Canada. GlaxoSmithKline Inc. (GSK), following discussions with Health Canada, is advising physicians against the concurrent use of paroxetine (Paxil and Paxil CR) and pimozide, since paroxetine was found to increase plasma pimozide levels in an open-label study of healthy volunteers who were administered both drugs. Elevation of pimozide blood concentration may result in QT interval prolongation and severe arrhythmias including Torsade de Pointes.

Reference:

'Dear Health-care Professional' letter from GlaxoSmithKline Inc., 22 July 2005 (http://www.hc-sc.gc.ca).