The FDA established the Limited Population Pathway for Antibacterial and Antifungal Drugs (LPAD pathway) as part of the 21st Century Cures Act that was signed into law in December 2016. The LPAD pathway is designed to facilitate the development and approval of antibacterial and antifungal drugs to treat serious or life-threatening infections in a limited population of patients with unmet need. The key feature of this pathway is that approval may be supported by a streamlined clinical development program involving smaller, shorter or fewer clinical trials. This critical express lane for drug development in the most serious conditions had yet to be used by any company... until now. Bridgewater, New Jersey, based Insmed ?(INSM[NGS]?-?$25.97??? ??Trade ) announced Friday after the close that it has received FDA approval of Arikayce (amikacin liposome inhalation suspension) for Mycobacterium avium complex (MAC) lung disease as part of a combination antibacterial drug regimen for adults with limited or no alternative treatment options. Arikayce is the first drug approved in the US specifically for patients with MAC lung disease and the first product approved via the LPAD pathway. Arikayce is a once-daily inhaled formulation of amikacin, an established intravenous antibiotic that has historically been associated with severe toxicity to hearing, balance and kidney function. Insmed?s proprietary Pulmovance liposomal drug delivery technology enables Arikayce to be delivered directly to the lungs, where it is taken up by lung macrophages where the infection resides. This approach prolongs the release of amikacin in the lungs while limiting systemic exposure.