Switches between branded (reference) medications and the corresponding generic medications or between two different corresponding generic medications occur commonly during the treatment of central nervous system disorders. Prescribing a generic product in place of a reference product can reduce patient and pharmacy costs. But there can be implications. Planned or unplanned switches from one product to another during ongoing treatment may introduce variability in drug exposure which could in turn compromise efficacy and/or tolerability. Studies comparing the initiation of reference versus generic products do not provide clear evidence of the superiority of reference or generic products generally, whereas several studies examining a switch between reference and generic products suggest that reductions in efficacy or medication adherence and persistence may be associated with generic substitution. Clinicians should work with patients to facilitate a consistent supply of reference or generic drug product that provides stable exposure to avoid clinical deterioration or poor tolerability.
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Contributors Manuscript preparation: JH, HCM, AW, MB and PB; Manuscript review and revisions: JH, HCM, AW, MB and PB; Final approval of manuscript: JH, HCM, AW, MB and PB.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests JH: Honoraria/advisory board/speaker: Pfizer, Amgen, BMS, Bayer, Boehringer, Eli-Lilly, Purdue, Allergan, AstraZeneca, Lundbeck, Novo-Nordisk, Servier, Janssen, Aralez. HCM: Honoraria/paid speaker: BMS, Janssen, Lundbeck, Otsuka, Sunovion; Research support: Acadia, Lundbeck, Janssen; Consultant: HLS Therapeutics, Janssen, Lundbeck, Otsuka, Perdue, Pfizer, Shire, Sunovion; No stocks or employment. AW: Consultant for Pfizer. MB: Former employee of Pfizer Canada Inc at the time of writing this manuscript. PB: Honoraria for advisory board participation, consultancy, grant funding, and/or giving lectures for Allergan, BMS, Janssen, Lundbeck, Otsuka, Pfizer, Sunovion, Takeda.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement There are no data in this work.
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