A unit of France’s Sanofi-Aventis SA has sued Irvine-based Allergan Inc. in a dispute over royalties related to Allergan’s wrinkle treatment Juvéderm.

Sanofi’s Genzyme, which the French drug maker bought in April for $20 billion, sued Allergan in federal court in Boston, according to a Bloomberg report.

Juvéderm is an injection used to fill in wrinkles on the lower face. It saw first-quarter sales of $88.2 million, up 49% from a year earlier.

Allergan saw total first-quarter sales of $1.27 billion.

Genzyme is suing over a patent for a gel used in Juvéderm to augment soft tissue.

The drug maker contends Allergan stopped paying royalties on the gel after a patent expired in July and declined a request to continue paying royalties through March 2012 on a second patent.

Allergan makes eye drugs and medical cosmetics, including Juvéderm and Botox for wrinkles.