Background and Importance According to literature, a formulation of regular human insulin (Actrapid®) 1 IU/mL eye drops was elaborated using a solution of artificial tears (Systane Ultra®), in sterile amber glass dropper bottles for the treatment of corneal ulcers. To test the stability, a 30-day galenic validation was performed, storing the eyedrops in refrigeration. The samples prepared at the Pharmacy Department presented turbidity from day 0, therefore it was decided to formulate it in 0.9% sodium chloride (normal saline).

Aim and Objectives Optimise and study the stability through galenic validation of 1 IU/mL insulin eye drops formulated using normal saline in sterile amber glass dropper bottles and in low density polyethylene (LDPE) dropper bottles.

Material and Methods We elaborated a 1 IU/mL regular human insulin eye drops using normal saline stored in refrigeration (2–8°C) in amber glass dropper bottles (IN1) and LPDE dropper bottles (IN2). All samples were prepared in a horizontal laminar-flow cabinet following the Good Practice Guidelines for sterile drug preparation. A 30-day galenic validation was carried out monitoring clarity, colour, pH, osmolality and sterility on days 0, 1, 2, 7, 15, 22, 30 testing three units per sampling point and analysed property. The pH value at which insulin commercial presentations are buffered is 6.9–7.8; and the pH value of normal saline is 6.0.

Results IN1: at day 0, the samples presented a pH around 8.5. After analysing this pH value, it is obtained that it was due to the sterilisation process of the amber glass dropper bottles, which uses buffered formol. The formulation is, therefore, rejected.

IN2: all samples presented, during the whole galenic validation, a transparent and homogeneous appearance, with absence of particulates, pH values of 6–6.3, an osmolality of 282–286 mOsm/kg and no microbiological growth.

Conclusion and Relevance The 1 IU/mL insulin eye drops packaged in LPDE dropper bottles showed no changes in the parameters studied throughout the 30-day galenic validation. They also remained within the eye pH range of maximum tolerability (3.5–10.5). It is required more physicochemical and microbiological stability studies to confirm the stability of the formulation.

Conflict of Interest No conflict of interest.