medigoxin and Tachycardia--Paroxysmal

Topics: Adolescent; Adult; Aged; Amiodarone; Benzofurans; Child; Digitalis; Digoxin; Female; Follow-Up Studies; Humans; Male; Medigoxin; Middle Aged; Plants, Medicinal; Plants, Toxic; Tachycardia, Paroxysmal

In clinical Arrhythmology it is often necessary to associate digitalis and antiarrhythmic agents. This calls for study of possible interaction between the employed drugs. We found a statistically significant correlation between digitalis and amiodarone plasma level in patients on long term treatment with both drugs. A statistically significant linear correlation between plasma amiodarone level and digoxin (0.25 mg/day) or beta-methyldigoxin (0.20 mg/day) was documented in 33 patients. 23 patients had been treated with these drugs for paraxysmal reciprocating supraventricular tachycardia since an average of 52 months (computerized follow-up). (Amiodarone average weekly dose was 1078 +/- 168 mg after a loading dose of 12 gm given over one month). 10 patients were on chronic treatment with higher weekly doses of amiodarone (average dose 2380 +/- 731 mg per week). Thyroid function tests (T4; T3; T3UP; TSH; rT3) were checked in every patients. Further studies are warranted to understand the mechanism of the interaction between amiodarone and digitalis. As a clinical implication we point out that amiodarone-digoxin (or betamethyldigoxin) interaction in our patients has neither resulted in over-therapeutic plasma level nor in signs of digitalis toxicity.

Topics: Aged; Amiodarone; Arrhythmias, Cardiac; Benzofurans; Digoxin; Drug Interactions; Female; Humans; Male; Medigoxin; Middle Aged; Tachycardia, Paroxysmal

The digitalis derivative beta-methyldigoxin has been shown to be quickly and well absorbed from the gut and, in hemodynamic studies, to start acting rapidly after intravenous administration. However, when tested on 6 patients suffering from paroxysmal reciprocating atrioventricular tachycardia, or having an accessory pathway who might develop this disorder, there was no effect on induced tachycardias or on AV conduction during rapid atrial pacing or the extrastimulus test. One of the 6 patients showed some increase in refractoriness of conduction through the AV node within 25 min after the injection. Beta-methyldigoxin does not appear to be a satisfactory alternative to other effective agents available for the prompt correction of paroxysmal reciprocating atrioventricular tachycardia.

Topics: Adolescent; Adult; Cardiac Pacing, Artificial; Digoxin; Electrocardiography; Electrophysiology; Heart Conduction System; Humans; Male; Medigoxin; Middle Aged; Tachycardia, Paroxysmal; Wolff-Parkinson-White Syndrome