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: 1.05 %
Drug XYZ: 0.85 %
NaCl qs
Aqua dist q.s. a.d. 50 mL
M.ft. isotonic solution
Provided, the E value of the drug PQR is 0.04, and the E value of the drug XYZ is 0.076.
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lb equals 0.397 g kg
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Answer: 0.397 g grams of NaCl will be needed.
- Volume of the solution: 50 mL
- Amount of NaCl needed to prepare an isotonic solution of this volume: 0.9/100 × 50 = 0.45 g
- Concentration of the PQR drug: 1.05 %.
- Quantity of the PQR drug present in the solution: 1.05 /100 × 50 = 0.525 g
- E value of the PQR drug (provided): 0.04
- Now, the NaCl-equivalent tonicity contributed by the PQR drug will be the product of drug's weight in g (0.525) and its E value ( 0.04 ), which is: 0.525 × 0.04 = 0.021 g
- Quantity of the XYZ drug present in the solution: 0.85 /100 × 50 = 0.425 g
- E value of the XYZ drug (provided): 0.076
- Now, the NaCl-equivalent tonicity contributed by the XYZ drug will be the product of drug's weight in g (0.425) and its E value ( 0.076 ), which is: 0.425 × 0.076 = 0.0323 g
- Therefore, the quantity of additional amount of NaCl required to make the product isotonic: 0.45 g - 0.021 g - 0.0323 g = 0.3967 g, rounded to 0.397 g g