Section 8.4 Special Dilutions Terminology: Diluent: Pediatric Compound Sterile Preparations (CSPs): Special Dilutions: Calculating Special Dilutions: Ratio-Proportion vs Dimensional Analysis Part A Calculating Special Dilutions: Step 1: Determine the total number of milligrams in the desired special dilution Step 2: Determine the milliliters of stock solution needed to prepare the special dilution Step 3: Determine the number of milliliters of diluent needed for the special dilution total volume (TV) drug volume (DV) = volume of diluent Part B Calculating Special Dilutions with Uncommon Dextrose Percentage Strengths: Steps for Calculating Special Dilutions of IV Dextrose Infusions: Step 1: Calculate the volume of concentrated dextrose solution. Identify the TV and % of each TV solution then use the formula desired %= number of ml needed stock % (this step CAN be done using dimensional analysis, but it is slightly confusing!) Step 2: Calculate the volume of sterile water needed by finding subtracting the volume found in step 1 from the total volume. (Check by adding the values found in steps 1 and 2)
Part A Calculating Special Dilutions: Ex 1: Prepare a special dilution of hydrocortisone solution with a total volume of 24 ml and a concentration of 5 mg/ml. The pharmacy has a stock solution of hydrocortisone with a concentration of 100 mg/ml and plans to add sterile water. (a) How many milligrams of folic acid will be needed for the special dilution? (b) How many milliliters of the stock solution will need to be drawn up? (c) How many milliliters of sterile water will need to be added? Ex 2: Prepare a special dilution of folic acid solution with a total volume of 10 ml and a concentration of 200 mcg/ml. The pharmacy has a 50 ml stock solution of folic acid with a concentration of 5 mg/ml and plans to add sterile water. (a) How many milligrams of folic acid will be needed for the special dilution? (b) How many milliliters of the stock solution will need to be drawn up? (c) How many milliliters of sterile water will need to be added?
Part B Calculating Special Dilutions with Uncommon Dextrose Percentage Strengths: TV stock % desired %= number of ml needed Ex 3: Determine how much of each solution will be needed to make the preparation (a) Prepare 750 ml of D1.5W using dextrose 5% and sterile water. (b) Prepare 1500 ml of D18W using dextrose 50% and sterile water. (c) Prepare 300 ml of D15W using dextrose 70% and sterile water. Part C Total Parenteral Nutrition (TPN): TPN Base solution: Most TPN solutions contain and. Additives:
Procedure for solving typical TPN problems: Step 1: Calculate the volume of the TPN base components using the following formula (TV/stock %) desired % = number of milliliters needed (for the given solution) (notice this is the same formula used in Part B) Separate calculations must be done to find the of Step 2: Calculate the volume of each additive based on the following formula: D= H= D = x ml, volumeof additive needed H Note: this process can also be done using dimensional analysis and may be easier that way Step 3: Sum all of the volumes found in Steps 1 and 2 Step 4: Determine the about of inactive solution, if necessary, to be added in order to get the desired TV (this will be the case if we see QSAD in the TPN order) Step 5: Verify the accuracy of your calculations by adding all of the volumes you found in Steps 1 4 together. sum the volume of each base solution and volume of each additive solution Ex 4: Determine the volume needed for each TPN order using the following stock solutions Dextrose 70% Sodium chloride 2.5 meq/ml Aminosyn 10% Calcium gluconate 4.65 meq/10 ml Liposyn 20% Magnesium sulfate 40.6 meq/10 ml Travasol 10% Potassium phosphate 15 mm/5 ml Potassium chloride 2 meq/ml Vitamin C 250 mg/ml
(a) A TPN order calls for these amounts to be made from the items on hand. The total volume is to be 1000ml. how much of each ingredient, additives, and sterile water do you need to prepare this TPN? Base Solution: Aminosyn 4.25 % Additives: Potassium chloride 24 meq ml Dextrose 20 % MVI 5 ml ml Sterile water QSAD Sodium chloride 24 meq ml TV of base (not including SW) ml TV of additives ml
(b) The following TPN has a total volume of 2500 ml Base Solution: Additives: Travasol 6.5 % Potassium chloride 140 meq Dextrose 15% Sodium chloride 105 meq Sterile Water QSAD Magnesium sulfate 12 meq Calcium gulconate 28 meq Potassium phosphate 13.2 mm Vitamin C 750 mg TV of base (not including SW) ml TV of additives ml