A randomized, double-blind, placebo-controlled study of intrathecal ziconotide in adults with severe chronic pain

A comprehensive review on ziconotide

Managing severe chronic pain is a challenging task, given the limited effectiveness of available pharmacological and non-pharmacological treatments. This issue continues to be a significant public health concern, requiring a substantial therapeutic response. Ziconotide, a synthetic peptide initially isolated from Conus magus in 1982 and approved by the US Food and Drug Administration and the European Medicines Agency in 2004, is the first-line intrathecal method for individuals experiencing severe chronic pain refractory to other therapeutic measures. Ziconotide produces powerful analgesia by blocking N-type calcium channels in the spinal cord, which inhibits the release of pain-relevant neurotransmitters from the central terminals of primary afferent neurons. However, despite possessing many favorable qualities, including the absence of tolerance development, respiratory depression, and withdrawal symptoms (largely due to the absence of a G-protein mediation mechanism), ziconotide's application is limited due to factors such as intrathecal administration and a narrow therapeutic window resulting from significant dose-related undesired effects of the central nervous system. This review aims to provide a comprehensive and clinically relevant summary of the literatures concerning the pharmacokinetics and metabolism of intrathecal ziconotide. It will also describe strategies intended to enhance clinical efficacy while reducing the incidence of side effects. Additionally, the review will explore the current efforts to refine the structure of ziconotide for better clinical outcomes. Lastly, it will prospect potential developments in the new class of selective N-type voltage-sensitive calcium-channel blockers.

A Systematic Guideline by the ASPN Workgroup on the Evidence, Education, and Treatment Algorithm for Painful Diabetic Neuropathy: SWEET

Introduction

Painful diabetic neuropathy (PDN) is a leading cause of pain and disability globally with a lack of consensus on the appropriate treatment of those suffering from this condition. Recent advancements in both pharmacotherapy and interventional approaches have broadened the treatment options for PDN. There exists a need for a comprehensive guideline for the safe and effective treatment of patients suffering from PDN.

Objective

The SWEET Guideline was developed to provide clinicians with the most comprehensive guideline for the safe and appropriate treatment of patients suffering from PDN.

Methods

The American Society of Pain and Neuroscience (ASPN) identified an educational need for a comprehensive clinical guideline to provide evidence-based recommendations for PDN. A multidisciplinary group of international experts developed the SWEET guideline. The world literature in English was searched using Medline, EMBASE, Cochrane CENTRAL, BioMed Central, Web of Science, Google Scholar, PubMed, Current Contents Connect, Meeting Abstracts, and Scopus to identify and compile the evidence for diabetic neuropathy pain treatments (per section as listed in the manuscript) for the treatment of pain. Manuscripts from 2000-present were included in the search process.

Results

After a comprehensive review and analysis of the available evidence, the ASPN SWEET guideline was able to rate the literature and provide therapy grades for most available treatments for PDN utilizing the United States Preventive Services Task Force criteria.

Conclusion

The ASPN SWEET Guideline represents the most comprehensive review of the available treatments for PDN and their appropriate and safe utilization.

A phage-displayed disulfide constrained peptide discovery platform yields novel human plasma protein binders

Disulfide constrained peptides (DCPs) show great potential as templates for drug discovery. They are characterized by conserved cysteine residues that form intramolecular disulfide bonds. Taking advantage of phage display technology, we designed and generated twenty-six DCP phage libraries with enriched molecular diversity to enable the discovery of ligands against disease-causing proteins of interest. The libraries were designed based on five DCP scaffolds, namely Momordica charantia 1 (Mch1), gurmarin, Asteropsin-A, antimicrobial peptide-1 (AMP-1), and potato carboxypeptidase inhibitor (CPI). We also report optimized workflows for screening and producing synthetic and recombinant DCPs. Examples of novel DCP binders identified against various protein targets are presented, including human IgG Fc, serum albumin, vascular endothelial growth factor-A (VEGF-A) and platelet-derived growth factor (PDGF). We identified DCPs against human IgG Fc and serum albumin with sub-micromolar affinity from primary panning campaigns, providing alternative tools for potential half-life extension of peptides and small protein therapeutics. Overall, the molecular diversity of the DCP scaffolds included in the designed libraries, coupled with their distinct biochemical and biophysical properties, enables efficient and robust identification of de novo binders to drug targets of therapeutic relevance.

IUPHAR review: Navigating the role of preclinical models in pain research

Chronic pain is a complex and challenging medical condition that affects millions of people worldwide. Understanding the underlying mechanisms of chronic pain is a key goal of preclinical pain research so that more effective treatment strategies can be developed. In this review, we explore nociception, pain, and the multifaceted factors that lead to chronic pain by focusing on preclinical models. We provide a detailed look into inflammatory and neuropathic pain models and discuss the most used animal models for studying the mechanisms behind these conditions. Additionally, we emphasize the vital role of these preclinical models in developing new pain-relief drugs, focusing on biologics and the therapeutic potential of NMDA and cannabinoid receptor antagonists. We also discuss the challenges of TRPV1 modulation for pain treatment, the clinical failures of neurokinin (NK)- 1 receptor antagonists, and the partial success story of Ziconotide to provide valuable lessons for preclinical pain models. Finally, we highlight the overall success and limitations of current treatments for chronic pain while providing critical insights into the development of more effective therapies to alleviate the burden of chronic pain.

Education and Experience in Intrathecal Drug Delivery Systems (IDDS) During Pain Medicine Fellowships

Objective

Targeted drug delivery (TDD) via intrathecal drug delivery systems (IDDS) exposure and clinical adoption remains low despite multiple well-designed trials that demonstrate safety, efficacy, reliability, and cost-saving benefits. This study aims to understand the possible contributing factors starting with Pain Medicine fellowship training.

Materials and Methods

An internet-based, anonymous pilot survey was distributed to pain medicine fellows enrolled in an Accreditation Council for Graduate Medical Education (ACGME) accredited pain medicine training program during the 2021-2022 academic year. Fellowship programs were identified using published online ACGME accreditation data. The survey was distributed via email to fellowship program directors and coordinators and was made available through pain medicine societies.

Results

Seventy-one of four hundred and twenty-three pain medicine fellows (17% response rate) completed the survey. Nine percent of respondents evidence-informed opinion coincided with the most recent Polyanalgesic Consensus Conference (PACC) guidelines recommendations for IDDS treatment indications. Fifty-one percent of respondents felt there was an unmet need for IDDS training. About one-third of respondents felt that lack of curriculum, faculty, and cases were barriers to IDDS use, respectively. Thirty-one percent of fellows reported sufficient training for IDDS in their fellowship programs. The majority (70%) of respondents somewhat or strongly support direct training by IDDS manufacturers.

