Continuous Subcutaneous Infusion of Ketorolac in Cancer Neuropathic Pain Unresponsive to Opioid and Adjuvant Drugs. A Case Report

Opioid-sparing effects of ketorolac in palliative care patients receiving opioids for chronic cancer-related pain: A systematic literature review

BACKGROUND

Standard of care in treatment of cancer-related pain involves opioids in combination with non-steroidal anti-inflammatory drugs (NSAID). Ketorolac, a NSAID, has demonstrated opioid-sparing effects in other clinical settings.

AIM

This systematic literature review investigated ketorolac's opioid-sparing effects in patients receiving opioids for chronic, cancer-related pain.

DESIGN

The primary outcome was total daily dose of opioids. Secondary outcomes included frequency of opioid use, use and frequency of 'rescue' medication and adverse events. Outcomes were described, and meta-analysed where possible. PROSPERO registration CRD42019130894.

DATA SOURCES

Articles included original research, from any study phase or methodology, published in English in a peer-reviewed journal or conference between 1990 and 2020; included subjects >18 years; had chronic cancer-related pain and described the use of opioid-sparing effect of ketorolac.

RESULTS

Nine articles were included. While there was significant heterogeneity, ketorolac may have an opioid-sparing effect, with significant reductions in total daily dose of morphine observed in a single randomised controlled trial (SMD -4.30 mg, 95% CI -5.36 to -3.25), but the changes in the before and after studies were not statistically significant -0.46 mg (95% CI -1.14 to 0.22). Ketorolac was associated with greater likelihood of complete pain relief, but the data were heterogeneous. Insufficient data were available to analyse frequency of opioid use, or rescue medication requirements.

CONCLUSIONS

Given the heterogeneity of the data, adequately powered, randomised controlled trials are required to establish any opioid-sparing effect of ketorolac. For patients not responding to conventional pain management, ketorolac may have a role in treatment augmentation.

Intravenous Ketorolac Infusion for Intractable Pleuritic Pain Secondary to Metastatic Epithelioid Hemangioendothelioma

Background: Epithelioid hemangioendothelioma (EHE) patients can experience severe pain. Nonsteroidal anti-inflammatory drugs, including ketorolac tromethamine, can effectively treat cancer-related pain, provide an opioid-sparing effect, and may be particularly effective for EHE pain. There are limited data describing prolonged (>5 days) continuous intravenous (IV) ketorolac infusion for cancer-related pain and no data on its use in EHE. Case Description: A 67-year-old woman with metastatic hepatic EHE suffered from chronic intractable pleuritic pain unresponsive to trials of nonopioid, opioid, adjuvant medications, and nonpharmacological interventions. In the hospital, continuous IV ketorolac infusion at 3.8 mg/hour (91.2 mg/day) effectively managed pain. With thorough monitoring, the patient was discharged on continuous IV ketorolac infusion at 3 mg/hour (72 mg/day). Infusion continued for 79 days without clinical or laboratory evidence of ketorolac toxicity. Conclusion: Ketorolac tromethamine as a long-term infusion is a potentially viable analgesic for patients with intractable EHE-related pain unresponsive to standard therapies.

Pre-treatment with Meloxicam Prevents the Spinal Inflammation and Oxidative Stress in DRG Neurons that Accompany Painful Cervical Radiculopathy

