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Understanding Therapeutic Equivalence in Epilepsy

Published online by Cambridge University Press:  07 November 2014

Tracy A. Glauser
Affiliation:
Co-Chairs of Leadership in Epilepsy, Advocacy, and Development (LEAD), and LEAD Faculty

Abstract

The issues surrounding generic drug substitution in patients with epilepsy are complex.The substitution of one formulation of an antiepileptic drug (AED) for another is controversial. Well-reasoned and defensible cases can be made both for and against such substitution. Although regulatory agencies require that generic and proprietary drugs have similar pharmacokinetic bioequivalence data, their therapeutic efficacy may not necessarily be identical. The paroxysmal nature of epilepsy, the narrow therapeutic index of some AEDs, the need to. individualize therapy to achieve seizure control, and the negative consequences of uncontrolled epilepsy distinguishes epilepsy from other clinical conditions. Epilepsy management with AEDs requires careful dose titration and consistent drug exposure at the optimal level for each patient, which can be altered if a different formulation of the AED is substituted. Unexpected variability in plasma concentrations could occur when a patient who has been receiving one formulation of an AED (generic or brand) receives an alternate formulation.Thus, no substitutions should be made for people with epilepsy without the knowledge and approval of the prescribing physician. Patients should be consulted about the substitution, with all risks and benefits carefully explained.

