A rapid semi quantitative capillary enzyme immunoassay for digoxin

Area of Science:

• Clinical Chemistry
• Biochemistry
• Immunology

Background:

• Digoxin is a critical medication for heart conditions, requiring precise therapeutic drug monitoring.
• Existing digoxin assays may be complex, time-consuming, or require specialized equipment.
• A need exists for a simpler, faster, and accessible method for digoxin quantification.

Purpose of the Study:

• To describe a novel, rapid, and sensitive enzyme immunoassay (EIA) for digoxin estimation.
• To validate the EIA method using clinical serum, plasma, and whole blood samples.
• To compare the performance of the EIA with established radioimmunoassay (RIA) techniques.

Main Methods:

• Development of a competitive enzyme immunoassay utilizing urease-conjugated antibodies and a digoxin-coated solid phase (glass capillary tube).
• Detection of bound enzyme activity via urea hydrolysis, indicated by a colorimetric pH change (bromocresol purple).
• Assay validation using 92 patient plasma samples and comparison with reference standards and RIA.

Main Results:

• The developed enzyme immunoassay (EIA) is rapid, with results available within 30 minutes.
• The method demonstrates high sensitivity and does not require specialized instrumentation or highly trained personnel.
• Excellent correlation was observed between the EIA results and those obtained by radioimmunoassay (RIA).

Conclusions:

• The described enzyme immunoassay provides a practical and reliable method for digoxin level determination.
• This assay is suitable for routine clinical laboratory use, offering a user-friendly alternative to traditional methods.
• The EIA facilitates timely therapeutic drug monitoring, potentially improving patient management and outcomes.