A start-up company formed by the founder of a Milwaukee-area drug ingredient maker is proposing to build a pharmaceutical research and development facility in Mequon, creating 50 jobs. Major Pharmaceuticals LLC wants to develop a two-story, 79,000-square-foot facility on a 7.7-acre parcel immediately south of Executive Drive and east of Commerce St., according to a filing with the city Plan Commission. That site is in Mequon Business Park, near the northeast corner of Donges Bay and Wauwatosa roads. The company, which will produce injectable serums, expects to complete the $10 million office and lab facility by late 2013, the filing said. Major Pharmaceuticals will have an estimated 50 full-time employees, including 10 chemists and pharmacists, 15 lab quality assurance technicians and 25 process operators. The commission is to review the proposal at its Monday night meeting.