Comparison of Immediate-Release and Controlled-Release Paroxetine Ingestions Reported to Texas Poison Control Centers between 2002 and 2008

Abstract

Background: Controlled-release (CR) paroxetine was created to improve the tolerability of immediate-release (IR) paroxetine while maintaining therapeutic benefits. There is limited information comparing the toxicity of the 2 paroxetine formulations. Objective: To compare the toxicity and management of paroxetine IR and paroxetine CR ingestions reported to poison control centers. Methods: Cases of ingestion of paroxetine that were reported to Texas poison control centers between 2002 and 2008, in which the final medical outcome and dose were known, were retrospectively reviewed. The rates for selected variables were determined for paroxetine IR and paroxetine CR and comparisons between the 2 were made by calculating the ratio of the drug's CR rate to the IR rate and 95% confidence interval. Compliance with simplified algorithms of triage management guidelines was determined for both formulations. Results: Included in the analysis were 405 cases of paroxetine IR ingestion and 169 cases of paroxetine CR ingestion for which a reported dose and final medical outcome were known. There were no statistically significant differences between the paroxetine CR and paroxetine IR formulations with respect to serious medical outcomes (ratio 0.69, 95% CI 0.34 to 1.31), self-harm or malicious intent (ratio 0.82, 95% CI 0.60 to 1.12), or referral to a healthcare facility (ratio 1.18, 95% CI 0.76 to 1.83). The rate of compliance with the triage algorithm for cases not already en route to or at a healthcare facility when the poison control center was contacted was 87% for paroxetine IR and 89% for paroxetine CR. Conclusions: The toxicity and management of paroxetine IR and paroxetine CR ingestions reported to Texas poison control centers were similar after adjusting for differences in dosage.