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Questions and Answers
What is the first step in performing calculations to adjust a pharmacy formula?
What is the first step in performing calculations to adjust a pharmacy formula?
How is the amount of an ingredient calculated using the ratio and proportion method?
How is the amount of an ingredient calculated using the ratio and proportion method?
What must be true about the units of the total quantity desired and the total quantity of the official formula?
What must be true about the units of the total quantity desired and the total quantity of the official formula?
Using the conversion factor method, how do you calculate the conversion factor?
Using the conversion factor method, how do you calculate the conversion factor?
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What is the likely consequence of not using the correct unit when calculating amounts of ingredients?
What is the likely consequence of not using the correct unit when calculating amounts of ingredients?
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If the total quantity of the official formula is 1000 ml, and you need 240 ml of the preparation, how much peppermint oil is needed if it requires 100 ml in the official formula?
If the total quantity of the official formula is 1000 ml, and you need 240 ml of the preparation, how much peppermint oil is needed if it requires 100 ml in the official formula?
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What method would you use to find the amount of peppermint powder needed for a preparation if the quantitative relationship is established?
What method would you use to find the amount of peppermint powder needed for a preparation if the quantitative relationship is established?
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What is the total volume of peppermint spirit if it is made from 240 ml of the official formula?
What is the total volume of peppermint spirit if it is made from 240 ml of the official formula?
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In the conversion factor method, what is the output when you properly apply the conversion using a known quantity?
In the conversion factor method, what is the output when you properly apply the conversion using a known quantity?
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Study Notes
Reducing and Enlarging Formulas
- Pharmaceutical preparations often use pre-tested formulas
- These formulas specify the amount of each ingredient for a given quantity
- Formulas may need adjusting for different quantities (reducing or enlarging)
- Adjustment is done based on either metric quantities or proportional parts
Objectives
- Calculate adjustments for pharmaceutical formulas in metric units
- Calculate adjustments for pharmaceutical formulas in proportional parts
Introduction
- Most pharmacy preparations based on tested and approved formulas
- Listed in the United States Pharmacopeia/National Formulary (USP/NF)
- Formulas indicate ingredient amounts for a specific quantity of preparation
- Adjustments are needed to meet specific needs
Ratio and Proportion Method
- Calculate ingredient amounts for a desired quantity using a ratio
- Ratio is derived by dividing the ingredient amount by the total preparation amount.
- Example: For a preparation formula that makes 1000mL of a liquid solution, if 100 mL of solution already has 10mL of ingredient A, the calculation to derive the ratio is 10/100 = 0.1
- Desired quantity is calculated by multiplying the ratio by the desired quantity
- Example: If a user desires 500ml of the solution, they need to multiply the ratio (0.1) by the desired quantity (500ml): 0.1*500ml = 50mL.
Conversion Factor Method
- Determine a conversion factor to scale the ingredients appropriately
- Convert the desired quantity to the same units as the original formula
- Multiply the conversion factor by the amount of each ingredient in the original formula
- This provides the scaled amount needed for the desired quantity
Formulas with Proportional Parts
- Formulas specify ingredient proportions (e.g., 2 parts A, 3 parts B)
- Proportional parts are relative weights or volumes, not always both
- In formulas involving solids, parts indicate ratios by weight, often expressed in grams
- Formulas involving liquids, parts often refer to volumes, expressed in milliliters.
- Example: To produce 1000g of an ointment for example, there are 5 parts coal tar, 10 parts zinc oxide and 50 parts of a hydrophilic ointment. This translates to 65 total ratio parts
- To calculate the amount of each ingredient, divide the total number of desired parts by the total number of parts within the formula
- Multiplying the results to the desired quantity for each ingredient would yield the required amount to produce the desired quantity.
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Description
Test your knowledge on adjusting pharmaceutical formulas for different quantities using metric units and proportional parts. This quiz focuses on the methods required to calculate ingredient amounts effectively for pharmacy preparations. Prepare yourself for real-world applications in pharmaceutical science.
