Bioassay is defined as the estimation of the potency of an active principle in a unit
quantity of preparation or detection and measurement of the concentration of the
substance in a preparation using biological methods (i.e. observation of pharmacological
effects on living tissues, microorganisms or immune cells or animal). Hence micro
bioassay, radioimmunoassay are also regarded as `bioassay'. Recently `biotechnology' has
also been considered for bioassay. Bioassay of the products like erythropoietin, hepatitis-
B vaccine etc. is being done through biotechnology.
Importance of Bioassay
Bioassays, as compared to other methods of assays (e.g. chemical or physical assay) are
less accurate, less elaborate, more laborious, more troublesome and more expensive.
However, bioassay is the only method of assay if (1) Active principle of drug is unknown
or cannot be isolated, e.g. insulin, posterior pituitary extract etc. (2) Chemical method is
either not available or if available, it is too complex and insensitive or requires higher
dose e.g. insulin, acetylcholine. (3) Chemical composition is not known, e.g. long acting
thyroid stimulants. (4) Chemical composition of drug differs but have the same
pharmacological action and vice-versa, e.g. cardiac glycosides, catecholamines etc.
Moreover, even if chemical methods are available and the results of bioassay conflict
with those of the chemical assay, the bioassay is relied upon and not the chemical assay,
since it is the assessment on living organism.
The purpose of bioassay is to ascertain the potency of a drug and hence it serves as the
quantitative part of any screening procedure (Research). Other purpose of bioassay is to
standardize the preparation so that each contains the uniform specified pharmacological
activity. In this way, it serves as a pointer in the Commercial Production of drugs when
chemical assays are not available or do not suffice. From the clinical point of view,
bioassay may help in the diagnosis of various conditions, e.g. gonadotrophins for
pregnancy.
Principle of Bioassay
The basic principle of bioassay is to compare the test substance with the International
Standard preparation of the same and to find out how much test substance is required to
produce the same biological effect, as produced by the standard. The standards are
internationally accepted samples of drugs maintained and recommended by the Expert
Committee of the Biological Standardization of W.H.O. They represent the fixed units of
activity (definite weight of preparation) for drugs. In India, standard drugs are maintained
in Government institutions like Central Drug Research Institute, Lucknow, Central Drug
Laboratory, Calcutta, etc.
The problem of biological variation must be minimized as far as possible. For that one
should keep uniform experimental conditions and assure the reproducibility of the
responses.
quantity of preparation or detection and measurement of the concentration of the
substance in a preparation using biological methods (i.e. observation of pharmacological
effects on living tissues, microorganisms or immune cells or animal). Hence micro
bioassay, radioimmunoassay are also regarded as `bioassay'. Recently `biotechnology' has
also been considered for bioassay. Bioassay of the products like erythropoietin, hepatitis-
B vaccine etc. is being done through biotechnology.
Importance of Bioassay
Bioassays, as compared to other methods of assays (e.g. chemical or physical assay) are
less accurate, less elaborate, more laborious, more troublesome and more expensive.
However, bioassay is the only method of assay if (1) Active principle of drug is unknown
or cannot be isolated, e.g. insulin, posterior pituitary extract etc. (2) Chemical method is
either not available or if available, it is too complex and insensitive or requires higher
dose e.g. insulin, acetylcholine. (3) Chemical composition is not known, e.g. long acting
thyroid stimulants. (4) Chemical composition of drug differs but have the same
pharmacological action and vice-versa, e.g. cardiac glycosides, catecholamines etc.
Moreover, even if chemical methods are available and the results of bioassay conflict
with those of the chemical assay, the bioassay is relied upon and not the chemical assay,
since it is the assessment on living organism.
The purpose of bioassay is to ascertain the potency of a drug and hence it serves as the
quantitative part of any screening procedure (Research). Other purpose of bioassay is to
standardize the preparation so that each contains the uniform specified pharmacological
activity. In this way, it serves as a pointer in the Commercial Production of drugs when
chemical assays are not available or do not suffice. From the clinical point of view,
bioassay may help in the diagnosis of various conditions, e.g. gonadotrophins for
pregnancy.
Principle of Bioassay
The basic principle of bioassay is to compare the test substance with the International
Standard preparation of the same and to find out how much test substance is required to
produce the same biological effect, as produced by the standard. The standards are
internationally accepted samples of drugs maintained and recommended by the Expert
Committee of the Biological Standardization of W.H.O. They represent the fixed units of
activity (definite weight of preparation) for drugs. In India, standard drugs are maintained
in Government institutions like Central Drug Research Institute, Lucknow, Central Drug
Laboratory, Calcutta, etc.
The problem of biological variation must be minimized as far as possible. For that one
should keep uniform experimental conditions and assure the reproducibility of the
responses.
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