Mylan Laboratories joined the race to launch a copycat version of Eli Lilly’s top-selling anti-psychotic, Zyprexa (olanzapine), after winning tentative US Food and Drug Administration approval for a generic version the drug.

Specifically, Mylan says it has won tentative approval for the 2.5mg, 5mg, 7.5mg, 10mg, 15mg and 20mg tablets strengths of the $4.8 billion dollar-a-year drug. Earlier this week, the world’s biggest generics manufacturer, Teva, said it had won similar approval [[29/03/05c]].

A US court ruling on the validity of a key patent covering Zyprexa is eagerly awaited. The patent in question is not actually due to expire until 2011, but three generics manufacturers – Teva, Dr Reddy’s and Ivax – have challenged its validity [[28/01/04d]]. They claim that the US giant “double patented” Zyprexa – the original patent, which was issued in 1978 and expired in 1995, covered the genus of compounds but another compound patent specifical covers Zyprexa until 2011. The generics firms claim this so-called double patenting contravenes patent rules.