Radioimmunoassay allows for the measurement of wide range of materials of clinical and biological importance. This technique has a significant impact on medical diagnosis due to the ease with which the tests can be carried out, while assuring precision, specificity and sensitivity.
The radioimmunoassay technique, as the name implies, achieves sensitivity through the use of radionuclides and specificity that is uniquely associated with immunochemical reactions. It can detect substance from a range of Nano gram(ng) to Pico gram(pg).
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Application of Radioimmunoassay
1. M.Pharm 1st Semester Seminar
Subject : Modern Analytical Technique
Topic : Application Of Radioimmunoassay (RIA)
By:
Anindya Jana
M.Pharm 1st Year (Pharmaceutics)
Regd. No. : 1661611006
2. • Radioimmunoassay (RIA) is a sensitive
method for measuring very small amounts
of antigen, antibody, or antigen-antibody
complex in the blood.
• The radioimmunoassay technique, as the
name implies, achieves sensitivity through
the use of radionuclides and specificity that
is uniquely associated with
immunochemical reaction.
Introduction
3. Before RIA Many methods like TLC, GLC, Spectrofluorometry &
ordinary radiolabelling assay were employed for the analysis of
‘drug’ in the plasma but they have many disadvantage like:
Less specific.
Less sensitive.
Involment of the processes of extraction, purification &
concentration of the specimen under investigation.
Heat treatment of the specimen resulted invariably in
degradation and destruction of the substances.
Many process involved make the analysis rigorous and
unnecessarily sluggish.
4. History
• Developed in 1959 by Rosalyn Yalow &
Soloman Berson for measurement of insulin
in plasma.
• It represented the first time that hormone
level in the blood could be detected by an in
vitro assay.
• In 1977 Yalow received the Nobel Prize for her
& Berson’s development of RIA.
5. Radioimmunoassay can detect
substance like :
• Hormones
• Vitamins
• Serum Protein
• Drugs
• Infective Agent
Sensitivity of
Radioimmunoassay :
It can detect substance from a
range of Nano gram(ng) to Pico
gram(pg) concentration.
Qualitative as well as Quantitative analysis.
7. Application Of Radioimmunoassay
1)Detection of Narcotic Drugs
Heroin & Morphine can be detected in hair with the use of
Radioimmunoassay (RIA).
In a research hair samples obtained from morphine treated mice and
heroin user contained Nano gram levels of drug per milligram of hair .
The result of the hair analysis for all subject admitting the use of
heroin were positive where as the result of only 30% of thin layer
chromatographic urine analysis of these same subjects were positive.
8. 2) Radioimmunoassay of Hydromorphone &
Hydrocodone in Human Plasma
Hydromorphone & Hydrocodone belongs to morphine group of drugs
and are used in combination with antitussive & analgesic antipyretic
mixture.
The RIA method is capable of estimating the above drug within a range
of 2.5 to 20 ng/mL using standard 100 µl plasma sample.
RIA is carried out using morphine-6-antiserum & dihydromorphine.
Free drug is separated from the bound drug using dextran coated
charcoal & an aliquot of the supinate containing the antiserum bound
drug is subsequently counted for radioactivity.
9. 3) Radioimmunoassay of Flunisolide in human plasma
Flunisolide is a fast-acting corticoid designed for the treatment of allergic
rhinitis, asthma, and other allied respiratory disorders in humans. As the
quantum of drug delivered by inhalation (i.e., the usual route of
administration of the drug), is invariably small, the plasma-levels attained
can also be fairly small. Hence, there is a need for a sensitive method of
plasma concentration evaluation which is satisfied by radioimmunoassay.
4) Measurement of Ferritin
Serum ferritin levels are indicative of iron stores present in a patient. Levels
are useful in differentiating true iron deficiency from the body's failure to
utilize these stores.
10. 5) Detection of Digoxin
This allows direct measurement of serum digoxin levels quickly and accurately.
It is important to rule out Digi toxicity quickly and accurately. We are also able
to filter out Digi bind to let the physician know how much the level has dropped
after Digi bind has been administered.
6) Thyroid Testing
This is used to determine the patient's thyroid status and to follow patients
after iodine-131 therapy to see if the dose was indeed effective.
11. Disadvantages of Radioimmunoassay
• Prolonged reaction time (in days) as a consequence highly diluted reagent
is used.
• Radioisotopes are costly.
• Possible health hazards due to handling of radioisotopes.
• Limited assay range.
• Lack of direct linear relationship between analyte concentration and
signal response.
• Difficult of automation.
• Lengthy counting time.
12. Reference
Annett M. Baumgartner, Peter F. Jones, Warner A. Baumgartner & Charles T. Black. Review on
Radioimmunoassay of hair for determining opiate-abuse histories – The journal of nuclear medicine; 1979 P.748
- 752
Ibrahim A. Darvish. Review on Immunoassay methods and their application in pharmaceutical analysis –
International journal of biomedical science; 2006 P.217 - 220
Yalow R, Berson S - Immunoassay of endogenous plasma insulin in man;1960 P.39 – 115
Pharmaceutical Drug Analysis by Ashutosh Kar; 2005 P.485 - 504