 10 = worst pain imaginable) over a period of ≥1 month while on standard treatment. The patients were required to have shown no benefit from standard treatment and no pain relief lasting over 1 month. The ketamine infusion therapy was composed of 3 sessions performed consecutively every other day. Midazolam was administered concomitantly to reduce the occurrence of central nervous system-related adverse events (AEs) secondary to ketamine. Each session was as follows: ketamine 0.2 mg/kg and midazolam 0.1 mg/kg were administered intravenously for 5 minutes as a loading dose, followed by a continuous infusion of ketamine 0.5 mg/kg/h and midazolam 0.025 mg/kg/h for 2 hours. AEs were assessed in the following ways: close monitoring of ECG, blood pressure, oxygen saturation, and evaluating the need for treatment of AEs during infu- sion and until discharge by an attending anesthesiologist; an open question about discomfort at the end of each session; spontaneous reports about AEs during each session; and the patients' and caregivers' checklist of AEs occurring at home for 2 weeks after discharge. All the descriptors of pain expressed by the patients in Korean were recorded and translated into appropriate English terminology on the basis of the literature on Korean verbal descriptors of pain. Each of the translated pain descriptors was then classified into 1 of 18 sensory items.

RESULTS

The overall VAS score for pain decreased from a baseline mean (SD) of 7.20 (1.77) to 5.46 (2.29) (P < 0.001) 2 weeks after treatment in 103 patients (53 males and 50 females; mean age, 52.56 [17.33] years) who completed the study. Variables such as age, sex, and the duration and diagnosis of pain were not found to be associated with analgesic effect. Seven of the 18 pain descriptors were found to have a significant response to ketamine infusion treatment between baseline and 2 weeks follow-up: burning pain (P = 0.008); dull, aching pain (P < 0.001); overly sensitive to touch (P = 0.002); stabbing pain (P = 0.008); electric pain (P = 0.031); tingling pain (P < 0.001); and squeezing pain (P < 0.001). A total of 52 patients reported AEs: 33 during infusion and 44 during recovery and up to 2 weeks follow up. The most commonly reported AEs were snoring (15 [15%]) during infusion and dizziness (43 [42%]) during recovery.

CONCLUSIONS

Ketamine infusion therapy was associated with reduced severity of neuropathic pain and generally well tolerated for up to 2 weeks in these patients with neuropathic pain refractory to standard treatment. Variables such as sex, age, and the diagnosis and duration of pain had no association with the analgesic effect of this treatment. Randomized controlled trials are needed to evaluate the efficacy and tolerability of treatment with ketamine infusion.

Validity of anaesthetic complication coding data as a clinical indicator

Clinical indicators using routinely collected International Statistical Classification of Diseases, Australian Modification (ICD-10-AM) data offer promise as tools for improvement of quality. The ICD-10-AM is the coding system used by Australian administrators to summarise information from the clinical record to describe a patient's hospital encounter. The use of anaesthesia complications as coded by this system has been proposed by two jurisdictions as a monitor of the quality of anaesthetic services. We undertook a review of cases identified by such indicators in a large tertiary hospital. Our results indicate the anaesthesia indicator dataset proposed by the Victorian and Queensland Health departments appears to have little clinical or quality improvement relevance.

Effect of ketamine on intravenous patient-controlled analgesia using hydromorphone and ketorolac after the Nuss surgery in pediatric patients

Background

Nuss surgery is preferred in pectus excavatum repair because this procedure produces excellent cosmetic results and prevents postoperative distressed pulmonary function. However, the procedure causes severe pain due to thoracic expansion. This study was designed to investigate the analgesic effect of small doses of ketamine on an intravenous patient-controlled analgesia (IV-PCA) using hydromorphone and ketorolac for pain control after Nuss surgery.

Methods

Forty-four patients undergoing elective Nuss surgery were randomly assigned to receive hydromorphone 3 µg/kg/hr, ketorolac 0.05 mg/kg/hr and ondansetron 0.1 mg/kg/day (Group HO, n = 22) or hydromorphone 3 µg/kg/hr, ketorolac 0.05 mg/kg/hr, ondansetron 0.1 mg/kg/day and ketamine 0.15 mg/kg/hr (Group HK, n = 22) via an IV-PCA pump after surgery. A blind observer evaluated each patient using the Modified Children's Hospital of Eastern Ontario Pain Scale (CHEOPS) for the assessment of pain control. The total administered PCA volume, side effects and parents satisfaction with pain control were assessed at postoperative 1, 4, 8, 12, 24, and 48 hours.

Results

There were no significant differences in Modified CHEOPS between the groups during postoperative 48 hours. The total PCA volume in group HK was significantly lower than that in group HO (P < 0.05). The side effects in both groups did not significantly differ except for pruritus. The levels of satisfaction from the parents were not significantly different between the groups.

Conclusions

A small dose of ketamine on IV-PCA reduced the total administered dose of IV-PCA with hydromorphone and ketorolac and reduced the incidence of pruritus after the Nuss procedure in pediatric patients.

A strategy for conversion from subcutaneous to oral ketamine in cancer pain patients: effect of a 1:1 ratio

CONTEXT

No consensus exists about the most appropriate dose ratio for conversion from parenteral to oral ketamine.

