ALLEGAN, Mich. — Perrigo Co. has begun shipping guaifenesin extended-release tablets 600 mg, a generic version of Mucinex tablets.

Perrigo said the launch entails product packaged in bottles "to a number of customers."

The company added that it expects to initiate a full-scale over-the-counter launch of product in blister packaging to retail and wholesale customers in store brands or own labels before the end of its current fiscal year in August.

In January, Perrigo announced that it won a summary judgment in patent litigation for its planned generic version of Mucinex and planned to launch the product within 90 days. Perrigo was sued by Adams Respiratory Therapeutics Inc., a subsidiary of Reckitt Benckiser Group, the New Drug Application holder and patent owner for Mucinex.

The Food and Drug Administration approved Perrigo’s Mucinex generic in late 2011.

Mucinex 600mg tablets, an expectorant indicated to relieve chest congestion and make coughs more productive, has estimated annual sales of approximately $135 million, according to Perrigo.