ALLEGAN, MI (WHTC) - Officials of Allegan-based drug maker Perrigo has asked the FDA for approval to make a generic form of ProAir HFA. The aerosol is used to treat and prevent bronchospasms in those four years old and older, and has had annual sales of over a billion dollars for its maker, Teva Branded Pharmaceutical Products Research and Development, which has filed a patent infringement lawsuit against Perrigo and another company.