The newest entry into the antidepressant market is Pristiq (desvenlafaxine).Pristiq (desvenlafaxine), is in the SNRI category of antidepressants and is manufactured by the Wyeth Corporation. This drug received FDA approval in March, 2008. Faced with the fact that Wyeth
is losing patent protection for its top-selling antidepressant Effexor XR(venlafaxine XR), the company needed a brand product that would potentially replace some of the revenue loss when Effexor XR goes generic in 2010. Sales of Effexor XR in 2007 hovered around 3.8 billion
dollars.

Wyeth claims that Pristiq has distinct advantages over Effexor XR. Among them are that patients can begin taking Pristiq at the therapeutic dose of 50 milligrams thereby circumventing the “start low, go slow” gradual increases associated with determining the appropriate dose for an individual. Another advantage of Pristiq, according to Dr. Philip Ninan, a Wyeth vice president for neuroscience, is that Pristiq is unlikely to interact with other medications metabolized by the liver.

But several analysts are skeptical of Pristiq, claiming that it has not set itself apart from other antidepressants on the market, and that its release appeared primarily to have the drug serve as a “patent extender” for Effexor XR. This is because Pristiq is a primary active metabolite of Effexor, meaning Pristiq is the chemical compound that results after Effexor is taken and then metabolized and processed by the body.

What are your thoughts on pharmaceutical companies that design “new” drugs from the active metabolites of predecessors that have lost patent protection?