Predictive value of the efficacy of glaucoma medications in animal models: preclinical to regulatory studies

To gain regulatory approval for a new medicine, a pharmaceutical company must take the new product through a series of clinical trials (Phases I-III). Animal models are important in the new drug-development process because they allow for the testing of the efficacy and safety of potential new medicines in a cost-efficient manner that avoids the risk of serious adverse events to humans. Unfortunately, there is no perfect animal treatment model for glaucoma. Animal studies hopefully predict the results of clinical studies, but with estimating efficacy, the limited size and duration of these studies, as well as the animal model selection, might restrict the ability to accurately predict future results. There is little information which compares various available animal models and how well these preclinical studies predict the efficacy of a new product in clinical trials. The purpose of this review article is to analyse animal model studies evaluating potential glaucoma products and determine parameters associated with commercial availability. We discuss how animal models provide some success in predicting commercial launch of a new glaucoma medicine, especially the hypertensive and monkey models, but highlight that caution must be used in interpreting individual models or studies.