Compulsory generic switching of antiepileptic drugs: high switchback rates to branded compounds compared with other drug classes.

Full Abstract

PURPOSE:
Compulsory generic substitution of antiepileptic drugs (AEDs) may lead to adverse effects in epilepsy patients because of seizure recurrence or increased toxicity. The study objectives were (a) to quantify and compare the switchback rates from generic to brand-name AEDs versus non-AEDs, and (b) to assess clinical implications of switching from branded Lamictal to generic lamotrigine (LTG) and whether signals exist suggesting outcome worsening.

METHODS:
By using a public-payer pharmacy-claims database from Ontario, Canada, switchback rates from generic to branded AEDs [Lamictal, Frisium (clobazam; CLB), and Depakene (VPA; divalproex)] were calculated and compared with non-AED long-term therapies, antihyperlipidemics and antidepressants, in January 2002 through March 2006. We then assessed pharmacy utilization and AED dosage among LTG patients switching back to branded Lamictal compared with those staying on generic formulation.

RESULTS:
The 1,354 patients (403 monotherapy, 951 polytherapy) were prescribed generic LTG, of whom 12.9% switched back to Lamictal (11.7% monotherapy, 13.4% polytherapy). Switchback rates of other AEDs were approximately 20% for CLB and VPA. The switchback rates for AEDs were substantially higher than for non-AEDs (1.5-2.9%). Significant increases in LTG doses were observed after generic substitution for those who did not switch back (6.2%; p<0.0001). The average number of codispensed AEDs and non-AED drugs significantly increased (p<0.0001) after LTG generic entry, especially in the generic group.

CONCLUSIONS:
These results reflect poor acceptance of switching AEDs to generic compounds. They may also indicate increased toxicity and/or loss of seizure control associated with generic AED use.

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Author information

Author/s: Andermann, Frederick (F); Duh, Mei Sheng (MS); Gosselin, Antoine (A); Paradis, Pierre Emmanuel (PE);

Affiliation: Montreal Neurological Institute and Hospital, McGill University, Montréal, Québec, Canada. andermannf(-atsign-)qc.aibn.com

Journal and publication information

Publication Type: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't

Journal: Epilepsia (Epilepsia), published in United States. (Language: eng)

Reference: 2007-Mar; vol 48 (issue 3) : pp 464-9

Dates: Created 2007/03/09; Completed 2007/05/30; Revised 2008/11/21;

PMID: 17346246, status: MEDLINE (last retrieval date: 12/26/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Adolescent
Adult
Anticonvulsants - pharmacokinetics; therapeutic use
Child
Cohort Studies
Cost-Benefit Analysis
Drug Costs
Drug Prescriptions - economics; standards; statistics & numerical data
Drug Therapy, Combination
Drugs, Generic - pharmacokinetics; therapeutic use
Epilepsy - drug therapy

Epilepsy - drug therapy
Female
Humans
Insurance, Pharmaceutical Services - legislation & jurisprudence; statistics & numerical data
Kaplan-Meiers Estimate
Male
Ontario
Patient Acceptance of Health Care
Therapeutic Equivalency
Treatment Outcome
Triazines - therapeutic use

Associated Chemicals: Anticonvulsants (0) ; Drugs, Generic (0) ; Triazines (0) ; lamotrigine (84057-84-1)

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