NaCl needed to make isotonic, Two drugs

8. Buffer and Isotonic Solution 8.2) Isotonic Solution 8.2.3) NaCl needed, Two drugs

8.2.3.1) NaCl needed, Two drugs Easy 1


Total tried:       Correct:       Wrong:

Calculate the gram amount of NaCl required to make the following sterile product isotonic.


      Rx:
      Drug PQR: 1.25 %
      Drug XYZ: 1.15 %
      NaCl qs
      Aqua dist q.s. a.d. 70 mL
      M.ft. isotonic solution
      Provided, the E value of the drug PQR is 0.03, and the E value of the drug XYZ is 0.462.


Click on the button below to see the answer and explanations

lb equals 0.232 g kg

    Answer: 0.232 g grams of NaCl will be needed.
    • Volume of the solution: 70 mL
    • Amount of NaCl needed to prepare an isotonic solution of this volume: 0.9/100 × 70 = 0.63 g
    • Concentration of the PQR drug: 1.25 %.
    • Quantity of the PQR drug present in the solution: 1.25 /100 × 70 = 0.875 g
    • E value of the PQR drug (provided): 0.03
    • Now, the NaCl-equivalent tonicity contributed by the PQR drug will be the product of drug's weight in g (0.875) and its E value ( 0.03 ), which is: 0.875 × 0.03 = 0.02625 g
    • Quantity of the XYZ drug present in the solution: 1.15 /100 × 70 = 0.805 g
    • E value of the XYZ drug (provided): 0.462
    • Now, the NaCl-equivalent tonicity contributed by the XYZ drug will be the product of drug's weight in g (0.805) and its E value ( 0.462 ), which is: 0.805 × 0.462 = 0.37191 g
    • Therefore, the quantity of additional amount of NaCl required to make the product isotonic: 0.63 g - 0.02625 g - 0.37191 g = 0.23184 g, rounded to 0.232 g g