Specialist healthcare company BTG has settled its US patent infringement complaint against Instituto Bioclon and Rare Disease Therapeutics with a $6m payment.The FTSE 250-listed group has agreed to allow Bioclon to start selling its crotalid treatment from October 2018 if the Mexico-based firm receives regulatory approval for its anti-venom product.BTG will receive a single-digit royalty on sales of any Bioclon drug that relies on the 414 patent until the end of the exclusivity period in 2028.Bioclon has agreed to withdraw its legal challenge to the validity of the 414 patent and BTG will reimburse it for its legal fees and costs, totalling $6m.Chief executive officer Louise Makin said: "Settling this litigation is good for our business as it removes uncertainty for our investors and other stakeholders."Most importantly, it allows us to concentrate on what we do best, delivering a first-class treatment and supporting our customers and their patients by continuing to invest in a product that has treated over 40,000 people."Shares in BTG had declined 1.78% to 716p by 12:54.