With the movement to curtail soaring healthcare costs, generic drugs have become increasingly popular. Many times we have no choice because many insurance plans will only pay for the generic. Other times we choose the generic because the price to us is better. In fact more than 80% of the drugs that we we take in the US are now generic, and this has saved Americans $193 billion dollars this past year.
But are generic drug the same as the original? The answer in many cases is no. For example the FDA requires that the generic have the same bioequivalence as the brand name. but the standard is very broad and the concentration of the active ingredient in the blood is allowed to fall as much as 20% below or 25% above that of the brand name. If you look at the math you will see that the biological activity of the generic is allowed to vary by 45% from the brand name. This is further complicated by the fact that pharmacies shop generics by price. The pills that you get one month may not have the same biological activity as the pills that you got another month.
This could possibly mean that if the pills you took one month only met the minimum requirement and the refill that you took another month met the maximum limit you would have increased the amount of medication that you get in our body by as much as 45%. Worse than that you would have no way of knowing from the labels that you were not getting the same amount of medication.
In many cases these differences are not important, but they are critical for medications used to treat conditions in which blood levels must be kept in a narrow range. These medications include, thyroid, anti-seizure, blood thinners, antidepressants, antipsychotics, asthma and immunosuppressants.
There is another important difference between the generic and the brand name. Although the generic must contain the same active ingredient as the original, the additional ingredients, known as excipients, can be different. These ingredients can effect the amount of the drug that is absorbed into the blood stream and can also be responsible for systemic side effects that do not occur with the brand name.