Alligation in Pharmaceutical Calculations is a method used in pharmacy for mixing solutions or components of different concentrations to achieve a desired concentration.
It’s useful in compounding and preparing pharmaceutical mixtures.
Alligation Medial:
This method calculates the average strength of a mixture based on the quantities and concentrations of the individual solutions.
Formula:
Where:
C1,C2,… = concentrations of the solutions.
Q1,Q2,… = quantities of the solutions.
Alligation Alternate:
This method is used to mix two solutions of known concentrations to achieve a desired concentration.
Steps:
Place the stronger and weaker concentrations on opposite sides of a grid.
Write the desired concentration in the middle.
Subtract the desired concentration from both the stronger and weaker concentrations (ignoring negative signs) to determine the parts of each solution.
Example:
To make 500 mL of a 10% solution using 15% and 5% solutions:
15 – 10 = 5 and 10 – 5 = 5
This means equal parts of the two solutions should be mixed.