Generic vs Branded Psychiatric Medications: Is There a Difference?

Jane Lowers; Robert H. Howland, MD

Disclosures

April 25, 2012

In This Article

Editor's Note:

As the psychopharmacology market boom of the 1990s and 2000s has matured, most antidepressants and many antipsychotics are becoming available in generic form. Anecdotally, some patients have reported variability in symptom control and side effects when switching from brand-name to generic products or vice versa; however, randomized controlled trials supporting this assertion are lacking. The US Food and Drug Administration (FDA) sets rules that govern the consistency between innovator and generic drugs and alternative agents. Medscape recently interviewed Dr. Robert Howland, associate professor of psychiatry at the University of Pittsburgh, Pennsylvania, on the distinctions between these agents as well as their significance for clinicians.

Branded vs Equivalent vs Alternative Psychiatric Medications

Medscape: Dr. Howland, could you review the difference between branded agents and their pharmaceutical equivalents and alternatives?

Dr. Howland: "Brand name" really refers to what the FDA would call an "innovator drug." It's usually the drug that was first in its class with a particular therapeutically active ingredient. Subsequent drug formulations containing the same active ingredient are considered either pharmaceutical equivalents or pharmaceutical alternatives.

The essence of this difference is that drugs can have the same active ingredient, but the FDA distinguishes between drugs that are pharmaceutically equivalent and drugs that are pharmaceutical alternatives. In both cases, the active ingredient is the same. For pharmaceutically equivalent drugs, the formulation is such that they are considered bioequivalent and would have the same intended therapeutic effects -- the same degree of efficacy, as well as safety and tolerability.

A "generic drug" is therefore defined as a drug that is shown to be pharmaceutically equivalent to the brand-name drug. Compared with the brand-name drug, a generic drug has to contain the same active ingredient; be identical in strength, dosage form, and route of administration; and be bioequivalent.

A pharmaceutical alternative drug has the same active ingredient, but the active ingredient may be chemically bound in a way that's somewhat different from the original drug formulation. Although the alternative drug contains the same active ingredient, the chemical formulation might result in differences in bioavailability. Although in most cases, a pharmaceutical alternative drug may be similar in terms of efficacy, safety, and tolerability, the FDA does not consider it to be a therapeutic equivalent, so it wouldn't be considered a generic.

One example to illustrate the difference between pharmaceutical equivalent and pharmaceutical alternative drugs would be the brand-name innovator drug Paxil®, which contains the active ingredient paroxetine. Paroxetine hydrochloride is the chemical that's contained in brand-name Paxil. The brand of drug called Pexeva® also contains the active ingredient paroxetine, but it's bound as paroxetine mesylate. So, Paxil and Pexeva are considered to be pharmaceutical alternative drugs: They contain the same chemical entity paroxetine, but they are not considered to be pharmaceutically equivalent because of the differences between paroxetine hydrochloride and paroxetine mesylate.

For the brand-name drug Paxil, there are generic versions, or therapeutic equivalents, containing paroxetine hydrochloride, and they are formulated according to the FDA's bioequivalence standards for generics. For the drug Pexeva, which is paroxetine mesylate, to my knowledge there are not yet any generic equivalents. Because Pexeva and Paxil are considered pharmaceutical alternative drugs, Pexeva cannot be substituted routinely by a pharmacist as a generic version of a prescription written for Paxil. Similarly, generic versions of Paxil -- that is, paroxetine hydrochloride -- cannot be substituted for a prescription written for Pexeva.

[Editor's note: A summary of FDA standards for generic drugs can be found here.] 

Capsule and tablet formulations of the same drug are not considered to be pharmaceutical equivalents, but they are pharmaceutical alternatives. Similarly, immediate-release, extended-release, delayed-release, and injectable formulations of the same drug are considered pharmaceutical alternatives. Each of those formulations contain the same active ingredient, but how they're delivered, in many respects, may lead to differences in bioavailability.

For example, olanzapine was originally developed in the tablet formulation, Zyprexa®. There is now an injectable formulation, olanzapine pamoate or Zyprexa Relprevv™, so the chemistry used to change the delivery system would make them pharmaceutical alternative drugs rather than pharmaceutical equivalents. Generic versions of a particular release formulation of a brand-name drug can be routinely substituted by a pharmacist, but pharmacists cannot substitute one release formulation for another.

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