Type
Review Article
Copyright
Copyright © Cambridge University Press 2010

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References

REFERENCES

1.Crawford, PFeely, M, Guberman, A, Kramer, G. Are there potential problems with generic substitution of antiepileptic drugs? A review of issues. Seizure. 2006;15:165176.Google Scholar
2.Feely, M, Crawford, PKramer, G, Guberman, A. Risk management in epilepsy: generic substitution and continuity of supply. Eur J Hosp Pharm Sci. 2005;11:3387.Google Scholar
3.Heaney, DC, Sander, JW. Antiepileptic drugs: generic versus branded treatments. Lancet Neurol. 2007;6:465468.Google Scholar
4.Zachry, WM III, Doan, QD, Clewell, JD, Smith, BJ. Case-control analysis of ambulance, emergency room, or inpatient hospital events for epilepsy and antiepileptic drug formulation changes. Epilepsia. 2009;50(3):493500.Google Scholar
5.US Food and Drug Administration. History of the FDA. http://www.fda.gov/AboutFDA/WhatWeDo/History/default.htm. Accessed January 20,2010.Google Scholar
6.Borgheini, G. The bioequivalence and therapeutic efficacy of generic versus brand-name psychoactive drugs. Clin Ther. 2003;25:15781592.Google Scholar
7.Guberman, A, Corman, C. Generic substitution for brand name antiepileptic drugs: a survey. Can J Neurol Sci. 2000;27:3743.Google Scholar
8.Welage, LS, Kirking, DM, Ascione, FJ, Gaither, CA. Understanding the scientific issues embedded in the generic drug approval process. J Am Pharm Assoc (Wash). 2001;41:856867.Google Scholar
9.US Food and Drug Administration Center for Drug Evaluation and Research. Approved Drug Products With Therapeutic Equivalence Evaluations. 27th ed. Rockville, MD: US Department of Health and Human Services; 2007.Google Scholar
10.Berg, MJ. What's the problem with generic antiepileptic drugs? A call to action. Neurology. 2007;68:12451246.CrossRefGoogle ScholarPubMed
11.Nuwer, MR, Browne, TR, Dodson, WE, et al.Generic substitutions for antiepileptic drugs. Neurology. 1990;40:16471651.CrossRefGoogle ScholarPubMed
12.Besag, FM. Is generic prescribing acceptable in epilepsy? Drug Sal 2000;23:173182.CrossRefGoogle ScholarPubMed
13.Dilantin Kapseals [package insert]. New York, NY: Parke-Davis; 2009.Google Scholar
14.Tegretol [package insert]. East Hanover, NJ: Novartis Pharmaceuticals Corp; 2009.Google Scholar
15.Topamax [package insert]. Titusville, NJ: Ortho-McNeil-Janssen Pharmaceuticals, Inc. 2009.Google Scholar
16.Depakote ER Tablets [package insert]. North Chicago, IL: Abbott Laboratories; 2009.Google Scholar
17.Neurontin [package insert]. New York, NY: Parke-Davis; 2009.Google Scholar
18.Lamictal [package insert]. Research Triangle Park, NC: GlaxoSmithKline; 2009.Google Scholar
19.Varia, SA, Schuller, S, Stella, VJ. Phenytoin prodrugs IV: hydrolysis of various 3-(hydroxymethyl) Phenytoin esters. J Pharm Sci. 1984;73:10741080.Google Scholar
20.Nightingale, SL, Morrison, JC. Generic drugs and the prescribing physician. JAMA. 1987;258:12001204.Google Scholar
21.Henney, JE. From the Food and Drug Administration: review of generic bioequivalence studies. JAMA. 1999;282(21):1995.Google Scholar
22.Banahan, BRBonnarens, JK. Generic substitution of NTI drugs: issues for formulary committee consideration. Formulary. 1998;33(11):10821096.Google Scholar
23.Department of Health and Human Services. Approved Drug Products with Therapeutic Equivalence Evaluations. 27th ed. Cumulative Supplement 12. 2007.Google Scholar
24.Crawford, P, Hall, WW, Chappell, B, Collings, J, Stewart, A. Generic prescribing for epilepsy. Is it safe? Seizure 1996;5:15.Google Scholar
25.Trimble, MR. Generic prescribing. Hum Psychopharmacol. 1987;2:12.Google Scholar
26.Cassels, C. No generic substitution of AEDs without physician and patient consent, says AAN. http://www.medscape.com/viewarticle/555489. Accessed March 25,2009.Google Scholar
27.Welty, TE, Pickering, PR, Hale, BC, Arazi, R. Loss of seizure control associated with generic substitution of carbamazepine. Ann Pharmacother. 1992;26:775777.CrossRefGoogle ScholarPubMed
28.Assessment: generic substitution for antiepileptic medication. Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology. Neurology. 1990;40:16411643.Google Scholar
29.Miller, JW, Anderson, GD, Doherty, MJ, Poolos, NP. Position statement on the coverage of anticonvulsant drugs for the treatment of epilepsy: what's the problem with generic antiepileptic drugs? A call to action. Neurology. 2007;69:18061808.Google Scholar
30.Epilepsy Foundation. Position on Switching of Antiepileptic Drugs, http://www.epi-lepsyfoundation.org/advocacy/care/genedrev.cfm. Accessed December 11,2009.Google Scholar
31.Wilner, AN. Physicians underestimate the frequency of generic carbamazepine substitution: results of a survey and review of the problem. Epilepsy Behav. 2002;3:522525.CrossRefGoogle ScholarPubMed
32.Berg, MJ, Gross, RA. Physician and patients perceive that generic drug substitution of anti-epileptic drugs can cause breakthrough seizures-results from a US survey [Abstract]. Epilepsia. 2006;47(suppl 4):155.Google Scholar
