New Delhi, July 21 -- NEW YORK - The maker of Wegovy filed a federal lawsuit against Eli Lilly on Monday, accusing its largest rival in the obesity drug market of running misleading advertisements that denigrate semaglutide, the active ingredient in Novo Nordisk's blockbuster weight-loss injections.

The complaint invokes the Lanham Act, the primary federal statute governing false advertising claims. Novo Nordisk alleges that marketing materials for Zepbound, Eli Lilly's competing glucagon-like peptide-1 receptor agonist, contain claims that are misleading or unsupported by clinical evidence when used to compare the two drugs directly.

The lawsuit arrives at a bruising moment in the commercial rivalry between two companies that together ...