Danielle DelVillano PharmD 1 Objectives Perform calculations to reduce or enlarge formulas for pharmaceutical preparations stated in metric quantities Perform calculations to reduce or enlarge formulas for pharmaceutical preparations stated in proportional parts ID: 476517
Download Presentation The PPT/PDF document "Pharmaceutical Calculations: Reducing an..." is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Pharmaceutical Calculations: Reducing and Enlarging Formulas
Danielle DelVillano, Pharm.D.
1Slide2
Objectives
Perform calculations to reduce or enlarge formulas for pharmaceutical preparations stated in metric quantitiesPerform calculations to reduce or enlarge formulas for pharmaceutical preparations stated in proportional parts
2Slide3
Determining the “Factor”
To go from a larger to smaller quantity, or vice versa, determine the “factor” by which to reduce or enlarge the formula
Ex. USP recipe is for 1000
mL
but you only wish to make 100
mL
of solution
Quantity of the formula desired = Factor Quantity of the formula givenThen multiply the quantity of each ingredient in the formula given by the factor to determine the amount of each ingredient needed to prepare the desired compund
3Slide4
Example 1
If a formula for 1000 mL contains 6
g
of a drug, how many grams of drug are needed to prepare 60
mL
of the formula?
60 mL (quantity desired) = 0.06 (factor) 1000 mL (quantity given) 6 g
x
0.06 = 0.36 g of drug needed
4Slide5
Problem 1: Solve by using factor
From the following formula, calculate the quantity of each ingredient required to make 240 mL
of calamine lotion
Calamine 80
g
Zinc Oxide 80
g
Glycerin 20 gBentonite magma 250 mLCalcium hydroxide solutionn, to make 1000
mL
5Slide6
Problem 1: Solve by using factor
240
mL
(quantity desired)
= 0.24 (factor)
1000
mL
(quantity required)Calamine: 80 g x 0.24 = 19.2 gZinc Oxide: 80 g
x
0.24 = 19.2 gGlycerin: 20
g
x
0.24 = 4.8
g
Bentonite: 250 mL x 0.24 = 60 mLCalcium hydroxide: to make 240 mL
6Slide7
Problem 1: Solve by Using Dimensional Analysis
Calamine
80
g
x
240 mL = 19.2 g 1000 mLZinc Oxide 80 g
x
240 mL = 19.2 g
1000
mL
Glycerin
20
mL
x 240 mL = 4.8 mL 1000 mL
Bentonite
250 mL x 240 mL = 60 mL 1000 mLCalcium hydroxide to make 240 mL
7Slide8
Problem 2
From the following formula for an estradiol vaginal gel, calculate the quantity of each ingredient required to prepare 1 lb of gel.
Estradiol
200
g
Polysorbate
80 1
gMethylcellulose Gel, 2% 95 g8Slide9
Problem 2: Solve Using a Factor
9Slide10
Problem 2: Solve Using Dimensional Analysis
10Slide11
Problem 3: Proportional Parts
From the following formula, calculate the quantity of each ingredient required to make 1000 g
of the ointment
Coal Tar 5 parts
Zinc Oxide 10 parts
Hydrophillic
Ointment 50 parts
11Slide12
Problem 3: Proportional Parts
Total number of parts: 5 + 10 + 50 = 65 parts
So 1000g will contain 65 parts
Coal Tar
5 parts
=
x g 65 parts 1000 g x = 76.92
g
Zinc Oxide
10 parts =
x
g
65 parts 1000 g y = 153.85 gHydrophillic
Ointment
50 parts
= x g 65 parts 1000 g z = 769.23 g
12Slide13
Additional Problems
13Slide14
Chapter 16 Problem 5
Calculate the quantity of each ingredient needed to prepare 15 mL
of the following ophthalmic solution:
Eryromycin
l
actobionate
500 mgDexamethasone sodium phosphate 100 mgGlycerin 2.5 mLSterile Water for Injection, a.d. 100 mL
14Slide15
Chapter 16 Problem 5
15Slide16
Chapter 16 Problem 10
According to the literature, when the product Amevive
(
alefacept
) is reconstituted with sterile water for injection it contains the following in each 0.5
mL
Alefacept
7.5 mgSucrose 12.5 mgGlycine 5 mgSodium citrate, dihydrate 3.6 mgCitric acid, monohydrate 0.06 mg
16Slide17
Chapter 16 Problem 10 continuted
How much alefacept
would be needed to manufacture a 5000 batch of vials for reconstitution?
A) 12.5 mg
B) 31.25
g
C) 37.5
gD) 45 g17Slide18
Chapter 16 Problem 10
18Slide19
Chapter 16 Problem 11
The formula for a ciprofloxacin otic
drop is given in the literature as follows:
Ciprofloxacin 1
g
Propylene glycol 50
mL
Glycerin qs ad 100 mLHow many grams of ciprofloxacin would be required to prepare 200 15 mL bottles of the ear drop?
19Slide20
Chapter 16 Problem 11
20Slide21
Questions
21Slide22
Reference
Ansel, H. C. (2009) Phamaceutical
Calculations
(13th Ed.).
Philadelphia:Lippincott
Williams & Wilkins, and
Wolters
Kluwer Publishers22