Stability Test of PACAP in Eye Drops

Area of Science:

• Ophthalmology
• Neuroscience
• Biochemistry

Background:

• Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide with significant cytoprotective effects, particularly in the eye.
• PACAP demonstrates therapeutic potential for ocular conditions, with previous studies confirming its ability to penetrate ocular barriers when formulated as eye drops.
• Convenient and safe delivery of PACAP via eye drops necessitates an understanding of its stability in ophthalmic formulations.

Purpose of the Study:

• To evaluate the stability of two PACAP forms, PACAP1-27 and PACAP1-38, in various eye drop media.
• To determine optimal storage conditions (temperature and medium) for maintaining PACAP integrity in eye drop solutions.

Main Methods:

• Stability assessment of PACAP1-27 and PACAP1-38 in four common media and one artificial tear solution.
• Analysis conducted at both room temperature and +4°C.
• Quantification of peptide stability using mass spectrometry.

Main Results:

• PACAP1-38 exhibited superior stability compared to PACAP1-27 across all tested conditions.
• Optimal stability for PACAP1-38 was observed in water and 0.9% saline solution when stored at +4°C, retaining 80-90% after two weeks.
• While PACAP1-38 degraded rapidly at room temperature in artificial tears, it remained stable at +4°C.

Conclusions:

• PACAP1-38 demonstrates enhanced stability in aqueous solutions, particularly at refrigeration temperatures, making it a viable candidate for ophthalmic drug delivery.
• The findings provide crucial data for the formulation and storage of PACAP-based eye drops for potential therapeutic applications in ocular diseases.
• Both PACAP1-27 and PACAP1-38 show potential for extended storage in various media, especially under refrigerated conditions.