Evaluation of Drop Volume Consistency of Eyedrop Bottles for New Generic Prostaglandin Analogue, Latanost® in Glaucoma Treatment

Difficulty in instilling eyedrop is a concern for it may cause a progression of blindness in glaucoma patients. Early depletion of eyedrop before the next scheduled medication refill is a common issue faced by patients, resulting in poorer compliance to the therapy. Hence, we hypothesize that the lack of drop volume consistency is due to the eye drop bottle-related mechanics during drop instillation. This study aims to select the best bottle designs by examining drop volume consistency during drop instillation. Ten eyedrop bottles of different volumes were filled with 2.5 mL purified water. Next, the drop uniformity test was performed by expelling 10 droplets by holding the bottle vertically and weighing with an analytical balance. Based on the outcome, bottle C, which demonstrated high drop consistency with low percentage standard deviation and near-linear regression, was chosen as the eyedrop container for Latanost® 0.005% w/v eye drops. Using bottle C, the drop volume of
Latanost® was estimated at 25.30 ± 1.87 μL. A 2.5 mL latanoprost solution can yield approximately 99.36 ± 7.52 drops per bottle. Besides that, the design of the eyedrop nozzle could determine the consistency of medication delivery. This report could better inform prescribers and patients in predicting the course of treatment. The selection of the right design of container closure system with a consistent drop delivery could significantly address the issue of early depletion of eyedrop before the next scheduled medication refill and difficulty in instilling eyedrop in glaucoma patients. This helps to improve medical treatment compliance in glaucoma patients