Painful neuropathic injuries are accompanied by robust inflammatory and oxidative stress responses that contribute to the development and maintenance of pain. After neural trauma the inflammatory enzyme cyclooxygenase-2 (COX-2) increases concurrent with pain onset. Although pre-treatment with the COX-2 inhibitor, meloxicam, before a painful nerve root compression prevents the development of pain, the pathophysiological mechanisms are unknown. This study evaluated if pre-treatment with meloxicam prior to painful root injury prevents pain by reducing spinal inflammation and peripheral oxidative stress. Glial activation and expression of the inflammatory mediator secreted phospholipase A2 (sPLA2) in the spinal cord were assessed at day 7 using immunohistochemistry. The extent of oxidative damage was measured using the oxidative stress marker, 8-hydroxyguanosine (8-OHG) and localization of 8-OHG with neurons, microglia and astrocytes in the spinal cord and peripherally in the dorsal root ganglion (DRG) at day 7. In addition to reducing pain, meloxicam reduced both spinal microglial and astrocytic activation at day 7 after nerve root compression. Spinal sPLA2 was also reduced with meloxicam treatment, with decreased production in neurons, microglia and astrocytes. Oxidative damage following nerve root compression was found predominantly in neurons rather than glial cells. The expression of 8-OHG in DRG neurons at day 7 was reduced with meloxicam. These findings suggest that meloxicam may prevent the onset of pain following nerve root compression by suppressing inflammation and oxidative stress both centrally in the spinal cord and peripherally in the DRG.

Comparison of the Pharmacokinetics of Ketorolac Tromethamine After Continuous Subcutaneous Infusion and Repeat Intramuscular Bolus Injections in Healthy Adult Subjects

Ketorolac tromethamine is a nonsteroidal anti-inflammatory drug that exhibits analgesic activity with no sedative or anxiolytic properties. Twelve healthy male subjects were enrolled in a study to receive either of 2 treatments over 2 periods in an open-label, randomized, 2-way crossover design: (A) 120 mg of ketorolac tromethamine administered as a continuous subcutaneous infusion over a 24-hour period; or (B) an identical total daily dose administered as 4 intramuscular bolus injections of 30 mg each given every 6 hours (current labeled treatment regimen). The pharmacokinetic and safety profiles were evaluated for both treatments. Both modes of administration have similar values for area under the curve (AUC) and half-life (t_1/2 ), suggesting that continuous subcutaneous infusion and repeated intramuscular bolus injections have similar bioavailability. The peak plasma concentration (C_max ) was 40% lower when ketorolac was administered as a continuous subcutaneous infusion compared with repeat intramuscular bolus injections. The concentration at steady-state (C_ss ) for continuous subcutaneous infusion was between the C_max and C_trough values obtained following the 4 intramuscular injections. Both treatment arms were well tolerated.

The role of subcutaneous ketorolac for pain management

This Hospital Pharmacy feature is extracted from Off-Label Drug Facts, a publication available from Wolters Kluwer Health. Off-Label Drug Facts is a practitioner-oriented resource for information about specific drug uses that are unapproved by the US Food and Drug Administration. This new guide to the literature enables the health care professional or clinician to quickly identify published studies on off-label uses and determine if a specific use is rational in a patient care scenario. References direct the reader to the full literature for more comprehensive information before patient care decisions are made. Direct questions or comments regarding Off-Label Drug Uses to jgeneral@ku.edu.

Long-term continuous subcutaneous infusion of ketoprofen combined with morphine: a safe and effective approach to cancer pain

OBJECTIVES

According to international guidelines, nonsteroidal anti-inflammatory drugs (NSAIDs) and opioids are the cornerstone drugs for cancer pain. In clinical practice, severe cancer pain often requires 3 step analgesics and alternative routes of administration, thus NSAIDs are usually abandoned. Our aim was to evaluate feasibility, safety, and efficacy of ketoprofen combined with opioids in long-term continuous subcutaneous infusion (CSI) for cancer pain in a prospective observational open-label pilot study.

METHODS

Ketoprofen was added to morphine CSI in 172 consecutive patients (study group, SG). Concomitantly, 48 received opioids CSI without ketoprofen for contraindication to NSAIDs (control group, CG). CSI was delivered through a single-use elastomeric pump refilled weekly. Safety was evaluated according to the number of adverse events and their severity. The measures of efficacy were pain relief (NRS, Numerical Rating Scale), percentage of patients that needed to increase morphine dosage, and median relative increase between weeks 2 and 4.

