The Use of Very-Low-Dose Methadone and Haloperidol for Pain Control in the Hospital Setting: A Preliminary Report

Haloperidol for Pain Management: A Narrative Review

The use of haloperidol in pain management has been a topic of interest for several decades. Haloperidol is a widely used antipsychotic medication with unique pharmacologic properties that make it a potential candidate for pain management. However, the efficacy and safety of haloperidol for pain management remain controversial. This narrative review provides a summary of the current literature on the use of haloperidol for pain management, including its pharmacology, clinical effectiveness, adverse effects, and dosing regimens. We performed a comprehensive search of the literature for this review. The most robust clinical data from the past decade suggest that haloperidol has good efficacy in the treatment of pain related to gastroparesis and migraines and has shown promise for opioid use reduction in patients with chronic pain or receiving palliative care. The overall side effect profile is excellent, with zero reported events of QT-related cardiac arrest and minimal reports of sedation and transient extrapyramidal effects such as akathisia. Dosing regimens used were heterogeneous, with most ranging from 1 to 5 mg per dose via intravenous, intramuscular, or oral route. Studies with designs that isolated the effects of haloperidol from combinations of other drugs were extremely limited. Further high-quality prospective studies are needed to determine the ideal role of haloperidol in the routine clinical management of painful conditions.

Antinociceptive effect of LMH-2, a new sigma-1 receptor antagonist analog of haloperidol, on the neuropathic pain of diabetic mice

This study evaluates the antiallodynic and antihyperalgesic effects of LMH-2, a new haloperidol (HAL) analog that acts as sigma-1 receptor (σ1 R) antagonist, in diabetic mice using a model of neuropathic pain induced by chronic hyperglycemia. Additionally, we compared its effects with those of HAL. Hyperglycemia was induced in mice by nicotinamide-streptozotocin administration (NA-STZ, 50-130 mg/kg). Four weeks later, mechanical allodynia was assessed using the up-down method, and hyperalgesia was evoked with formalin 0.5%. We evaluated antiallodynic and antihyperalgesic effects of LMH-2 (5.6-56.2 mg/kg), HAL (0.018-0.18 mg/kg) and gabapentin (GBP, 5.6-56.2 mg/kg). The results showed that LMH-2 had a more significant antiallodynic effect compared to HAL and GBP (90.4±8.7 vs 75.1±3.1 and 41.9±2.3%, respectively; P<0.05), as well as an antihyperalgesic effect (96.3±1.2 vs 86.9±7.41 and 86.9±4.8%, respectively; P<0.05). Moreover, the antiallodynic and antihyperalgesic effect of both LMH-2 and HAL were completely abolished by PRE-084 (σ1 R agonist); and partially by pramipexole (a D2-like receptor agonist). Finally, the effect of all treatments on the rotarod test, barra, open field and exploratory behaviors showed that LMH-2 did not alter the animals' balance or the exploratory behavior, unlike as HAL or GBP. The molecular docking included indicate that LMH-2 has lower affinity to the D2R than HAL. These results provide evidence that LMH-2 exerts its antinociceptive effects as a σ1 R antagonist without the adverse effects induced by HAL or GBP. Consequently, LMH-2 can be considered a good and safe strategy for treating neuropathic pain caused by hyperglycemia in patients with diabetes.

Quetiapine and other antipsychotics combined with opioids in legal autopsy cases: A random finding or cause of fatal outcome?

Opioid poisoning is a frequent cause of death in drug addicts and occurs with opioid treatment. Quetiapine is often found in forensic autopsies and may increase the risk of fatal opioid poisoning by enhancing sedation, respiratory depression, hypotension and QT prolongation. We systematically searched for studies of acute toxicity of quetiapine or other antipsychotics combined with morphine or methadone. Case reports describing toxicity of quetiapine combined with morphine or methadone were also included. We retrieved one human study that observed pharmacokinetic interaction between quetiapine and methadone, and 16 other human studies. Fourteen investigated the combination of droperidol and morphine in treatment doses, and some indicated an additive sedative effect. Five animal studies with acepromazine in combination with morphine or methadone were located and indicated an additive effect on sedation and hypotension. Six forensic case reports in which death could have been caused solely by quetiapine, the opioid, or other drugs were found. Thus, acute toxicity of quetiapine combined with morphine or methadone has not been studied. Because of quetiapine's effects on alpha-adrenoceptors, muscarinic and histamine receptors, human ether-a-go-go-channels and methadone kinetics, we suggest further research to clarify if the indicated additive effects of opioids and droperidol or acepromazine are also true for quetiapine.

