A pharmaceutical scientist explains how generic drugs do and do not differ from brand-name drugs. (istock)

Consumer Reports recently talked with Vinod P. Shah about generic drugs. He’s a pharmaceutical scientist and consultant for the U.S. Pharmacopeia who worked for 30 years at the Food and Drug Administration, where he developed guidelines for testing and approving generic drugs.

Are generic drugs truly the same as their brand-name equivalents?

To gain FDA approval, the generic must demonstrate that it has the same active ingredient and that it is identical in strength, dosage form, route of administration and labeling as the innovative product.

It must also be bioequivalent, meaning that once administered, there must be no significant difference in the rate and extent of absorption compared with the innovative product. To measure this we give the drug to healthy volunteers and measure blood concentrations using strict analytical methods and validation procedures.

Generic manufacturers have to meet the same requirements for purity and manufacturing quality as the makers of the innovative product.

For all these reasons, I feel very confident that the generic products approved in this country are safe and effective. My gut feeling is that people think brand-name products must be better because they’re more expensive, but that’s a psychological effect, not a real effect. The body does not know whether the drug came from a brand-name or a generic company.

Does that mean everything in a generic drug is the same as in the brand-name version?

No. For oral dosages — tablets and capsules — the generic drug need not have the same inactive ingredients. In fact, generic manufacturers may not even know what the inactive ingredients are in the brand-name drugs.

Some people taking certain kinds of medicine say they have trouble switching to generic versions. Are they imagining it?

No. This problem involves what we call narrow therapeutic index (NTI) drugs, including anti-
seizure medications, blood thinners and thyroid hormone replacements. For them to work properly, you have to maintain a specific concentration in the blood. You have to regularly check blood levels to make sure the concentration is right.

Either a brand-name or generic NTI drug can work, but once you have identified a suitable version, it may not be advisable to switch back and forth, even between two generics, because the formulation characteristics might be different and affect the blood concentration. If you want to change, you should have close blood monitoring at the beginning.

Will we ever see generic versions of the expensive bioengineered drugs used to treat such conditions as rheumatoid arthritis and multiple sclerosis?

The FDA has come up with draft guidelines for what manufacturers will have to do for these so-called biosimilar products. The generics that we’re accustomed to seeing are small molecules that can be easily synthesized without living organisms. But these biotech drugs are large molecules that have to be prepared with living organisms in a very complex manufacturing process. The generic manufacturers don’t know how the original manufacturer does it, so they will have to figure it out on their own. It remains to be seen how much cheaper these biosimilars will be than the brand-name originals.

Copyright 2012. Consumers Union
of United States Inc.