Lecture 3: Percentage Strength, Ratio Strength, Concentrations, and Other Methods of Potency (9.23.24)

Percent (%)

Parts in 100

% (w/v)

Grams per 100 mL (any liquid) (assumes the solution preparation has specific gravity = 1) =

% (v/v)

Milliliters per 100 mL (any liquid) =

% (w/w)

Grams per 100 g (any preparation) =

1% (w/w)

1 g / 100 g = 10 mg / 1 g = 10 mg / g =

1% (w/v)

1 g / 100 mL = 1 g / dL = 10 mg / 1 mL = 10 mg / mL

%w/v

Solution or suspensions of solid in liquid

%v/v

Solution of liquid in liquid

%w/w

Mixture of solids, semisolids

%w/v

Solution of gas in liquid

Ratio

What does precent strength indicate?

Ratio strength

Alternative way to indicate concentration parts of ingredient: total parts

Mg% (milligram percent)

Mg per 100 mL

Ppm (parts per million)

Parts per 1 million

Ppb (parts per billion)

parts per 1 billion

Potency

Expression of drug activity in terms of concentration of the amount of a given drug required to produce a defined effect

Biologic drugs

Any drug produced from a biological source

Units

The expression of potency for biologic drugs

USP unit

Potency according to US Pharmacopeia standard

I.U (international unit)

Potency according to International Pharmacopeia standard

Tissue culture infectious dose, TCID50

Quantity of virus that infects 50% of exposed cultures

Flocculating unit, Lf unit

Quantity of antitoxin that can precipitate 1 unit of toxin

U-100

100 units/mL =

U-500

500 units/mL =

NO RELATION

A USP unit for one drug has _____ to a USP unit for another drug

Amount of Active Pharmaceutical Ingredient / Total Quantity (Q)

Concentration (C) =

Units of Activity / Total Weight or Volume

(Specifically for "units") Concentration =

n solute (grams) / m solute (mole)

Molecular weight of solute (g/mol) =