Abstract

Objectives To investigate the frequency with which sedation was reported in post-marketing surveillance studies of four second generation antihistamines: loratadine, cetirizine, fexofenadine, and acrivastine.

Design Prescription-event monitoring studies.

Setting Prescriptions were obtained for each cohort in the immediate post-marketing period.

Subjects Event data were obtained for a total of 43,363 patients.

Main outcome measure Reporting of sedation or drowsiness.

Results The odds ratios (adjusted for age and sex) for the incidence of sedation were 0.63 (95% confidence interval 0.36 to 1.11; P=0.1) for fexofenadine; 2.79 (1.69 to 4.58; P < 0.0001) for acrivastine, and 3.53 (2.07 to 5.42; P < 0.0001) for cetirizine compared with loratadine.  No increased risk of accident or injury was evident with any of the four drugs.

Conclusions Although the risk of sedation was low with all four drugs, fexofenadine and loratadine may be more appropriate for people working in safety critical jobs.