title: Examining the utilization and tolerability of the non-sedating antihistamine levocetirizine in England using prescription-event monitoring data.
abstract: BACKGROUND
  Levocetirizine was launched onto the UK market in September 2001. It is indicated for symptomatic treatment of allergic rhinitis (AR), including persistent AR and chronic idiopathic urticaria.
  
  
  OBJECTIVE
  The aim of the study was to monitor the safety of levocetirizine prescribed in the primary care setting in England, in the immediate postmarketing period.
  
  
  METHODS
  Exposure data were derived from dispensed prescriptions written by primary care physicians (general practitioners [GPs]) for levocetirizine (November 2001-November 2002): patient demographic, indication, pattern of use and outcome (event) data from enhanced prescription-event monitoring (PEM) questionnaires (with additional questions to gather further relevant information) returned by GPs. Incidence density observation rates (IDobs) [number of first reports/1000 patient-months] between months 1 and 2 (IDobs(m1/m2)) were compared for the whole cohort and by groups defined by indication and pattern of use.
  
  
  RESULTS
  The cohort comprised 12 367 patients (median age 37 years [interquartile range 22-55]; 58% female). The most frequent indication was AR (67%; n = 8275). After 2 months, 35.7% (n = 2414) of patients were still taking levocetirizine. 'Condition improved' was the most common event and reason for stopping treatment. Headache/migraine was uncommon but associated with starting treatment (IDobs(m1/m2) 2.4 [95% CI 1.1, 6.0]), as was drowsiness/sedation (IDobs(m1/m2) 11.5 [95% CI 4.2, 43.9]). Cardiovascular events occurred rarely or very rarely, as did most central and peripheral nervous system events. No serious adverse drug reactions (ADRs) were reported. Events related to effectiveness were more frequent in month 1 than month 2 for all patient subgroups.
  
  
  CONCLUSIONS
  This postmarketing surveillance study shows that levocetirizine is well tolerated when used in general practice in England. No previously unrecognized ADRs were detected. This study highlights how modifications to PEM, such as additional questions, are contributing to the evaluation of drug utilization factors in relation to risks.
authors.affiliation: Drug Safety Research Unit, Southampton, UK.
authors.forename: Deborah
authors.initials: D
authors.lastname: Layton
authors.forename: Vicki
authors.initials: V
authors.lastname: Osborne
authors.forename: Anna
authors.initials: A
authors.lastname: Gilchrist
authors.forename: Saad A W
authors.initials: SA
authors.lastname: Shakir
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017332:Cetirizine / Q000009:adverse effects* / Q000627:therapeutic use*; D002648:Child; D004363:Drug Utilization; D004739:England; D005260:Female; D039563:Histamine H1 Antagonists, Non-Sedating / Q000009:adverse effects* / Q000627:therapeutic use*; D006801:Humans; D006967:Hypersensitivity / Q000188:drug therapy; D008297:Male; D008875:Middle Aged; D011358:Product Surveillance, Postmarketing; D055815:Young Adult
chemical_list: D039563:Histamine H1 Antagonists, Non-Sedating; C472067:levocetirizine; D017332:Cetirizine
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