RESUMEN
Local anesthetics are a class of drugs, which have wide applications in the treatment of acute and chronic pain. However, their analgesic effects only last for a few hours because of their short half-life, which is insufficient for clinical application, especially for long-term surgery or postoperative analgesia. Herein, an injectable hydrogel/microsphere (GEL/MS) composite co-encapsulating bupivacaine (BUP) and dexmedetomidine (DEX) was developed for effective sustained analgesia. The GEL/MS composite appeared as a three-dimensional porous network microstructure and displayed sustained sequential release of DEX and BUP over several days in vitro, without obvious burst release. In this composite, DEX was released from the GEL matrix preferentially, exhibited long-term vasoconstriction effect and improved the local anesthetic concentration at injection site by preventing BUP from diffusing into the blood circulation. BUP was released subsequently from the MS for blockage of the Na+ channel on nerve cell membranes and provided long-term analgesia. In vivo analgesic effect demonstrated that DEX significantly prolonged the effect of analgesia when synergistically administered with BUP in the GEL/MS composite. Moreover, the GEL/MS composite exhibited good biodegradability and biocompatibility in histological analyses. Taken together, the administration of BUP and DEX in the GEL/MS composite achieved a synergistic effect in prolonging analgesia without causing toxicity, and thus represented a potential strategy for long-acting analgesia therapy.
Asunto(s)
Analgesia/métodos , Bupivacaína/química , Dexmedetomidina/química , Hidrogeles/química , Animales , Bupivacaína/uso terapéutico , Dexmedetomidina/uso terapéutico , Femenino , Masculino , Microesferas , Ratas , Ratas WistarRESUMEN
Chronic low back pain: Chronic pain is the most common cause for people to utilize healthcare resources and has a considerable impact upon patients' lives. The most prevalent chronic pain condition is chronic low back pain (CLBP). CLBP may be nociceptive or neuropathic, or may incorporate both components. The presence of a neuropathic component is associated with more intense pain of longer duration, and a higher prevalence of co-morbidities. However, many physicians' knowledge of chronic pain mechanisms is currently limited and there are no universally accepted treatment guidelines, so the condition is not particularly well managed. DIAGNOSIS: Diagnosis should begin with a focused medical history and physical examination, to exclude serious spinal pathology that may require evaluation by an appropriate specialist. Most patients have non-specific CLBP, which cannot be attributed to a particular cause. It is important to try and establish whether a neuropathic component is present, by combining the findings of physical and neurological examinations with the patient's history. This may prove difficult, however, even when using screening instruments. Multimodal management: The multifactorial nature of CLBP indicates that the most logical treatment approach is multimodal: i.e. integrated multidisciplinary therapy with co-ordinated somatic and psychotherapeutic elements. As both nociceptive and neuropathic components may be present, combining analgesic agents with different mechanisms of action is a rational treatment modality. Individually tailored combination therapy can improve analgesia whilst reducing the doses of constituent agents, thereby lessening the incidence of side effects. CONCLUSIONS: This paper outlines the development of CLBP and the underlying mechanisms involved, as well as providing information on diagnosis and the use of a wide range of pharmaceutical agents in managing the condition (including NSAIDs, COX-2 inhibitors, tricyclic antidepressants, opioids and anticonvulsants), supplemented by appropriate non-pharmacological measures such as exercise programs, manual therapies, behavioral therapies, interventional pain management and traction. Surgery may be appropriate in carefully selected patients.
Asunto(s)
Analgésicos/uso terapéutico , Dolor Crónico/terapia , Dolor de la Región Lumbar/terapia , Analgésicos Opioides/administración & dosificación , Antiinflamatorios no Esteroideos/uso terapéutico , Anticonvulsivantes/uso terapéutico , Dolor Crónico/tratamiento farmacológico , Terapia Combinada , Inhibidores de la Ciclooxigenasa 2/uso terapéutico , Humanos , Dolor de la Región Lumbar/tratamiento farmacológicoRESUMEN
Poor management of post-operative acute pain can contribute to medical complications including pneumonia, deep vein thrombosis, infection and delayed healing, as well as the development of chronic pain. It is therefore important that all patients undergoing surgery should receive adequate pain management. However, evidence suggests this is not currently the case; between 10% and 50% of patients develop chronic pain after various common operations, and one recent US study recorded >80% of patients experiencing post-operative pain. At the first meeting of the acute chapter of the Change Pain Advisory Board, key priorities for improving post-operative pain management were identified in four different areas. Firstly, patients should be more involved in decisions regarding their own treatment, particularly when fateful alternatives are being considered. For this to be meaningful, relevant information should be provided so they are well informed about the various options available. Good physician/patient communication is also essential. Secondly, better professional education and training of the various members of the multidisciplinary pain management team would enhance their skills and knowledge, and thereby improve patient care. Thirdly, there is scope for optimizing treatment. Examples include the use of synergistic analgesia to target pain at different points along pain pathways, more widespread adoption of patient-controlled analgesia, and the use of minimally invasive rather than open surgery. Fourthly, organizational change could provide similar benefits; introducing acute pain services and increasing their availability towards the 24 hours/day ideal, greater adherence to protocols, increased use of patient-reported outcomes, and greater receptivity to technological advances would all help to enhance performance and increase patient satisfaction. It must be acknowledged that implementing these recommendations would incur a considerable cost that purchasers of healthcare may be unwilling or unable to finance. Nevertheless, change is under way and the political will exists for it to continue.