Introduction Assay: Definition Calculation Potency: Definition Calculation Purity: Definition Calculation

2. Contents:-
•Introduction
•Assay:
Definition
Calculation
•Potency:
Definition
Calculation
•Purity:
Definition
Calculation

3. Introduction:
• Pharmaceutical industry is quality oriented
industry that requires high accuracy in while
producing drug hence the assay or potency or
purity of Drug sample is a key factor to confirm
the quality of the drug.
• Pharmaceutical industry producing life saving
drugs due to that it is important to understand
difference between assay potency and purity of
the drug.

4. Assay:
Definition:
An analytic procedure in laboratory for quantitative
assessing or measuring the presence or amount of a target
entity.
In the pharmaceutical industry, an assay is the main test for
any drug Substance / product.
As there is multiple tests for the drug product but the assay
is a test that gives proper information of drug content
percentage.

5. Assay:
Calculation:
Three different ways:
 Assay on as is basis,
 Assay on dried basis and
 Assay on anhydrous basis.

6. Assay Calculation:
Assay On As Is Basis:

7. Assay Calculation:
Assay On As Is Basis:

8. Assay Calculation:
Assay On Dry Basis:

9. Assay Calculation:
Assay On Dry Basis:

10. Assay Calculation:
Assay On Anhydrous Basis:

11. Assay Calculation:
Assay On Anhydrous Basis:

12. Potency:
Definition:
Potency is a measure of drug activity expressed in terms of
the amount required to produce an effect of given intensity.
A highly potent drug evokes a given response at low
concentrations, while a drug of lower potency evokes the
same response only at higher concentrations.

13. Potency Calculation:
Potency can be calculated by eliminating % of impurity,
heavy metal, sulfated ash, residual solvent and LOD or
Water content from the targeted drug.
For Example:
Potency = [100 – (moisture or LOD + residual solvents +
heavy metals + sulphated ash + impurities)]

14. Potency Calculation:
Suppose For Example,
A. % impurity present is = 0.3 %
B. Residual solvent is = 100 ppm or 0.01 %
C. Sulfated ash is = 0.2 %
D. Heavy Metal = 10 ppm or 0.001 %
E. LOD or Water content is = 2 % and
F. Target value of assay is = 100 %
So, by applying value in formula,
Potency = [100-( 0.3+0.01+0.2+0.001+2)]
= 100 – 2.511
= 97.489 %
• This will be the potency of the drug after eliminating all impurities.

15. Purity:
Definition:
Purity of the drug is determined by the area
normalization method.
It is directly calculated by Chromatographic system
and found on the chromatograms obtained from the
HPLC / GC system.

16. Purity Calculation:
% Purity = (Area of desired peak) X 100
Sum of area of all peaks

17. Purity Calculation:
Suppose,
Area of Drug peak in chromatogram = 1000,
Sum of area of all peaks = 500000
Then the calculated value will be as follow:
% Purity = 1000 X 100
500000
= 0.2%
= 100-0.2
= 99.8%
% Purity = (Area of desired peak) X 100
Sum of area of all peaks