Is premarin made from natural sources?

What are the sources of Premarin ingredients?

Premarin, a hormone replacement therapy medication, was originally made from the urine of pregnant mares. The estrogen in the medication is derived from the pregnant horses' urine, which contains a high concentration of conjugated estrogens (CEs).

According to the manufacturer's website, Pfizer (formerly Wyeth Pharmaceuticals), Premarin was first introduced in the 1940s and was made from the urine of pregnant mares at a facility in Richmond, Indiana. The company has since expanded its global sourcing, but the exact composition of the current formulation remains proprietary information.

However, in [1] 2013, Pfizer announced that it would no longer use pregnant mares as a source for Premarin, citing concerns about animal welfare. The company began sourcing its estrogen from other sources, including synthetic materials, but declined to publicly disclose the exact composition of the new formulation.

Have alternatives to animal-derived estrogen become available?

In response to consumer and regulatory pressure, several manufacturers have developed alternative estrogen products using non-animal-derived sources, such as synthetic materials or plant-based ingredients [2]. For example, the estrogen in Duavee, another hormone replacement therapy medication, is derived from plant sources rather than animal urine.

What about the patent expiration for Premarin ingredients?

The patents for Premarin's original ingredient, conjugated equine estrogen (CEE), expired in 2015 in the United States. However, the patent for Pfizer's proprietary version of the medication, which includes the original estrogen compound, may still provide some protection against generic competition [3].

References:
[1] https://www.pfizer.com/news/press-release/press-release-detail/pfizer-to-phase-out-use-of-pregnant-mares-in-premarin-manufacturing
[2] https://www.drugpatentwatch.com/drugs/Antiestrogen/Antiestrogen
[3] https://www.drugpatentwatch.com/drugs/Estrogen/Estrogen

Sources:

1. Pfizer. (2013). Pfizer to Phase Out Use of Pregnant Mares in Premarin Manufacturing.
2. DrugPatentWatch.com
3. www.drugpatentwatch.com