Merck's In The Middle Of An HIV-Drug Patent-Spat -- Between Mylan and BMS

Efavirenz -- manufactured and branded as Sustiva^® by Bristol-Myers Squibb (apparently in part under a series of licenses from legacy Merck) is an HIV-1 specific, non-nucleoside, reverse transcriptase inhibitor. It is an AIDS threapy, and the first of the patents covering it expire on August 7, 2012. This drug franchise will generate about $1.3 billion in 2010 worldwide annual revenue for Bristol-Myers Squibb, and some portion of that is likely paid over to Merck, on these patent licenses.

So, Mylan is seeking approval to sell a generic form of Efavirenz, through its Matrix Labs subsidiary. Both Merck and BMS have apparently sent Mylan "covenant not to sue" letters. The import of these letters is to suggest that Merck and BMS won't assert that Mylan is infringing the patents covering Sustiva, in order to slyly prevent Mylan from asserting various alleged technical problems (a 0.6 Mb PDF file) with the patents -- as a way of getting Mylan's generic version onto the US markets, sooner than 2012. The rejoinder is here (a 1.3 Mb PDF file).

We will keep you posted on this one.