The company said that shipments of the product to its pharmacy customers have already started.
Pennsaid (diclofenac sodium topical solution) 1.5% w/w is indicated to treat signs and symptoms of osteoarthritis of the knee.
Brand sales were about $38m for the 12 months before any generic competition.
Perrigo chairman, president and CEO Joseph Papa said: "This product approval and launch further strengthens our leading Rx position and highlights our commitment to bringing new affordable products to the market."
The company develops, manufactures and distributes OTC and generic prescription (Rx) pharmaceuticals, nutritional products and active pharmaceutical ingredients (API), and receives royalties from multiple sclerosis drug Tysabri.
In November, the company signed an agreement to acquire Belgian OTC healthcare firm Omega Pharma, for about €3.6bn.
The acquisition is expected to improve Perrigo’s OTC product offering and expand its distribution through Omega’s well established platform.