Conclusion

A wide variability exists surrounding IDDS training during ACGME accredited pain medicine fellowship. Insufficient case exposure and lack of a standardized curriculum may play a role in future therapy adoption. The results from this study call for a more standardized training approach with an emphasis on adequate clinical exposure, utilization of peer reviewed educational curriculum and supplemental material to aid pain medicine fellows' education.

Machine learning analysis predicts a person's sex based on mechanical but not thermal pain thresholds

Sex differences in pain perception have been extensively studied, but precision medicine applications such as sex-specific pain pharmacology have barely progressed beyond proof-of-concept. A data set of pain thresholds to mechanical (blunt and punctate pressure) and thermal (heat and cold) stimuli applied to non-sensitized and sensitized (capsaicin, menthol) forearm skin of 69 male and 56 female healthy volunteers was analyzed for data structures contingent with the prior sex structure using unsupervised and supervised approaches. A working hypothesis that the relevance of sex differences could be approached via reversibility of the association, i.e., sex should be identifiable from pain thresholds, was verified with trained machine learning algorithms that could infer a person's sex in a 20% validation sample not seen to the algorithms during training, with balanced accuracy of up to 79%. This was only possible with thresholds for mechanical stimuli, but not for thermal stimuli or sensitization responses, which were not sufficient to train an algorithm that could assign sex better than by guessing or when trained with nonsense (permuted) information. This enabled the translation to the molecular level of nociceptive targets that convert mechanical but not thermal information into signals interpreted as pain, which could eventually be used for pharmacological precision medicine approaches to pain. By exploiting a key feature of machine learning, which allows for the recognition of data structures and the reduction of information to the minimum relevant, experimental human pain data could be characterized in a way that incorporates "non" logic that could be translated directly to the molecular pharmacological level, pointing toward sex-specific precision medicine for pain.

The American Society of Pain and Neuroscience (ASPN) Evidence-Based Clinical Guideline of Interventional Treatments for Low Back Pain

Introduction

Painful lumbar spinal disorders represent a leading cause of disability in the US and worldwide. Interventional treatments for lumbar disorders are an effective treatment for the pain and disability from low back pain. Although many established and emerging interventional procedures are currently available, there exists a need for a defined guideline for their appropriateness, effectiveness, and safety.

Objective

The ASPN Back Guideline was developed to provide clinicians the most comprehensive review of interventional treatments for lower back disorders. Clinicians should utilize the ASPN Back Guideline to evaluate the quality of the literature, safety, and efficacy of interventional treatments for lower back disorders.

Methods

The American Society of Pain and Neuroscience (ASPN) identified an educational need for a comprehensive clinical guideline to provide evidence-based recommendations. Experts from the fields of Anesthesiology, Physiatry, Neurology, Neurosurgery, Radiology, and Pain Psychology developed the ASPN Back Guideline. The world literature in English was searched using Medline, EMBASE, Cochrane CENTRAL, BioMed Central, Web of Science, Google Scholar, PubMed, Current Contents Connect, Scopus, and meeting abstracts to identify and compile the evidence (per section) for back-related pain. Search words were selected based upon the section represented. Identified peer-reviewed literature was critiqued using United States Preventive Services Task Force (USPSTF) criteria and consensus points are presented.

Results

After a comprehensive review and analysis of the available evidence, the ASPN Back Guideline group was able to rate the literature and provide therapy grades to each of the most commonly available interventional treatments for low back pain.

Conclusion

The ASPN Back Guideline represents the first comprehensive analysis and grading of the existing and emerging interventional treatments available for low back pain. This will be a living document which will be periodically updated to the current standard of care based on the available evidence within peer-reviewed literature.

Controversies in intrathecal drug delivery for cancer pain

Pain and suffering related to cancer are challenging issues that continue to deserve consideration for treatment optimization. Advances in analgesic management and control of the underlying cancer have improved symptom management, yet many patients still suffer from uncontrolled pain. Intrathecal drug delivery has an established role in the management of refractory cancer pain, but there are significant knowledge gaps in our understanding and application of this therapy. This review addresses several areas of controversy, including the importance of intrathecal catheter tip location, the necessity of an intrathecal trial and the role of intrathecal ziconotide and local anesthetics. In each area, the evidence is discussed, with an emphasis on presenting practical clinical guidance and highlighting deficiencies in our knowledge that are worthy of future investigation.

Evidence-Based Treatment of Painful Diabetic Neuropathy: a Systematic Review

PURPOSE OF REVIEW

Painful diabetic neuropathy (PDN) manifests with pain typically in the distal lower extremities and can be challenging to treat. The authors appraised the literature for evidence on conservative, pharmacological, and neuromodulation treatment options for PDN.

RECENT FINDINGS

Intensive glycemic control with insulin in patients with type 1 diabetes may be associated with lower odds of distal symmetric polyneuropathy compared to patients who receive conventional insulin therapy. First-line pharmacologic therapy for PDN includes gabapentinoids (pregabalin and gabapentin) and duloxetine. Additional pharmacologic modalities that are approved by the Food and Drug Administration (FDA) but are considered second-line agents include tapentadol and 8% capsaicin patch, although studies have revealed modest treatment effects from these modalities. There is level I evidence on the use of dorsal column spinal cord stimulation (SCS) for treatment of PDN, delivering either a 10-kHz waveform or tonic waveform. In summary, this review provides an overview of treatment options for PDN. Furthermore, it provides updates on the level of evidence for SCS therapy in cases of PDN refractory to conventional medical therapy.

Intrathecal Drug Delivery: Advances and Applications in the Management of Chronic Pain Patient

Advances in our understanding of the biology of spinal systems in organizing and defining the content of exteroceptive information upon which higher centers define the state of the organism and its role in the regulation of somatic and automatic output, defining the motor response of the organism, along with the unique biology and spatial organization of this space, have resulted in an increased focus on therapeutics targeted at this extracranial neuraxial space. Intrathecal (IT) drug delivery systems (IDDS) are well-established as an effective therapeutic approach to patients with chronic non-malignant or malignant pain and as a tool for management of patients with severe spasticity and to deliver therapeutics that address a myriad of spinal pathologies. The risk to benefit ratio of IDD makes it a useful interventional approach. While not without risks, this approach has a significant therapeutic safety margin when employed using drugs with a validated safety profile and by skilled practioners. The present review addresses current advances in our understanding of the biology and dynamics of the intrathecal space, therapeutic platforms, novel therapeutics, delivery technology, issues of safety and rational implementation of its therapy, with a particular emphasis upon the management of pain.

