Percentage

Percentage
The term percent and its corresponding sign (%) mean ‘‘by the hundred’’ or ‘‘in a hundred,’’ and percentage means ‘‘rate per hundred’’; so 50 percent (or 50%) and a percentage of 50 are equivalent expressions.
A percent may also be expressed as a ratio, represented as a common or decimal fraction. For example, 50% means 50 parts in 100 of the same kind, and may be expressed as 50?100 or 0.50.
Percentage is an essential part of pharmaceutical calculations. The pharmacist encounters it frequently and uses it as a convenient means of expressing the concentration of an active or inactive material in a pharmaceutical preparation.

Percentage preparation
The percentage concentrations of active and inactive constituents in various types of pharmaceutical preparations are defined as follows by the United States Pharmacopeia:
• Percent weight-in-volume (w/v) expresses the number of grams of a constituent in 100 mL of solution or liquid preparation and is used regardless of whether water or another liquid is the solvent or vehicle. Expressed as: % w/v.
• Percent volume-in-volume (v/v) expresses the number of milliliters of a constituent in 100 mL of solution or liquid preparation. Expressed as: % v/v.
• Percent weight-in-weight (w/w) expresses the number of grams of a constituent in 100 g of solution or preparation. Expressed as: % w/w.

The term percent, or the symbol %, when used without qualification means:
• for solutions or suspensions of solids in liquids, percent weight-in-volume;
• for solutions of liquids in liquids, percent volume-in-volume;
• for mixtures of solids or semisolids, percent weight-in-weight; and
• for solutions of gases in liquids, percent weight-in-volume.

Special consideration in percentage calculation
In most instances, use of percentage concentrations in the manufacture and labeling of pharmaceutical preparations is restricted to instances in which the dose of the active therapeutic ingredient (ATI) is not specific.
For example, the ATIs in ointments, lotions, external solutions, and similar products may commonly be expressed in percent strength (e.g., a 1% hydrocortisone ointment).
However, in most dosage forms, such as tablets, capsules, injections, oral solutions, and syrups, among others, the amounts of ATIs are expressed in definitive units of measure, such as milligrams per capsule, milligrams per milliliter, or other terms.





Percentage
The term percent and its corresponding sign (%) mean ‘‘by the hundred’’ or ‘‘in a hundred,’’ and percentage means ‘‘rate per hundred’’; so 50 percent (or 50%) and a percentage of 50 are equivalent expressions.
A percent may also be expressed as a ratio, represented as a common or decimal fraction. For example, 50% means 50 parts in 100 of the same kind, and may be expressed as 50?100 or 0.50.
Percentage is an essential part of pharmaceutical calculations. The pharmacist encounters it frequently and uses it as a convenient means of expressing the concentration of an active or inactive material in a pharmaceutical preparation.

Percentage preparation
The percentage concentrations of active and inactive constituents in various types of pharmaceutical preparations are defined as follows by the United States Pharmacopeia:
• Percent weight-in-volume (w/v) expresses the number of grams of a constituent in 100 mL of solution or liquid preparation and is used regardless of whether water or another liquid is the solvent or vehicle. Expressed as: % w/v.
• Percent volume-in-volume (v/v) expresses the number of milliliters of a constituent in 100 mL of solution or liquid preparation. Expressed as: % v/v.
• Percent weight-in-weight (w/w) expresses the number of grams of a constituent in 100 g of solution or preparation. Expressed as: % w/w.

The term percent, or the symbol %, when used without qualification means:
• for solutions or suspensions of solids in liquids, percent weight-in-volume;
• for solutions of liquids in liquids, percent volume-in-volume;
• for mixtures of solids or semisolids, percent weight-in-weight; and
• for solutions of gases in liquids, percent weight-in-volume.

Special consideration in percentage calculation
In most instances, use of percentage concentrations in the manufacture and labeling of pharmaceutical preparations is restricted to instances in which the dose of the active therapeutic ingredient (ATI) is not specific.
For example, the ATIs in ointments, lotions, external solutions, and similar products may commonly be expressed in percent strength (e.g., a 1% hydrocortisone ointment).
However, in most dosage forms, such as tablets, capsules, injections, oral solutions, and syrups, among others, the amounts of ATIs are expressed in definitive units of measure, such as milligrams per capsule, milligrams per milliliter, or other terms.