ST. LOUIS (AP) — KV Pharmaceutical Co. said Monday it added a potential $120 million to an agreement that gives it rights to Gestiva, a drug intended to prevent premature birth. Under the new deal, KV paid Hologic Inc. $70 million and agreed to pay up to $120 million for future regulatory and sales milestones on the drug. In 2008, KV agreed to buy Gestiva from Hologic in a deal worth potentially $82 million at the time. It paid $7.5 million to Hologic, but the Gestiva assets were not transferred to KV. The transfer date of rights had been tied to Food and Drug Administration approval. KV would have been able to terminate the agreement in mid-February if the FDA hadn’t approved the drug. The FDA issued an “approvable” letter for Gestiva in October 2006. Approval was again delayed in January 2009 with an FDA request for more information. Gestiva is intended to prevent premature birth in women who are pregnant with a single fetus and have experienced spontaneous premature birth before.