Small Molecules as Modulators of Voltage-Gated Calcium Channels in Neurological Disorders: State of the Art and Perspectives

Voltage-gated calcium channels (VGCCs) are widely expressed in the brain, heart and vessels, smooth and skeletal muscle, as well as in endocrine cells. VGCCs mediate gene transcription, synaptic and neuronal structural plasticity, muscle contraction, the release of hormones and neurotransmitters, and membrane excitability. Therefore, it is not surprising that VGCC dysfunction results in severe pathologies, such as cardiovascular conditions, neurological and psychiatric disorders, altered glycemic levels, and abnormal smooth muscle tone. The latest research findings and clinical evidence increasingly show the critical role played by VGCCs in autism spectrum disorders, Parkinson's disease, drug addiction, pain, and epilepsy. These findings outline the importance of developing selective calcium channel inhibitors and modulators to treat such prevailing conditions of the central nervous system. Several small molecules inhibiting calcium channels are currently used in clinical practice to successfully treat pain and cardiovascular conditions. However, the limited palette of molecules available and the emerging extent of VGCC pathophysiology require the development of additional drugs targeting these channels. Here, we provide an overview of the role of calcium channels in neurological disorders and discuss possible strategies to generate novel therapeutics.

Physicochemical Stability Study of the Morphine-Ropivacaine-Ziconotide Association in Implantable Pumps for Intrathecal Administration

PURPOSE

This study aimed to investigate the physicochemical stability of morphine-ropivacaine-ziconotide mixtures used in intrathecal analgesia.

MATERIALS AND METHODS

Eight mixtures were studied to assess their stability profiles according to the initial drug concentrations used. The solutions obtained were put in implantable pumps and stored at 37 °C over a period of 60 days. Assays were performed using ultra high-pressure liquid chromatography. Turbidity and pH were also measured throughout the study.

RESULTS

Results confirmed excellent physicochemical stability for morphine and ropivacaine. Concerning ziconotide, three of the eight mixtures did not show any sign of chemical instability: average concentrations remained constant throughout the 60 days. A decrease of the concentration was observed for the five other mixtures. Moreover, the appearance of a degradation product linked to oxidation confirmed the ziconotide degradation.

CONCLUSIONS

All these results are in favor of a physicochemical stable preparation for three of the mixture profiles when stored in implantable pumps at 37 °C up to 60 days. For the five others, the efficacy should decrease over time owing to the degradation of ziconotide. The decrease in kinetics of the ziconotide concentration depends on the mixing profile. One possibility is to adapt the filling intervals according to the profile of the mixture. Finally, the results show the period of stability ensuring maximum analgesic efficacy for the eight mixture profiles studied.

Comparison of quinazoline and benzoylpyrazoline chemotypes targeting the CaVα-β interaction as antagonists of the N-type CaV2.2 channel

Structural studies with an α subunit fragment of voltage-gated calcium (CaV) channels in complex with the CaVβ subunits revealed a high homology between the various CaVα-β subunits, predicting that targeting of this interface would result in nonselective compounds. Despite this likelihood, my laboratory initiated a rational structure-based screening campaign focusing on "hot spots" on the alpha interacting domain (AID) of the CaVβ2a subunits and identified the small molecule 2-(3,5-dimethylisoxazol-4-yl)-N-((4-((3-phenylpropyl)amino)quinazolin-2-yl)methyl)acetamide ( IPPQ ) which selectively targeted the interface between the N-type calcium (CaV2.2) channel and CaVβ. IPPQ (i) specifically bound to CaVβ2a; (ii) inhibited CaVβ2 's interaction with CaV.2-AID; (iii) inhibited CaV2.2 currents in sensory neurons; (iv) inhibited pre-synaptic localization of CaV2.2 in vivo; and (v) inhibited spinal neurotransmission, which resulted in decreased neurotransmitter release. IPPQ was anti-nociceptive in naïve rats and reversed mechanical allodynia and thermal hyperalgesia in rodent models of acute, neuropathic, and genetic pain. In structure-activity relationship (SAR) studies focused on improving binding affinity of IPPQ , another compound (BTT-369), a benzoyl-3,4-dihydro-1'H,2 H-3,4'-bipyrazole class of compounds, was reported by Chen and colleagues, based on work conducted in my laboratory beginning in 2008. BTT-369 contains tetraaryldihydrobipyrazole scaffold - a chemotype featuring phenyl groups known to be significantly metabolized, lower the systemic half-life, and increase the potential for toxicity. Furthermore, the benzoylpyrazoline skeleton in BTT-369 is patented across multiple therapeutic indications. Prior to embarking on an extensive optimization campaign of IPPQ , we performed a head-to-head comparison of the two compounds. We conclude that IPPQ is superior to BTT-369 for on-target efficacy, setting the stage for SAR studies to improve on IPPQ for the development of novel pain therapeutics.

Intrathecal Analgesia in Cancer Pain

The number of new cancer cases has been increasing globally over the last several decades.

The American Society of Pain and Neuroscience (ASPN) Best Practices and Guidelines for the Interventional Management of Cancer-Associated Pain

Moderate to severe pain occurs in many cancer patients during their clinical course and may stem from the primary pathology, metastasis, or as treatment side effects. Uncontrolled pain using conservative medical therapy can often lead to patient distress, loss of productivity, shorter life expectancy, longer hospital stays, and increase in healthcare utilization. Various publications shed light on strategies for conservative medical management for cancer pain and a few international publications have reviewed limited interventional data. Our multi-institutional working group was assembled to review and highlight the body of evidence that exists for opioid utilization for cancer pain, adjunct medication such as ketamine and methadone and interventional therapies. We discuss neurolysis via injections, neuromodulation including targeted drug delivery and spinal cord stimulation, vertebral tumor ablation and augmentation, radiotherapy and surgical techniques. In the United States, there is a significant variance in the interventional treatment of cancer pain based on fellowship training. As a first of its kind, this best practices and interventional guideline will offer evidenced-based recommendations for reducing pain and suffering associated with malignancy.

Short-Term Outcomes of a High-Volume, Low-Concentration Bolus Starting Dose Technique With Ziconotide: A Case Series

Background and Objectives

There have been numerous recommendations for a starting dose of intrathecal ziconotide. The therapy remains underutilized partially due to reports of inefficacy and/or intolerance. This study describes short‐term outcomes of a high‐volume, low‐concentration bolus (HVLC‐B) ziconotide starting dose technique for patients with chronic spine pain. Intrathecal pumps are available with a Patient Therapy Manager (PTM), or patient‐controlled intrathecal bolus device. Commonly published recommendations for a bolus dose has been 10% of the daily dose. This article describes an inversion of the traditional 10% rule‐of‐thumb. This article describes using the basal rate at a lowest programmable dose and utilizing the bolus for the majority of the medication delivery. Such an inversion may be considered a high volume bolus. The lowest commercially available concentration of ziconotide from the manufacturer is 25 mcg/mL. Pope and Deer (Neuromodulation, 18, 414–420 [2015]) described use of a dilution down to 5 mcg/mL. For purposes of this article, such dilutions to one‐fifth of the commercially available solution are considered sufficiently dilute to qualify for the term “low concentration.” Furthermore, the patients in this analysis received dilutions down to one‐fiftieth of the lowest commercially available solution.

