Posted by yxibow on February 27, 2009, at 0:56:56
In reply to Re: Any problems with Generic Lamictal? » JayBTV2, posted by seldomseen on February 26, 2009, at 7:15:04
> Well, the term "bioequivalent", according to the FDA, means that the manufacturer of the generic drug has to be 90% confident that maximal plasma concentration of the drug/active metabolites *AND* the area under the plasma absorption/distribution curve is between 80-120% of the name brand.
>
> This "wobble" is why drugs with a narrow therapeutic range can not be substituted with generic. There can be some differences between generic and name brand. Are these differences clincially significant for a drug like lamictal? Well, everyone is different.
>
> What worries me the most is when pharmacies switch generic manufacturers. I don't think the FDA mandates that the generics demonstrate equivalence to each other, just to the name brand (does anyone know???).
>
> In that instance there could up to a 40% difference between the two generics. Kinda scary.
>
> SeldomThere are conceivable differences between generics and their originals, as noted, with drugs that have small margins.
In fact the FDA requires those specific agents to be more scrupulously monitored to my knowledge and may not approve all generics, such as Synthroid and other drugs under "1.8 Description of Special Situations"
If you're not taking Lamictal for epilepsy, the serious danger is less with a generic. Those are drugs that are closely monitored by doctors who treat epilepsy for obvious reasons.
That being said, a number of drugs for epilepsy have been generic for quite a while (and also offlabel as we know for psychiatric uses).
Its unlikely that significant changes would be noticed with things such as benzodiazepines which have not seen a new drug since 1981 except for the Xanax patent extension. I think the same goes for propranolol.
You can attempt to ask your pharmacist for the same generic -- the trouble is the lead time may be something that you have to consider since pharmacies need to follow market rates of drugs for cost reasons.
That it would be 40% different, I can't see -- all approved agents that are therapeutically equivalent in vivo/in vitro (this is from the Orange Book) are designated AB. All the agents for lamotrigine are AB.
So they all have to match the noted AUC curves as you had mentioned.I can see up to maybe a 20% difference, although that is a high estimate, and the constant plasma level I think would be less.
Nonetheless, I do have my own concerns about these, I'm not saying there aren't possible situations especially with larger quantities of a medication.So far for lamotrigine I believe I have gotten Teva's generic because I believe they often get a headway in the market and gain the "180 day exclusive". There are now however half a dozen other companies that are approved AB to make the same agent, so who knows.
Personally, I guess because it has been a drug that has had various effects on me, I am a little concerned when generic Seroquel comes to the US. Generic APs concern me a bit.However, of course, I believe all typicals are generic, and risperidone (Risperdal), is now the first generic atypical to my knowledge.
-- Jay
poster:yxibow
thread:882387
URL: http://www.dr-bob.org/babble/20090223/msgs/882736.html