Chronic pain negatively impacts the quality of life in a variety of patient populations. The current therapeutic repertoire is inadequate in managing patient pain and warrants the development of new therapeutics. Adenosine and its four cognate receptors (A1 , A2A , A2B and A3 ) have important roles in physiological and pathophysiological states, including chronic pain. Preclinical and clinical studies have revealed that while adenosine and agonists of the A1 and A2A receptors have antinociceptive properties, their therapeutic utility is limited by adverse cardiovascular side effects. In contrast, our understanding of the A3 receptor is only in its infancy, but exciting preclinical observations of A3 receptor antinociception, which have been bolstered by clinical trials of A3 receptor agonists in other disease states, suggest pain relief without cardiovascular side effects and with sufficient tolerability. Our goal herein is to briefly discuss adenosine and its receptors in the context of pathological pain and to consider the current data regarding A3 receptor-mediated antinociception. We will highlight recent findings regarding the impact of the A3 receptor on pain pathways and examine the current state of selective A3 receptor agonists used for these studies. The adenosine-to-A3 receptor pathway represents an important endogenous system that can be targeted to provide safe, effective pain relief from chronic pain.

The group of synthetic low-molecular peptides exhibiting profound analgesic activity was developed by modifying the salmon calcitonin molecule fragment sCT16-21, which retains the previously reported analgesic activity of the full-sized molecule. The mechanism of analgesic action of these synthetic oligopeptides has been investigated and their analgesic effect was compared with analgesic activity of ketorolac tromethamine, one of the strongest non-steroidal anti-inflammatory drug painkiller. It was demonstrated that the analgesic effect of the developed synthetic oligopeptides was associated with the specific binding of the clathrin heavy chain. It is postulated that inhibition of clathrin-mediated endocytosis of pain receptors in the postsynaptic vesicular cycle causes is more efficient analgesia than inhibition of those receptors on plasma membranes that may allow to replace opioid and non-steroidal anti-inflammatory drug’s analgesics with a much less toxic low-molecular synthetic peptides with non-narcotic type of analgesia.

Chronic pain management represents a serious healthcare problem worldwide. The use of opioid analgesics for pain has always been hampered by their side effects; in particular, the addictive liability associated with chronic use. Finding a morphine replacement has been a long-standing goal in the field of analgesia. In traditional Chinese medicine, processed Buthus martensii Karsch (BmK) scorpion has been used as a painkiller to treat chronic inflammatory arthritis and spondylitis, so called "Scorpio-analgesia". However, the molecular basis and the underline mechanism for the Scorpio-analgesia are still unclear.

The number of candidate molecules for new non-narcotic analgesics is extremely limited. Here, we report the identification of thiowurtzine, a new potent analgesic molecule with promising application in chronic pain treatment. We describe the chemical synthesis of this unique compound derived from the hexaazaisowurtzitane (CL-20) explosive molecule. Then, we use animal experiments to assess its analgesic activity in vivo upon chemical, thermal, and mechanical exposures, compared to the effect of several reference drugs. Finally, we investigate the potential receptors of thiowurtzine in order to better understand its complex mechanism of action. We use docking, molecular modeling, and molecular dynamics simulations to identify and characterize the potential targets of the drug and confirm the results of the animal experiments. Our findings finally indicate that thiowurtzine may have a complex mechanism of action by essentially targeting the mu opioid receptor, the TRPA1 ion channel, and the Cav voltage-gated calcium channel.

Although acetaminophen (ApAP) is one of the most commonly used medicines worldwide, hepatotoxicity is a risk with overdose or in patients with compromised liver function. ApAP overdose is the most common cause of acute fulminant hepatic failure. Oxidation of ApAP to N-acetyl-p-benzoquinone imine (NAPQI) is the mechanism for hepatotoxicity. 1 is a non-hepatotoxic, metabolically unstable lipophilic ApAP analog that is not antipyretic. The newly synthesized 3 is a non-hepatotoxic ApAP analog that is stable, lipophilic, and retains analgesia and antipyresis. Intraperitoneal or po administration of the new chemical entities (NCEs), 3b and 3r, in concentrations equal to a toxic dose of ApAP did not result in the formation of NAPQI. Unlike livers from NCE-treated mice, the livers from ApAP-treated mice demonstrated large amounts of nitrotyrosine, a marker of mitochondrial free radical formation, and loss of hepatic tight junction integrity. Given the widespread use of ApAP, hepatotoxicity risk with overuse, and the ongoing opioid epidemic, these NCEs represent a novel, non-narcotic therapeutic pipeline.

Total knee arthroplasty (TKA) is currently regarded as an effective treatment for knee osteoarthritis, relieving patients' pain and significantly enhancing their quality of life and activity levels, allowing them to return to work and daily life after surgery. However, some TKA patients suffer from varying degrees of postoperative residual pain and opioid abuse, which negatively impacts their recovery and quality of life. It has been reported that preoperative treatment with multimodal analgesics improves postoperative pain and reduces opioid consumption. However, there is no conclusive evidence that pre-emptive analgesia provides the same benefits in TKA. In order to inform future research, this protocol focuses on the efficacy and safety of oral analgesics used in TKA pre-emptive analgesia.

This systematic review aims to evaluate the effects of ibuprofen compared to other drugs on the risk and intensity of postoperative pain resulting from endodontic treatment in adult patients.