RESULTS

Toxicity typically attributable to NSAIDs were recorded in 4.1% of patients after 3 months of treatment and the combination of NSAIDs and corticosteroids seems not to influence the risk of gastrointestinal adverse effects. The local side effects related to the CSI regimen were negligible in both the groups. By the fourth week, pain was well controlled (NRS 0 to 2) in 80% of patients receiving ketoprofen compared with 46% of patients without ketoprofen (P<0.01.) Moreover, the percentage of patients needing to increase the morphine dosage (40.5% vs. 68.7% P<0.01) and the relative dose increase (12% vs. 25% P<0.005) were significantly lower in the SG.

CONCLUSIONS

Ketoprofen CSI in combination with opioids is a feasible, safe, and effective approach to cancer pain.

Neuropathic pain: could nurses become more involved?

Neuropathic pain can take a heavy toll on quality of life, impacting negatively on emotions, disrupting sleep, and impairing energy and mobility. It can destroy the enjoyment of life and the opportunity to continue in employment. In some cases, it can lead to suicidal thoughts and intentions. Nurses are well placed to become more effective in identifying and treating this challenging condition. This article outlines what we currently understand are the causes or 'generators' of neuropathic pain and the mechanisms that maintain pain. It explores strategies for the diagnosis of neuropathic pain and reviews a couple of typical case studies from clinical practice. Using these case studies, this article discusses assessment, patient expectation, treatment options and realistic outcomes. Finally, it is intended to stimulate debate as to why, when, how and where nurses could become key practitioners in identifying the development of neuropathic pain, assessing its impact on patients and encouraging the initiation of treatment.

Emerging drugs for neuropathic pain

Although there are many analgesics on the market for the treatment of nociceptive pain, there are none with FDA approval for the treatment of neuropathic pain. With a better understanding of the anatomy and physiology of pain, there is a significant effort in developing new drugs that interact specifically with pain pathways. This higher drug specificity is likely to result in drugs that are more efficacious with fewer side effects. This has led to the development of many drugs for the treatment of neuropathic pain. These drugs are divided into the following therapeutic classes: 1) N-methyl-D-aspartate (NMDA) receptor antagonists, 2) ion channel antagonists, 3) alpha2-agonists, 4) nicotinic receptor agonists, 5) prostaglandin receptor antagonists, 6) adenosine agonists and adenosine kinase inhibitors, 7) neuropeptide antagonists, and 8) prosaposins. The results of preclinical and clinical trials are promising for these new agents. Whether these agents will be efficacious as single agents is yet to be determined; however, preliminary results show that combination therapy may be more beneficial with fewer side effects.

Differential effects of naproxen and rofecoxib on the development of hypersensitivity following nerve injury in rats

The present study was undertaken to determine the effects of cyclooxygenase (COX) inhibitors on the development of neuropathic pain in rats following chronic constriction injury (CCI). A single intraperitoneal administration of naproxen, a nonselective COX inhibitor (10 or 30 mg/kg), or rofecoxib, a selective COX-2 inhibitor (3 or 10 mg/kg) 2 h before nerve injury did not attenuate the development of neuropathic state for 28 days. However, the administration of naproxen [10 or 30 mg/kg, intraperitonelly (i.p.)], but not rofecoxib (3 or 10 mg/kg, i.p.), on day 7 attenuated hypersensitivity but did not alter its development for 28 days. Furthermore, naproxen significantly reduced hyperalgesia and allodynia for 4 h, but the efficacy was not observed 24 h after the treatment, whereas rofecoxib failed to modify the hypersensitivity following perineural (p.n.) or intrathecal (i.t.) administration on day 7. Chronic administration of naproxen (3, 10 or 30 mg/kg), but not rofecoxib (1, 3 or 10 mg/kg), 2 h before, daily for 7 days, after nerve injury significantly attenuated and further delayed the development of hypersensitivity for 21 days following nerve injury. These results suggest that the development of hypersensitivity in the CCI model is not COX-2 dependent and that the chronic administration of naproxen started early before peripheral nerve injury could attenuate the development of hypersensitivity.

