Diclofenaco intramuscular no tratamento agudo da migrânea: um estudo duplo cego placebo controlado Intramuscular diclofenac in the acute treatment of migraine: a double-blind placebo controlled study

O objetivo do presente estudo é avaliar, com mascaramento duplo, o efeito do diclofenaco sobre a dor e sintomas associados em pacientes com crise de migrânea. Sessenta pacientes com migrânea com aura e sessenta pacientes com migrânea sem aura foram randomizados para receber diclofenaco intramuscular, na dose de 75 mg, associado com injeção intravenosa de solução salina, 10 ml, ou para receber solução salina isoladamente. Três parâmetros de avaliação analgésica e uma escala analógica para avaliar os sintomas associados foram usados. Aferimos ainda os percentuais de recorrência e de utilização de medicação de resgate. Pacientes que receberam diclofenaco apresentaram redução na intensidade da dor estatisticamente significativa, 60 minutos após a administração, em dois dos três parâmetros utilizados (migrânea sem aura) e nos três parâmetros utilizados (migrânea com aura). Não observamos diferença, comparado com o placebo, na intensidade dos sintomas associados. Houve redução da recorrência e da utilização de medicação de resgate. A despeito de ser uma opção no tratamento das migrâneas em unidades de emergência, o diclofenaco apresenta início de ação lento e nenhum efeito nos sintomas associados.<br>The aim of this study is to assess, in a double blind fashion, the effect of diclofenac on the pain and associated symptoms in patients with acute migraine. 60 patients with migraine with aura and 60 patients with migraine without aura were assigned at random to receiving intramuscular diclofenac, 75 mg associated to intravenous physiological saline, 10 ml, or physiological saline alone. We used 3 parameters of analgesic evaluation and an analogical scale to asses associated symptoms. We also observed the recurrence and rescue medication percentiles. Patients receiving diclofenac showed a statistically significant improvement of pain 60 minutes after the administration in two of the three parameters(migraine without aura) and in all parameters (migraine with aura). They did not present difference, compared to placebo, on the intensity of associated symptoms. We observed a reduction on the recurrence and rescue medication utilization. Despite being an option to treat migraines attacks in the emergency room settings, diclofenac has a slow onset action and no effects on the associated symptoms

Participation of ATP-sensitive K+ channels in the peripheral antinociceptive effect of fentanyl in rats

We examined the effect of several K+ channel blockers such as glibenclamide, tolbutamide, charybdotoxin (ChTX), apamin, tetraethylammonium chloride (TEA), 4-aminopyridine (4-AP), and cesium on the ability of fentanyl, a clinically used selective µ-opioid receptor agonist, to promote peripheral antinociception. Antinociception was measured by the paw pressure test in male Wistar rats weighing 180-250 g (N = 5 animals per group). Carrageenan (250 µg/paw) decreased the threshold of responsiveness to noxious pressure (delta = 188.1 ± 5.3 g). This mechanical hyperalgesia was reduced by fentanyl (0.5, 1.5 and 3 µg/paw) in a peripherally mediated and dose-dependent fashion (17.3, 45.3 and 62.6%, respectively). The selective blockers of ATP-sensitive K+ channels glibenclamide (40, 80 and 160 µg/paw) and tolbutamide (80, 160 and 240 µg/paw) dose dependently antagonized the antinociception induced by fentanyl (1.5 µg/paw). In contrast, the effect of fentanyl was unaffected by the large conductance Ca2+-activated K+ channel blocker ChTX (2 µg/paw), the small conductance Ca2+-activated K+ channel blocker apamin (10 µg/paw), or the non-specific K+ channel blocker TEA (150 µg/paw), 4-AP (50 µg/paw), and cesium (250 µg/paw). These results extend previously reported data on the peripheral analgesic effect of morphine and fentanyl, suggesting for the first time that the peripheral µ-opioid receptor-mediated antinociceptive effect of fentanyl depends on activation of ATP-sensitive, but not other, K+ channels