Continuous subcutaneous infusion for pain control in dying patients: experiences from a tertiary palliative care center

BACKGROUND

Continuous subcutaneous infusion (CSCI) via ambulatory infusion pump (AIP) is a valuable method of pain control in palliative care. When using CSCI, low-dose methadone as add-on to other opioids might be an option in complex pain situations. This study aimed to investigate the effects, and adverse effects, of CSCI for pain control in dying patients, with particular interest in methadone use.

METHODS

This was an observational cohort study. Imminently dying patients with pain, admitted to specialized palliative inpatient wards and introduced on CSCI, were monitored daily by staff for symptoms (Integrated Palliative Care Outcome Scale - IPOS), sedation (Richmond Agitation and Sedation Scale - RASS), performance status (Eastern Cooperative Oncology Group - ECOG) and delirium (Confusion Assessment Method - CAM).

RESULTS

Ninety-three patients with a median survival of 4 days were included. Of the 47 patients who survived ≥3 days, the proportion of patients with severe/overwhelming pain decreased from 45 to 19% (p < 0.001) after starting CSCI, with only a moderate increase in morphine equivalent daily dose of opioids (MEDD). Alertness was marginally decreased (1 point on the 10-point RASS scale, p = 0.001), whereas performance status and prevalence of delirium, regardless of age, remained unchanged. Both patients with methadone as add-on (MET, n = 13) and patients with only other opioids (NMET, n = 34), improved in pain control (p < 0.05 and 0.001, respectively), despite that MET patients had higher pain scores at baseline (p < 0.05) and were on a higher MEDD (240 mg vs.133 mg). No serious adverse effects demanding treatment stop were reported.

CONCLUSIONS

CSCI via AIP is an effective way to reduce pain in dying patients without increased adverse effects. Add-on methadone may be beneficial in patients with severe complex pain.

Factors Associated with Improvement in Uncontrolled Cancer Pain without Increasing the Opioid Daily Dose among Patients Seen by an Inpatient Palliative Care Team

Background: Increasing the total opioid dose is the standard approach for managing uncontrolled cancer pain. Other than simply increasing the opioid dose, palliative care interventions are multidimensional and may improve pain control in the absence of opioid dose increase. Objective: The purpose of this study was to determine the proportion of patients referred to our inpatient palliative care (IPC) team who achieved clinically improved pain (CIP) without opioid dose increase. Design: We reviewed consecutive patients referred to our IPC team. Setting/Subjects: Eligibility criteria included (1) taking opioid medication; (2) having ≥2 consecutive visits with the IPC team; and (3) an Edmonton Symptom Assessment Scale (ESAS) pain score ≥4 at consultation. Measurements: We assessed patient demographics and clinical variables, including cancer type, opioid prescription data (type, route, and oral morphine equivalent daily dose [MEDD]), presence of opioid rotation, psychological consultation, changes in adjuvant medications (e.g., corticosteroids; antiepileptics-gabapentin and pregabalin; benzodiazepines; and neuroleptics), and achievement of CIP. Results: Of the 300 patients enrolled, CIP was achieved in 196 (65%) patients. Of CIP patients, 85 (43%) achieved CIP without an increase in MEDD. CIP without MEDD increase was associated with more adjuvant medication changes (p = 0.003), less opioid rotation (p = 0.005), and lower symptom distress scale of ESAS (p = 0.04). Conclusions: Nearly half of the patients achieved CIP without MEDD increase, suggesting that the multidimensional palliative care intervention is effective in improving pain control in many opioid-tolerant patients without the need to increase the opioid dose.