Materials and Methods

A case series of patients with chronic spine pain with or without radicular pain received a starting dose intrathecal ziconotide regimen based on a specific HVLC‐B technique. Efficacy, tolerability, and pump settings are reported and analyzed.

Results

In total, 17 patients were identified who started ziconotide with the specified HVLC‐B starting regimen. One of the 17 patients reported side effects that led to discontinuation of the therapy, although the side effect was not typical of ziconotide but rather likely attributable to other medications the patient was taking. Fifteen of the 17 reported improved pain control with intrathecal ziconotide. Sixteen of the 17 patients remained on intrathecal ziconotide throughout the 4.7‐month average follow‐up period. One patient who failed to obtain pain relief chose to remain on the therapy because of reported resolution of lower limb numbness.

Conclusions

The HVLC‐B starting regimen was effective and well tolerated in this short‐term study of patients with chronic spine pain. More studies are needed to better elucidate long‐term outcomes in larger patient populations.

A safety review of approved intrathecal analgesics for chronic pain management

Introduction: Intrathecal (IT) drug therapy is an effective treatment option for patients with chronic pain of malignant or nonmalignant origin, with an established safety profile and fewer adverse effects compared to oral or parenteral pain medications. Morphine (a μ-opioid receptor agonist) and ziconotide (a non-opioid calcium channel antagonist) are the only IT agents approved by the U.S. Food and Drug Administration for the treatment of chronic pain. Although both are considered first-line IT therapies, each drug has unique properties and considerations.Areas Covered: This review will evaluate the pivotal trials that established the use of morphine and ziconotide as first-line IT therapy for patients with chronic pain, as well as safety and efficacy data generated from various retrospective and prospective studies.Expert Opinion: Morphine and ziconotide are effective IT therapies for patients with chronic malignant or nonmalignant pain that is refractory to other interventions. IT ziconotide is recommended as a first-line therapy due to its efficacy and avoidance of many adverse effects commonly associated with opioids. The use of IT morphine is also considered first-line; however, the risks of respiratory depression, withdrawal with drug discontinuation or pump malfunction, and the development of tolerance require careful patient selection and management.

Intrathecal pain management with ziconotide: Time for consensus?

This article summarizes recommendations made by six pain specialists who discussed the rationale for ziconotide intrathecal analgesia (ITA) and the requirement for evidence-based guidance on its use, from a European perspective. Riemser Pharma GmbH (Greifswald, Germany), which holds the European marketing authorization for ziconotide, hosted the meeting. The group agreed that ITA is under-used in Europe, adding that ziconotide ITA has potential to be a first-line alternative to morphine; both are already first-line options in the USA. Ziconotide ITA (initiated using a low-dose, slow-titration approach) is suitable for many patients with noncancer- or cancer-related chronic refractory pain and no history of psychosis. Adopting ziconotide as first-line ITA could reduce opioid usage in these patient populations. The group advocated a risk-reduction strategy for all candidate patients, including compulsory prescreening for neuropsychosis, and requested US-European alignment of the licensed starting dose for ziconotide: the low-and-slow approach practiced in the USA has a better tolerability profile than the fixed high starting dose licensed in Europe. Of note, an update to the European Summary of Product Characteristics is anticipated in early 2021. The group acknowledged that the Polyanalgesic Consensus Conference (PACC) treatment algorithms for ziconotide ITA provide useful guidance, but recommendations tailored specifically for European settings are required. Before a consensus process can formally begin, the group called for additional European prospective studies to investigate ziconotide in low-and-slow dosing strategies, in different patient settings. Such data would enable European guidance to have the most appropriate evidence at its core.

[What became of Prialt®? : Observational study on the use of ziconotide in the treatment of chronic pain]

Hintergrund

Prialt® ist seit Februar 2005 von der europäischen Arzneimittelbehörde zugelassen und ist neben Morphin das einzige Analgetikum, welches über die offizielle Marktzulassung in der intrathekalen Schmerztherapie verfügt. Da es nicht über Opioidrezeptoren wirkt, galt es zum Zeitpunkt der Markteinführung als nebenwirkungs- und risikoärmer in der Behandlung chronischer Schmerzen als Morphin. Trotzdem gilt es noch heute als Orphan Drug und Studien über den Langzeiteinsatz und hierunter aufgetretene Nebenwirkungen sind rar.

Fragestellung

Welchen Stellenwert nimmt Prialt® verglichen mit anderen intrathekal verabreichten Analgetika ein? Wie wirken sich die Startdosis und die Geschwindigkeit der Aufdosierung auf die schmerzlindernde Wirkung und das Auftreten von Nebenwirkungen in der Langzeittherapie aus?

Material und Methoden

Zum einen wurden anhand von Arztbriefen retrospektiv alle Patienten erfasst, die zwischen Februar 2005 und dem Ende des Beobachtungszeitraums im Oktober 2018 Ziconotid in Monotherapie in der Neurochirurgie des Universitätsklinikums Jena erhielten. Zum anderen wurden diese Patienten anhand eines erstellten Fragebogens hinsichtlich ihrer Erfahrung mit Ziconotid befragt.

Ergebnisse

Bei allen zwölf in die Studie eingeschlossenen Teilnehmern kam es zu mindestens einer Arzneimittelnebenwirkung. Am häufigsten wurde über Vergesslichkeit und Sensibilitätsstörungen mit jeweils 25 % berichtet. Ein Drittel der Patienten musste die Behandlung aufgrund von Nebenwirkungen beenden. Die mittlere Initialdosis betrug 1,98 µg/Tag.

Diskussion

Trotz leitliniengerechter Behandlung hat sich Ziconotid am Universitätsklinikum Jena nicht gegen Morphin und andere Opioidanalgetika in der intrathekalen Schmerztherapie durchgesetzt. Die Gründe hierfür sind vielfältig, wobei die enge therapeutische Breite, das häufige Auftreten von Nebenwirkungen und die schwierige therapeutische Handhabung, vor allem im ambulanten Setting, von besonderer Bedeutung sind.

