For years, Hersh & Hersh has represented hundreds of users of a top-selling anti-psychotic drug in suits against its maker. Now the firm is taking on bigger clients against the same company: states that say they’ve been footing the public health costs from the drug.

H&H’s first such client against pharmaceutical giant Eli Lilly & Co. is the state of New Mexico, which claims it spent about $18 million on Zyprexa-related medical expenses between 1999 and 2005.