title: Sedative Effects of Levocetirizine: A Systematic Review and Meta-Analysis of Randomized Controlled Studies.
abstract: BACKGROUND
  As a substrate of P-glycoprotein, levocetirizine should not cause sedative effects. However, while cetirizine, a mixture of levocetirizine and dextrocetirizine, can slightly penetrate the blood brain barrier, the sedative effects of levocetirizine are still under study.
  
  
  OBJECTIVE
  The aim of this study was to investigate the sedative effects of levocetirizine.
  
  
  METHODS
  An electronic literature search was performed using Medline and EMBASE from January 01, 2001 through August 6, 2015. Randomized controlled trials (RCTs) comparing levocetirizine with other antihistamines or placebo for patients with allergy and healthy subjects were selected. Primary outcome was risk ratio between levocetirizine and comparators. Secondary outcome was change in psychomotor speed. Data were pooled for meta-analysis using a fixed-effect model.
  
  
  RESULTS
  Forty-eight studies of 18,014 patients met the inclusion criteria. When compared to placebo, levocetirizine produced modest sedative effects (RR: 1.67; 95% CI 1.17, 2.38). However, when compared to other second-generation antihistamines, sedative effects of levocetirizine did not differ (RR: 1.23; 95% CI 0.96, 1.58). In subgroup analysis, there was no difference between the sedative effects of levocetirizine and fexofenadine (RR: 1.7; 95% CI 0.59, 4.88), desloratadine (RR: 1.58; 95% CI 0.9, 2.77), loratadine (RR: 1.56; 95% CI 0.28, 8.56), bilastine (RR: 1.17; 95% CI 0.48, 2.84), olopatadine (RR: 1.09; 95% CI 0.81, 1.47), azelastine (RR: 0.19; 95% CI 0.01, 3.68) and rupatadine (RR: 1.47; 95% CI 0.14, 15.72). When compared to first-generation antihistamines, levocetirizine had less sedative effects and less change of reaction time (mean difference: -250.76 s; 95% CI -338.53, -162.98).
  
  
  CONCLUSIONS
  Levocetirizine has modest sedative effects with a risk ratio of 1.67 when compared with placebo. The sedative effects observed for levocetirizine are not different from other second-generation antihistamines.
authors.affiliation: Department of Otolaryngology, Faculty of Medicine, Chulalongkorn University, 1873 Rama 4 Road, Pathumwan, Bangkok, 10330, Thailand. drkornkiat@yahoo.com.
authors.forename: Kornkiat
authors.identifier: http://orcid.org/0000-0001-7537-4718
authors.initials: K
authors.lastname: Snidvongs
authors.affiliation: Department of Otolaryngology, Faculty of Medicine, Chulalongkorn University, 1873 Rama 4 Road, Pathumwan, Bangkok, 10330, Thailand.
authors.forename: Kachorn
authors.initials: K
authors.lastname: Seresirikachorn
authors.affiliation: Department of Otolaryngology, Faculty of Medicine, Chulalongkorn University, 1873 Rama 4 Road, Pathumwan, Bangkok, 10330, Thailand.
authors.forename: Likhit
authors.initials: L
authors.lastname: Khattiyawittayakun
authors.affiliation: Department of Otolaryngology, Sawan Pracharak Hospital, Atthakawi Road, Tambon Paknam Pho, Amphoe Mueang Nakhon Sawan, Nakhon Sawan, 60000, Thailand.
authors.forename: Wirach
authors.initials: W
authors.lastname: Chitsuthipakorn
mesh_terms: D017332:Cetirizine / Q000627:therapeutic use*; D006801:Humans; D006993:Hypnotics and Sedatives / Q000627:therapeutic use*; D016032:Randomized Controlled Trials as Topic; D014581:Urticaria / Q000188:drug therapy*
chemical_list: D006993:Hypnotics and Sedatives; C472067:levocetirizine; D017332:Cetirizine