Pain pathways and potential new targets for pain relief

Pain is an unpleasant sensory and emotional experience that affects a sizable percentage of people on a daily basis. Sensory neurons known as nociceptors built specifically to detect damaging stimuli can be found throughout the body. They transmit information about noxious stimuli from mechanical, thermal, and chemical sources to the central nervous system and higher brain centers via electrical signals. Nociceptors express various channels and receptors such as voltage-gated sodium and calcium channels, transient receptor potential channels, and opioid receptors that allow them to respond in a highly specific manner to noxious stimuli. Attenuating the pain response can be achieved by inhibiting or altering the expression of these pain targets. Achieving a deeper understanding of how these receptors can be affected at the molecular level can lead to the development of novel pain therapies. This review will discuss the mechanisms of pain, introduce the various receptors that are responsible for detecting pain, and future directions in pharmacological therapies.

Stability Study of Admixtures Combining Ziconotide With Morphine or Sufentanil in Polypropylene Syringes

BACKGROUND

The association of morphine ziconotide or sufentanil ziconotide was used to manage cancer pain. Moving these patients is sometimes difficult. In order to transport these syringes for pump refilling, it could be interesting to demonstrate the stability of the mixture and so to be able to ensure the best transport conditions of syringes.

MATERIALS AND METHODS

A stability indicating UPLC-DAD method was developed and validated according to the ICH guidelines. Fur mixtures of each association have been stored in 5 ± 3°C and 25 ± 2°C and were evaluated for seven days and compared to the initial observed concentrations.

RESULTS

The stability of these associations was demonstrated at 5°C for seven days thanks to relative concentrations (95% confidence intervals of the mean of three samples) systematically positioned between 95% and 105%. No degradation product was observed during the stability study.

CONCLUSION

This study shows the stability of these association morphine ziconotide or sufentanil ziconotide at 5°C for seven days in polypropylen syringes. This result will allow the transport of the preparation under optimal conditions. Advance preparations for intrathecal pump refills could also be feasible.

Effect of First-Line Ziconotide Intrathecal Drug Therapy for Neuropathic Pain on Disability, Emotional Well-Being, and Pain Catastrophizing

BACKGROUND

Previous studies have shown decreased pain scores with ziconotide as a first-line agent for intrathecal drug therapy (IDT). Subset analysis suggests that patients with neuropathic pain have greater improvement. We prospectively examine the role of first-line ziconotide IDT on the tridimensional pain experience in ziconotide IDT-naive patients with neuropathic pain.

METHODS

We included patients who underwent a successful ziconotide trial and were scheduled for standard-of-care IDT pump placement. Scores were collected at baseline and latest follow-up for the following measures: Short-Form 36 (SF-36), Oswestry Disability Index (ODI), Beck Depression Inventory, and Pain Catastrophizing Scale (PCS). Numeric rating scale (NRS) scores were also collected at each follow-up visit to monitor patients' pain levels and to guide ziconotide dose titration. Responders were identified as patients who had a previously established minimum clinically important difference of a ≥1.2-point reduction in NRS current scores.

RESULTS

Eleven of 14 patients completed long-term follow-up. There were 7 responders based on NRS minimum clinically important difference. At a mean (±standard error of the mean) follow-up of 10.91 ± 0.70 months, SF-36 emotional well-being (P = 0.04), SF-36 pain (P = 0.02), and ODI (P = 0.03) significantly improved for the entire cohort and in responders (SF-36 emotional well-being, P = 0.01; SF-36 pain, P = 0.04; ODI, P = 0.02). PCS-Rumination (P = 0.02), PCS-Helplessness (P = 0.02), and PCS-Total (P = 0.003) scores improved significantly for responders only.

CONCLUSIONS

We show that ziconotide IDT improves pain as well as emotional components and function. Our study adds prospective evidence to the literature on IDT for neuropathic pain, specifically its role in improving disability, emotional well-being, and catastrophizing.

Intracerebroventricular administration of N-type calcium channel blocker ziconotide displays anticonvulsant, anxiolytic, and sedative effects in rats: A preclinical and pilot study

OBJECTIVE

Ziconotide (ω-conotoxin MVIIA peptide) is a novel analgesic agent acting on voltage-gated calcium channels and is administered intrathecally for neuropathic pain. While antiepileptic activities of other types of calcium channel blockers (T- or L-type) are well established, there is no information regarding the effect of ziconotide as an N-type calcium channel antagonist in pentylenetetrazol-induced seizures or its anxiolytic and sedative activities. The present study is the first to report on these effects.

METHODS

To evaluate the anticonvulsant activity of ziconotide in the pentylenetetrazol (60 mg/kg) seizure model, ziconotide was administered intracerebroventricular (i.c.v.) as a single dose (1 μg/rat) or repeatedly (chronic administration: 0.1, 0.3, or 1 μg/rat once a day for seven days). The anxiolytic and sedative actions of ziconotide were evaluated with the elevated plus maze, light/dark (LD) box, and pentobarbital-induced sleep tests. Immediately after behavioral testing, the amygdala was completely removed bilaterally to determine corticosterone levels by immunoassay.

RESULTS

In all dosing regimens, ziconotide significantly decreased the seizure frequency and also delayed the latency period compared with control. Chronic administration affected the percentage of mortality protection, while a single dose of ziconotide did not. In behavioral tests, ziconotide significantly increased both the number of entries and the percentage of time spent in the open arms of the elevated plus maze. Furthermore, ziconotide significantly increased the latency period and the number of entries into the light compartment during the LD box examination. Chronic administration of ziconotide significantly reduced the latency to sleep and increased sleeping time, whereas these parameters were not affected by a single dose. Additionally, amygdala corticosterone levels were significantly decreased in rats treated with ziconotide compared with control.

CONCLUSION

Ziconotide displays beneficial neurobehavioral effects in a model of epilepsy with anxiety as its comorbid event. It seems that at least one of the mechanisms involved in these effects is associated with a decrease in brain corticosterone levels. The main advantage of ziconotide over benzodiazepines (routine anxiolytic and sedative drugs) is that it does not cause tolerance, dependency, and addiction. Therefore, more than ever, it is necessary to improve the convenience of drug delivery protocols and attenuate the adverse effects associated with ziconotide-based therapies.

Patient Satisfaction Following Intrathecal Targeted Drug Delivery for Benign Chronic Pain: Results of a Single-Center Survey Study

OBJECTIVES

Targeted Drug Delivery (TDD) is commonly used for the management of patients with intractable pain. Past studies have proven efficacy in pain relief and reduction in opioid use and cost-effectiveness in long-term pain management. There are few studies investigating satisfaction among patients with implanted pain pumps that are managed with targeted intrathecal medications.

MATERIAL AND METHODS

Patients in a single medical practice implanted with pain pumps for relief of intractable pain were identified and extracted from the electronic health record (EHR). Six hundred and ten active TDD patients were identified and an anonymous 18-question survey was administered to determine satisfaction with TDD therapy. During an 18-month period from May 2018 to August 2019, patients were invited to take a satisfaction survey. Both primary and secondary outcomes were reported as proportions; P < 0.05 was considered significant.

