Chloramphenicol drug molecule. Ball-and-stick molecular model of chloramphenicol, a broad-spectrum antibiotic effective against a wide range of bacterial infections. Because of this, and because it is cheap and easy to manufacture, this antibiotic is widely used in the developing world. For example, it is often prescribed in the form of an ointment to treat eye infections like conjunctivitis. Its chemical formula is C11H12Cl2N2O5. Atoms are represented as spheres with conventional colour coding: hydrogen (white), carbon (black), oxygen (red), nitrogen (blue), and chlorine (green).