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[Digitalis poisoning, risk factors and digitalis intolerance]
Insights
Blood Digoxin levels in heart failure patients correlate with disease severity, not just dosage. Higher concentrations indicate more severe insufficiency and risk of digitalis intoxication.
Area of Science:
- Pharmacology
- Cardiology
- Clinical Chemistry
Context:
- Congestive heart failure (CHF) management often involves Digoxin.
- Accurate Digoxin monitoring is crucial for therapeutic efficacy and safety.
- Patient factors, including cardiac function, can influence drug pharmacokinetics.
Purpose:
- To investigate the relationship between blood Digoxin concentration and the stage of cardiac insufficiency in CHF patients.
- To determine the threshold for Digoxin toxicity in relation to cardiac function.
- To assess the correlation between Digoxin levels and clinical signs of digitalis intoxication.
Summary:
- Radioimmunoassay revealed that blood Digoxin concentration in CHF patients is influenced by both drug dosage and the severity of cardiac insufficiency.
- Higher Digoxin levels were observed in patients with more advanced stages of heart failure, even with equivalent daily doses.
- In 75% of patients exhibiting digitalis intoxication, Digoxin blood concentrations exceeded 2.5 ng/ml.
- Animal studies demonstrated a reduced toxic threshold for Strophantin in conditions mimicking acute cardiac events (myocardial infarction, pulmonary embolism, CHF).
Impact:
- Highlights the importance of considering cardiac insufficiency stage in Digoxin dosing and therapeutic drug monitoring.
- Provides a clinical threshold (2.5 ng/ml) for identifying potential Digoxin toxicity in CHF patients.
- Informs clinical practice by emphasizing individualized Digoxin management based on patient's cardiac status.
- Suggests that altered cardiac function in acute conditions may increase susceptibility to cardiac glycoside toxicity.
Abstract:
It was established by means of radioimmunoassay that the blood concentration of Digoxin in patients with congestive heart failure depends not only on the dose of the drug given, but also on the stage of cardiac insufficiency. With equal daily doses, higher Digoxin concentrations were observed in patients with more severe cardiac insufficiency. The analysis of the obtained data has demonstrated that in 75% of the patients with signs of digitalis intoxication the concentration of Digoxin in blood exceeded 2.5 ng/ml. In animal experiments it was established that a distinct reduction of the toxic threshold took place in rabbits with acute myocardial infarction, acute pulmonary embolism, congestive cardiac failure, this threshold being determined by the amount of intravenously injected Strophantin that causes persistent ventricular tachycardia.