French drugmaker Sanofi has filed a lawsuit against Eli Lilly and Co., accusing the U.S. drugmaker of infringing upon patents that protect its insulin Lantus.

Sanofi said Thursday after markets closed that its lawsuit, filed in U.S. District Court, alleges the infringement of four patents, and the case was triggered by a notification from Lilly that it had submitted an application for approval to the U.S. Food and Drug Administration.

Indianapolis-based Lilly is seeking approval for a potential long-lasting insulin labeled LY2963016 that it developed with German drugmaker Boehringer Ingelheim. The company said on Friday that its insulin does not infringe on the patents.

Insulin helps people with diabetes, a chronic condition in which the body either does not make enough insulin to break down the sugar in foods or uses it inefficiently. Diabetes, which is growing rapidly worldwide, can cause early death or serious complications like blindness or heart disease.

The litigation could delay a possible FDA approval of the Lilly drug, and it gives Sanofi more time to switch to a new and improved version, Bernstein analyst Dr. Tim Anderson said in a research note.

"For (Lilly), on the other hand, the delay merely means that it will have to sit on its hands a bit longer before launching its version of Sanofi's drug," the analyst wrote in a research note.

The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.

Compare Brokers