Targeting Neuropathic Pain: Pathobiology, Current Treatment and Peptidomimetics as a New Therapeutic Opportunity

There is a huge need for pharmaceutical agents for the treatment of chronic Neuropathic Pain (NP), a complex condition where patients can suffer from either hyperalgesia or allodynia originating from central or peripheral nerve injuries. To date, the therapeutic guidelines include the use of tricyclic antidepressants, serotonin-noradrenaline reuptake inhibitors and anticonvulsants, beside the use of natural compounds and non-pharmacological options. Unfortunately, these drugs suffer from limited efficacy and serious dose-dependent adverse effects. In the last decades, the heptapeptide SP1-7, the major bioactive metabolite produced by Substance P (SP) cleavage, has been extensively investigated as a potential target for the development of novel peptidomimetic molecules to treat NP. Although the physiological effects of this SP fragment have been studied in detail, the mechanism behind its action is not fully clarified and the target for SP1-7 has not been identified yet. Nevertheless, specific binding sites for the heptapeptide have been found in brain and spinal cord of both mouse and rats. Several Structure-Affinity Relationship (SAR) studies on SP1-7 and some of its synthetic analogues have been carried out aiming to developing more metabolically stable and effective small molecule SP1-7-related amides that could be used as research tools for a better understanding of the SP1-7 system and, in a longer perspective, as potential therapeutic agents for future treatment of NP.

Safe and Appropriate Use of Methadone in Hospice and Palliative Care: Expert Consensus White Paper

Methadone has several unique characteristics that make it an attractive option for pain relief in serious illness, but the safety of methadone has been called into question after reports of a disproportionate increase in opioid-induced deaths in recent years. The American Pain Society, College on Problems of Drug Dependence, and the Heart Rhythm Society collaborated to issue guidelines on best practices to maximize methadone safety and efficacy, but guidelines for the end-of-life scenario have not yet been developed. A panel of 15 interprofessional hospice and palliative care experts from the U.S. and Canada convened in February 2015 to evaluate the American Pain Society methadone recommendations for applicability in the hospice and palliative care setting. The goal was to develop guidelines for safe and effective management of methadone therapy in hospice and palliative care. This article represents the consensus opinion of the hospice and palliative care experts for methadone use at end of life, including guidance on appropriate candidates for methadone, detail in dosing, titration, and monitoring of patients' response to methadone therapy.

Neuroleptanalgesia for acute abdominal pain: a systematic review

BACKGROUND

Acute abdominal pain (AAP) comprises up to 10% of all emergency department (ED) visits. Current pain management practice is moving toward multi-modal analgesia regimens that decrease opioid use.

OBJECTIVE

This project sought to determine whether, in patients with AAP (population), does administration of butyrophenone antipsychotics (intervention) compared to placebo, usual care, or opiates alone (comparisons) improve analgesia or decrease opiate consumption (outcomes)?

METHODS

A structured search was performed in Cochrane CENTRAL, CINAHL, Database of Abstracts of Reviews of Effects, Directory of Open Access Journals, Embase, IEEE-Xplorer, Latin American and Caribbean Health Sciences Literature, Magiran, PubMed, Scientific Information Database, Scopus, TÜBİTAK ULAKBİM, and Web of Science. Clinical trial registries (ClinicalTrials.gov, World Health Organization International Clinical Trials Registry Platform, and Australian New Zealand Clinical Trials Registry), relevant bibliographies, and conference proceedings were also searched. Searches were not limited by date, language, or publication status. Studies eligible for inclusion were prospective randomized clinical trials enrolling patients (age ≥18 years) with AAP treated in acute care environments (ED, intensive care unit, postoperative). The butyrophenone must have been administered either intravenously or intra-muscularly. Comparison groups included placebo, opiate only, corticosteroids, non-steroidal anti-inflammatory drugs, or acetaminophen.

RESULTS

We identified 7,217 references. Six studies met inclusion criteria. One study assessed ED patients with AAP associated with gastroparesis, whereas five studies assessed patients with postoperative AAP: abdominal hysterectomy (n=4), sleeve gastrectomy (n=1). Three of four studies found improvements in pain intensity with butyrophenone use. Three of five studies reported no change in postoperative opiate consumption, while two reported a decrease. One ED study reported no change in patient satisfaction, while one postoperative study reported improved satisfaction scores. Both extrapyramidal side effects (n=3) and sedation (n=3) were reported as unchanged.

