title: Diphenhydramine as Adjuvant Therapy for Acute Migraine: An Emergency Department-Based Randomized Clinical Trial.
abstract: OBJECTIVE
  More than 1 million patients present to US emergency departments (EDs) annually seeking care for acute migraine. Parenteral antihistamines have long been used in combination with antidopaminergics such as metoclopramide to treat acute migraine in the ED. High-quality data supporting this practice do not exist. We determine whether administration of diphenhydramine 50 mg intravenously+metoclopramide 10 mg intravenously results in greater rates of sustained headache relief than placebo+metoclopramide 10 mg intravenously.
  
  
  METHODS
  This was a randomized, double-blind, clinical trial comparing 2 active treatments for acute migraine in an ED. Eligible patients were adults younger than 65 years presenting with an acute moderate or severe headache meeting International Classification of Headache Disorders-2 migraine criteria. Patients were stratified according to presence or absence of allergic symptoms. The primary outcome was sustained headache relief, defined as achieving a headache level of mild or none within 2 hours of medication administration and maintaining this level of relief without use of any additional headache medication for 48 hours. Secondary efficacy outcomes included mean improvement on a 0 to 10 verbal scale between baseline and 1 hour, the frequency with which subjects indicated they would want the same medication the next time they present to the ED with migraine, and the ED throughput time. Sample size calculation using a 2-sided α of .05, a β of .20, and a 15% difference between study arms determined the need for 374 patients. An interim analysis was conducted when data were available for 200 subjects.
  
  
  RESULTS
  Four hundred twenty patients were approached for participation. Two hundred eight eligible patients consented to participate and were randomized. At the planned interim analysis, the data and safety monitoring board recommended that the study be halted for futility. Baseline characteristics were comparable between the groups. Fourteen percent (29/208) of the sample reported allergic symptoms. Of patients randomized to diphenhydramine, 40% (40/100) reported sustained relief at 48 hours, as did 37% (38/103) of patients randomized to placebo (95% confidence interval [CI] for difference of 3%: -10% to 16%). One hour after medication administration, patients randomized to diphenhydramine improved by a mean of 5.1 on the 0 to 10 scale versus 4.8 for those randomized to placebo (95% CI for difference of 0.3: -0.6 to 1.1). Eighty-five percent (84/99) of the patients in the diphenhydramine arm reported they would want the same medication combination during a subsequent ED visit, as did 76% (77/102) of those who received placebo (95% CI for difference of 9%: -2% to 20%). Median ED length of stay was 122 minutes (interquartile range 84 to 180 minutes) in the diphenhydramine group and 139 minutes (interquartile range 90 to 235 minutes) in the placebo arm. Rates of adverse effects, including akathisia, were comparable between the groups.
  
  
  CONCLUSIONS
  Intravenous diphenhydramine, when administered as adjuvant therapy with metoclopramide, does not improve migraine outcomes.
authors: Department of Emergency Medicine, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY. Electronic address: bwfriedmanmd@gmail.com.
authors: Benjamin W
authors: BW
authors: Friedman
authors: Department of Emergency Medicine, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY.
authors: Lisa
authors: L
authors: Cabral
authors: Department of Emergency Medicine, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY.
authors: Victoria
authors: V
authors: Adewunmi
authors: Pharmacy Department, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY.
authors: Clemencia
authors: C
authors: Solorzano
authors: Department of Emergency Medicine, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY.
authors: David
authors: D
authors: Esses
authors: Department of Emergency Medicine, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY.
authors: Polly E
authors: PE
authors: Bijur
authors: Department of Emergency Medicine, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY.
authors: E John
authors: EJ
authors: Gallagher
mesh_terms: D000208:Acute Disease; D000328:Adult; D004155:Diphenhydramine / Q000008:administration & dosage / Q000627:therapeutic use*; D065127:Dopamine D2 Receptor Antagonists / Q000008:administration & dosage / Q000627:therapeutic use*; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage / Q000627:therapeutic use*; D008297:Male; D008787:Metoclopramide / Q000008:administration & dosage / Q000627:therapeutic use*; D008875:Middle Aged; D008881:Migraine Disorders / Q000188:drug therapy*; D010147:Pain Measurement; D012720:Severity of Illness Index; D016896:Treatment Outcome
chemical_list: D065127:Dopamine D2 Receptor Antagonists; D006993:Hypnotics and Sedatives; D004155:Diphenhydramine; D008787:Metoclopramide