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26th July 2022
Antihistamines are able to provide a greater level of symptom relief, 2 hours post-dose in patients with vertigo in comparison to benzodiazepines. However, neither class of drugs seems to be better than placebo after only one week. These were the key findings from a systematic review and meta-analysis by researchers from the Department of Emergency Medicine, Indiana University School of Medicine, Indianapolis, US.
Vertigo is a symptom of vestibular dysfunction and described as a sensation of motion, most commonly rotational motion. The term dizziness is non-specific but usually refers to a sense of disorientation with vertigo being a subtype of dizziness. The sensation of dizziness is common condition and affects about 15% to 20% of adults annually and vestibular vertigo accounts for about a quarter of dizziness cases with an annual prevalence of 5%. Pharmacological treatments for the management of vertigo are referred to as vestibular suppressants and there are a wide of drug classes such as anticholinergics (scopolamine), antihistamines (cinnarizine), benzodiazepines (clonazepam) and dopamine receptor antagonist (prochlorperazine) and histamine-1 receptor antagonists (betahistine). In a 2017 updated clinical practice guideline, it was recommended that benzodiazepines and/or antihistamines could be used in the management of one of the most common forms of vertigo, benign paroxysmal positional vertigo. Despite this, there is an absence of comparative data for these two drug classes.
As a result, for the present study, the US team undertook a systematic review and meta-analysis to assess the efficacy of both drug classes in the management of acute vertigo due to any underlying cause. The team searched for randomised trials which included any antihistamine or benzodiazepine compared with an active comparator, placebo or no intervention in patients with acute vertigo and which had lasted for less than 2 weeks. The primary outcome of interest was the change in a 10 or 100-point vertigo or dizziness visual analogue scale (VAS) score at 2 hours post-treatment. Secondary outcomes included change in nausea VAS score at 2 hours and resolution of vertigo after one week and a month.
Antihistamines and improvement in vertigo scores
A total of 27 trials met the inclusion criteria, of which, 17 with 1586 participants were included in the meta-analysis.
For the primary outcome, 7 trials with 802 were included. Antihistamines were associated with a 16.1-point (95% CI 7.2 – 25) greater decrease in mean VAS vertigo scores compared to benzodiazepines. However, when compared to other active treatments, antihistamines performed to a similar extent (mean difference = 7.4, 95% CI -1.12 to 15.8).
For the secondary outcomes, after one week, there was no evidence to suggest a higher likelihood of complete symptom resolution from antihistamines (relative risk, RR = 1.03, 95% CI 0.56 – 1.89) or after 4 weeks. Similarly, the improvement with benzodiazepines was no better than placebo after one or 4 weeks.
The authors concluded that there was moderately strong evidence to show that single dose antihistamines provided better relief of vertigo symptoms after 2 hours than benzodiazepines. Furthermore, the evidence did not support an association between benzodiazepine use with an improvement in acute vertigo.
Hunter BR et al. Efficacy of Benzodiazepines or Antihistamines for Patients With Acute Vertigo: A Systematic Review and Meta-analysis JAMA Neurol 2022
27th November 2020
While the precise cause of CSU remains unclear, contemporary European guidelines advocate the use of second-generation antihistamines as a first-line treatment for the condition. Although these drugs can be effective, for patients in which symptom control remains inadequate, the guidance recommends up-dosing to four times the recommended dose as a second-line treatment option.
This latter commendation is based on expert opinion and for this study, a team from the Allergology Department, Complexo Hospital, A Coruna, Spain, set out to review the available evidence to support this approach. They included studies published in English or Spanish with patients at least 12 years of age with CSU on regular (as opposed to “on-demand”) therapy with a second-generation antihistamine. Other inclusion criteria were that the study should have a single antihistamine (rather than a combination), a placebo arm and using the drug at a higher than recommended dosage.
In total and after removal of duplicates and exclusions, only 14 articles were analysed in detail including 20 to 439 patients. Six studies focused on fexofenadine (up-dosing to 720 mg), 2 on cetirizine, levocetirizine, rupatadine, desloratadine and 1 trial with either ebastine or bilastine. Furthermore, only 5 of these trials were placebo controlled and all studies lasted between 2 and 8 weeks except for one fexofenadine trial which lasted 16 weeks. A higher dose of fexofenadine produced a dose-dependent significant response and controlled CSU in the majority of patients. Commenting on their findings, the authors noted that of the 14 trials, only 6 were of high quality and that the high level of heterogeneity in sample size, design, duration etc, which made it very difficult to make comparisons. Interestingly, they also note that despite current guideline recommendations, most studies did not find a significant impact on symptom control from up-dosing.
The authors concluded that while up-dosing appears both effective and safe, there is a lack of evidence to support this approach and called for further studies to validate the recommendations in guidelines.
Iriarte SP T et al. Up-dosing antihistamines inn chronic spontaneous urticaria: efficacy and safety. A systematic review of the literature. J Investig Allergol Clin Immunol 2020 doi: 10.18176/jiaci.0649