Posted by yxibow on January 6, 2007, at 23:20:34
In reply to Generics » linkadge, posted by ed_uk on January 6, 2007, at 16:45:45
> Hi Link,
>
> >So, generics are allowed to be as much off as +/- 20%?
>
> >If you were taking 375mg of effexor, you could have as much as much as 150mg difference between two doses.
>
> No, the amount of drug in a generic tablet/cap will be almost identical to the amount of drug in a branded tablet/cap. When comparing a new generic product to the orginal branded product, bioequivalence studies are performed. In the UK, the following criteria are assessed:
>
> Product A = the test product ie. the new generic
> Product B = the reference product ie. the original brand
>
> A group of volunteers are given the medication. Pharmacokinetic parameters (AUC, Cmax and Tmax) are determined for each product (A and B). The ratio of A/B for AUC and Cmax and 90% geometric confidence intervals for AUC and Cmax respectively are determined. These values must fall within the accepted regulatory range of 80-125% (0.80-1.25 range) to indicate that A is bioequivalent to B.
>
> EdYou can go to Drugs@FDA and search around for the generic table, I dont remember offhand but I think I posted something about it in the past -- we do the same AB for generics. Most generics are labeled as AB.
The important thing is not the hue and cry over generics being different than the expensive "original" -- which I understand -- its that if your insurance is much cheaper for the generics, insist that your pharmacy start you on a particular brand of generic -- typically like for the benzodiazepines there can be half a dozen -- and keep you on it and inform you if there are changes. Also remember, and this may sound mean spirited, but there is a placebo effect knowing that you are getting a different generic or are being switched off to a generic. That very knowledge can cause subtle changes especially in affective/anxiety disorders to fool the mind into thinking that their medication is no longer working. I'm not saying it can't be the case -- as Ed was explaining about the AUC curve, but for medications like long half life benzodiazepines, its really should not be an issue to take a generic -- Klonopin is at least 16 hours and Valium is more than 24 hours.
Now there are a few medications, biologicals, a few rare antibiotics, insulin, synthroid, etc, that are not AB rated. Those are I think by decree to be have to have a closer tolerance, original or not. Don't quote me on that but I believe it is the case.
-- Jay
poster:yxibow
thread:719885
URL: http://www.dr-bob.org/babble/20070101/msgs/720027.html