How many milligrams of NaCl should be used to make the following prescription isotonic?
Dextrose anhydrous 2.5%
Sodium chloride q.s.
Sterile water for injection Ad 1L
There is only dextrose anhydrous 5% available
To make the prescription isotonic, the amount of sodium chloride (NaCl) needed can be calculated using the formula:
NaCl (mg) = Dextrose (g) * 1000 * (0.9 - Dextrose concentration) / 0.2
In this case, the dextrose concentration is 2.5%, which can also be represented as 0.025.
NaCl (mg) = 0.025g * 1000 * (0.9 - 0.025) / 0.2
NaCl (mg) = 25 * (0.875) / 0.2
NaCl (mg) = 109.375 mg
Therefore, to make the prescription isotonic, approximately 109.375 milligrams of NaCl should be used.
To make the prescription solution isotonic, we need to calculate the amount of NaCl (sodium chloride) needed.
First, we need to determine the concentration of the dextrose anhydrous solution we have, which is 2.5%. We know that the final solution needs to be 1 liter, so we can use this information to calculate the amount of dextrose anhydrous present.
2.5% of 1 liter is equivalent to 0.025 x 1000 mL = 25 mL of dextrose anhydrous.
Next, we need to find the concentration of the available dextrose anhydrous solution, which is 5%. Since this is double the concentration we need, we will be diluting it. To find the amount of the 5% dextrose anhydrous solution to use, we can set up a proportion:
5% / 2.5% = x mL / 25 mL
Cross-multiplying and solving for x, we get:
2.5x = 125
x = 50 mL
So, we need to use 50 mL of the 5% dextrose anhydrous solution.
Finally, we need to calculate the amount of NaCl needed to make the solution isotonic. Since the prescription states "Sodium chloride q.s." (quantum sufficit - the amount necessary), we need to determine the appropriate amount.
For isotonicity, the concentration of NaCl is usually around 0.9%. This means that 0.9 grams of NaCl is present in 100 mL of solution.
So, if we have 50 mL of the 5% dextrose anhydrous solution, we need to calculate the amount of NaCl needed based on the concentration.
5% of 50 mL is 2.5 mL, which contains 2.5 grams of dextrose anhydrous.
To find the amount of NaCl needed, we can set up another proportion:
2.5 g / 100 mL = x g / 0.9 g
Cross-multiplying and solving for x, we get:
0.9x = 2.5 * 0.9
x = 2.25 g
Therefore, to make the prescription isotonic, we would need to use 2.25 grams (2250 milligrams) of NaCl.