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Co-Director, Drug Information & Pharmacy Resource Center, Shands at the University of Florida, Clinical Professor, College of Pharmacy, University of Florida, Post Office Box 100316, 1600 SW Archer Road (G225), Gainesville, Florida 32610, hatton{at}ufl.edu
Published Online, July 24, 2007. www.theannals.com, DOI 10.1345/aph.1K076a
The FDA's bioequivalency standards are rigorous and are designed to allow for generic interchange with the same consistency as lot-to-lot variability of brand-name drugs.2 If there are problems with the FDA's standards, then they should be changed. The first step, however, is to prove scientifically that there are problems with specific drugs, patient populations (eg, pediatrics), or diseases. At this point, there is only anecdotal evidence. There are no published randomized controlled trials that have demonstrated that A-rated AEDs are not bioequivalent to branded AEDs. In fact, FDA-sponsored studies for generic carbamazepine showed no difference in safety or efficacy for brand-names of carbamazepine.2
Case reports are limited by lack of control groups. When patients are switched to a generic drug and a problem occurs, patients and prescribers associate the problem with the generic drug. However, problems occur every day when patients remain on a brand-name AED. In this case, the problem is not blamed on the brand. Randomized, blinded controlled trials are needed to avoid this bias.
When Coumadin came off patent and generic versions of warfarin first became available, there were concerns that the generic versions would result in unnecessary variation in international normalized ratios (INRs) and, possibly, worse patient outcomes.3,4 Randomized trials do not support anecdotal observations of problems with INRs,5 and a recent large epidemiologic study of generic and brand-name warfarin did not find any differences in INR monitoring or patient outcomes.6
If controlled data generated for AEDs reveal problems, the FDA should make its standards more rigorous or exempt certain drugs from its equivalency standards. Further, various lots of brand-name drugs should be studied to ensure that they are bioequivalent. Any brand manufacturing change should require evidence that the brand continues to meet more stringent standards.
I agree with Dr. Welty that state-by-state changes in laws that forbid generic interchange of drugs based on diseases are not a positive development. If these laws are passed, a pharmacist could not easily dispense generic gabapentin to a patient prescribed Neurontin for pain unless the prescriber were required to put the indication for use (ie, epilepsy) on the prescription. In Florida, where I reside, this practice would not differ much from current law, which forbids generic interchange when "medically necessary" is written on the face of an AED prescription.
The forced dispensing of brand-name drugs will increase patients' out-of-pocket expenses and/or prescribers' and pharmacists' workloads. At best, if patients cannot afford higher copayments for brand-name drugs, written authorization for generic prescriptions will generate telephone calls and faxes, At worst, if patients are unable to pay for higher priced brand-name drugs, patient adherence could be affected.
Payors, whether patients or third parties, should not be expected to increase their expenditures by paying for brand-name drugs without evidence to support the higher costs. The group that will definitely benefit financially from mandated brand-name dispensing will be brand-name manufacturers, who will have exclusivity that will never expire. It is interesting to note that state legislative initiatives to limit generic interchanges are occurring at a time when more widely prescribed drugs are coming off patent and drug companies' revenues are falling. It frightens me when "policy makers" (ie, politicians) make unscientific healthcare decisions.
References
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