RESULTS

Four hundred and forty-three patients (74% of the active pump population) completed the survey. The majority of patients reported improvement in pain, improvement of physical function, improvement in quality of life and reduction in opioid use. Complete discontinuation of oral opioid intake was reported in 38.9% of patients. The majority of patients had a 40 cc reservoir implanted in an upper buttock pocket site and overall, 91% of patients were happy with pump pocket location.

CONCLUSION

Intrathecal TDD therapy can relieve pain and improve quality of life in patients with intractable pain and offers a reasonable alternative to long-term oral or skin patch opioid management. Patients utilizing TDD therapy reported high degrees of satisfaction.

PnAn13, an antinociceptive synthetic peptide inspired in the Phoneutria nigriventer toxin PnTx4(6-1) (δ-Ctenitoxin-Pn1a)

Animal venoms are an almost inexhaustible source for promising molecules with biological activity and the venom of Phoneutria nigriventer spider is a good example of this. Among several other toxins obtained from this venom, PnTx4(6–1), also called δ-Ctenitoxin-Pn1a, was isolated and initially described as an insect toxin that binds to the site 3 of sodium channels in cockroach nerve cord synaptosomes (Periplaneta americana) and slows down sodium current inactivation in isolated axons of this animal. This toxin did not cause any apparent toxicity to mice when intracerebroventricularly injected (30 μg). Subsequently, it was demonstrated that PnTx4(6–1) has an antinociceptive effect in three different pain models: inflammatory, induced by carrageenan; nociceptive, induced by prostaglandin E₂ and neuropathic, induced by sciatic nerve constriction. Using diverse antagonists from receptors, it was shown that the cannabinoid system, via the CB₁ receptor, and the opioid system, through the μ and δ receptors, are both involved in the antinociceptive effect of PnTx4(6–1). In the present work, it was synthesized a peptide, named PnAn13, based on the amino acid sequence of PnTx4(6–1) in order to try to reproduce or increase the analgesic effect of the toxin. As it was seen for the toxin, PnAn13 had antinociceptive activity, when intrathecally injected, and this effect involved the cannabinoid and opioid systems. In addition, when it was evaluated the peripheral effect of PnAn13, via intraplantar administration, this peptide was able to reverse the hyperalgesic threshold, evoked by prostaglandin E₂. Therefore, using different pharmacological tools, it was shown the participation of cannabinoid and opioid systems in this effect.

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A synthetic peptide PnAn13, reproduced the antinociceptive effects of the PnTx4(6-1) (δ-Ctenitoxin-Pn1a) toxin.

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PnAn13 showed a clear analgesic effect in the nociceptive in vivo rat pain model, both centrally and peripherally.

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The antinociceptive effect of PnAn13 involves cannabinoid and opioid systems.

Effectiveness and Safety of Intrathecal Ziconotide: Final Results of the Patient Registry of Intrathecal Ziconotide Management (PRIZM)

Background and Objectives

The Patient Registry of Intrathecal Ziconotide Management evaluated the long-term effectiveness and safety of intrathecal ziconotide.

Methods

The study was a prospective, multicenter observational study of intrathecal ziconotide in US clinical practice. Patients were adults with severe chronic pain that warranted intrathecal therapy. Ziconotide was initiated as the single agent in the pump; however, other intrathecal medications were permitted. The primary efficacy outcome was ≥30% reduction in numeric pain rating scale score from baseline at week 12. A secondary outcome was patient global impression of change. Adverse events were solicited at each visit.

Results

The registry enrolled 93 patients. Seventy-four and 28 patients completed 12 weeks and 18 months of treatment, respectively. In the overall patient population, 17.4% had ≥30% pain reduction from baseline at week 12, with a mean reduction in pain of 10.9%. At month 18, 38.5% of patients had ≥30% pain reduction from baseline, with a mean pain reduction of 24.7%. Patient-rated improvement was reported in 67% of patients at week 12 and 71% at month 18. Almost all patients experienced adverse events, the most common of which were nausea (25.8%), confusional state (22.6%), and dizziness (20.4%).

Conclusions

Final study analyses showed that intrathecal ziconotide provided clinically meaningful pain relief in 17.4% and 38.5% of patients at week 12 and month 18, respectively. At these same time points, patient-rated improvement was reported in at least two-thirds of patients. The safety profile was consistent with that listed in the ziconotide prescribing information.

Targeting the CaVα-CaVβ interaction yields an antagonist of the N-type CaV2.2 channel with broad antinociceptive efficacy

Inhibition of voltage-gated calcium (CaV) channels is a potential therapy for many neurological diseases including chronic pain. Neuronal CaV1/CaV2 channels are composed of α, β, γ and α2δ subunits. The β subunits of CaV channels are cytoplasmic proteins that increase the surface expression of the pore-forming α subunit of CaV. We targeted the high-affinity protein-protein interface of CaVβ's pocket within the CaVα subunit. Structure-based virtual screening of 50,000 small molecule library docked to the β subunit led to the identification of 2-(3,5-dimethylisoxazol-4-yl)-N-((4-((3-phenylpropyl)amino)quinazolin-2-yl)methyl)acetamide (IPPQ). This small molecule bound to CaVβ and inhibited its coupling with N-type voltage-gated calcium (CaV2.2) channels, leading to a reduction in CaV2.2 currents in rat dorsal root ganglion sensory neurons, decreased presynaptic localization of CaV2.2 in vivo, decreased frequency of spontaneous excitatory postsynaptic potentials and miniature excitatory postsynaptic potentials, and inhibited release of the nociceptive neurotransmitter calcitonin gene-related peptide from spinal cord. IPPQ did not target opioid receptors nor did it engage inhibitory G protein-coupled receptor signaling. IPPQ was antinociceptive in naive animals and reversed allodynia and hyperalgesia in models of acute (postsurgical) and neuropathic (spinal nerve ligation, chemotherapy- and gp120-induced peripheral neuropathy, and genome-edited neuropathy) pain. IPPQ did not cause akinesia or motor impairment, a common adverse effect of CaV2.2 targeting drugs, when injected into the brain. IPPQ, a quinazoline analog, represents a novel class of CaV2.2-targeting compounds that may serve as probes to interrogate CaVα-CaVβ function and ultimately be developed as a nonopioid therapeutic for chronic pain.

Intrathecal Therapy for Chronic Pain: A Review of Morphine and Ziconotide as Firstline Options

Objectives

To evaluate the evidence for morphine and ziconotide as firstline intrathecal (IT) analgesia agents for patients with chronic pain.

Methods

Medline was searched (through July 2017) for “ziconotide” or “morphine” AND “intrathecal” AND “chronic pain,” with results limited to studies in human populations.

