Pharmacologic agents directed at the treatment of pain associated with maladaptive neuronal plasticity

Managing the neuroinflammatory pain of endometriosis in light of chronic pelvic pain

INTRODUCTION

Endometriosis affects 5% to 10% of reproductive age women and may be associated with severely painful and debilitating symptoms as well as infertility. Endometriosis involves hormonal fluctuations, angiogenesis, neurogenesis, vascular changes and neuroinflammatory processes. The neuroinflammatory component of endometriosis makes it a systemic disorder, similar to other chronic epithelial inflammatory conditions.

AREAS COVERED

Inflammatory mediators, mast cells, macrophages, and glial cells play a role in endometriosis which can result in peripheral sensitization and central sensitization. There is overlap between chronic pelvic pain and endometriosis, but the two conditions are distinct. Effective treatment is based on a personalized approach using a variety of pharmacologic and other treatment options.

EXPERT OPINION

Hormonal therapies are a first-line approach, but endometriosis is a challenging condition to manage. 'Add-back' hormonal therapy has been effective. Painful symptoms are likely caused by the interplay of multiple factors and there may be a neuropathic component. Analgesics and anticonvulsants may be appropriate. A holistic approach and multimodal treatments are likely to be most effective. In addition to pharmacologic treatment, there are surgical and alternative medicine options. Endometriosis may also have a psychological component.

The Impact of P-Glycoprotein on Opioid Analgesics: What's the Real Meaning in Pain Management and Palliative Care?

Opioids are widely used in cancer and non-cancer pain management. However, many transporters at the blood-brain barrier (BBB), such as P-glycoprotein (P-gp, ABCB1/MDR1), may impair their delivery to the brain, thus leading to opioid tolerance. Nonetheless, opioids may regulate P-gp expression, thus altering the transport of other compounds, namely chemotherapeutic agents, resulting in pharmacoresistance. Other kinds of painkillers (e.g., acetaminophen, dexamethasone) and adjuvant drugs used for neuropathic pain may act as P-gp substrates and modulate its expression, thus making pain management challenging. Inflammatory conditions are also believed to upregulate P-gp. The role of P-gp in drug-drug interactions is currently under investigation, since many P-gp substrates may also act as substrates for the cytochrome P450 enzymes, which metabolize a wide range of xenobiotics and endobiotics. Genetic variability of the ABCB1/MDR1 gene may be accountable for inter-individual variation in opioid-induced analgesia. P-gp also plays a role in the management of opioid-induced adverse effects, such as constipation. Peripherally acting mu-opioid receptors antagonists (PAMORAs), such as naloxegol and naldemedine, are substrates of P-gp, which prevent their penetration in the central nervous system. In our review, we explore the interactions between P-gp and opioidergic drugs, with their implications in clinical practice.

Current and Future Therapeutic Options in Pain Management: Multi-mechanistic Opioids Involving Both MOR and NOP Receptor Activation

Opioids are widely used in chronic pain management, despite major concerns about their risk of adverse events, particularly abuse, misuse, and respiratory depression from overdose. Multi-mechanistic opioids, such as tapentadol and buprenorphine, have been widely studied as a valid alternative to traditional opioids for their safer profile. Special interest was focused on the role of the nociceptin opioid peptide (NOP) receptor in terms of analgesia and improved tolerability. Nociceptin opioid peptide receptor agonists were shown to reinforce the antinociceptive effect of mu opioid receptor (MOR) agonists and modulate some of their adverse effects. Therefore, multi-mechanistic opioids involving both MOR and NOP receptor activation became a major field of pharmaceutical and clinical investigations. Buprenorphine was re-discovered in a new perspective, as an atypical analgesic and as a substitution therapy for opioid use disorders; and buprenorphine derivatives have been tested in animal models of nociceptive and neuropathic pain. Similarly, cebranopadol, a full MOR/NOP receptor agonist, has been clinically evaluated for its potent analgesic efficacy and better tolerability profile, compared with traditional opioids. This review overviews pharmacological mechanisms of the NOP receptor system, including its role in pain management and in the development of opioid tolerance. Clinical data on buprenorphine suggest its role as a safer alternative to traditional opioids, particularly in patients with non-cancer pain; while data on cebranopadol still require phase III study results to approve its introduction on the market. Other bifunctional MOR/NOP receptor ligands, such as BU08028, BU10038, and AT-121, are currently under pharmacological investigations and could represent promising analgesic agents for the future.

