Personal injury suits were filed against Syntex.

The Palo Alto drug company said it will fight the five suits, which seek more than $2.5 billion in punitive and compensatory damages from its subsidiary, Syntex Agribusiness, in Missouri state courts on behalf of 190 people claiming injury from a chemical called dioxin. The substance was manufactured by a now-defunct company called Northeastern Pharmaceutical & Chemical, which once leased part of a plant in Verona, Mo., owned by the subsidiary. Several related lawsuits against Syntex already are pending.