Surfactants serve multiple roles in pharmaceutical preparations. They include: modulating solubility and bioavailability of APIs; increasing the stability of active ingredients in the dosage forms; helping active ingredients to maintain preferred polymorphic forms; maintaining the pH and/or osmolality of liquid formulations; acting as antioxidants, emulsifying agents, aerosol propellants, tablet binders, and disintegrants; preventing aggregation or dissociation; and modulating immunogenic responses of active ingredients. Non-ionic surfactants such as ethers of fatty alcohols are most commonly used in pharmaceuticals. Gemini surfactants are effective potential transfection agents for non-viral gene therapy.