33.Burkhardt, RT, Leppik, IE, Blesi, K, Scott, S, Gapany, SR, Cloyd, JC. Lower Phenytoin serum levels in persons switched from brand to generic Phenytoin. Neurology. 2004;63:14941496.Google Scholar
34.Gilman, JT, Alvarez, LA, Duchowny, M. Carbamazepine toxicity resulting from generic substitution. Neurology. 1993;43:26962697.Google Scholar
35.MacDonald, JT. Breakthrough seizure following substitution of Depakene capsules (Abbott) with a generic product. Neurology. 1987;37(12):1885.Google Scholar
36.Wilner, AN. Therapeutic equivalency of generic antiepileptic drugs: results of a survey. Epilepsy Behav. 2004;5:995998.CrossRefGoogle ScholarPubMed
37.Haskins, LS, Tomaszewski, KJ, Crawford, P. Patient and physician reactions to generic antiepileptic substitution in the treatment of epilepsy. Epilepsy Behav. 2005;7:98105.CrossRefGoogle ScholarPubMed
38.Kramer, GK, Steinhoff, BJ, Feucht, M, Pfafflin, M, May, T. Generic antiepileptic drugs: experiences of physicians in Germany, Austria, and Switzerland [Abstract]. Epilepsia. 2006;47(suppl 4):193.Google Scholar
39.Krämer, G, Steinhoff, BJ, Feucht, M, Pfäfflin, M, May, TW. Experiences with generic drugs in epilepsy patients. Results of an internet-based questionnaire study in Germany, Austria, and Switzerland [in German]. Akt Neurol. 2006;33:431438.Google Scholar
40.Mayer, TMay, TW, Altenmüller, DM, Sandmann, M, Wolf, P. Clinical problems with generic antiepileptic drugs: comparison of sustained-release formulations of carbamazepine. Clin Drug Investig. 1999;18:1726.Google Scholar
41.Makus, KG, McCormick, J. Substituting generic lamotrigine for brand-name lamotrigine (Lamictal) in patients with epilepsy: an observational assessment of outcomes in Canada. [Abstract]. Epilepsia. 2006;47(suppl 4):194.Google Scholar
42.Makus, KG, McCormick, J. Identification of adverse reactions that can occur on substitution of generic for branded lamotrigine in patients with epilepsy. Clin Ther. 2007;29:334341.CrossRefGoogle ScholarPubMed
43.Andermann, F, Duh, MS, Gosselin, A, Lefebvre, P, Paradis, PE. Adverse clinical consequences of compulsory generic switching of antiepileptic drugs [Abstract]. Epilepsia. 2006;47(suppl 4):189.Google Scholar
44.Andermann, F, Duh, MS, Gosselin, A, Paradis, PE. Compulsory generic switching of antiepileptic drugs: high switchback rates to branded compounds compared with other drug classes. Epilepsia. 2007;48:464469.Google Scholar
45.Jobst, BC, Holmes, GL. Prescribing antiepileptic drugs: should patients be switched on the basis of cost? CNS Drugs. 2004;18:617628.CrossRefGoogle ScholarPubMed
46.Heaney, DC, Begley, CE. Economic evaluation of epilepsy treatment: a review of the literature. Epilepsia. 2002;43(suppl 4):1016.Google Scholar
47. State laws or statutes governing generic substitution by pharmacists. http://profession-als.epilepsy.com/page/statutes_by_pharmacists.html. Accessed March 25, 2009.Google Scholar
48. Tennessee Code Annotated, Title 53, Chapter 10, Part 2; section 53-10-210. Pharmacy, Pharmacists - Requires notification before interchanging or substituting for a prescribed anti-epileptic drug in certain situations. Amendment No. 2 to HB0121.Google Scholar
49. Tennessee Code Annotated, Title 53, Chapter 10, Part 2; section 53-10-204. Substitution authorized - Instructions of prescribenGoogle Scholar
50. Tennessee Code Annotated, Title 53, Chapter 10, Part 2; section 53-10-205. Least expensive generic equivalent if authorized by prescribenGoogle Scholar
51.American Pharmaceutical Association. Substitution of critical dose drugs: issues, analysis, and decision making. http://www.pharmacist.com/AM/Template.cfm?Section=Home2_CONTENTID=144238JEMPLATE=/CM/ContentDisplay.cfm. Accessed March 25, 2009.Google Scholar
52.National Institute for Clinical Excellence. The epilepsies: the diagnosis and management of the epilepsies in adults and children in primary and secondary care. Clinical Guideline 20. National Collaborating Center for Primary Care. October 2004. http://www.nice.org.uk/guidance/index.jsp?action=bylD&o=10954. Accessed March 25, 2009.Google Scholar
53.Scottish Intercollegiate Guidelines Network. Diagnosis and management of epilepsy in adults: a national clinical guideline. Edinburgh, Scotland: Royal College of Physicians, April 2003. http://www.sign.ac.uk/guidelines/fulltext/70/index.html. Accessed March 25, 2009.Google Scholar
54.British Epilepsy Association. Epilepsy Action position statements: Consistency of Supply, http://www.epilepsy.org.uk/about/positionstatements/consistency.html. Accessed March 25,2009.Google Scholar
55.Perucca, E, Albani, F, Capovilla, G, Bernardina, BD, Michelucci, R, Zaceara, G. Recommendations of the Italian League Against Epilepsy working group on generic products of antiepileptic drugs. Epilepsia. 2006;47(suppl 5):1620.CrossRefGoogle Scholar
56.Generics -- equal or not? Aust Prescriber. 2003;26:124125.Google Scholar
57.American Epilepsy Society. The substitution of different formulations of antiepileptic drugs for the treatment of epilepsy. Position statement November 29,2007. http://www.aesnet.org/index.cfm?objectid=77B10758-E7FF-0F41-2C82BE234AB8CD24. Accessed December 4, 2009.Google Scholar