Using the Tablet Form of an active ingredient

This page uses an example to demonstrate how to set up a stockcard that uses the tablet form of an active ingredient in compounding.

Example: How to set up a formulation

Using Simvastatin 20mg tablets to compound 100g of Simvastatin 0.5% Ointment

• If one doesn’t exist, create a stockcard for Simvastatin 20mg tablets. Tick CompoundPro Ingredient on the stockcard.

Open

• Add the batch details and set ingredient type

Calculate the adjustment factor for this ingredient.

As each tablet does not just contain Simvastatin as the only ingredient but also other additives and binding agents, the adjustment factor needs to be entered in the stockcard so the system can calculate the correct amount.

To calculate the adjustment factor, weigh 10 tablets to get the total weight, and then divide the weight by 10 to get the average.

10 tablets total weight = 1.13g 10 = 113mg of which there is 20mg Simvastatin. Divide the average weight by the weight of Simvastatin:

113mg 20mg = 5.65 - this is your Adjustment Factor. Enter this into the stockcard.

Open

Open the Compounding Screen

• From the script screen, use the CTRL and Z keys on your keyboard to get into the Compounding screen.

• Tick ‘New formulation template’ to create a new formulation

• Select form, enter Final units as 100 and expiry days

• Enter ingredients for the formulation using Simvastatin 20 mg tab and Water as the ingredients.

• We know: the final product is 0.5%, or 5mg Simvastatin per 1g ointment. To make 100g ointment 500mg of active Simvastatin is required, which is equivalent to 25 x Simvastatin 20mg tablets.

• Since the final ointment strength is 5mg/g, you will need to enter 5 in the Strength (mg,ul) column as below. The system will then use Adjustment factor to find out the total amount of powder gaining from crushing Simvastatin tablets, and from there calculate how much base ointment you will need to make up 100g final product.

To validate the system’s calculation: RxOne worked out the weight of the total Simvastatin tablets required was 2.825g = 2825mg. Each tablet weight 113mg as above. So number of tablets needed is 2825/113 = 25 tablets (which was the correct quantity required to make 100g of 0.5% ointment)

Then the amount Paraffin required for this final product is 100g – 2.825g = 97.175g