Search Results (93)

Opioids are among the most effective drugs for treating moderate to severe pain. Unfortunately, opioid use, even short-term, can lead to addiction, tolerance, overdose, and respiratory depression. Therefore, efforts to design and develop novel compounds that would retain analgesic activity while reducing side effects continue unabated. The present study was designed to investigate the respiratory and cardiovascular effects of the hybrid peptide LENART01, which has evidenced potent antinociceptive and antimicrobial activity. This hybrid peptide, composed of N-terminally located dermorphin and C-terminal modified ranatensin pharmacophore, was tested in vivo in anesthetized rats. The main effect of LENART01 was apnea in 70% of examined animals, sighing, and a significant increase in blood pressure. Interestingly, the hybrid induced sighs less frequently than ranatensin, and apnea dependent on vagus nerve mu opioid receptor activation much less frequently and less intensely than dermorphin itself. This shows that LENART01 is a safer opioid system-related agent as compared to dermorphin for its prospective use in the treatment of pain. Full article

Objectives: The incidence of postoperative pain in patients that undergo spinal interventions is significantly increased, affecting their functional outcomes and quality of life. Dexmedetomidine (DEX) belongs to the category of centrally acting nonopioid agents with highly selective α2 adrenoreceptor agonist activity that are frequently applied in spinal surgery based on its antinociceptive and anxiolytic properties. Although many studies displayed the effectiveness of DEX in postoperative pain management, the impact of DEX on functional improvement after spinal surgeries is still debatable. Purpose: This systematic review focuses on the intraoperative and postoperative role of dexmedetomidine (DEX) as an analgesic agent in elective and emergency adult spine surgery. Methods: An electronic literature review search was conducted via Web of Science and PubMed to assess the impact of DEX on postoperative pain management, postoperative delirium (POD), and postoperative cognitive dysfunction (POCD). Discussion: Twenty-one studies were retrieved, three of which were review articles. The effects of DEX were studied for up to 48 h postoperatively. In most cases, its administration was associated with reduced intraoperative and postoperative opioid consumption. However, findings on pain control were less conclusive due to heterogeneity in dosing protocols, concomitant medications, the timing of administration, and pain scoring systems. DEX appears to reduce the incidence of POD and POCD, particularly when used in combination with other drugs. Conclusions: Although the present study supports that the intraoperative administration of dexmedetomidine decreases the pain intensity and/or opioid consumption as well as the development of POD and POCD in patients undergoing spinal surgeries during the first 24 h postoperatively, the current literature should be expanded to allow for the safe generalisation of findings over longer follow-up periods. Further research into the neuroprotective, analgesic, and anti-inflammatory roles of DEX is warranted. Full article

Background: The blood–brain barrier (BBB) plays a critical role in protecting the central nervous system (CNS) but also limits drug delivery. Insufficient knowledge of how the CNS promotes the onset and maintenance of peripheral neuropathic pain limits therapeutic methods for the treatment of persistent neuropathic pain. Thus, this study aimed to evaluate the ability of a novel combination of Palmitoylethanolamide (PEA) and Equisetum arvense L. (Equisetum A.L.) to cross the BBB and modulate nociceptive pathways. Methods: Using a humanised in vitro BBB tri-culture model, the permeability, cytotoxicity, and integrity of the barrier were assessed after exposure to two different PEA forms, PEA ultramicronized (PEA-um) and PEA80mesh, Equisetum A.L., and a combination of the last two samples. The samples exhibited no cytotoxicity, maintained tight junction integrity, and efficiently crossed the blood–brain barrier (BBB), with the combination displaying the highest permeability. The eluate from the BBB model was then used to stimulate the co-culture of CCF-STTG1 astrocytes and SH-SY5Y neurons pre-treated with H₂O₂ 200 µM. Results: Treatment with the combination significantly increased cell viability (1.8-fold, p < 0.05), reduced oxidative stress (2.5-fold, p < 0.05), and decreased pro-inflammatory cytokines (TNFα, IL-1β) compared to single agents. Mechanistic analysis revealed modulation of key targets involved in pain pathways, including decreased FAAH and NAAA activity, increased levels of endocannabinoids (AEA and 2-AG), upregulation of CB2 receptor expression, enhanced PPARα activity, and reduced phosphorylation of PKA and TRPV1. Conclusions: These findings suggest that the combination of PEA and Equisetum A.L. effectively crosses the BBB and exerts combined anti-inflammatory and analgesic effects at the CNS level, suggesting a possible role in modulating neuroinflammatory and nociception responses. Full article