CONCLUSION

Based on available evidence, we cannot draw a conclusion on the efficacy or benefit of neuroleptanalgesia in the management of patients with AAP. However, preliminary data suggest that it may improve analgesia and decrease opiate consumption.

Methadone: Maximizing Safety and Efficacy for Pain Control in Patients with Cancer

Methadone is a valuable opioid in the management of patients who have cancer with pain. Methadone is a mu-, kappa-, and delta-opioid agonist, and an N-methyl-D-aspartate receptor antagonist. These mechanisms of action make methadone an attractive option for complex pain syndromes. It is critically important that providers consider a patient's risk status before beginning methadone. Careful consideration must be given to dosing methadone in both opioid-naïve and opioid-tolerant patients, with vigilant monitoring for therapeutic effectiveness and potential toxicity until the patient achieves steady state.

Methadone as a First-Line Opioid in Cancer Pain Management: A Systematic Review

AIM

The objective of this review was to assess the existent evidence for the use of methadone as a first-line therapy in cancer pain management.

METHODS

A systematic literature search on MEDLINE and Embase databases was carried out from each database, setting up the date to August 30, 2017. Studies were included if methadone was a first-line drug as a Step 3 of World Health Organization analgesic ladder, or at low doses (Step 2), if they were conducted in adult patients with cancer pain, and if they contained outcomes on pain- and opioid-related adverse effects.

RESULTS

The initial search yielded 219 records. Ten articles were considered after the initial screening according to inclusion and exclusion criteria. They included three longitudinal open-label studies. In two studies methadone was initiated at low doses (≤10 mg/day). These studies suggested that methadone was effective in providing analgesia and well tolerated as first opioid at different starting doses and in different conditions and settings. Five additional studies were randomized controlled studies with morphine in patients who had received opioids for moderate pain. Methadone, compared with oral morphine, or transdermal fentanyl, either at low (Step 2 level) or relatively higher doses (Step 3 level), provided similar analgesia with similar adverse effects profile with limited dose escalation in time.

CONCLUSION

Available data are not sufficient to draw net conclusion. However, open-label and controlled studies have shown that methadone may be effective as first-line drug in the management of cancer pain, providing analgesia and adverse effect profiles similar to those produced by other opioids. The finding that methadone doses tend to remain stable suggests that metabolic characteristics and extraopioid analgesic effects, as its well antihyperalgesic properties may be interesting potential advantages. Further studies should provide information regarding the long-term use of methadone or the need to switch from methadone to other opioids when a loss of analgesic response occurs.

Practical Pharmacology of Methadone: A Long-acting Opioid

Methadone is a naturally long-acting analgesic with unique pharmacodynamic and pharmacokinetic properties compared to other opioids, available now in India, to treat severe pain. It has the potential to dramatically relieve suffering among patients with serious illness who are living with persistent physical pain. However, clinicians must appreciate its unique pharmacologic properties and its use in clinical practice safely and effectively. The available formulation in India is a racemic mixture of the S- and R-enantiomers, and as such, it will have a propensity for drug-drug and drug-genetic interactions that can increase the risk of Torsades de Point and respiratory depression. Appropriate patient selection, careful dosing and thorough monitoring of methadone will mitigate these risks.

Randomized Controlled Double-blind Trial Comparing Haloperidol Combined With Conventional Therapy to Conventional Therapy Alone in Patients With Symptomatic Gastroparesis

OBJECTIVE

Gastroparesis is a debilitating condition that causes nausea, vomiting, and abdominal pain. Management includes analgesics and antiemetics, but symptoms are often refractory. Haloperidol has been utilized in the palliative care setting for similar symptoms. The study objective was to determine whether haloperidol as an adjunct to conventional therapy would improve symptoms in gastroparesis patients presenting to the emergency department (ED).

