Podcast
Questions and Answers
What is the first step in using the ratio and proportion method to calculate the amount of an ingredient needed?
What is the first step in using the ratio and proportion method to calculate the amount of an ingredient needed?
When using the conversion factor method, what must be true of the total quantities being compared?
When using the conversion factor method, what must be true of the total quantities being compared?
In the example of preparing Peppermint Spirit, how much peppermint oil is needed to make 240 ml?
In the example of preparing Peppermint Spirit, how much peppermint oil is needed to make 240 ml?
Which calculation method utilizes a conversion factor derived from the total quantities desired?
Which calculation method utilizes a conversion factor derived from the total quantities desired?
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What is the typical purpose of reducing or enlarging pharmaceutical formulas?
What is the typical purpose of reducing or enlarging pharmaceutical formulas?
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In the example for Peppermint Spirit, what is the amount of peppermint powder needed?
In the example for Peppermint Spirit, what is the amount of peppermint powder needed?
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What is a crucial step after establishing the total quantity of the official formula when calculating ingredient amounts?
What is a crucial step after establishing the total quantity of the official formula when calculating ingredient amounts?
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What should be done first when preparing to adjust a formula for a new volume?
What should be done first when preparing to adjust a formula for a new volume?
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Study Notes
Reducing and Enlarging Formulas
- Formulas for pharmaceutical preparations often need adjustment.
- Calculations are performed to reduce or enlarge formulas.
- Metric quantities and proportional parts are used.
- Official formulas from USP/NF are often the basis.
- These formulas specify ingredient amounts required for a given quantity.
Ratio and Proportion Method
- A ratio and proportion method is used for calculations.
- The method compares a desired quantity to the original formula quantity.
- Example using Peppermint Spirit: If the original formula is for 1000ml and a quantity of 240 ml is needed, ratios are set up (100ml/1000ml = xml/240ml)
- Cross-multiplication to solve for the unknown variable is used.
- Formula is solved for the correct amounts of ingredients required for the new quantity.
Conversion Factor Method
- Conversion factor is calculated by dividing the desired quantity by the original quantity.
- Both quantities (desired and original) must have the same unit.
- The conversion factor is then multiplied by the original ingredient amount to find the new needed amount for the revised formula.
- Example using Cocoa Syrup: If the desired quantity is 120 ml and the original quantity is 1000 ml; the formula (120/1000) gives the conversion factor, which then multiplies the amount of each ingredient from the original formula to find the new amounts if a 120ml quantity is wanted.
Formulas with Proportional Parts
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Formulas often use proportional parts for ingredients, rather than exact measurements.
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Proportional parts represent the relative amounts of each ingredient.
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Solids/semisolids are usually reported in grams and liquids in milliliters.
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Example using an Ointment Formula: If an ointment formula has 5 parts of coal tar to 10 parts of zinc oxide and 50 parts of hydrophilic ointment; and a 1000g quantity is wanted, calculations are required to determine the correct amount of each ingredient for the 1000g desired quantity. (using proportions)
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Description
Test your knowledge on reducing and enlarging pharmaceutical formulas using ratio and proportion, as well as the conversion factor method. This quiz covers official formulas and calculations needed to adjust ingredient amounts for desired quantities. Perfect for students in pharmaceutical studies or anyone interested in medication preparation!