Background: Cannabidiol (CBD), a non-intoxicating phytocannabinoid, has garnered interest as a potential therapeutic agent for managing pain and inflammation associated with upper-quarter disorders, including temporomandibular disorders (TMDs), orofacial pain, myofascial dysfunction, and postoperative dental pain. Methods: This systematic review critically evaluated clinical, preclinical, and mechanistic studies on the efficacy and safety of CBD in the management of such conditions. A total of 10 studies, comprising randomized clinical trials and animal models, met the inclusion criteria and were assessed for methodological quality and risk of bias. Results: The findings suggest that CBD demonstrates analgesic, anti-inflammatory, and muscle-relaxant effects in chronic myofascial TMDs and bruxism, particularly when applied topically or intraorally. In contrast, studies on acute nociceptive pain (e.g., pulpitis, third molar surgery) yielded inconsistent results. Notably, CBD enhanced the effects of conventional analgesics such as opioids and NSAIDs in several preclinical models, indicating synergistic potential. However, substantial heterogeneity in CBD dosage, formulation, administration routes, and outcome measures limited comparability across studies. Adverse effects were minimal in clinical trials, yet underreported. Conclusions: While early evidence supports CBD’s potential as an adjunctive treatment for certain upper-quarter conditions, especially those involving chronic myofascial pain, further high-quality, condition-specific trials are required to establish standardized dosing, delivery methods, and long-term safety. Full article

The existing literature offers limited experimental evidence on the role of botulinum neurotoxin type E (BoNT-E) in pain transmission. The present study investigated the antinociceptive effects of subcutaneously administered BoNT-E in chronic orofacial pain conditions. This study used orofacial formalin-induced pronociceptive behavior and complete Freund’s adjuvant (CFA)-induced thermal hyperalgesia as inflammatory pain models in male Sprague Dawley rats. A neuropathic pain model was also developed by causing an injury to the inferior alveolar nerve. Subcutaneously administered BoNT-E (6, 10 units/kg) significantly reduced nociceptive behavior during the second phase of the formalin test compared to that of the vehicle treatment. These doses similarly alleviated thermal hypersensitivity in the CFA-treated rats. Moreover, BoNT-E (6, 10 units/kg) markedly attenuated mechanical allodynia in rats with an inferior alveolar nerve injury. At a dose of 10 units/kg, BoNT-E produced antinociceptive effects that became evident 8 h post-injection and persisted for 48 h. Notably, BoNT-E (10 units/kg) significantly reduced the number of c-fos-immunostained neurons in the trigeminal subnucleus caudalis of rats with an inferior alveolar nerve injury. In comparison, intraperitoneally administered gabapentin (30, 100 mg/kg) demonstrated significant mechanical anti-allodynic effects but exhibited lower analgesic efficacy than that of BoNT-E. These findings highlight the potential of BoNT-E as a therapeutic agent for chronic pain management. Full article

Introduction: Rheumatoid arthritis (RA) is a systemic inflammatory and autoimmune disease characterized by joint swelling, pain, damage to the cartilage, and disability. In the present study, we aimed to evaluate the anti-oxidant, anti-inflammatory, and immune-modulatory properties of Quantum Health Accelerator^® as water enriched with vital bio-quantum information/energy (EW) following complete Freund’s adjuvant (CFA)-induced RA in rats. Methods: Forty adult male Wistar rats (180–220 g) were divided into five groups. Arthritis was induced on day one using a single subcutaneous injection of CFA into the left hind footpad of the rat. Rats were assigned to receive methotrexate (MTX, 2 mg/kg/week, intraperitoneally), EW (orally, instead of normal water ad libitum), or their combination for 29 days. The anti-RA activities were determined by paw edema, joint diameter, arthritis score, and several nociceptive behavioral tests (thermal hyperalgesia, cold allodynia, and tactile allodynia). The levels of inflammatory (TNF-α, CRP, RF, and anti-CCP), anti-inflammatory (IL-10), and oxidative stress (NO, MDA, and GSH) markers were measured in serum. In addition, the levels of IFN-γ, IL-4, IL-17, and TGF-β were assessed in the spleen-isolated lymphocytes. Results: We found that treatment with MTX, EW, and their combination remarkably ameliorated thermal hyperalgesia, cold allodynia, and tactile allodynia results following CFA-induced RA in rats. In addition, EW also notably attenuated arthritis score, joint diameter, inflammatory cytokines, and oxidative markers while propagating anti-inflammatory and anti-oxidative mediators. Conclusions: We reveal that EW possesses anti-arthritic effects, possibly through anti-oxidative, anti-inflammatory, and immunomodulatory properties. Collectively, EW may be a promising therapeutic agent for treating RA. Full article

