Send Correspondence to journal:
Re: The risks and costs of multiple-generic substitution of topiramate

We read with interest the article by Duh et al. who investigated the clinical and economic consequences following the generic substitution of one versus multiple generics of topiramate. [1] Using a database comprising pharmacy and medical claims, the authors concluded that many generic substitutions of topiramate were associated with negative outcomes including hospitalizations, fracture injuries, and overall health care costs.

We feel the thrust to use brand name drugs even for conditions which have a narrow therapeutic index such as epilepsy is predominantly industry driven. We also note that this article is industry supported. Physicians are consistently reminded by industry representatives that generics are somehow less potent than brand name drugs and that seizure control frequently deteriorates when a patient is switched to a generic. Our experience points to the contrary.

The majority of patients who are switched to a generic version either due to treating doctor or patient preferences experience no change in their seizure frequency or side-effect profile. Generic versions have to meet the same FDA standards of bioequivalence as the brand name medication. In addition, there is no scientific evidence to support that generics are inferior in quality. Under President Obama’s administration, there is a new urgency to reform health care with the goal of providing high quality health care to all Americans. Generic versions play an important role in this equation by providing essential drugs at an affordable price and thus reducing overall health care costs.

The authors used ICD diagnostic codes to determine that the use of generics led to more frequent hospitalization. They found no significant differences in the number of outpatient visits among the three studied periods. Many of these diagnostic codes for inpatient hospitalization were for reasons other than epilepsy. As the authors acknowledge, inaccuracy in coding could have confounded the results.

Seizure patients who experience deterioration in their seizure control usually do not warrant inpatient admission unless they are in status epilepticus. These patients are assessed in an outpatient setting and their anti-epileptic drugs are adjusted. We believe there is no scientific evidence to suggest that generics lead to more frequent hospitalizations.

References

1. Duh MS, Paradis PE, Latremouille-Viau D, et al. The risks and costs of multiple-generic substitution of topiramate. Neurology 2009;72:2122-2129.

Send Correspondence to journal:
Re: Reply from the authors

We appreciate Sethi et al.’s interest in our article and would like to respond to some of their points. [1]

Our research was based on insurance claims data. We analyzed real-world prescribing patterns, medical resource utilization, and costs for patients with epilepsy treated with antiepileptic drugs (AEDs). Our findings provide important information for policy makers, treating physicians, and patients.

Several other peer-reviewed articles comparing medical resource utilization between periods of generic versus brand use of AEDs found that a significant minority of patients do experience negative health outcomes after AED substitution. In addition, there were negative economic consequences for the health system. [2-7] Our research also showed the highest risk was associated with patterns of switching between multiple generic versions of an AED.

Encouraging generic drug use may be an effective system-wide strategy to control rising prescription drug costs. However, our research highlights the need for additional data concerning the impact on patients who switch between generic versions of an AED. We found that this pattern of treatment is associated with worse health outcomes and higher costs to the health care system.

We hope that policymakers will draw upon rigorous scientific evidence like ours to enact policies that will improve patient outcomes and control rising health care costs.

References

2. Andermann F, Duh MS, Gosselin A, Paradis PE. Compulsory generic switching of antiepileptic drugs: high switchback rates to brand compounds compared to other drug classes. Epilepsia 2006;48:464–469.

3. LeLorier J, Duh MS, Paradis PE, et al. Clinical consequences of generic substitution of lamotrigine for patients with epilepsy. Neurology 2008;70:2179–2186.

4. Duh MS, Andermann F, Paradis PE, Weiner J, Manjunath R, Crémieux PY. The economic consequences of generic substitution for antiepileptic drugs in a public payer setting: the case of lamotrigine. Dis Manage 2007;10:216–225.

5. LeLorier J, Duh MS, Paradis PE, et al. Economic impact of generic substitution of lamotrigine: projected costs in the United States using findings in a Canadian setting. Curr Med Res Opin 2008;24:1069–1081.

6. Zachry WM, Doan QD, Clewell JD, et al. Case-control analysis of ambulance, emergency room, or inpatient hospital events for epilepsy and antiepileptic drug formulation changes. Epilepsia 2009;50:493-500.

7. Paradis PE, Latrémouille-Viau D, Moore Y, et al. Projected economic impact of clinical findings of generic entry of topiramate on G4 European countries. Curr Med Res Opin 2009;25:1793–1805.