New Insights Into the Pharmacological Management of Postoperative Pain: A Narrative Review

Postoperative pain is prevalent and often undertreated. There is a risk that untreated or suboptimally treated postoperative pain may transition into chronic postoperative pain, which can be challenging to treat. Clinical guidelines recommend the use of multimodal analgesia, including non-steroidal anti-inflammatory drugs (NSAIDs), acetaminophen, and, in some cases, opioids. NSAIDs are a broad class of drugs with different attributes such as cyclo-oxygenase (COX)-1 or COX-2 selectivity, onset of action, and analgesic potency. NSAIDs are associated with gastrointestinal and cardiovascular side effects and should be administered at the lowest effective dose for the shortest effective duration but can be effective in postoperative pain. The role of opioids in postoperative analgesia is long-standing but has recently come under scrutiny. Opioids are often used in multimodal analgesic combinations in such a way as to minimize the total consumption of opioids without sacrificing analgesic benefit. Special clinical considerations are required for surgical patients already on opioid regimens or with opioid use disorder. A particularly useful fixed-dose combination product for postoperative analgesia is dexketoprofen-tramadol, which confers safe and effective postoperative pain control and reduces the risk of persistent postoperative pain.

What Is New in the Clinical Management of Low Back Pain: A Narrative Review

Low back pain (LBP) is a prevalent condition associated with disability. Treating patients with LBP becomes further complicated by the potential presence of underlying conditions, such as cancer or traumatic injury, or biopsychosocial aspects. LBP usually has a neuropathic component that must be assessed and treated appropriately. Pharmacological management of LBP requires a thorough knowledge of the available agents and the mechanisms of the LBP. Although there are effective pharmacological treatments for LBP, it is important to consider safety issues. Fixed-dose combination products may be helpful, as they can reduce opioid consumption without sacrificing analgesic benefits. Neuromodulation is an important and sometimes overlooked treatment option for LBP and may be appropriate for chronic LBP requiring long-term treatment. Imaging studies support neuroplastic changes in the brain as a result of neuromodulation. Interventional approaches to chronic LBP are numerous and must be appropriately selected based on the individual patient. Evidence in support of epidural injections for LBP is strong for short-term pain control but moderate to limited for long-term relief. Rehabilitation for LBP can be an important element of long-term care, and new forms of rehabilitation programs are being developed using telemedicine. A variety of new and established treatments are available for patients with LBP, and clinicians and patients may benefit from emerging new treatment modalities.

Delivery of Multimodal Analgesia to Effectively Treat Acute Pain: A Review From Roma Pain Days

It is crucial that acute pain be promptly and adequately treated in order to prevent it from transitioning to chronic pain, a devastating and sometimes permanent condition that is challenging to treat and associated with disability, reduced quality of life, and depression. Guidelines for the treatment of acute low-back pain (LBP) are predicated on assumptions that all acute LBP is benign, temporary, and traditionally treated with a “wait and see” approach. LBP is far from a monolithic condition: etiology, the presence of underlying conditions, mental health status, social situation, patient’s age and occupation, and comorbidities all present different risk factors for chronic LBP that should be considered in treating acute LBP or other forms of acute pain. A multimodal approach to acute pain has been shown to be safe and effective. In particular, the combination product of oral dexketoprofen and tramadol has been shown effective in controlling acute pain, which spares the use of opioids and is well tolerated. Chronic pain must be viewed as a global health crisis, and the timely and adequate control of acute painful conditions is a good strategy to reduce its prevalence. Experts at Roma Pain Days discussed this important topic which is the foundation of this review.