STUDY DESIGN AND METHODS

This was a randomized, double-blind, placebo-controlled trial of adult ED patients with acute exacerbation of previously diagnosed gastroparesis. The treatment group received 5 mg of haloperidol plus conventional therapy (determined by the treating physician). The control group received a placebo plus conventional therapy. The severity of each subject's abdominal pain and nausea were assessed before intervention and every 15 minutes thereafter for 1 hour using a 10-point scale for pain and a 5-point scale for nausea. Primary outcomes were decreased pain and nausea 1 hour after treatment.

RESULTS

Of the 33 study patients, 15 were randomized to receive haloperidol. Before treatment, the mean intensity of pain was 8.5 in the haloperidol group and 8.28 in the placebo group; mean pretreatment nausea scores were 4.53 and 4.11, respectively. One hour after therapy, the mean pain and nausea scores in the haloperidol group were 3.13 and 1.83 compared to 7.17 and 3.39 in the placebo group. The reduction in mean pain intensity therapy was 5.37 in the haloperidol group (p ≤ 0.001) compared to 1.11 in the placebo group (p = 0.11). The reduction in mean nausea score was 2.70 in the haloperidol group (p ≤ 0.001) and 0.72 in the placebo group (p = 0.05). Therefore, the reductions in symptom scores were statistically significant in the haloperidol group but not in the placebo group. No adverse events were reported.

CONCLUSIONS

Haloperidol as an adjunctive therapy is superior to placebo for acute gastroparesis symptoms.

Very-Low-Dose Methadone To Treat Refractory Neuropathic Pain in Children with Cancer

BACKGROUND

Compared with nociceptive pain, neuropathic pain is a challenging diagnosis to make and successfully treat in children with cancer.

OBJECTIVE

The objective of this case report was to see whether very-low-dose methadone (VLDM) (defined as <50% of accepted starting analgesic dose of methadone for children) would be an effective strategy to treat refractory neuropathic pain due to vincristine in two children with acute lymphoblastic leukemia.

METHODS

This case report is based on the clinical experience and parent-reported outcomes of two children with refractory neuropathic pain who received VLDM.

RESULTS

Based on parent/caregiver-reported outcome scores over a one-year period, both children's refractory neuropathic pain syndrome was successfully treated with the addition of VLDM to their pre-existing regimen of gabapentin. Neither child suffered any adverse effects from methadone.

CONCLUSIONS

VLDM shows promise as an effective, safe, and inexpensive way to treat refractory neuropathic pain in children with cancer.

Endogenous Opiates and Behavior: 2015

This paper is the thirty-eighth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2015 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia, stress and social status, tolerance and dependence, learning and memory, eating and drinking, drug abuse and alcohol, sexual activity and hormones, pregnancy, development and endocrinology, mental illness and mood, seizures and neurologic disorders, electrical-related activity and neurophysiology, general activity and locomotion, gastrointestinal, renal and hepatic functions, cardiovascular responses, respiration and thermoregulation, and immunological responses.

Investigational sigma-1 receptor antagonists for the treatment of pain

INTRODUCTION

The sigma-1 receptor (σ1R) is a ligand-regulated molecular chaperone that interacts with other proteins, including NMDA and opioid receptors, to modulate their activity. Convergent evidence indicates that σ1R antagonists exert inhibitory effects (and agonists stimulatory effects) on pain by stepping down the intracellular signaling cascades involved in transduction of noxious stimuli and plastic changes (i.e., sensitization phenomena) associated with chronic pain states.

AREAS COVERED

This review addresses three primary domains. The first focuses on mechanisms underlying the antinociceptive effects of σ1R antagonists. The second addresses evidence gained using pharmacological tools and experimental drugs in the discovery phase and clinical development. Finally, the article outlines the potential benefits of σ1R antagonists, alone or in combination, in the context of available pain therapeutics.

EXPERT OPINION

There is a critical need for new analgesics based on new mechanisms of action. Target identification requires convincing evidence relating targets to function. In turn, target validation requires confirmation of therapeutic benefits, ideally in humans. Current preclinical evidence provides strong rationale for σ1R antagonists in pain. The outcome of clinical studies with the most advanced investigational σ1R antagonist, S1RA (E-52862), will be of great interest to ascertain the potential of this new therapeutic approach to pain management.