Posted by Michael Bell on March 11, 2006, at 11:41:38
In reply to Bioequivalence, posted by ed_uk on March 8, 2006, at 16:05:06
But that's exactly the problem. Bioequivalency only discusses the absorption rate of the drug into the bloodstream, NOT the rate and completeness of the absorbtio at the site of action. This is the whole reason that the FDA has recognized that there are major problems with the guidelines for bioequivlency, because it may not equal thereapeutic equivalency.
Acording to the FDA, for a drug to be bioequivalent, it must. "deliver the same amount of active ingredients into a patient's bloodstream in the same amount of time as the innovator drug"
However, what happens to the drug after it enters the bloodstream is not assessed. How well is it absorbed at the site of action, which in this case is mainly the small intestine.
The FDA equates bioequivalence with therapeutic equivalence, but the Dept. of Pharmaceutics and Pharamaceutical chemistry noted that this leaves out major important determining factors, by stating:
"It is important to note that the FDA designation of thera-peutic equivalence does not consider several formulation char-acteristics, including packaging, scoring configuration, shape, or pharmaceutical excipients (e.g., colors, preservatives, fla-vors)."
The theory has always been that the new nardil is not being absorbed as well at the site of action of the drug.
> In order for the 'new' Nardil formulation to be approved, it would have had to have been shown to be bioequivalent to the 'old' formulation.
>
> Excipients can affect the rate and extent of absorption of a drug. Two formulations are considered to be bioequivalent when their absorption parameters are the same.
>
> Ed
poster:Michael Bell
thread:617166
URL: http://www.dr-bob.org/babble/20060310/msgs/618831.html