Which two USP tests are needed for ophthalmic ointments?

Which two USP tests are needed for ophthalmic ointments?

• A. pH and viscosity
• B. Sterility and metal particle content
• C. Water content and color
• D. Microbial limits and odor

Answer: (B)

The essential idea is safety for a product that goes directly into the eye: ophthalmic ointments must be both sterile and free of foreign particulates. Sterility is critical because any viable microorganism in an eye preparation can cause serious infections, including vision-threatening conditions. The metal particle content test is important because even tiny metal fragments can scratch or irritate the delicate ocular surface and trigger inflammation or injury. The USP requires these two checks to ensure the product is free from microbial contamination and from metal particulates, providing both microbial safety and mechanical safety for the eye. Other properties like pH, viscosity, water content, color, or odor are relevant to performance and quality, but they do not address the same direct safety concerns that sterility and absence of metal particulates do.

The essential idea is safety for a product that goes directly into the eye: ophthalmic ointments must be both sterile and free of foreign particulates. Sterility is critical because any viable microorganism in an eye preparation can cause serious infections, including vision-threatening conditions. The metal particle content test is important because even tiny metal fragments can scratch or irritate the delicate ocular surface and trigger inflammation or injury. The USP requires these two checks to ensure the product is free from microbial contamination and from metal particulates, providing both microbial safety and mechanical safety for the eye. Other properties like pH, viscosity, water content, color, or odor are relevant to performance and quality, but they do not address the same direct safety concerns that sterility and absence of metal particulates do.