US healthcare major, Wyeth, has announced the planned closure of its plant in Rouses Point, New York, as plummeting demand for its female hormone replacement therapy, Premarin, which is manufactured at the site, has dented its long-term viability.

Sales of Premarin and the firm’s other female HRT, Prempro, have tumbled in the wake of a study that revealed health risks associated with their long-term use. Results of the Women's Health Initiative trial showed that Prempro was associated with a greater risk of breast cancer, stroke and heart disease [[10/07/02b]], findings that were replicated in the UK's Million Women Study [[08/08/03a]].

The group said it will begin cutting down its workforce in 2006 for three years, with eventual closure scheduled for 2009. In the meantime, Wyeth said it is exploring options for sale of the site and is working to identify potential buyers.

In a statement, the company said that the move is “part of Wyeth's continuing assessment and realignment of its manufacturing network designed to create more efficient operating processes and full production capacity at its plants."

Meanwhile, the US Food and Drug Administration has approved a new “black-box warning” for Wyeth’s smallpox vaccine Dryvax, which highlights that cases of myopericarditis - inflammation of the heart and the surrounding sac - have been observed in healthy adults after immunisation.

The problem was first brought to light back in 2003, following a drive in the USA to vaccinate its healthcare workers against smallpox. Even though the disease was wiped out in 1979, experts fear it may be revived as part of an act of bioterrorism and, consequently, the US government has stockpiled smallpox vaccines in case this scenario is realised.

Investors seemed relatively unmoved by the news, as Wyeth’s stock closed at $45.29 on October 11, down just $0.19 from the previous day.