title: Drowsiness and motor responses to consecutive daily doses of promethazine and loratadine.
abstract: OBJECTIVE
  Limited information is available regarding sedation and motor function following repeat dosing of antihistamines. This study examined how promethazine and loratadine affect day-time drowsiness, the commencement of voluntary movement, and involuntary movement when administered on consecutive days.
  
  
  METHODS
  Ten healthy young subjects (24±5years) were recruited into a double-blind, placebo-controlled, three-way crossover study. Subjects ingested either promethazine, loratadine or a placebo, and ingested the same drug 24h later. Measures of drowsiness, simple reaction time (SRT), choice reaction time (CRT), and postural tremor were obtained pre-ingestion, 1h post-ingestion and 2h post-ingestion on each day.
  
  
  RESULTS
  Consecutive daily doses of promethazine and loratadine affected SRT and CRT, respectively, whereby reaction time deficits were less pronounced following the repeat dose. A reduced tremor response was also observed following consecutive daily dosing of promethazine, in contrast to loratadine which caused an increase in tremor amplitude with the consecutive daily dose.
  
  
  CONCLUSIONS
  Reaction time and tremor responses differed following the single dose compared to consecutive doses.
  
  
  CONCLUSIONS
  Sufferers of allergic rhinitis often require antihistamine dosing regimens that continue over multiple days. Future studies will benefit from examining drowsiness and movement responses following single doses as well as consecutive dosing.
authors.affiliation: School of Pharmacy, Griffith University, Gold Coast, Australia; Griffith Health Institute, Griffith University, Gold Coast, Australia.
authors.forename: Lyndsee
authors.initials: L
authors.lastname: Baumann-Birkbeck
authors.affiliation: School of Pharmacy, Griffith University, Gold Coast, Australia; Griffith Health Institute, Griffith University, Gold Coast, Australia.
authors.forename: Gary D
authors.initials: GD
authors.lastname: Grant
authors.affiliation: School of Pharmacy, Griffith University, Gold Coast, Australia; Griffith Health Institute, Griffith University, Gold Coast, Australia.
authors.forename: Shailendra
authors.initials: S
authors.lastname: Anoopkumar-Dukie
authors.affiliation: Centre for Musculoskeletal Research, Griffith University, Gold Coast, Australia; Griffith Health Institute, Griffith University, Gold Coast, Australia. Electronic address: j.kavanagh@griffith.edu.au.
authors.forename: Justin J
authors.initials: JJ
authors.lastname: Kavanagh
mesh_terms: D000328:Adult; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D006634:Histamine H1 Antagonists / Q000008:administration & dosage* / Q000009:adverse effects; D006801:Humans; D017336:Loratadine / Q000008:administration & dosage* / Q000009:adverse effects; D008297:Male; D011398:Promethazine / Q000008:administration & dosage* / Q000009:adverse effects; D011930:Reaction Time / Q000187:drug effects* / Q000502:physiology; D012894:Sleep Stages / Q000187:drug effects* / Q000502:physiology; D014202:Tremor / Q000139:chemically induced* / Q000503:physiopathology; D055815:Young Adult
chemical_list: D006634:Histamine H1 Antagonists; D017336:Loratadine; D011398:Promethazine
keywords: Antihistamine; Choice reaction time; Postural tremor; Sedation; Simple reaction time