How many milligrams of boric acid should be used in compounding the following prescription? Round your answer to the closest whole number.
Tetracaine HCl: 3%
Procaine HCl: 0.8 g
Boric acid: qs
Purified water: ad 60 mL
Make an isotonic solution.
Hint: Tetracaine HCl E-value = 0.18; Procaine HCl E-value = 0.21; Boric acid E-value = 0.52