Lecture 4: Altering Product Strength, Dilution, Strengthening, Alligation (9.30.24)

Dilution

Altering product strength

Decreases

If the quantity of diluent increases, what happens to the product strength?

Q2 x C2

Q1 x C1 =

Q1 and Q2

MUST be in the same units

Q

Total quantity of the component at that concentration (C)

C1 and C2

MUST be concentrations and MUST be in the same units

Stock solution

A concentrated solution of active (e.g. drug) or inactive (e.g. colorant) substance that is used by pharmacists as a convenience to prepare solutions of lesser concentration (a dilution)

DILUTION

Q1 x C1

STOCK

Q2 x C2

% w/w

Undiluted (concentrated acids)

% w/v

Diluted acids

Specific gravity or density

What about undiluted (concentrated) acids needs to be taken into consideration?

Increase

Quality of solute _____ in final product

Increases

If the quantity of solute increases, product strength _____

Stays the same

Adding weight of pure chemical to an existing product, quantity of the diluent _____

Additive

Admixing an existing product with a similar product of greater concentration, diluent of the two products are _____

Mass solute / total mass (or volume) mixture

C (w/w) =

Mass solute (final mixture)

Mass solute in existing product + mass solute to add =

Alligation

An arithmetic method of solving problems that involves the mixing of solutions or mixtures of solids of different percentage strengths

Alligation medial

A method to calculate the "weighted average" strength of a mixture of two or more substances of known quantity and concentration

Alligation alternate

A method to determine the quantities of ingredients of different strengths needed to make a mixture of a desired strength

Alligation alternate

Mix two stock solutions (solution A and B), of different concentrations, to achieve a formulation (solution C)

Intermediate (between) the two stock solutions

What MUST the concentration of the formulation be?

A

Higher concentration

B

Lower concentration

A > C > B

Numerically the three concentrations

x / y = c - b / a - c

Alligation alternate equation