A COMPARISON OF THE POSTMARKETING SAFETY OF 4 SELECTIVE SEROTONIN REUPTAKE INHIBITORS INCLUDING THE INVESTIGATION OF SYMPTOMS OCCURRING ON WITHDRAWAL

1 We have addressed the question of whether there is a 'serotonin with drawal syndrome' by analysis of spontaneous reports of suspected adver se drug reactions (ADRs) associated with four SSRIs. A comparison of t he postmarketing safety profiles of the four SSRIs has also been made. 2 The UK database of ADRs was examined for reactions associated with fluoxetine, fluvoxamine, paroxetine and sertraline. The safety profile s of the four SSRIs were similar. However, withdrawal reactions with p aroxetine constitute a greater proportion of reports (5.1%) than with the other SSRIs (0.06-0.9%). They have been reported more often with p aroxetine (0.3 reports per thousand prescriptions) than with sertralin e and fluvoxamine (0.03), and least often with fluoxetine (0.002). 3 D escriptions of withdrawal reactions received and further details of 21 7 reports of withdrawal reaction with paroxetine obtained by mailing a questionnaire to the reporting doctor were examined. Withdrawal sympt oms were diverse but most commonly comprised dizziness, paraesthesia, tremor, anxiety, nausea and palpitation. They usually occurred after 2 days and lasted for an average of 10 days. There was no evidence of a physical drug dependency syndrome. 4 Symptoms different from the prev ious depressive illness occur after discontinuing an SSRI, and are rep orted most often with paroxetine. Paroxetine is the most pharmacologic ally specific of the SSRIs, but it is not clear whether the reactions constitute a 'serotonin withdrawal syndrome'.