Patent ID: 8273362

Claim:
A cationic ophthalmic oil-in-water emulsion, comprising: a cationic agent; at least one non ionic surfactant; colloid particles having an oily core surrounded by an interfacial film; said oily core comprising a prostaglandin, wherein, the prostaglandin is latanoprost, the cationic agent is cetalkonium chloride, and the at least one non ionic surfactant is not a polyoxyethylene castor oil derivative; wherein the emulsion does not contain phospholipids; wherein the emulsion contains no substance susceptible of affecting the zeta potential overtime; and wherein the emulsion has a positive zeta potential and meets the zeta potential stability Test A requirements, wherein the requirements comprise: the difference between the zeta potential measured when the emulsion is prepared and the zeta potential measured after 15 hours of storage is less than the standard of error of measurement, wherein, the storage for 15 hours is in glass vials (Type I) of 10 mL effective capacity containing between 5-10 mL of the emulsion sealed under nitrogen atmosphere (without bubbling) at 80° C., and, the zeta potential is measured by electrophoretic mobility in an apparatus equipped with suitable software and calibrated with the supplied standard, where, the emulsion is diluted in double distilled water to obtain scattering intensity allowing optimal particle detection, a sample count rate between 100 to 1000 KPcs is used in homodyne detection, three consecutive measurements are performed at 25° C. using a constant cell drive of 150 mV, the measurements are averaged, the measurements are converted into zeta potential values through the Smoluchowsky equation, using the dielectric constants and viscosity of water.