OBJECTIVES

To confirm that a 1:1 dose ratio is suitable for converting subcutaneous (s.c.) to oral ketamine in cancer patients.

METHODS

Patients with opioid poorly responsive cancer pain, who responded to 0.4, 0.6, or 0.8 mg s.c. ketamine bolus, were treated with 0.1, 0.15, or 0.2mg/kg/h ketamine infusion, respectively. Switching to the oral route, by applying a 1:1 dose ratio, was carried out in patients who experienced adequate pain relief and continued to need ketamine as a coanalgesic. Pain, somnolence, feelings of insobriety, confusion, and cardiovascular parameters were assessed throughout the process.

RESULTS

Twenty-nine patients were enrolled in the study. Ketamine infusion decreased pain intensity from severe to no pain or slight pain in 23 of 29 and six of 29 patients, respectively. The median of s.c. ketamine doses was 0.2mg/kg/h (range 0.1-0.5). After oral switching, 27 of 29 patients remained as successfully controlled as when receiving s.c. ketamine. The other two patients needed a slight dose ratio readjustment, to 1:1.3 and 1:1.5, to maintain pain control. The median of oral ketamine doses was 300 mg/day (interquartile range 240-382.5). Seven of 29 patients receiving s.c. ketamine developed moderate and transitory side effects, such as feelings of insobriety and somnolence. No side effects were present while receiving oral ketamine. No significant changes were observed in cardiovascular parameters.

CONCLUSION

A 1:1 dose ratio for conversion from s.c. to oral ketamine is safe and effective in cancer pain patients.

Management of breakthrough pain in patients with cancer

Breakthrough pain (BTP) in patients with cancer lacks a consensus definition and is subsequently inadequately diagnosed and assessed, therefore making it more challenging to manage. Cancer pain is generally moderate to severe in intensity and persistent in nature. Despite the problematic definition of BTP, it is generally described as having similar intensity, but may also be transitory and variable in predictability. Most breakthrough analgesia fails to be effective in the time required for BTP. No useful analgesia is therefore provided but drug adverse effects escalate. Cancer pain management relies on the WHO analgesic ladder. The frequency of BTP and its inadequate management means that it has significant adverse effects on patients, their families and those involved in their care. This article outlines a systematic, clinical and evidence-based approach to managing BTP in patients with cancer that emphasizes a holistic approach and an understanding of multidimensional 'total pain'. Guidelines for managing BTP are presented and areas of developing research are identified.

Symptomatic management of calciphylaxis: a case series and review of the literature

Calciphylaxis, or calcific uremic arteriopathy, is a rare complication of end-stage renal impairment. It is characterized by the development of small vessel vasculopathy with subcutaneous necrosis and ulceration. Intense pain and cutaneous hyperesthesia are prominent features. Mortality rates are high, and the resulting morbidity is significant. While symptomatic management is the mainstay of treatment, it can be challenging. We describe the symptomatic management of a series of three patients with calciphylaxis. Particular emphasis is placed on the use of multimodal analgesia with high-dose opioids, ketamine, and benzodiazepines and on the use of preemptive analgesia.

First “hybrid” ligands of vanilloid TRPV1 and cannabinoid CB2receptors and non-polyunsaturated fatty acid-derived CB2-selective ligands

12-Phenylacetyl-ricinoleoyl-vanillamide (phenylacetylrinvanil, PhAR, IDN5890), is an ultra-potent agonist of human vanilloid TRPV1 receptors also endowed with moderate affinity for human cannabinoid CB(2) receptors. To improve its CB(2) affinity and temper its potency at TRPV1, the modification of the polar headgroup and the lipophilic 12-acylgroup of PhAR was pursued. Replacement of the vanillyl headgroup of PhAR with various aromatic or alkyl amino groups decreased activity at TRPV1 receptors, although the dopamine, cyclopropylamine, 1'-(R)- and 1'-(S)-methyl-ethanolamine, and ethanolamine derivatives retained significant potency (EC(50) 31-126 nM). Within these compounds, the 12-phenylacetylricinoleyl cyclopropylamide and ethanolamide were the strongest ligands at CB(2) receptors, with K(i) of 22 and 44 nM, and 14- and >20-fold selectivity over cannabinoid CB(1) receptors, respectively. The propyl- and allyl-derivatives also exhibited high affinity at CB(2) receptors (K(i)=40 and 22 nM, with 40 and >80-fold selectivity over CB(1) receptors, respectively), but no activity at TRPV1 receptors. The cyclopropyl- and allyl-derivatives behaved as CB(2) inverse agonists in the GTP-gamma-S binding assay. Addition of para-methoxy, -tert-butyl or -chlorine groups to the 12-phenylacetyl moiety of PhAR produced compounds that retained full potency at TRPV1 receptors, but with improved selectivity over CB(2) or CB(1) receptors. Thus, the manipulation of PhAR led to the development of the first CB(2)/TRPV1 dual ligands and of an entirely new class of inverse agonists at CB(2) receptors. Both types of compounds might find application in the treatment of inflammation, and represent new molecular probes to investigate the endocannabinoid-endovanilloid signalling system.