The search for effective pain management solutions remains a critical challenge, especially amidst growing concerns over the use of conventional opioids. In the US, opioid-related mortality rates have surged to as many as 80 deaths per 100,000 people in some states, with an estimated economic burden of USD 1.5 trillion annually—exceeding the gross domestic product (GDP) of most US industrial sectors. A remarkable breakthrough lies in the discovery that indole and oxindole alkaloids, produced by several genera within the plant Tribe Naucleeae, act on opioid receptors without activating the beta-arrestin-2 pathway, the primary driver of respiratory depression and overdose deaths. This systematic review explores the pharmacological properties, mechanisms of action, dosing considerations, interactions, and long-term effects of mitragynine and corynoxeine, alkaloids from the Southeast Asian plant Mitragyna speciosa (kratom) and others in the Tribe Naucleeae. Mitragynine, a partial opioid receptor agonist, and corynoxeine, known for its anti-inflammatory and neuroprotective effects, demonstrate significant therapeutic potential for managing diverse pain types—including neuropathic, inflammatory, nociceptive, visceral, and central pain syndromes—with a focus on cancer pain. Unlike traditional opioids, these compounds do not recruit beta-arrestin-2, avoiding key adverse effects such as respiratory depression, severe constipation, and rapid tolerance development. Their distinct pharmacological profiles make them innovative candidates for safer, non-lethal pain relief. However, challenges persist, including the unregulated nature of kratom products, inconsistencies in potency due to crude extract variability, potential for misuse, and adverse drug interactions. Addressing these issues requires establishing standardized quality control protocols, such as Good Manufacturing Practices (GMP), to ensure consistent potency and purity. Clear labeling requirements with dosage guidelines and warnings should be mandated to ensure safe use and prevent misuse. Furthermore, the implementation of regulatory oversight to monitor product quality and enforce compliance is essential. This review emphasizes the urgency of focused research to optimize dosing regimens, characterize the pharmacodynamic profiles of these alkaloids, and evaluate long-term safety. By addressing these gaps, the mitragynine- and corynoxeine-related drug classes can transition from promising plant-derived molecules to validated pharmacotherapeutic agents, potentially revolutionizing the field of pain management. Full article

Due to its central role in pain, inflammation, and related disorders, the Transient Receptor Potential (TPR) Vanilloid Type-1 (TRPV1) ion channel represents an attractive target for the development of novel antinociceptive and anti-inflammatory agents. Capsaicin, the natural component of chili peppers, is one of the most investigated agonists of this receptor. Several modifications of its structure have been attempted, aiming at finding TRPV1 agonists with improved characteristics, but, to date, no capsaicin-derived agents have reached the market. Based on our previous knowledge of the design and synthesis of TRPV1 agonists, in this paper we propose two small series of indole-2-carboxamides as novel and selective agonists for this ion channel. The newly developed compounds have been structurally characterized and tested in vitro for their ability to modulate TRPV1, in terms of efficacy, potency (EC₅₀), and desensitization (IC₅₀) properties. For the most promising derivatives, selectivity over the TRP ankyrin-1 (TRPA1) channel has been reported. From our study, compound 6g arose as a promising candidate for further evaluation, also in correlation with its in silico-predicted drug-like properties. Full article

Background/Objectives: Approximately one in five individuals will experience major depressive disorder (MDD), and 30% exhibit resistance to standard antidepressant treatments, resulting in a diagnosis of treatment-resistant depression (TRD). Historically, opium was used effectively to treat depression; however, when other medications were introduced, its use was discontinued due to addiction and other hazards. Recently, kappa opioid receptor (KOR) antagonism has been proposed as a potential mechanism for treating TRD. The main research question is whether commonly used psychotropic medications possess KOR antagonist properties and whether this characteristic could contribute to their efficacy in TRD. Methods: We investigated the antinociceptive effects of many psychotropic medications and their interactions with the opioid system. Mice were tested with a hotplate or tail-flick after being injected with different doses of these agents. Results: The antidepressants mianserin and mirtazapine (separately) induced dose-dependent antinociception, each yielding a biphasic dose–response curve. Similarly, the antidepressant venlafaxine produced a potent effect and reboxetine produced a weak effect. The antipsychotics risperidone and amisulpride exhibited a dose-dependent antinociceptive effect. The sedative–hypnotic zolpidem induced a weak bi-phasic dose-dependent antinociceptive effect. All seven psychotropic medications elicited antinociception, which was reversed by the non-selective opiate antagonist naloxone and, separately, by the kappa-selective antagonist Nor-BNI. Conclusions: Clinical studies are mandatory to establish the potential efficacy of augmentation of the treatment with antidepressants with these drugs in persons with treatment-resistant depression and the optimal dosage of medications prescribed. We suggest a possible beneficial effect of antidepressants with kappa antagonistic properties. Full article

