What is the Difference Between Content Uniformity and Assay

The main difference between content uniformity and assay is that content uniformity is a test in which evaluation units are done individually whereas assay is a test in which multiple units are done simultaneously. Furthermore, the evaluation procedure of content uniformity tests is the same for all units.

Content uniformity and assay are two types of analytical tests used in the determination of the quality of pharmaceutical products.

Key Areas Covered

1. What is Content Uniformity
     – Definition, Procedure, Importance
2. What is an Assay
     – Definition, Procedure, Importance
3. What are the Similarities Between Content Uniformity and Assay
     – Outline of Common Features
4. What is the Difference Between Content Uniformity and Assay
     – Comparison of Key Differences

Key Terms

Analytical Tests, Assay, Content Uniformity, Qualitative, Sample Processing

What is Content Uniformity

Content uniformity is a test used to evaluate the equality of the dosage of a pharmaceutical drug. The method is applicable for tablets which contain the active ingredient in less than 10 mg or 10% W/W. Also, this test is not applicable to multivitamin drugs or trace elements. During this test, 10 tablets can be taken randomly from a sample in order to determine the amount of active pharmaceutical ingredient in them.

Figure 1: Pharmaceutical Drugs

Then, the mean value can be calculated. The mean value of an active pharmaceutical ingredient has to be within 85-115% or 75-125% of the average value. After that, the same test is performed for another 20 tablets if 2-3 tablets are out of range. The sample is not considered as fulfilling the required dose if the total sample of 30 tablets has more than three tablets that are out of the range of 85 to 115% or more than three tablets that are out of the range of 75 to 125%.

What is an Assay

An assay is another analytic procedure used to characterize the main functional component of a sample. Also, an assay can be an either quantitative and/or qualitative test. Moreover, the original application of an assay is to determine the purity of metals. However, assays are widely used in pharmaceutical industry to characterize the active pharmaceutical ingredient. In addition, assays are widely used in other areas including laboratory medicine, pharmacology, environmental biology, immunology, molecular biology, and biochemistry.

Figure 2: A Colorimetric Assay

Furthermore, the main functional component tested in an assay is known as the analyte or the target component. Here, the target of an assay can vary from a pharmaceutical drug, a metal, biological molecules such as proteins, DNA, RNA, antibodies, etc., or even a cell of a living organism. However, the main characteristic feature of an assay is that all the exogenous reactants or reagents, as well as the experimental conditions of the assay, should be kept constant while only the target of the assay varies either in quantity or quality.

Similarities Between Content Uniformity and Assay

• Content uniformity and assay are two types of analytical tests used in the determination of the quality of a pharmaceutical product.
• In both tests, the same procedure is followed for each sample unit.
• Also, both tests are performed for the active ingredient.

Difference Between Content Uniformity and Assay

Definition

Content uniformity refers to a pharmaceutical analysis technique used to ensure that each dosage form includes the equivalent amount of active pharmaceutical ingredient or drug substance while assay refers to an investigative procedure for qualitatively assessing or quantitatively measuring the presence, amount, or functional activity of a target entity. Thus, this is the main difference between content uniformity and assay.

Type of Target

Also, the types of targets are a major difference between content uniformity and assay. Pharmaceutical drugs are the target for content uniformity test while DNA, RNA, protein, carbohydrates, antibodies, metal ions, pharmaceutical drugs, etc. can be the target for an assay. 

Sample Processing

Each unit is evaluated individually in content uniformity test while all the multiple units are processed simultaneously in an assay. Hence, this is another difference between content uniformity and assay.

Type of Test

Furthermore, one other difference between content uniformity and assay is that the content uniformity is a type of qualitative test while an assay can be either qualitative or quantitative.

Importance

Moreover, content uniformity test is important to evaluate the uniformity of the dosage of a pharmaceutical drug while an assay helps to characterize the main functional component of a sample.

Conclusion

Content uniformity is a test that evaluates the equality of the dosage of a pharmaceutical drug. Therefore, it is a type of qualitative assay. Significantly, each unit of this test is processed individually. In comparison, an assay is a type of analytical test that helps to determine both quality and quantity of the main functional component of a sample. Here, all the units are processed simultaneously. Therefore, the main difference between content uniformity and assay is the method of processing samples.

References:

1. Patil, Mahesh. “Content Uniformity Test.” Chrominfo, 1 Jan. 1970, Available Here.
2. 2. Dutta, Siddhartha. “Assays, Types of Assays, Principle and Prerequisites of Assays and Bi…” LinkedIn SlideShare, 5 Aug. 2017, Available Here.

Image Courtesy:

1. “colors-colours-health-medicine-143654” (Pexels License) via Pexels
2. “Resazurin assay for mammalian cell viability” By – TwoOars – I (- TwoOars) created this work entirely by myself. (CC BY-SA 3.0) via Commons Wikimedia