Quantal vs Graded Bioassay: Understand the Difference with Quiz and Flashcards

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Questions and Answers

What is the primary difference between direct and indirect bioassays?

Direct bioassays measure the pharmacological activity of a drug, while indirect bioassays measure the chemical structure. (correct)

Direct bioassays are more precise, while indirect bioassays are less precise.

Direct bioassays are used for chemical assays, while indirect bioassays are used for bioassays.

Direct bioassays are based on quantitative responses, while indirect bioassays are based on qualititative responses.

When is chemical assay preferred over bioassay?

When the drug is sensitive to low doses.

When the active principle of the drug is not known.

When the chemical structure of the drug is fully known. (correct)

When the biological activity of the drug cannot be defined by a chemical assay.

What is the purpose of bioassay in the standardization of drugs obtained from natural sources?

To isolate the active principle of the drug.

To determine the pharmacological activity of the drug.

To determine the chemical structure of the drug.

To compare the strength of the drug from various sources. (correct)

What is the purpose of comparing a test substance with the International Standard preparation?

To standardize the drug. Signup and view all the answers

Why is bioassay used to measure the pharmacological activity of peptide hormones?

Because peptide hormones cannot be purified. Signup and view all the answers

What is the advantage of bioassay over chemical assay in certain situations?

Bioassay can measure the pharmacological activity of a drug when the chemical structure is unknown. Signup and view all the answers

What is the primary objective of bioassay?

To determine the potency of a test substance Signup and view all the answers

What is the characteristic of a quantal bioassay?

An all-or-none response is observed Signup and view all the answers

What is the purpose of using a standard preparation in bioassay?

To provide a reference point for comparison Signup and view all the answers

What is the acceptable limit of accuracy in bioassay?

± 20% of true value Signup and view all the answers

What is the characteristic of a graded bioassay?

A graded response is observed Signup and view all the answers

What is the purpose of minimizing biological variation in bioassay?

To reduce the error in the measurement Signup and view all the answers

What is the primary role of pharmacists?

To serve as a source of therapeutic substances and provide information about their use and actions Signup and view all the answers

What has evolved over time in the concept of drug quality?

Simple checks of the final product Signup and view all the answers

What is one of the responsibilities of pharmacists?

To ensure the quality of a drug Signup and view all the answers

What is a key aspect of drug quality assurance?

Ensuring the stability of a drug Signup and view all the answers

What is a type of test used to evaluate the quality of a drug?

All of the above Signup and view all the answers

What is the goal of pharmaceutical assays?

To ensure the quality of a drug Signup and view all the answers

Study Notes

Types of Bioassays

Direct assays
Indirect assays:
- Based on quantitative responses (Graded)
- Based on quantal responses (“all or none”; Quantal)

Comparison of Chemical and Bioassay

Bioassay:
- Less precise
- More time-consuming
- Active constituent and structure not known
- More sensitive
Chemical Assay:
- More precise
- Less time-consuming
- Active constituent and structure fully known
- Less sensitive

Indications of Bioassay

Chemical method is not available or is too complex
Insensitive to low doses (e.g., Histamine)
Active principle cannot be isolated (e.g., insulin)
To measure the pharmacological activity of new or chemically undefined substances
Biological activity of drug cannot be defined by a chemical assay (e.g., Cis- and Trans- form of methyl phenidate)
To compare the strength of a drug obtained from various sources due to different compositions
Biological standardization of drugs obtained from natural sources

Principles of Bioassay

Compare the test substance with the International Standard preparation
Determine how much test substance is required to produce the same biological effect
Activity assayed should be the activity of interest
Standard and test sample should have similar pharmacological effects and mode of action
Minimize biological variation by keeping experimental conditions constant

Quantal Bioassay

All or none response in all individuals (e.g., Digitalis induced cardiac arrest in guinea pigs)
Not precise
Employed for: Comparison of LD50 and ED50

Graded Bioassay

As the dose increases, there is an equivalent rise in response
Potency is estimated by comparing test sample responses with the standard response curve
Example: Acetylcholine producing contraction of smooth muscle of frog Rectus abdominis

Accuracy Limits of Bioassay

Accuracy improves the efficiency of bioassay for pharmaceutical biological products
An accuracy within ± 20% of true value is good; within ± 10% is excellent

Introduction to Concepts in Pharmaceutical Assays and Determination

Primary role of pharmacists is to serve as a source of therapeutic substances and provide information about their use and actions
Responsibilities of pharmacists include:
- Assuring high-quality drugs in terms of chemical identity, purity, potency, stability, efficacy, safety, and acceptability

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Description

Learn about the bioassay technique used to compare the activity of a test substance to a standard substance. Understand the importance of similar pharmacological effects and mode of action. Discover how to minimize biological variation in experiments.