Posted by SLS on August 2, 2012, at 6:45:07
In reply to Re: Are generics always inferior to name brand?, posted by jono_in_adelaide on August 2, 2012, at 0:29:21
> I am convinced that this is largely mind over matter, the FDA and their equivalents in other countries requirs substantial bioavaliability testing of generics before they are allowed onto the market - you cant set your self up stamping out diazepam and sertraline tablets just because you think it would be a good money spinner.
> Power of suggestion is a potent force!
It might depend on how narrow the therapeutic window is for the drug in question. For drugs like antibiotics and NSAIDs, there is very little difference in effectiveness because there is little need to be precise in dosing. The dosage range within which these drugs remain effective is virtually unlimited up until one reaches the threshold of toxicity, which is relatively high. This is not true of anticonvulsants / mood-stabilizers. The therapeutic window is relatively narrow. There is very little tolerance to differences in dosing. At too low a dosage, no efficacy exists; at too high a dosage side effects and toxicity appear. The difference in these dosages are very small; so small that the range of the deviations in bioequivalency allowed by the FDA (80-125%) is often greater than the therapeutic window of the drug. It is also important to consider that different generics are not required to be bioequivalant to each other. Switching between generics might be problematic, especially when one preparation occupies the higher end of the allowed range versus reference and the other the lower end. A 40% difference? I am not sure of my math. Interestingly, nortriptyline, a tricyclic antidepressant (TCA), has a window of efficacy for which the therapeutic effects actually disappear if one takes too much of it. No other TCA demonstrates this behavior.
Generics look good in theory and on paper. I use generics for almost every drug they were designed to replace. The one exception is Lamictal (lamotrigine), an AED. I relapsed on the two generic preparations I tried; something that I was required to do by my prescription plan. Restarting the name-brand allowed me to recapture the therapeutic effect.
There is much debate and conflicting reports to be found regarding the issue of the clinical equivalence of generic AEDs to name-brand. The two citations I included above demonstrate that this issue requires further examination.
Some see things as they are and ask why.
I dream of things that never were and ask why not.
- George Bernard Shaw