Eye-drops in therapy – facts and myths about preservatives

Drugs in ophthalmology are most often applied topically in the conjunctival sac. All preparations administered through this route must meet specific requirements and, therefore, not just a simple solution or suspension of the drug in water. In addition to the therapeutic substance, eye drops contain various additives: buffers, preservatives, stabilisers, antioxidants, and isotonic substances to increase solubility and viscosity. Excipients are essential components of drugs that determine their quality and properties and can increase the effectiveness of treatment, e.g. by increasing the penetration of the drug through biological barriers. However, because of the high demands placed on ocular medicines, the choice of excipients is very limited. This article discusses the facts and myths surrounding the use of excipients, including preservatives, in eye drops.