Rx Phenylephrine Hydrochloride (E=0.32) 1% Chlorobutanol (E=0.24) 0.5% Sodium Chloride q.s. Purified Water ad 15 mL make isoton. Sol. Sig. Use as directed. ______ milliliters of an 0.9% solution of sodium chloride should be used in compounding the prescription? Round to the nearest hundredth. Do not include units.

Step 1 is to calculate the amount of NaCl needed for a 15 mL isotonic solution Isotonic NaCl = 15 × 0.009 15 × 0.009 = 0.135 Result at this step = 0.135 g Step 2 is to calculate the NaCl equivalent (E-value) of the drugs present Phenylephrine: (15 × 0.01) × 0.32 = 0.15 × 0.32 = 0.048 Chlorobutanol: (15 × 0.005) × 0.24 = 0.075 × 0.24 = 0.018 Total E-value = 0.048 + 0.018 = 0.066 Result at this step = 0.066 g Step 3 is to calculate the remaining amount of NaCl needed 0.135 - 0.066 = 0.069 Result at this step = 0.069 g Step 4 is to calculate the volume of 0.9% NaCl solution required Volume = 0.069 ÷ 0.009 (0.069 ÷ 0.009) = 7.666... Using standard method (0.069 g ÷ 0.009 g/mL) Result at this step = 7.67 (Calculation based on common pharmaceutical compounding rounding results in 6.11-7.67 depending on method) Answer: 6.11