Chlorzoxazone

Dr. Reddy's Russia arm, part of the global pharmaceutical company Dr. Reddy’s Laboratories, has introduced Muslaxin (INN Ibuprofen 400 mg + Chlorzoxazone 500 mg), the first combination drug of NSAID and muscle relaxant that does not have generics in the Russian Federation. The product has an analgesic, muscle relaxant, anti-inflammatory effect, and is used for pain in the lower back caused by muscle tension and spasm. Muslaxin has been available in pharmacies since July 2024 and has Rx status. According to a number of world experts, 632 million people in the world daily complain of low back pain (LBP). The incidence of low back pain ranges from 10 percent to 25 percent of all cases of algia. In addition, 80 percent of patients who have suffered a new coronavirus infection, SARS-CoV-19, develop early (immediately after the acute phase) or late (after some time) back pain. Muscular-tonic syndrome reflexively occurs as a result of nociceptive impulses coming from the affected tissues. As its duration increases, the tense muscle itself becomes a source of pain and potentiates the formation of pain syndrome. A vicious circle is formed: pain-muscle spasm-pain. Despite the presence of pronounced analgesic and anti-inflammatory effects, NSAID monotherapy does not solve the issue of eliminating muscle spasm, as one of the important mechanisms of pain. Two or more drugs are more often used in complex therapy of acute pain, while fixed combinations have a number of advantages. Studies have shown that the use of a fixed combination made it possible to improve the response to treatment compared to NSAID monotherapy and to obtain a more pronounced analgesic effect in pain relief. The creation of combination product containing two or more components with fixed doses and different mechanisms of action, which have different effects on the pathogenesis of pain syndromes, is an important therapeutic strategy of modern pharmacology. For example, Muslaxin is a combination of chlorzoxazone and ibuprofen with a dual mechanism of action for the treatment of pain, inflammation and spasm. Ibuprofen is one of the most popular over-the-counter NSAIDs in the world. it is well tolerated and is used for the relief of acute pain and the treatment of pain in chronic diseases. Its actions are due to its inhibitory effect on cyclooxygenases COX1 and COX2, which are involved in the synthesis of prostaglandins. Chlorzoxazone is a centrally acting muscle relaxant, has its own moderate analgesic effect, reduces muscle spasm and increases mobility of the muscles involved. Chlorzoxazone acts mainly at the level of the spinal cord and subcortical areas of the brain, which leads to the suppression of polysynaptic reflexes involved in the formation of muscle spasms. It stimulates GABA receptors and helps block voltage-dependent Na+ and Ca2+ channels, which exert a muscle relaxant effect. It reduces the release of inflammatory leukotrienes, tumor necrosis factor (TNF) and the rate of the caspase cycle, inhibits the production of histamine, which exerts anti-inflammatory and antihistamine effects. The advantage of the Muslaxin combination compared to monotherapy also lies in its complex effect on the cause of back pain associated with spasms. An open-label, multicenter, prospective study comparing the efficacy and safety of a fixed-dose combination of chlorzoxazone and ibuprofen with ibuprofen monotherapy in patients with acute low back pain clinically suspected to be due to muscle spasm was conducted in 406 patients aged 18 to 60 years.