Answers of March Compounding corner

Cases

You have received a prescription in your pharmacy, as follows:

Zinc Ointment BP 25 gram

Apply twice daily

Patient : Kevin, 7 years

 

Question

1. What is the formula of zinc ointment BP?

2. What is the main problem of Zinc in this preparation? Give a solution.

3. Calculate the formula for preparation.

4. Your pharmacy doesn’t have a Simple ointment, so you must make it first. Calculate the Simple ointment for preparation.

5. How do you make a Simple Ointment BP?

6. How do you make Zinc Ointment BP?

7. Please make label of the prescription.

 

Answer

1. Zinc Ointment BP

Zinc Oxide, finely sifted 150 g

Simple Ointment 850 g

 

Simple ointment BP

Wool Fat 50 g  

Hard Paraffin 50 g  

Cetostearyl Alcohol 50 g  

White Soft Paraffin or Yellow Soft Paraffin 850 g

 

2. Zinc Oxide in storage will react with air and form ZnCO3 (clot)

ZnO +CO2 → ZnCO3

Solution : Zinc oxide must be finely sifted through 100 mesh

 

3.

Ingredients	Formula BP	Preparation
Zinc Oxide	150 g	150/1000 x 25 = 3.75 g
Simple Ointment	850 g	850/1000 x 25 = 21.25 g
Total	1000 g	25 g

 

4. You can add 10 - 20% of base

21.25 g + 20% = 25.5 g

Ingredients	Formula BP	Preparation
Wool Fat	50 g	50/1000 x 25.5 g = 1.275 g
Hard Paraffin	50 g	50/1000 x 25.5 g = 1.275 g
Cetostearyl Alcohol	50 g	50/1000 x 25.5 g = 1.275 g
White Soft Paraffin	850 g	850/1000 x 25.5 g = 21.675 g
Total	1000 g	30 g

 

5. Simple ointment BP

Key : Mix the ingredients, then heat gently with stirring until homogeneous. Stir until cold.

1. Weigh 1.275 g of Wool Fat on a Class II or electronic balance.

2. Weigh 1.275 g of Hard Paraffin on a Class II or electronic balance.

3. Weigh 1.275 g of Cetostearyl Alcohol on a Class II or electronic balance.

4. Weigh 21.675 g of White Soft Paraffin on a Class II or electronic balance.

5. Mix 1-4 on evaporating dish porcelain, and heat until all ingredients have melted.

6. Move into porcelain mortar, and stir with a pestle until homogeneous.

7. Stir until cold.

 

6. Zinc Ointment BP

Key : Triturate the Zinc Oxide with a portion of the Simple Ointment until smooth, and gradually  add the remainder of the Simple Ointment and mix thoroughly.

1. Finely sift Zinc Oxide BP through 100-mesh sieve.

2. Weigh 3.75 g of sifted Zinc Oxide on a Class II or electronic balance, and transfer it into a glass tile.

3. Weigh 21.25 g of Simple Ointment BP on a Class II or electronic balance, and transfer it into the same glass tile.

4. Triturate the Zinc Oxide with the Simple Ointment BP until a smooth product is formed.

5. Weigh 25 g of the product, and pack it into amber glass jar.

6. Label and dispense.

 

7. Label

Kevin, 7 Years   Zinc Ointment BP                                25 g Apply to the affected areas TWO times a day. For external use only Do not use after (3 months) Date of Dispensing