A simple high-throughput enzymeimmunoassay for norethisterone (norethindrone)

Area of Science:

• Biochemistry
• Analytical Chemistry
• Immunology

Background:

• Accurate determination of norethisterone levels is crucial for pharmacokinetic and field studies.
• Existing enzymeimmunoassay (EIA) methods may require larger sample volumes or complex separation techniques.

Purpose of the Study:

• To develop a sensitive and high-throughput direct enzymeimmunoassay for determining norethisterone concentrations in small plasma volumes.
• To validate the developed assay against a established method.

Main Methods:

• A direct enzymeimmunoassay (EIA) was developed using a solid-phase antiserum against norethisterone coupled to magnetisable cellulose.
• Antibody-bound and free fractions were separated using a magnetic device.
• Norethisterone/horseradish peroxidase conjugate and o-phenylenediamine/hydrogen peroxide substrate were used for detection.

Main Results:

• The developed direct EIA demonstrated high sensitivity, suitable for 10 microliter plasma aliquots.
• The assay allowed for the processing of at least 100 samples per day.
• Results showed excellent agreement (r > 0.99) with a well-validated extraction-based EIA.

Conclusions:

• The direct EIA is a sensitive, high-throughput, and reliable method for norethisterone quantification.
• This assay is advantageous for processing large sample numbers in pharmacokinetic studies and field investigations.
• The simplified procedure enhances efficiency without compromising accuracy.