Effect of etodolac, a COX-2 inhibitor, on neuropathic pain in a rat model

Etodolac, a cyclooxygenase-2 inhibitor, may alleviate nociceptive pain and inhibit the activation of osteoclasts. The aim of the present study was to determine whether etodolac can alleviate heat-evoked hyperalgesia and investigate its possible protective effects on osteoporosis induced by chronic constriction injury (CCI) in rats. A CCI to the sciatic nerve was performed, after which the rats received etodolac orally in a volume of 2 ml at 0, 1, and 10 mg/kg/day for 1 to 5 weeks following surgery (experiment 1); at 0 and 10 mg/kg/day for 1 day to 5 weeks following surgery (experiment 2); and at 0 mg/kg/day for 1 to 5 weeks, 10 mg/kg/day for 1 to 2 weeks after surgery, or 10 mg/kg/day for 1 to 3 weeks after surgery (experiment 3). Paw withdrawal latency after exposure to heat, bone mineral content (BMC) and bone mineral density (BMD) in the whole tibial bone, and the number of tartrate resistant acid phosphate (TRAP)-positive multinucleated osteoclasts were measured. Etodolac alleviated heat-evoked hyperalgesia in the CCI rats and the increase in number of TRAP-positive multinucleated osteoclasts on the CCI-side was abrogated, however, it did not inhibit the decrease of BMC and BMD on the CCI-side. Our results suggest that etodolac is useful for treatment of neuropathic pain.

Intraplantar injection of a cyclooxygenase inhibitor ketorolac reduces immunoreactivities of substance P, calcitonin gene-related peptide, and dynorphin in the dorsal horn of rats with nerve injury or inflammation

We previously reported that partial sciatic nerve ligation (PSNL) dramatically up-regulates cyclooxygenase 2 (COX2) in injured sciatic nerve, and local injection of the COX inhibitor, ketorolac, reverses tactile allodynia and suppresses increased phosphorylation of the transcription factor cAMP responsive element binding protein [Eur J Neurosci 15 (2002) 1037]. These findings suggest that peripheral prostaglandins (PGs) are over-produced and contribute to the central plasticity and the maintenance of neuropathic pain after nerve injury. PGs, particularly PGE2, are well known to facilitate the release of the pro-nociceptive neuropeptide substance P (SP) and calcitonin gene-related peptide (CGRP) from primary sensory afferents. Thus, suppressing peripheral PG over-production may inhibit the release of these two neuropeptides from primary afferents and thereby increase the content of these neuropeptides remaining in afferent terminals in the dorsal horn. In this study we tested this hypothesis by examining the immunoreactivities of SP and CGRP in the dorsal horn of PSNL rats intraplantarly injected with saline and ketorolac. Four weeks after PSNL, SP- and CGRP-immunoreactivities (IR) in the ipsilateral dorsal horn were not significantly different from the contralateral side. Five days following intraplantar injection of ketorolac, CGRP- and SP-IR in the ipsilateral and contralateral dorsal horn were dramatically reduced compared with saline-injected PSNL rats. Local ketorolac also suppressed PSNL-induced increase in dynorphin-IR in dorsal horn neurons. Since abundant production of PGs during inflammation is well documented, we further examined the effect of intraplantar ketorolac on neuropeptide expression in the dorsal horn following carrageenan inflammation. We observed that co-administration of ketorolac with carrageenan in the hindpaw also reduced SP- and dynorphin-IR in the ipsilateral and contralateral dorsal horn. These findings are in contrast to our hypothesis, suggesting that peripherally over-produced PGs following nerve injury and inflammation possibly contribute to the production of SP and CGRP in primary sensory neurons, to the up-regulation of dynorphin in the dorsal horn neurons, and finally to the mechanisms of neuropathic and inflammation pain.

