All Generics are not Created Equal
Variability in generic drugs between manufacturers is an industry-wide problem and patient complaints about generics could be related to variations in dosage and formulation
It’s a misperception that generic drugs are all made the same and are exactly equivalent to the brand or even one another. Variability between manufacturers of the same drug exists and has the potential to cause irregularity in how patients feel. At times, people have reported experiencing side effects or feeling “off” when their pharmacy changes manufacturers.
As written about in a previous post on medication quality issues, the FDA allows for the bioavailability of a generic drug to vary from a minimum of 80% to a maximum of 125% from the original brand formulation. With such a large allowed variability, the simple act of refilling your prescription could result in differences in how a patient feels especially when the manufacturer changes.
To delve deeper into this, Valisure tested the variability in dosage of six different manufacturers of Lisinopril, a popular ACE inhibitor that is commonly used to treat high blood pressure. 110M prescriptions for Lisinopril were written in 2016, making it the second most prescribed drug in the U.S.
We analyzed 20mg of the Lisinopril brand name drug along with five generics currently available on the market from five different global manufacturers – two made in the U.S.; two from China; and two from India. We then tested three different lots from each of the same manufacturers.
As the graphic above illustrates, the brand was almost 100% consistent in dosage, or active ingredient, in the three different lots that we tested from that particular manufacturer. Conversely, in the generic labeled G5 for example, the dosage within three different lots from that manufacturer varied almost 10% both up and down from the intended 20mg dosage. Another manufacturer, labeled G1, appears to be consistent across the three batches, however each batch is approximately 5% higher than the labeled dosage.
The data suggests that these six manufacturers are not only formulated differently, but that there exists variability in the amount of the active ingredient present from manufacturer to manufacturer. Variability in the active ingredient, within the same manufacturer, also exists from lot to lot.
A patient could potentially experience negative effects when substitutions are made from one generic to another or from refill to refill from the same manufacturer, even though they are deemed bioequivalent. For example, a patient who might be doing well on a generic drug that delivers more active ingredient than the branded product could experience negative effects if switched to a different generic that delivers less of the active ingredient.
While all the drugs Valisure tested met FDA testing requirements, analysis of the formulations revealed variability in dosage that could potentially effect patients refill-to-refill, particularly as pharmacies continue their current practice of chasing the lowest price available for a particular drug, sacrificing consistency when patients refill their prescriptions.
At Valisure, not only is it important to us that you know exactly what’s in your medications but that your medications stay as consistent as possible from refill to refill.