What is the resultant ratio strength of an ointment prepared by combining 10 g of 10% betamethasone valerate ointment, 40 g of 5% betamethasone valerate ointment and 10 g of ointment base?

Step 1. Calculate the total weight of active drug. From 10 g of 10%: 10 g x 0.10 = 1 g From 40 g of 5%: 40 g x 0.05 = 2 g Total drug = 1 g + 2 g = 3 g Step 2. Calculate the total weight of the final ointment. Total weight = 10 g + 40 g + 10 g = 60 g Step 3. Calculate ratio strength (1:X). 3 g / 60 g = 1 / X X = 60 / 3 = 20 Ratio strength = 1:20