Serum digoxin by radioimmunoassay

Area of Science:

• Cardiology
• Clinical Pharmacology
• Nephrology

Background:

• Digoxin is a critical medication for managing heart conditions.
• Accurate monitoring of serum digoxin levels is essential for therapeutic efficacy and safety.
• Renal function significantly impacts digoxin clearance and serum concentrations.

Purpose of the Study:

• To establish the relationship between digoxin dosage and serum levels.
• To identify serum digoxin concentration thresholds associated with toxicity.
• To evaluate the utility of serum digoxin monitoring in patients with impaired renal function.

Main Methods:

• Radioimmunoassay (RIA) technique was employed for serum digoxin quantification.
• Serum samples were collected from patients receiving varying daily oral digoxin doses (0.25 mg and 0.5 mg).
• Correlation between serum digoxin levels, urinary excretion, renal function, and electrocardiographic (ECG) findings of toxicity was assessed.

Main Results:

• Mean serum digoxin levels were 0.83 ± 0.06 ng/mL for 0.25 mg/day and 1.30 ± 0.14 ng/mL for 0.5 mg/day.
• Patients with ECG evidence of digoxin toxicity had a mean serum level of 2.81 ± 0.21 ng/mL.
• Higher serum digoxin levels were associated with impaired renal function and increased 24-hour urinary digoxin excretion.

Conclusions:

• Serum digoxin levels are dose-dependent and influenced by renal function.
• Monitoring serum digoxin is crucial, especially in patients with renal impairment, to prevent toxicity.
• The RIA method provides a specific, sensitive, and reproducible means for assessing serum digoxin levels, aiding in dose optimization.