Compounding Calculations

Ingredient Roles

Ingredients can perform three roles within a formulation, either active, excipient and base.

Active ingredients are provided in their prescribed strength, either mg, IU, or mcg.
Excipients and provided as a percentage of the final units.
Base ingredients fill the remaining quantity not taken up by the actives and excipients.

Adjustment factors

An adjustment factor is a number that will convert between the prescribed strength and the grams per unit. The adjustment factor usually represents the adjustment needed for the assay and/or loss on drying, but can also represent things such as the activity IU/gram or the ratio of active to excipients of crushed commercial medicines. Adjustment factors are only applied to active ingredients.

Packing statistics

Pack stats represent the density of a dry packed powder within a certain capsule size. Pack stats are optionally specified in milligrams for each batch. When using a capsule calculation method, pack stats are considered for each ingredient to determine the volume of that ingredient within the capsule size. This helps ensure that the amount of base is enough to fill the capsule, no more, no less.

Liquid density

Liquid density (or specific gravity) is only applicable to ingredients that are ticked as a liquid. This defines the relationship between the mass of the ingredient and it's volume. This conversion allows you measure liquids in mL within sold (w/w) preparations, or weigh liquids using a balance within liquid preparations. It also is used in "Molded" calculations to determine displacement of the base.

Powder density

Powder density is the density of a loose uncompressed powder within a 1mL volume. This statistic is used only for the powder calculation method to determine the amount of base required to add to the powder such that each scoop contains the correct amount of active.

Powder displacement

Powder displacement can be configured to override the default powder displacement on the dosage form. This statistic is only used within the 'Molded' calculation method, in order to add additional base to account for the amount an ingredient will displace.

Calculation methods

The calculation method selected for the dosage form will determine if the final units should be in grams, mL's or another unit (e.g capsules, scoops, suppositories etc.) Using a liquid calculation will change how the liquid ingredients are treated with a formulation, it is important to carefully interpret any formulation reference to determine if the final units is in grams w/w or in mL's w/v, v/v.

Capsule

This calculation type is used when preparing capsules and will include the packing statistics in the calculation. The final quantity displayed in this calculation type is the number of capsules. Percentage represents their volume within the capsule size. The percentage is determined using the packing statistics of the ingredient.

Solids will be calculated in grams.
Liquids are not supported as liquids cannot have packing statistics.
Base is calculated as the volume of base remaining required to fill all capsules. Liquid bases are not supported

Liquids (w/v) and (v/v)

This calculation type is used when the final units is measured in mL's (e.g. suspensions)

Solids will be calculated in grams.
Liquids will be calculated in mL's with grams equivalent shown.
Base is calculated as an estimated volume of base required to fill the remainder of the final volume. The user will be prompted to QS the base to the final volume.

The liquid density/ specific gravity can be found on the ingredient batch’s certificate of analysis (CoA) or manually calculated by weighing 1mL of the liquid ingredient.

Solid (w/w)

This calculation type is used when the final units is in grams, such as creams/ointments.

Solids will be calculated in grams.
Liquids will be calculated in grams with mL's equivalent shown.
Base is calculated as the amount in grams needed to fill the final weight with mL's equivalent shown.

Portions/Powder (w/w)

This calculation type is used when the dose is administered in loose powder form and measured in using a standard volume scoop.

Solids will be calculated in grams.
Liquids will be calculated in grams with mL's equivalent shown.
Base is calculated using the powder density of all ingredients as the amount in grams needed to fill the remaining volume.

Molded (w/w)

This calculation type is used for suppositories and troches, but can also be used for any unit of volume where displacement should be considered. When using the molded calculation type, multiple 'dosage forms' should be created with a default base and individualised base displacement values to more accurately consider the displacement for a particular base.

Solids will be calculated in grams.
Liquids will be calculated in grams with mL's equivalent shown.
Base is displaced by each individual ingredient displacement value or by the default provided by the dosage form. Is it calculated as the amount of base required to ensure that a single unit of volume contains the correct strength of active.

Enter via quantity

When importing a reference formula into a formulation reference it may be necessary to enter the absolute values provided by the reference in order to convert them to their relative strength and percentages. This is important as Compound Direct requires the ingredients to be recorded as strength or percentage. Once toggled on, you can enter the grams for each solid ingredient for the given final quantity and wastage provided by the reference.

Liquid in w/w preparations

If importing a liquid ingredient which has been specified in mL's by the formulation reference into a solid (w/w) preparation it is necessary that the liquid density be specified for the ingredient so that percentage or strength of the ingredient can be accurately determined. This is because the formulation reference contains pre-calculated absolute volumes that need to be converted to grams for a (w/w) calculation type. Before you enter this formulation, please provide a liquid density for the batches.