Hokie, while this is true, I wasnt referring to that. I was referring to other things. For example, lets look at the market experience. Acetaminophen from tylenol have more than 50 years of experience, while acetaminophen from a generic company that recently started has 0. A patient might feel better swallowing their capsules which are smaller, or easier to go down.
In terms of "bioequivalence", there are many cases where different therapeutic responses are not seen as equal. Two or more products might appear "identical" or "equivalent" because they contain the same drug, in same dosage strength, and in the same dosage form. However, if the formulation materials such as diluents, binders, disintegrants, lubricants, are not the same, then it is possible the product might exhibit differences. For example, dilantin toxicities in the late 1960's (long time ago, but not really) in Australia (not USA FDA, but still). The toxicity was due to a domestic product, binder, that released more dilantin, increasing the bioavailibity. Digoxin was another example that exhibited varying avaibility from different manufactueres, although the dosage form was the same. Just the method of manufactuer might change the whole entire picture. This is the reason why we are not allow to change a patient who have been on synthoid to another one, etc.
While, we have gone a long way since the 60's and the FDA does requires dissolution test to make sure everything is okay now, not all "generic" are equal still. For example, I do have a few complaints of customers saying that the nicotine patch do not "Stick" as well. The ointment base that a medication is in might be different as well. While a drug might be equal, it might take longer for the same drug made by different manufacters to reach their peak differently (even though the AUC is still the same), etc.
My original post was still referring to other stuff, hence things/drugs. So for example, give me the real oreo over pathmark oreo. That is still generic.
You have quite a bit of information that is wrong.
In the case of Dilantin, it was only discovered the Dilantin product has a long acting formulation after it was off patent. It was not designed that way, rather that was discovered after new manufacturers got into the market. They don't even quite know why the product has such a stable controlled blood level property that it does. That is why today, we have generic phenytoin & brand name Dilantin. No, they are not interchangeable, but that does not make one over the other better. You just titrate the individual.
Premarin is an example of a drug which can't be marketed as a generic because they can't get the exact amount of each component. But, that market has fallen way off anyway. But, that was the primary reason synthetic estrogens were developed - to be able to refine & define the basic drug which helped Estradiol & much later all the generics which came after.
The levothyroxine issue is longer & has a far more interesting history. Synthroid was the first manufacturer & has been in the market for over 40 years, altho the company making it has changed hands many times. The Synthroid drug itself has also changed as well. It was reformulated in 1981, an exciepient was added to the 50mcg tablet in 1983. In 1989 the dyes were changed in 3 of the strengths & in 1991, the exciepient was removed from the 50mcg tablet. Synthroid along with every other levothyroxine product had to undergo NDA applications in August 2000. That is when they were are define bioequivalently with the reference drugs being Synthroid & Levoxyl.
Then we get to the issue of the bioequivalence study of levothyroxine done by Dr Dong at UCSF in the 80's. It was demonstrated there was no significant difference. But, politics, money & pressure prevented the study from being published. (This was a HUGE scandal!!!) It was resurrected much later & bioequivalent has been indeed be demonstrated. The bioequivalence codes for levothyroxine products are a bit more complicated than for other drugs, but they are rated AB1, AB2, AB3 or BX depending on how the compare based on the reference drug.
Levothyroxine is inherently an unstable drug & is subject to recalls frequently due to this very instability.
And, as part of each ANDA, the manufacturer does indeed have to demonstrate dissolution characteristics as well as adhesive properties, in the case of patches. But, the variants are not in the drug product itself, more in the patient, particularly the skin of the patient. I have many, many patients who prefer the adhesive properties of the Mylan fentanyl to the Duragesic fentanyl (no - not due to the ease of removing the fentanyl). Some will react to the adhesive or it will not "stick" - but those same folks will buy BandAid, Curad or store brand.
For myself, I will use generic drugs anytime because I know they are the same. However, I buy brand name Cheerios, Best Foods mayonaise (west of the Rockies) and Dreyer's ice cream. They taste better to me. I prefer the taste of Hydrox cookies to Oreos & just won't buy a store brand of either.
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