A randomised controlled study on the use of anti-inflammatory drugs in patients with cancer pain on morphine therapy: effects on dose-escalation and a pharmacoeconomic analysis

The role of non-steroidal anti-inflammatory drugs (NSAIDs) in cancer pain has been well established in the treatment of mild pain and in association with opioids in the treatment of moderate to severe pain. The aim of this study was to verify the effects of NSAIDs on morphine escalation in advanced cancer patients with pain followed-up at home and to assess the pharmacoeconomic implications. A prospective randomised controlled study was carried out in 156 consecutive advanced cancer patients with pain followed-up at home in the period December 1999-December 2000. In this group of patients, 47 were selected with pain progression after 1 week of opioid stabilisation. Patients were randomly assigned to one of two groups: group 'O' patients were treated with continuing opioid escalation according to their clinical needs; group 'OK' received ketorolac 60 mg/daily orally (p.o.) in three doses and then continued opioid escalation according to their clinical situation. Performance status, doses of morphine before and after starting treatment, mean weekly pain intensity (assessed by means of a numerical scale from 0 to 10), mean weekly symptoms intensity, adverse effects and pain mechanisms were recorded. Moreover, drug costs per day in both groups were calculated. Patients who received ketorolac in addition to morphine showed a better analgesia after a week in comparison to the group treated with morphine only (P=0.005). Thereafter, morphine escalation was slower and the maximum morphine dose was lower in the group treated with ketorolac. The incidence and the severity of gastric discomfort was more evident in patients treated with ketorolac, while constipation was significantly increased in patients who received morphine only. Drug costs per day were similar in both groups; statistical differences were observed in patients who started on lower morphine doses (<100 mg/daily) in the two groups (4.3 in the ketorolac-morphine group versus 3.4 in the morphine group; P=0.012). The use of NSAIDs reduces the need for an opioid dose escalation or allows the use of lower doses. Their use is associated with a more intense gastric discomfort, but results in less opioid-related constipation. The eventual additive cost for NSAIDs therapy is negligible, especially in patients taking high doses of morphine.

Role for both spinal cord COX-1 and COX-2 in maintenance of mechanical hypersensitivity following peripheral nerve injury

The effectiveness of non-steroidal anti-inflammatory drugs (NSAIDs) in treating neuropathic pain caused by nerve injury has been controversial. In the present study, 4 weeks following partial sciatic nerve ligation, a single intrathecal injection of the cyclooxygenase (COX)-1 preferring inhibitor ketorolac (50 microg) significantly attenuated tactile allodynia for 6 days. The COX-2 preferring inhibitor, NS-398 (60 microg) significantly reversed tactile allodynia 2 h following injection but this anti-allodynic effect did not last greater than 24 h. Surprisingly, the non-selective COX inhibitor, piroxicam (60 microg) was without effect. These data agree with previous studies suggesting that spinal prostaglandin synthesis is important in the maintenance of hypersensitivity states following nerve injury. They differ from results in other models by suggesting that both COX isoenzymes are important in this spinal process, and for the first time demonstrate a remarkably long duration of action from a single intrathecal injection of ketorolac. Inhibition of spinal COX may be an important mechanism of action in treating some patients with neuropathic pain following peripheral nerve injury.

Pharmacologic treatment of neuropathic pain

Neuropathic pain, or pain after nervous system injury, can be very refractory to pharmacologic interventions. Through a better understanding of the pathophysiology of neuropathic pain, it has been suggested that nonopioid agents, such as antidepressants and anticonvulsants, may be more efficacious in the treatment of neuropathic pain than common analgesics, such as opioids or nonsteroidal anti-inflammatory drugs. However, this has not been consistently demonstrated in clinical studies. Conversely, many confounding factors of neuropathic pain make it difficult to interpret clinical studies. Therefore, we must develop a better understanding of the preclinical models of neuropathic pain to better understand the application of new and old drugs to the human neuropathic pain state. This article provides an overview of the commonly used preclinical neuropathic pain models, followed by a summary of the efficacy of currently available agents in preclinical pain models and human correlates.

