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Monday, October 12, 2009

Why has conjugated estrogen never come out in a generic form?

I have been taking it for twenty years now and it is still very expensive, even with my co-pay. I realize HRT is very controversial. Does that have something to do with it?
Answer:
Good question and I assume that you are referring to Premarin庐 (conjugated estrogen). HRT controversy really has nothing to do with a lack of generic. The real reason is that Wyeth (the manufacturer) got lucky with this one.and it has to do with the drug's composition.Also, Wyeth still has one non-expired patent that protects Premarin (this type of patent is called an Orange Book patent). US Patent 5,210,081 does not expire until February 26, 2012. A generic company would have to circumvent or invalidate this patent if they wanted to launch a generic version of it.Third, Wyeth had filed a Citizen's Petition (legal maneuver) to block the generics from launching a generic.BTW, here is some history on Premarin:
Premarin is extracted from pregnant mare urine (hence the name). Reliable estimates indicate there are now at least 50,000 production mares on dedicated farms in N. America (mostly located in Canada).Premarin contains a number of different estrogens. Precisely how each of these various estrogens contribute to the drug's overall effectiveness has not been definitively determined -- and is the real reason for the lack of generics. Premarin's approval in 1942 predated the current requirements for such comprehensive analysis of products under review for marketing approval.Previously it was thought that two estrogens were the sole active ingredients in Premarin. Newer laboratory and clinical studies show this may not be the case. Rather, other components in Premarin may contribute to the drug's effectiveness.Although this finding does not prove that the DHES in Premarin has an important therapeutic effect, "it underscores the lack of precise knowledge of the makeup of Premarin and the relative importance of its components, and therefore the lack of a standard on which to evaluate a generic copy."In November 1994, Wyeth filed a citizen petition requesting that DHES be reclassified as a concomitant component. The firm maintained that the compound contributes to the drug's potency, and therefore, effectiveness, and further requested that FDA require the compound to be included in any generic copies of the drug.
The HRT controversy has probably hurt your chances of ever getting a generic. Most companies don't want to spend the time or effort it would take to get approval for a drug that many doctors have stopped prescribing.Before the controversy, a generic for Premarin was not approved because there was no good information on the actual active ingredient. Premarin is a mix of substances obtained from pregnant mare urine (hence the name - Premarin. My understanding is that it would be difficult to replicate Wyeth's manufacturing process and no company has successfully made a synthetic version.

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