These eye drops and ointments contain a combination of a steroid and one or more types of antibiotic for treatment of infection and inflammation of the eye. The steroid reduces inflammation while the antibiotic treats or prevents infection which may be the cause of the infection. Examples of steroids that are used in these eye drops are hydrocortisone, loteprednol, prednisolone, and dexamethasone . Examples of antibiotics used in these formulations include tobramycin, neomycin, bacitracin, polymixin B, and gentamycin. These antibiotics have different mechanisms of action and two or three may be combined in one formulation.
The two most generally accepted methods to prove the safety of a generic version of a drug are to either repeat most of the chemistry, animal and human studies originally done, or to show that the drug performs comparably with the original brand name drug. This second option is called a "comparative bioavailability" study. During this type of study, volunteers are given the original drug, and then separately later the generic drug. The rates at which the drug is delivered to the patient (into their blood stream or otherwise absorbed) are measured to ensure they are the same. Because the same active ingredient is used the major concern is just that it delivers the common chemical(s) at the same rate so that they have the same effect. Please note that the methods that the manufacturers use may vary from country to country.