Pharmacy Technician Certification Board Practice Exam

If a patient has a prescription for Xalatan 0.005% ophthalmic solution with directions of 1 gtt ou nightly, how many days will a 2.5ml bottle last?

1. 50 days

2. 28 days

3. 25 days

4. 18 days

The correct answer is: 25 days

To determine how many days a 2.5 ml bottle of Xalatan 0.005% ophthalmic solution will last when the patient is instructed to use 1 drop in both eyes nightly, it's important to consider the volume of one drop and the total volume in the bottle. Typically, one drop from an eye dropper is approximately 0.05 ml. Since the prescription indicates 1 drop in each eye, the total volume used per application would be 0.1 ml (0.05 ml for each eye). The total volume in the 2.5 ml bottle can be divided by the volume used per day to find the duration of the bottle's supply: 2.5 ml / 0.1 ml per day = 25 days. Each drop is accounted for correctly as two drops per night (one per eye), and the calculations reflect the actual volume administered according to the patient's instructions. Therefore, a 2.5 ml bottle will last 25 days under the given usage conditions, confirming that this is the correct answer.