Opioid poorly-responsive cancer pain. Part 3. Clinical strategies to improve opioid responsiveness

Some pain syndromes may be difficult to treat due to a poor response to opioids. This situation demands a range of alternative measures, including the use of adjuvant drugs with independent effects, such as antidepressants, sodium channel-blocking agents, steroids and anti-inflammatory drugs (NSAIDs); drugs that reduce opioid side effects; and drugs that enhance analgesia produced by opioids, such as N-methyl-D-aspartate (NMDA) antagonists, calcium channel antagonists, and clonidine. Other approaches, including opioid trials, neural blockade when necessary, and psychological interventions, also may be useful.

Analgesic effects of nonsteroidal anti-inflammatory drugs in cancer pain due to somatic or visceral mechanisms

The role of nonsteroidal anti-inflammatory drugs (NSAIDs) is well established in the treatment of cancer pain. This class of drugs is considered particularly effective in pain due to somatic mechanisms, although proof of this observation is lacking. To ascertain whether NSAIDs are more effective in specific nociceptive forms of cancer pain, they were administered alone or added to opioids in 32 patients with a sole pain mechanism, somatic pain due to bone metastases (17 patients) or visceral pain (15 patients), respectively. Pain intensity, mean doses of opioids used, and symptoms were recorded after starting NSAID. A significant reduction in pain intensity was found at 3, 7, and 14 days. No differences in pain intensity between the two groups were observed. However, patients with a visceral mechanism required higher opioid doses after a week of treatment. No differences in adverse effects were reported. NSAIDs may be useful drugs in the management of cancer pain, regardless of the mechanism of pain involved. The incidence of adverse effects during prolonged administration should be assessed in future studies.

Prolonged central intravenous ketorolac continuous infusion in a cancer patient with intractable bone pain

OBJECTIVE

To report the case of a prolonged intravenous ketorolac continuous infusion given via a central line in a cancer patient with intractable bone pain.

CASE SUMMARY

A 56-year-old Hispanic man with stage IV non-small-cell lung cancer and multiple bone metastases was admitted to the hospital for intractable pain inadequately controlled at home by conventional therapy. He was treated with an intravenous continuous infusion of ketorolac 120 mg in 250 mL of NaCl 0.9% infused over 24 hours. The ketorolac was given via a central line for 14 days in addition to fentanyl patient-controlled analgesia. Over this time period the patient reported his pain to be well controlled. His requests for bolus doses of fentanyl decreased dramatically and the dose of the continuous intravenous fentanyl was reduced by 22%. In addition, the total daily dose of ketorolac was reduced following a change from intermittent bolus dosing to a continuous infusion.

DISCUSSION

The management of cancer pain secondary to bone metastasis is a difficult and challenging problem frequently encountered by the healthcare team. The use of nonsteroidal antiinflammatory drugs (NSAIDs) as adjuvant therapy is a common practice. However, many terminally ill patients are unable to take oral medications, thus limiting NSAID treatment options. Ketorolac tromethamine is approved by the Food and Drug Administration (FDA) as a parenteral NSAID. As with other NSAIDs, the risk of adverse drug reactions must be considered when using this class of medication. The FDA has approved ketorolac for the short-term (< or = 5 d) management of moderately severe acute pain that requires analgesia at the opioid level, usually in the postoperative setting. However, certain patients may benefit from long-term use exceeding the FDA-recommended guidelines of 5 days of maximum therapy.

CONCLUSIONS

A prolonged central intravenous ketorolac continuous infusion was successful in treating a cancer patient with intractable bone pain secondary to widely metastatic non-small-cell lung cancer.