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Evaluation of Switching Patterns in FDA’s Sentinel System: A New Tool to Assess Generic Drugs

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A Commentary to this article was published on 09 October 2018

Abstract

Introduction

Nearly 90% of drugs dispensed in the US are generic products.

Objective

The aim of this study was to develop and implement a tool for analyzing manufacturer-level drug utilization and switching patterns within the US Food and Drug Administration’s Sentinel system.

Methods

A descriptive tool was designed to analyze data in the Sentinel common data model and was tested with two case studies—metoprolol extended release (ER) and lamotrigine ER—using claims data from four Sentinel data partners. We plotted initiators of each brand and generic product over time. For metoprolol ER, we evaluated rates of switching from generics around the time of manufacturing issues. For lamotrigine ER, we examined rates of switching back to the brand among those who switched from brand to generic.

Results

We identified 1,651,285 initiators of metoprolol ER products between July 2008 and September 2015. We observed a large decrease in monthly metoprolol ER initiators (from 25,465 in December 2008 to 13,128 in February 2009), corresponding to recalls by generic manufacturers. We observed simultaneous increases in utilization of the authorized generic and brand products. We identified 4266 initiators of lamotrigine ER with an epilepsy diagnosis between January 2012 and September 2015. Among those who switched from brand to generic, the cumulative incidence of switching back was close to 20% at 2 years. Switchback rates were higher for the first available generic products.

Conclusions

This developed tool was able to elucidate novel utilization and switching patterns in two case studies. Such information can be used to support surveillance of generic drugs and biosimilars.

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Acknowledgements

The authors thank the Data Partners who provided data used in the analysis: Aetna (Aetna Informatics, Blue Bell, PA), HealthCore, (HealthCore, Inc. Government & Academic Research, Alexandria, VA), Humana (Humana, Inc., Comprehensive Health Insights, Miramar, FL), and Optum (OptumInsight Life Sciences Inc., Waltham, MA). The authors thank Timothy Glavin and Adee Kennedy for their assistance. The Sentinel program is funded by the US Food and Drug Administration through the Department of Health and Human Services contract number HHSF223201400030I. The views expressed in this paper are those of the authors and are not intended to convey official US Food and Drug Administration policy or guidance.

Author information

Authors and Affiliations

  1. Division of Pharmacoepidemiology and Pharmacoeconomics, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA

    Joshua J. Gagne

  2. Department of Population Medicine, Harvard Medical School, Harvard Pilgrim Health Care Institute, Boston, MA, USA

    Jennifer R. Popovic, Andrew B. Petrone & Anita K. Wagner

  3. RTI International, Waltham, MA, USA

    Jennifer R. Popovic

  4. Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, MD, USA

    Michael Nguyen, Sukhminder K. Sandhu, Patty Greene, Rima Izem, Wenlei Jiang, Zhong Wang, Yueqin Zhao & Sarah K. Dutcher

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  1. Joshua J. Gagne
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Corresponding author

Correspondence to Joshua J. Gagne.

Ethics declarations

Source of funding

The Sentinel program is funded by the US Food and Drug Administration through the Department of Health and Human Services contract number HHSF223201400030I. The views expressed in this paper are those of the authors and are not intended to convey official US Food and Drug Administration policy or guidance.

Conflict of interest

Joshua J. Gagne has received salary support from grants from Novartis Pharmaceuticals Corporation and Eli Lilly and Company to Brigham and Women’s Hospital and is a consultant to Aetion, Inc. and to Optum, Inc., all for unrelated work. Jennifer R. Popovic, Michael Nguyen, Sukhminder K. Sandhu, Patty Greene, Rima Izem, Wenlei Jiang, Zhong Wang, Yueqin Zhao, Andrew B. Petrone, Anita K. Wagner, Sarah K. Dutcher have no conflicts of interest.

Research involving human participants

This study was conducted within the Sentinel system and represents a public health activity under the auspices of the US Food and Drug Administration. Activities conducted within Sentinel are not under the purview of institutional review boards.

Appendix

Appendix

Metoprolol ER products and approval dates

Group

Product Approval Date

ToprolXL_Brand

January 10, 1992

Metoprolol_AG_Par

November 21, 2006a

Metoprolol_Sandoz

July 31, 2006

Metoprolol_Nesher

May 18, 2007

Metoprolol_Actavis

August 3, 2009

Metoprolol_Wockhardt

July 22, 2010

Metoprolol_Mylan

December 15, 2011

Metoprolol_DrReddys

August 1, 2012

Lamotrigine ER products and approval dates

Group

Product Approval Date

LamictalXR_Brand

May 29, 2009

Lamotrigine_Anchenb

December 26, 2012

Lamotrigine_Wockhardt

January 4, 2013

Lamotrigine_Par

January 18, 2013

Lamotrigine_Wilshire

June 17, 2013

Lamotrigine_DrReddys

June 19, 2013

Lamotrigine_Actavis

October 17, 2013

Lamotrigine_Torrentb

December 23, 2013

  1. aDate AG started marketing under NDA 019962
  2. bProduct was never marketed

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Gagne, J.J., Popovic, J.R., Nguyen, M. et al. Evaluation of Switching Patterns in FDA’s Sentinel System: A New Tool to Assess Generic Drugs. Drug Saf 41, 1313–1323 (2018). https://doi.org/10.1007/s40264-018-0709-4

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