If the prazi is in liquid form you will need to know what the concentration is. E.G. if it is a 50% solution w/v (50 grams/100 mls) then if you want 37.5 grams you will need to add 75mls of liquid, and if it is a 25%w/v stock solution you will need to add 150mls. The same principle will apply if you have it in tablet form as they will not be 100% active ingredient.