ALLEGAN, MI (WHTC) - A generic version of Mucinex will be on store shelves soon, as the FDA has allowed Allegan-based drug maker Perrigo to immediately begin manufacturing and marketing 600 milligram doses of the extended release cough and congestion treatment. Company officials admitted special challenges had to be cleared in the effort to tap into the 135 million-dollar annual income generated by Adams Laboratories for this product.