Intravenous dipyrone for the acute treatment of episodic tension-type headache: a randomized, placebo-controlled, double-blind study. Efficacy and safety of metamizol vs. acetylsalicylic acid in patients with moderate episodic tension-type headache: a randomized, double-blind, placebo- and active-controlled, multicentre study. [Efficacy of three drugs in the treatment of migrainous aura: a randomized placebo-controlled study]. Intravenous dipyrone in the acute treatment of migraine without aura and migraine with aura: a randomized, double blind, placebo controlled study.
Acute headaches are responsible for a significant percentage of the case load at primary care units and emergency rooms in Brazil. Dipyrone (metamizol) is easily available in these settings, being the most frequently used drug. We conducted a randomized, placebo-controlled, double-blind study to assess the effect of dipyrone in the acute treatment of episodic tension-type headache. Sixty patients were randomized to receive placebo (intravenous injection of 10 ml saline) or 1 g dipyrone in 10 ml saline. We used seven parameters of analgesic evaluation. The patients receiving dipyrone showed a statistically significant improvement (P<0.05) of pain compared to placebo up to 30 min after drug administration. The therapeutic gain was 30% in 30 min and 40% in 60 min. The number of patients needed to be treated for at least one to have benefit was 3.3 in 30 min and 2.2 in 60 min. There were statistically significant reductions in the recurrence (dipyrone = 25%, placebo = 50%) and use of rescue medication (dipyrone = 20%, placebo = 47.6%) for the dipyrone group. Intravenous dipyrone is an effective drug for the relief of pain in tension-type headache and its use is justified in the emergency room setting. We assessed the efficacy and safety of oral single doses of 0.5 and 1 g metamizol vs. 1 g acetylsalicylic acid (ASA) in 417 patients with moderate episodic tension-type headache included in a randomized, double-blind, placebo- and active-controlled, parallel, multicentre trial. Eligibility criteria included 18-65 years of age, history of at least two episodes of tension-type headache per month in the 3 months prior to enrollment, and successful previous pain relief with a non-opioid analgesic. Treatment arms were metamizol 0.5 g (n = 102), metamizol 1 g (n = 108), ASA 1 g (n = 102) and placebo (n = 105). The analgesic efficacy of 0.5 and 1 g metamizol vs. placebo was highly statistically significant (alpha: 0.025; one-sided) for sum of pain intensity differences, maximum pain intensity difference, number of patients with at least 50% pain reduction, time to 50% pain reduction, maximum pain relief and total pain relief. A trend towards an earlier onset of a more profound pain relief of 0.5 and 1 g metamizol over 1 g ASA was noticed. All medications including placebo were almost equally safe and well tolerated. In spite of the enormous amount of research regarding classification, epidemiology, diagnosis, pathophysiology and treatment of migraines, aura, one of its hallmarks, stays much less studied. The objective of this study is, therefore, to evaluate the evolution of aura in patients submitted to placebo and three different drugs available in Brazilian public health units. We studied 86 patients during an acute migrainous attack, with aura at the moment of the evaluation. Patients were randomized to receive one of the following substances, in a parenteral route: placebo, dipyrone, chlorpromazine and magnesium sulphate. Magnesium sulphate was superior to placebo (p <0,05) 30 and 60 minutes after its administration. Dipyrone and chlorpromazine reduced the duration of the aura, when compared to placebo, 60 minutes following their administration. Our findings make possible some speculations about the pathophysiology of migraine, as well as about the therapeutic approach of patients presenting migrainous aura. Dipyrone (Metamizol) has been used in the acute treatment of migraines in Brazil. Some investigators have found it to be a highly effective medication for migraine pain and associated symptoms.
                To conduct a randomized, placebo controlled, double blind study to assess the effect of dipyrone on the pain and symptoms associated with migraine without aura or with aura and the adverse effect profile of this medication.
                For the migraine without aura group, 44 patients were assigned at random to receive 1 g intravenous dipyrone, and 30 patients received 10 mL 0.9% physiological saline. For the migraine with aura group, 30 patients received both dipyrone or placebo. We used seven parameters of analgesic evaluation and an analog scale to assess nausea, photophobia, and phonophobia.
                Patients receiving dipyrone demonstrated a statistically superior improvement (P<.05 and P<.01) in pain and all associated symptoms compared with control subjects.
                Dipyrone is an effective drug for the relief of acute migraine pain and associated symptoms.