Gramicidin is primarily used as an antibiotic in topical formulations to treat bacterial infections. It is effective against a range of Gram-positive bacteria and is commonly found in ointments, creams, and eye drops for skin and eye infections. Its mechanism involves disrupting bacterial cell membranes, leading to cell death. Gramicidin is often combined with other antibiotics like neomycin and polymyxin B to broaden its spectrum of activity. It is particularly useful in preventing infections in minor cuts, burns, and surgical wounds. Additionally, it is employed in research settings to study ion transport across cell membranes due to its ability to form channels that allow the passage of monovalent cations.