The pathophysiology of fibromyalgia, a condition that causes chronic pain throughout the body, involves abnormal pain signaling, genetic predispositions, and abnormal neuroendocrine function, significantly impairing quality of life. Fibromyalgia is commonly characterized by musculoskeletal pain, chronic fatigue, and severe sleep alterations. Changes in the central processing of sensory input and defects in endogenous pain inhibition could be the basis of enhanced and persistent pain sensitivity in individuals with fibromyalgia. The term central sensitivity syndrome was chosen as an umbrella term for fibromyalgia and related illnesses, including myalgic encephalomyelitis/chronic fatigue syndrome, migraine, and irritable bowel syndrome. Given the substantial impact of fibromyalgia on health, there is a need for new prevention and treatment strategies, particularly those involving bioavailable nutraceuticals and/or phytochemicals. This approach is particularly important considering the adverse effects of current fibromyalgia pharmaceutical treatments, such as antidepressants and anticonvulsants, which can lead to physical dependence and tolerance. Natural products have recently been considered for the design of innovative analgesics and antinociceptive agents to manage fibromyalgia pain. Polyphenols show promise in the management of neuropathic pain and fibromyalgia, especially considering how anti-inflammatory treatments, including corticosteroids and nonsteroidal medical drugs, are effective only when inflammatory processes coexist and are not recommended as the primary treatment for fibromyalgia. Full article

Background: Curcumin appears to be well tolerated and effective for managing chronic inflammatory pain, but its poor oral bioavailability has been a hurdle in its use as a therapeutic agent. The current study was performed to characterize a novel co-amorphous compound based on curcumin/L-arginine 1:2 (CAC12). Methods: Stability, solubility and structural characterization of the CAC12 were carried out by spectrometry techniques and in vitro assays, whereas the antinociceptive and anti-inflammatory effects were evaluated by CFA or carrageenan models. The mechanism of action was determined by cytokine quantification, and pharmacokinetic parameters were obtained through UPLC-MS/MS. The co-amorphous compound was prepared by fast solvent evaporation. Powder XRD, ¹³C-NMR, ATR-FTIR and TGA/DSC thermal analysis showed a 1:2 stoichiometry for the CAC12. Results: CAC12 was 1000 times more soluble than curcumin, and it was stable for 1 month at 40 °C and 75% relative humidity or for 60 min in physiological medium at pH 4.5–6.8. Co-amorphous curcumin/L-arginine, but not curcumin + L-arginine, decreased carrageenan- or CFA-induced inflammation and nociception by decreasing IL-1α, IL-1β, IL-6, TNF-α, MCP-1 and CXCL1 cytokines. The bioavailability of free plasmatic curcumin increased about 22.4 times when it was given as CAC12 relative to a phytosome formulation at the equivalent dose. Conclusions: Results suggest the possible use of CAC12 to treat inflammatory pain disorders in human beings. Full article

Waltheria, a genus within the Malvaceae family, is abundantly distributed in tropical and subtropical areas worldwide. Many species of this genus are widely utilized in various ways, including chewing, in folk medicine, acting as an anti-inflammatory agent, and treating gastrointestinal disorders, rheumatism, and asthma, among other conditions. These applications are largely due to their secondary metabolites, primarily quinolone alkaloids and cyclopeptides. Several biological activities have been reported for Waltheria species, including antifungal, anticancer, trypanocidal, acetylcholinesterase inhibitory, potential anti-HIV, antinociceptive, analgesic, anti-inflammatory, antibacterial, antioxidant, and leishmanicidal activities. This review not only presents information on isolated alkaloids and their biological activities but also delves into biosynthetic, chemosystematic, medicinal chemistry, and total synthesis aspects. Additionally, the manuscript highlights other applications of alkaloids of the genus, such as a study on their herbicidal activity, which shows significant potential for agricultural use. Full article

