Which type of ophthalmic medication typically has a longer shelf life?

• A. Solutions
• B. Ointments/gels
• C. Suspensions
• D. Inserts

Answer: (B)

Stability and shelf life hinge on how the formulation handles water and chemical reactions. Water-containing eye drops (solutions and suspensions) are more prone to hydrolysis, oxidation, and microbial growth, so their potency can degrade faster and they often require preservatives and strict storage. Oil-based ointments and certain gels have little or no free water, making them chemically more stable and less susceptible to contamination. That stability translates into a longer period during which the medication remains effective, even under typical storage conditions. Inserts can be long-lasting too, but their stability depends on the specific material and design, whereas oil-based ophthalmic ointments typically have the longest shelf life among common formulations.