Results

The literature supports the use of morphine (based primarily on noncontrolled, prospective, and retrospective studies) and ziconotide (based on randomized controlled trials and prospective observational studies) as first-choice IT therapies. The 2016 Polyanalgesic Consensus Conference (PACC) guidelines recommended both morphine and ziconotide as firstline IT monotherapy for localized and diffuse chronic pain of cancer-related and non–cancer-related etiologies; however, one consensus point emphasized ziconotide use, unless contraindicated, as firstline IT therapy in patients with chronic non–cancer-related pain. Initial IT therapy choice should take into consideration individual patient characteristics (e.g., pain location, response to previous therapies, comorbid medical conditions, psychiatric history). Trialing is recommended to assess medication efficacy and tolerability. For both morphine and ziconotide, the PACC guidelines recommend conservative initial dosing strategies. Due to its narrow therapeutic window, ziconotide requires careful dose titration. Ziconotide is contraindicated in patients with a history of psychosis. IT morphine administration may be associated with serious side effects (e.g., respiratory depression, catheter tip granuloma), require dose increases, and cause dependence over time.

Conclusion

Based on the available evidence, morphine and ziconotide are recommended as firstline IT monotherapy for cancer-related and non–cancer-related pain. The choice of first-in-pump therapy should take into consideration patient characteristics and the advantages and disadvantages of each medication.

Phα1β Spider Toxin Reverses Glial Structural Plasticity Upon Peripheral Inflammation

The incoming signals from injured sensory neurons upon peripheral inflammation are processed in the dorsal horn of spinal cord, where glial cells accumulate and play a critical role in initiating allodynia (increased pain in response to light-touch). However, how painful stimuli in the periphery engage glial reactivity in the spinal cord remains unclear. Here, we found that a hind paw inflammation induced by CFA produces robust morphological changes in spinal astrocytes and microglia compatible with the reactive phenotype. Strikingly, we discovered that a single intrathecal injection with venom peptides that inhibit calcium channels reversed all the glial pathological features of the peripheral inflammation. These effects were more apparent in rats treated with the Phα1β spider toxin (non-specific calcium channel antagonist) than ω-MVIIA cone snail toxin (selective N-type calcium channel antagonist). These data reveal for the first time a venom peptide acting on glial structural remodeling in vivo. We, therefore, suggest that calcium-dependent plasticity is an essential trigger for glial cells to initiate reactivity, which may represent a new target for the antinociceptive effects of Phα1β and ω-MVIIA toxins in inflammatory pain conditions.

Managing Chronic Non-Malignant Pain in the Elderly: Intrathecal Therapy

Intrathecal drug delivery (IDD) was first described in 1981 by Onofrio, who used a pump for continuous and intrathecal delivery of morphine to treat cancer pain. Over the following four decades, many reports supported this treatment method with implanted pumps for cancer and non-cancer pain. To date, more than 300,000 pumps for pain therapy and spasticity have been implanted worldwide. This article reviews current knowledge regarding intrathecal opioid therapy, focusing particularly on the use of IDD in elderly patients. Current literature is presented, and the arguments in favor of and against this therapy in elderly patients are discussed.

Near-resolution of persistent idiopathic facial pain with low-dose lumbar intrathecal ziconotide: a case report

Purpose

Persistent idiopathic facial pain (PIFP) is a poorly defined and debilitating chronic pain state with a challenging and often inadequate treatment course. This is the first case report identifying the novel use of low-dose lumbar intrathecal ziconotide to successfully treat PIFP with nearly complete resolution of pain and minimal to no side effects.

Methods

The patient was a 37 year-old female whose PIFP was refractory to multimodal medication management and multiple neurovascular surgical interventions. A single-shot lumbar intrathecal trial of ziconotide (2.5 mL, equivalent 2.5 μg) was injected when she was at her baseline pain level — VAS 7/10. She received complete resolution of her pain for about 9 hours, concordant with ziconotide’s half-life. She was subsequently implanted with a lumbar intrathecal delivery system.

Results

The patient experienced complete resolution of her facial pain with a single-shot intrathecal trial of ziconotide. The intrathecal pump system has provided nearly complete (VAS 1/10) pain relief. Two flares of pain occurred 10 and 18 months after pump placement, which subsequently resolved after increasing the ziconotide dose by 0.5 μg/day on each occasion. The patient is currently maintained on a dose of 2.0 μg/day and is pain-free.

Conclusion

This is the first case report describing the use of a single-shot lumbar intrathecal trial of ziconotide and subsequent placement of lumbar (as opposed to thoracic) intrathecal ziconotide pump for PIFP. A single-injection intrathecal trial is a low-risk, viable option for patients with this debilitating and frustrating pain condition. Successful trials and subsequent intrathecal pump placement with ziconotide may supplant multimodal medication management and/or invasive orofacial surgical intervention for PIFP.

Unique aspects of clinical trials of invasive therapies for chronic pain

Nearly all who review the literature conclude that the role of invasive procedures to treat chronic pain is poorly characterized because of the lack of “definitive” studies. The overt nature of invasive treatments, along with the risks, technical skills, and costs involved create challenges to study them. However, these challenges do not completely preclude evaluating invasive procedure effectiveness and safety using well-designed methods. This article reviews the challenges of studying outcomes of invasive therapies to treat pain and discuss possible solutions. Although the following discussion can apply to most invasive therapies to treat chronic pain, it is beyond the scope of the article to individually cover every invasive therapy used. Therefore, most of the examples focus on injection therapies to treat spine pain, spinal cord stimulation, and intrathecal drug therapies.

Ziconotide-induced psychosis: A case report and literature review

Ziconotide is an intrathecally administered medication indicated for the treatment of severe chronic pain in patients who are intolerant of or refractory to other treatment options. A black box warning is included in the packaging and states ziconotide is contraindicated in patients with a preexisting history of psychosis. Patients taking ziconotide should be monitored for evidence of cognitive impairment, hallucinations, or changes in mood, and ziconotide should be discontinued if neurological or psychiatric signs and symptoms appear. We present a case of a 49-year-old white male with no previous neuropsychiatric history who received ziconotide for several years before he developed command auditory hallucinations within 24 hours of a dose increase. Upon admission to the emergency room, the patient's pain management physician was contacted and the ziconotide dose was decreased and eventually discontinued. Because of a continuation of symptoms, the patient was transferred from the emergency room to an acute care psychiatric hospital where he was started on risperidone 1 mg orally at bedtime. At discharge, the patient was noted to be in good behavioral control without any hallucinations. The patient was encouraged to follow up with his pain management physician to determine if ziconotide should be reconsidered.