The genus Croton (Euphorbiaceae) encompasses numerous species recognized for their diverse medicinal applications, particularly in pain management. This systematic review aims to compile and analyze the scientific evidence on the antinociceptive properties of Croton species. The review protocol was registered in the Open Science Framework (OSF) associated project: osf.io/z4juf. Using the PRISMA methodology, an exhaustive search was conducted in databases such as PubMed, Scopus, and Web of Science to identify relevant studies published to date. The review includes preclinical studies in animal models that investigate the mechanisms of action and efficacy of Croton extracts and isolated compounds in pain inhibition. The results indicate that 28 Croton species exhibit significant antinociceptive effects, attributed to bioactive compounds such as diterpenes, alkaloids, and flavonoids. These compounds interact with multiple biological pathways, including ion channels, such as TRPV1, K/ATP, and ASIC channels, as well as the inhibition of the synthesis of inflammatory mediators, particularly prostaglandins. This review highlights the potential of Croton as a source of novel analgesic agents and emphasizes the necessity for further clinical studies. Additionally, integrating ethnobotanical and pharmacological knowledge is suggested to develop innovative and effective treatments for pain management. Full article

Post-traumatic trigeminal neuropathy (PTTN) is a sensory abnormality caused by injury to the trigeminal nerve during orofacial surgery. However, existing analgesics are ineffective against PTTN. Abnormal microglial activation in the caudal part of the spinal trigeminal nucleus caudal part (Sp5C), where the central trigeminal nerve terminals reside, plays an important role in PTTN pathogenesis. Therefore, regulating microglial activity in Sp5C appears to be an important approach to controlling pain in PTTN. Cannabinoid receptor 2 (CB₂) is expressed in immune cells including microglia, and its activation has anti-inflammatory effects. The current study demonstrates that the repeated intranasal administration of CB₂ agonist HU-308 ameliorates the infraorbital nerve cut (IONC)-induced hyperresponsiveness to acetone (cutaneous cooling). The therapeutic efficacy of oral HU-308 was found to be less pronounced in alleviating cold hypersensitivity in IONC mice compared to intranasal administration, indicating the potential advantages of the intranasal route. Furthermore, repeated intranasal administration of HU-308 suppressed the activation of Sp5C microglia in IONC mice. Additionally, pretreatment with the CB₂ antagonist, SR 144528, significantly blocked the anti-nociceptive effect of repeated intranasal administration of HU-308 on cold hypersensitization in IONC mice. These data suggest that the continuous stimulation of CB₂ ameliorates PTTN-induced pain via the inhibition of microglial activation. Thus, CB₂ agonists are potential candidates for novel therapeutic agents against PTTN. Full article

Background/Objectives: To address the unmet clinical needs in the treatment of epilepsy and pain, the continued development of more effective and safer anticonvulsants and analgesics is still necessary. Therefore, herein we report synthesis and antiseizure/antinociceptive evaluation of a focused series of 3-(benzo[b]thiophen-2-yl)pyrrolidine-2,5-dione derivatives. Methods: The anticonvulsant properties were investigated in acute models of seizures, namely the maximal electroshock (MES), the 6 Hz (32 mA), and subcutaneous pentylenetetrazole (scPTZ) seizure models, whereas analgesic activity was tested in the model of a tonic pain/formalin test and oxaliplatin-induced neuropathic pain (in CD-1-mice, i.p.). In addition, a number of in vitro assays were performed, aiming at the evaluation of the drug-like properties of the compounds disclosed herein. Results: We identified 33 as a lead compound with the most promising antiseizure properties, i.e., ED₅₀ (MES) = 27.4 mg/kg and ED₅₀ (6 Hz, 32 mA) = 30.8 mg/kg. Furthermore, 33 at a dose of 100 mg/kg significantly prolonged the latency time to the first seizure episode in the scPTZ model and at high doses did not impaire coordination of mice in the rotarod test (TD₅₀ > 200 mg/kg). Apart from broad antiseizure protection, 33 demonstrated a significant analgesic effect in the formalin test (45 mg/kg, i.p.), and effectively alleviated allodynia in the oxaliplatin-induced neuropathic pain model (30 and 45 mg/kg). The binding assays suggest that the most plausible mechanism of action relies on interaction with the neuronal voltage-sensitive sodium channel (site 2). Furthermore, the drug-like potential of 33 supports favorable in vitro results, i.e., no hepatocytotoxicity and neurocytotoxicity at a high concentration of 100 μM, as well as a lack of mutagenicity at a concentration as high as 500 μM. Conclusions: Compound 33 identified in the current studies is proposed to be an interesting candidate for further preclinical development as therapy for epilepsy and neuropathic pain. Full article