Generic and Therapeutic Substitutions

I was on the local DC news today regarding generic substitution.

Generic substitution is when your doctor writes for a prescription medication, but the pharmacists substitutes this with a generic medication. This is perfectly legal and, in general, a good thing for patients. For the most part, and for most drugs, the generic is just as good as the brand drug. However, as the news piece points out, there are some instances where the small difference between the generic and the brand name medication may make a difference. These are usually medicines where doses are very small such as hormones (thyroid medications, birth control pills) and medicines that have to be closely monitored. This does not necessarily mean that the generic is worse than the branded medication, but that switching from one to the other could have potential adverse effects.

One of the things that I spoke with the reporter about that is not in the above video (I have control over what I say, but not what they choose to sue), and only got a brief mention by the new anchor after the video was shown was about therapeutic substitution. This is a completely different ball game and a major concern of mine.

Therapeutic substitution is when your doctor writes a prescription for a branded drug and the pharmacist substitutes it not with the generic equivalent, but with a completely different generic drug in the same class. In this case, you are getting a totally different medication. For example, let's say your doctor writes a prescription for Crestor or Lipitor, both very potent cholesterol lowering drugs. You bring this prescription to the pharmacist, but instead of getting Crestor or Lipitor, you get simvastatin, a generic cholesterol medication. The difference here is that where the brand and generic equivalent will work about the same, this is not the case with a therapeutic substitution. Simvastatin will work in many patients but is not nearly as good as lowering cholesterol as Crestor or Lipitor. Thus, if the patient got switched and needed more cholesterol lowering than the simvastatin could provide (which is why I would write Crestor or Lipitor in the first place), that patient's cholesterol levels could be too high despite medication, potentially leading to heart attack and strokes. This is just one of many examples.

The practice of therapeutic substitution is currently illegal, but this could change. In Washington, DC where I practice, there is current legislation pending that would not only allow, but might compel a pharmacist to switch patients to cheaper medication, whether or not they were the same. In the case of DC, this is designed to save the government money from the millions of dollars its spends on prescription medications for our Medicaid patients.

With health care costs so high, physicians should do their best to try and write generic medications when possible. In additions, our pharmacist colleagues can be a tremendous help in figuring out ways to lower the costs of medications by using generics, whether it be a direct generic substitution or even therapeutic substitution. Pharmacist and blogger Mr.Medsaver has been doing this for quite some time, and I routinely read his helpful posts. However, pharmacists are not trained clinicians and do not know (and can not know) all the details of the patient's history or the rationale for the doctor choosing one drug over another. Though the pharmacist's suggestions are always welcome, I do not believe the should be allowed, and certainly not compelled or heaven forbid incentivized, to switch medications within the same therapeutic class. This could be very dangerous for patients.