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Narrow therapeutic index drugs: a clinical pharmacological consideration to flecainide

Abstract : Purpose The therapeutic index (TI) is the range of doses at which a medication is effective without unacceptable adverse events. Drugs with a narrow TI (NTIDs) have a narrow window between their effective doses and those at which they produce adverse toxic effects. Generic drugs may be substituted for brand-name drugs provided that they meet the recommended bioequivalence (BE) limits. However, an appropriate range of BE for NTIDs is essential to define due to the potential for ineffectiveness or adverse events. Flecainide is an an-tiarrhythmic agent that has the potential to be considered an NTID. This review aims to evaluate the literature surrounding guidelines on generic substitution for NTIDs and to evaluate the evidence for flecainide to be considered an NTID. Methods A review of recommendations from various regulatory authorities regarding BE and NTIDs, and publications regarding the NTID characteristics of flecainide, was carried out. Results Regulatory authorities generally recommend reduced BE limits for NTIDs. Some, but not all, regulatory authorities specify flecainide as an NTID. The literature review demonstrated that flecainide displays NTID characteristics including a steep drug dose–response relationship for safety and efficacy , a need for therapeutic drug monitoring of pharmacokinetic (PK) or pharmacodynamics measures and intra-subject variability in its PK properties. Conclusions There is much evidence for flecainide to be considered an NTID based on both preclinical and clinical data. A clear understanding of the potential of proarrhythmic effects or lack of efficacy, careful patient selection and regular monitoring are essential for the safe and rational administration of flecainide.
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Contributor : Laurent Jonchère Connect in order to contact the contributor
Submitted on : Thursday, April 16, 2015 - 4:25:08 PM
Last modification on : Wednesday, September 14, 2022 - 10:20:04 AM
Long-term archiving on: : Tuesday, April 18, 2017 - 10:20:45 PM


Narrow therapeutic index drugs...
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Juan Tamargo, Jean-Yves Le Heuzey, Phillipe Mabo. Narrow therapeutic index drugs: a clinical pharmacological consideration to flecainide. European Journal of Clinical Pharmacology, Springer Verlag, 2015, 71 (5), pp.549-567. ⟨10.1007/s00228-015-1832-0⟩. ⟨hal-01143095⟩



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