When people discover that I’m a pharmacist and that I practiced for over 40 years before becoming a full-time writer, some of the inevitable questions I get asked are, “What about generics?” “Are they really the same as brand name drugs?” “Are they safe to take?”

Those are fair questions since studies indicate that approximately 80% of the prescriptions filled in the United States are for generic drugs. The primary reason is the cost differences. Generics often save patients more than 75% over branded drug pricing.

In 2010 alone, consumers saved $158 billion by buying drugs as generics. That calculates to over $3 billion every week, and that number is expected to grow over the next several years as more brand name pharmaceuticals become available as generics.

But is the cheaper drug choice a good decision, considering that your health is at stake? Studies show that cheap pricing does not mean cheap quality regarding generics, and most generic drugs perform the same as their branded counterparts, which are called the innovator (or original) drugs. The following is both the science and the economics to back up that statement.

When a manufacturer develops a new drug, at some point along that development process (long before marketing and product launch) the manufacturer obtains a patent on that drug for a period of 20 years. The patent allows the manufacturer to exclusively produce and market the product. It protects the manufacturer from competition so that the company can recoup its investment and profit from its development efforts.

At the end of that 20-year period, multiple companies may acquire FDA approval to make and sell the innovator (original brand) product without having to repeat the costly clinical trials or pay for expensive advertising, marketing and promotion that the original manufacturer had to go through to launch the innovator product.

I should note, however, that the FDA requires all approved generic formulations to have the same quality and perform as well as the innovator drug. Initially, the generic manufacturer must file an Abbreviated New Drug Application (ANDA) and then all generic offerings must pass rigorous tests for quality, purity and potency.

Each generic manufacturer must provide proof that its product is the same biochemically as the original brand and that the generic drug is bioequivalent to the original.  Bioequivalence is a measure of the absorption and distribution of an administered drug, and it’s the standard of comparison for the effects of the original formula to that of the generic version after each enters the body.

So, at this point, specific questions still remain: “How effective are those bioequivalence tests?” “Do generic drugs really perform the same as the brand name products?” The answer is both “Yes” and “No”, and I realize that this can add confusion. Therefore, allow me to provide the longer explanation.

Between 1996 and 2007, the FDA evaluated 2070 human studies conducted on the differences between the absorption rate of branded drugs and their generic equivalents and found only an average 3.5% difference (some generics performed better and some slightly less). In my opinion, that variance is small and too clinically insignificant for be of consequence.

Additionally, 38 published studies compared cardiovascular generics to their branded counterparts, and there was no evidence that the original formulas performed better than the generics.

That’s good news and the above studies would seem to give the green light for overall generic substitution. BUT, there are some exceptions that should be noted so that medical professionals and their patients use caution when switching to certain generics or when switching between different manufacturers of generics.

The Waxman-Hatch Act of 1984 lowered generic standards for the FDA so that each generic only has to perform with an 80% to 125% bioequivalence to the original drug. That means each generic could be a quarter more potent or 20% less potent than the original.

That difference can be particularly significant when switching between generic offerings for the same formula. Hypothetically, one generic of a specific antibiotic could be 20% sub-potent and another generic brand of the same antibiotic could be 25% more potent. Potentially, this could create a 45% difference between generics and still meet FDA approval for distribution.

I sincerely believe that this is a rare occurrence, particularly since I mentioned above that studies indicate, on average, that there is a mere 3.5% variance in potency between tested generics and their branded originals. Most of the time this is insignificant, particularly for single fill medications—that is, those prescriptions (like antibiotics, cough syrups, etc) that are filled only once and then not needed after the medical situation has been resolved.

The variance might be significant, however, for maintenance medications—that is, those medications that we take for chronic conditions over a period of months, years or for life. These include (but not limited to) blood pressure, thyroid, seizure, antipsychotic and heart regulating medications, and specific dose adjustments might be required to produce similar therapeutic effects to the original brand.

The FDA has taken these variables into consideration and grades all brand and generic versions of drugs as bioequivalent or not to other generic versions of the same drug, and classifies them as such for easy reference. All drug products approved for consumer use are listed in the FDA’s “Approved Drug Products with Therapeutic Equivalence Evaluations” manual.

This publication is commonly referred to as The Orange Book and the list classifies drugs as follows: “A” list drugs are considered interchangeable as generics with no known or suspected bioequivalent problems; “B” list drugs, on the other hand, are those drugs NOT considered pharmaceutically bioequivalent to their generic counterparts (for one reason or another) and should not be used interchangeably.

There is also an “AB” category for those drugs that initially had potential bioequivalence issues but have subsequently been resolved. These drugs should be substituted generically with caution.

The general conclusion is that most generics should work just fine, but I would resist allowing the pharmacy to switch back and forth indiscriminately between generic manufacturers. Whatever generic brand of medication you are started on is the one that you should remain on to prevent potential adverse effects, particularly for medications used long-term.

Thoughts? Comments? I’d love to hear them!