Pain therapeutics from cone snail venoms: From Ziconotide to novel non-opioid pathways

There have been numerous attempts to develop non-opioid drugs for severe pain, but the vast majority of these efforts have failed. A notable exception is Ziconotide (Prialt®), approved by the FDA in 2004. In this review, we summarize the present status of Ziconotide as a therapeutic drug and introduce a wider framework: the potential of venom peptides from cone snails as a resource providing a continuous pipeline for the discovery of non-opioid pain therapeutics. An auxiliary theme that we hope to develop is that these venoms, already a validated starting point for non-opioid drug leads, should also provide an opportunity for identifying novel molecular targets for future pain drugs. This review comprises several sections: the first focuses on Ziconotide as a therapeutic (including a historical retrospective and a clinical perspective); followed by sections on other promising Conus venom peptides that are either in clinical or pre-clinical development. We conclude with a discussion on why the outlook for discovery appears exceptionally promising. The combination of new technologies in diverse fields, including the development of novel high-content assays and revolutionary advancements in transcriptomics and proteomics, puts us at the cusp of providing a continuous pipeline of non-opioid drug innovations for pain. SIGNIFICANCE: The current opioid epidemic is the deadliest drug crisis in American history. Thus, this review on the discovery of non-opioid pain therapeutics and pathways from cone snail venoms is significant and timely.

Role of primary care physicians in intrathecal pain management: a narrative review of the literature

OBJECTIVES

The majority of patients seeking medical care for chronic pain consult a primary care physician (PCP). Because systemic opioids are commonly prescribed to patients with chronic pain, PCPs are attempting to balance the competing priorities of providing adequate pain relief while reducing risks for opioid misuse and overdose. It is important for PCPs to be aware of pain management strategies other than systemic opioid dose escalation when patients with chronic pain fail to respond to conservative therapies and to initiate a multimodal treatment plan.

METHODS

The Medline database and evidence-based treatment guidelines were searched to identify publications on intrathecal (IT) therapy for the management of chronic pain. Selection of publications relevant to PCPs was based on the authors' clinical and research expertise.

RESULTS

IT administration delivers analgesic medication directly into the cerebrospinal fluid, avoiding first-pass effect and bypassing the blood-brain barrier, thereby requiring lower medication doses. Morphine, a µ-opioid receptor agonist, and ziconotide, a non-opioid, selective N-type calcium channel blocker, are the only analgesics approved by the US Food and Drug Administration to treat chronic refractory pain by the IT route. Patients who are potential candidates for IT therapy may benefit from evaluation by an interventional pain physician. PCPs can play an important role in patient selection and referral for IT therapy and provide ongoing collaborative care for patients receiving IT therapy, including monitoring for efficacy and adverse events and facilitating communication with the treating specialist.

CONCLUSIONS

Collaboration between PCPs and pain specialists may improve outcomes of and patient satisfaction with IT therapy and other interventional treatments.

In vitro-engineered non-antibody protein therapeutics

Antibodies have proved to be a valuable mode of therapy for numerous diseases, mainly owing to their high target binding affinity and specificity. Unfortunately, antibodies are also limited in several respects, chief amongst those being the extremely high cost of manufacture. Therefore, non-antibody binding proteins have long been sought after as alternative therapies. New binding protein scaffolds are constantly being designed or discovered with some already approved for human use by the FDA. This review focuses on protein scaffolds that are either already being used in humans or are currently being evaluated in clinical trials. Although not all are expected to be approved, the significant benefits ensure that these molecules will continue to be investigated and developed as therapeutic alternatives to antibodies. Based on the location of the amino acids that mediate ligand binding, we place all the protein scaffolds under clinical development into two general categories: scaffolds with ligand-binding residues located in exposed flexible loops, and those with the binding residues located in protein secondary structures, such as α-helices. Scaffolds that fall under the first category include adnectins, anticalins, avimers, Fynomers, Kunitz domains, and knottins, while those belonging to the second category include affibodies, β-hairpin mimetics, and designed ankyrin repeat proteins (DARPins). Most of these scaffolds are thermostable and can be easily produced in microorganisms or completely synthesized chemically. In addition, many of these scaffolds derive from human proteins and thus possess very low immunogenic potential. Additional advantages and limitations of these protein scaffolds as therapeutics compared to antibodies will be discussed.

G-Protein Coupled Receptors Targeted by Analgesic Venom Peptides

Chronic pain is a complex and debilitating condition associated with a large personal and socioeconomic burden. Current pharmacological approaches to treating chronic pain such as opioids, antidepressants and anticonvulsants exhibit limited efficacy in many patients and are associated with dose-limiting side effects that hinder their clinical use. Therefore, improved strategies for the pharmacological treatment of pathological pain are urgently needed. G-protein coupled receptors (GPCRs) are ubiquitously expressed on the surface of cells and act to transduce extracellular signals and regulate physiological processes. In the context of pain, numerous and diverse families of GPCRs expressed in pain pathways regulate most aspects of physiological and pathological pain and are thus implicated as potential targets for therapy of chronic pain. In the search for novel compounds that produce analgesia via GPCR modulation, animal venoms offer an enormous and virtually untapped source of potent and selective peptide molecules. While many venom peptides target voltage-gated and ligand-gated ion channels to inhibit neuronal excitability and blunt synaptic transmission of pain signals, only a small proportion are known to interact with GPCRs. Of these, only a few have shown analgesic potential in vivo. Here we review the current state of knowledge regarding venom peptides that target GPCRs to produce analgesia, and their development as therapeutic compounds.

Intrathecal pain management: a team-based approach

Objective

Physician assistants (PAs), nurse practitioners (NPs), and registered nurses (RNs) provide professional services on pain management teams. This review provides an overview of the practical management of chronic pain with intrathecal (IT) therapy using an interprofessional approach (eg, physicians and other health care professionals), with a focus on the contributions of PAs, NPs, and RNs.

Methods

Narrative review based on literature searches of the Medline database and treatment guidelines on the use of IT therapy in the management of patients with chronic pain.

Results

The specific roles and responsibilities of PAs, NPs, and RNs in the management of patients receiving IT therapy vary by practice. In many pain treatment centers, PAs, NPs, and RNs are responsible for patient education, postimplant maintenance, and ongoing supportive care of patients receiving IT therapy. Topics that we address include patient selection, patient expectations and goal setting, medication selection, outcome assessment, and treatment adjustment. Currently, morphine and ziconotide (a nonopioid, selective N-type calcium channel blocker) are the only agents approved by the US Food and Drug Administration for IT analgesia. We provide relevant information on the dosing, titration, and adverse effect management of these medications for PAs, NPs, and RNs responsible for administering IT therapy.

Conclusion

PAs, NPs, and RNs are valuable members of IT pain management teams. Treatment success requires ongoing monitoring of efficacy and adverse effects, with corresponding adjustments to medication selection and dosing, in addition to good communication among the health care professionals involved in patient care.