Preservatives in ophthalmic formulations: a narrative review on myths, truths and news

Abstract

As people age and life expectancy increases, they are more likely to develop chronic conditions such as glaucoma, dry eye and reactive hypersensitivity. These conditions also require long-term topical ophthalmic treatments, which may contain preservatives. The main function of preservatives in ophthalmic formulations is to preserve the drug product and prevent contamination, so that they can be used safely until their expiration date. The use of preservatives for short periods can be beneficial, for example by facilitating pharmacokinetic aspects of antibiotics, thanks to their potential epithelial toxicity. But in prolonged treatments, preservatives have been shown to cause toxicity on the ocular surface, which is dependent on their concentration, frequency of instillation and total time of use. This has been observed mainly in glaucoma and dry eye disease, affecting the patient's quality of life, therapeutic compliance and expected results. In turn, it is also beginning to be relevant in view of the growing boom in the pharmacological management of presbyopia and myopia (in the pediatric population); which in most cases tends to be prolonged.

Therefore, new preservative options that are gentler and friendlier to the ocular surface are being developed, as well as innovative strategies to avoid the use of preservatives altogether. This paper has reviewed and updated the subject, highlighting the importance of considering and identifying the presence and/or variety of preservatives in prolonged treatments.