a patient uses a sol. of timolol twice a day for glaucoma.?

Question

the total % of drug in the sol. is 0.25% and the patient uses 2gtts bid in each eye(1gtt=0.2ml) the total daily dose per eye is
a. 0.5mg
b. 1.5mg
c. 1.0mg
d. 2.0mg
how u solve this

Answer 1

Letter D. 2.0 mg daily dose in each eye.

=>Stock is 2.5 mg/1 ml (Each ml of 0.25 % contain 2.5 mg)
=>2 drops BID with 1 gtt = 0.2 ml makes daily total of 0.8 ml.

Let X= be the daily dose per eye.

-->> X / 0.8 ml X 2.5 mg / 1 ml

-->> X (1 ml) x 2.5 mg (0.8 /ml)

-->> X ml = 2.0 mg/ml (cancel the ml)

-->> X = 2 .0mg