NEW YORK (AP) — Irish drugmaker Shire PLC said Tuesday it settled patent lawsuits against Novartis AG's Sandoz unit, which was trying to market a generic version of Shire's attention deficit hyperactivity disorder drug Adderall XR. Under the agreement, Sandoz will be able to sell an authorized generic version of Adderall XR once it gains Food and Drug Administration marketing approval. Shire will receive royalty payments on the sale of the drug. The companies are dropping all litigation, and Shire said Sandoz is acknowledging two of the patents on Adderall XR are valid and enforceable. Shire has already entered similar settlements with Impax Laboratories Inc. and Barr Laboratories, a unit of Teva Pharmaceutical Industries Ltd. It said there are no remaining patent challenges related to generic versions of Adderall XR, and no generic versions have received FDA approval.