The US Food and Drug Administration (FDA) has approved Merck & Co Inc.s combination treatment for complicated forms of urinary tract and abdominal infections, the drugmaker said on Wednesday. ADVERTISEMENT Recarbrio, approved for patients over 18 years of age, is a combination of a previously approved antibiotics imipenem-cilastatin and Mercks relebactam. "It is important that the use of Recarbrio be reserved for situations when there are limited or no alternative antibacterial drugs for treating a patients infection, the FDA said in a statement. (https://reut.rs/2JKTXfD) The approvals were based on limited clinical safety and efficacy data for Recarbrio, the company noted. Relebactam is expected to bring in revenue of $50 million in 2020 and $150 million in 2024, Cowen & Co analyst Steve Scala said ahead of the approval. The relebactam combination had been granted FDAs fast track status, which allows the agency to expedite the review process for certain drugs meant for serious conditions with an unmet medical need. Merck, which expects to make Recarbrio available later this year, already has an approved treatment, Zerbaxa, for complicated urinary tract infections and intra-abdominal infections. The company added Zerbaxa to its portfolio through its acquisition of Cubist Pharmaceuticals in 2014.