Colomycin, also known as Colistimethate sodium or Colistin, is an antibiotic medication primarily used in the treatment of infections caused by certain types of bacteria that are resistant to other antibiotics. It belongs to a class of drugs known as polymyxins, which work by damaging the bacterial cell membrane, leading to bacterial death. Colomycin is effective against a wide range of gram-negative bacteria, including Pseudomonas aeruginosa, which often causes infections in individuals with cystic fibrosis or those who are immunocompromised. It can be administered via inhalation, injection, or intravenously, depending on the location and severity of the infection. Due to its potential for nephrotoxicity and neurotoxicity, Colomycin is usually reserved for treating serious infections when other antibiotics are not effective.