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Karin LiltorpKarin Liltorp, Ph.D., is currently working as senior consultant at NNE Pharmaplan.

Due to the generally lower prices of generic drugs compared to the original, they benefit health care systems by providing large savings. Manufacturers of generics are under more or less the same regulations as the original producers, and so the quality of generic products is in line with documented requirements. Thus the original products are not “by default” better than the generic products!

However, I would claim that there are differences that should not be neglected. Products manufactured via different processes using different excipients will be different. Working for an analytical contract research organization, I have often observed large differences between tablets of the same product from different suppliers. Whether these differences have any consequences for the patients depends on the specific product.

A generic product contains the same active pharmaceutical ingredient as the original product at the same dose levels. This is why we are told that the products are the same. Still, significant variations in bioavailability might occur: The particle sizes that determine the dissolution rate may differ. Furthermore, the excipients may have a significant effect on the uptake in vivo.

For approval of a generic product, you have to show bioequivalence. These studies should ensure that the performance of the products are the same. But due to human nature, quite significant differences are allowed: ± 20% for AUC (area under the curve) – and peak concentration is only evaluated in some cases. This means that generics may be 20% more effective or 20% less effective than the original product, with the result that two generic products could vary 40% in their effectiveness.

The wide limits set for biological variations are based on the fact that different individuals may not respond the same way to a given drug product: If I take a compound, my uptake will almost surely be different from your uptake, as we have large differences in our “inner environment.” Within a single individual, however, the variations are expected to be smaller: Each time I take the same product, I will experience, more or less, the same uptake profile. If I suddenly get a new product, I will have to adapt to a new profile, which might lead to unpleasant side effects. Especially for some products such as central nervous system drugs or drugs with a narrow therapeutic window, these changes could be significant.

The economic impetus to use the cheapest product increases the risk that a patient in treatment for a chronic condition will be required to take various generic products of the same drug, thereby exposing the patient to much larger fluctuations than necessary.  Therefore, it might be relevant to research the consequences of this practice.

Wouldn’t it be healthier to ensure that you get the same drug each time, whether it is generic or the original?