• pharmacoepidemiology;
  • post-marketing drug surveillance;
  • adverse drug events;
  • anti-allergy medication



To investigate a possible increased risk of esophageal obstruction among users of loratadine and pseudoephedrine (Claritin-D® 24-Hour ‘C-D 24’, the original, round, extended-release formulation) compared to two other tablet formulations of loratadine.


Pharmacy data of 12 managed care plans were screened to identify users in the three groups from 1 September 1996 to 31 December 1998. Users with a medical claim following their first loratadine prescription (Index prescription) indicating an esophageal obstruction or endoscopic procedure were considered claims-identified cases. Medical records were reviewed to validate case status.


There were 233 901 users (61% female) and 245 claims-identified cases occurring within 30 days after the first prescription. The incidence rate per 10 000 users of claims-identified cases occurring on the Index prescription date was higher among C-D 24 users (IR = 1.4) than Claritin® Regular (C-R) users (IR = 0.07; p < 0.002) or Claritin-D® 12-Hour (C-D 12) users (IR = 0.3; p > 0.05). Medical record review of 15 claims-identified cases confirmed two cases of acute esophageal obstruction, both among C-D 24 users.


Claims-based analysis suggested an increased risk of endoscopic procedures on the Index date among C-D 24 users compared to C-R users. However, after medical record review, the study did not provide conclusive evidence of an association between C-D 24 use and esophageal obstruction. This study highlights the importance of validating findings from claims data using medical records. Copyright © 2003 John Wiley & Sons, Ltd.