The clinical and laboratorial evaluation of transdermal ketamine, fentanyl, clonidine or their combination in chronic low back pain Avaliação clínica e laboratorial da cetamina transdérmica, do fentanil transdérmico, da clonidina transdérmica ou suas associações na dor lombar crônica Evaluación clínica y de laboratorio de cetamina transdérmica, del fentanyl transdérmico, de la clonidina transdérmica o de sus asociaciones en el dolor lumbar crónico

Objectives: chronic low back pain may result in central sensitization, with involvement of different receptors. The aim of this study was to evaluate the analgesic action of transdermal (T) ketamine (a NMDA antagonist), clonidine (an α2-agonist), fentanyl (an opioid agonist), or their combination in chronic low back pain. Methods: after the institutional approval and informed consent signature, 54 patients were prospectively randomized into 6 groups. Each patient had two of the T preparations applied in different arms. The effect of either T ketamine (1 mg/h), T clonidine (25 μg/h) or T fentanyl (25 μg/h), combined with T placebo (CloG, KetG and FenG); or the combination of T ketamine and clonidine RESUMO