I. CONVERSION OF ATRIAL FIBRILLATION/FLUTTER TO SINUS RHYTHM:
ESPECIALLY IN PATIENTS WITH KNOWN STRUCTURAL HEART DISEASE OR OTHER RISK FACTORS FOR TOXICITY. PATIENTS WITH SYMPTOMATIC ATRIAL FIBRILLATION/FLUTTER SHOULD BE TREATED WITH QUINIDINE GLUCONATE ONLY AFTER VENTRICULAR RATE CONTROL (E.G., WITH DIGITALIS OR BETA BLOCKERS) HAS FAILED TO PROVIDE SATISFACTORY CONTROL OF SYMPTOMS.
ADEQUATE TRIALS HAVE NOT IDENTIFIED AN OPTIMAL REGIMEN OF QUINIDINE GLUCONATE FOR CONVERSION OF ATRIAL FIBRILLATION/FLUTTER TO SINUS RHYTHM. IN ONE REPORTED REGIMEN, THE PATIENT FIRST RECEIVES TWO TABLETS (648 MG; 403 MG OF QUINIDINE BASE) OF QUINIDINE GLUCONATE EVERY EIGHT HOURS. IF THIS REGIMEN HAS NOT RESULTED IN CONVERSION AFTER 3 OR 4 DOSES, THEN THE DOSE IS CAUTIOUSLY INCREASED. IF, AT ANY POINT DURING ADMINISTRATION, THE QRS COMPLEX WIDENS TO 130% OF ITS PRE-TREATMENT DURATION; THE QTC INTERVAL WIDENS TO 130% OF ITS PRE-TREATMENT DURATION AND IS THEN LONGER THAN 500 MS; P WAVES DISAPPEAR; OR THE PATIENT DEVELOPS SIGNIFICANT TACHYCARDIA, SYMPTOMATIC BRADYCARDIA, OR HYPOTENSION, THEN QUINIDINE GLUCONATE IS DISCONTINUED, AND OTHER MEANS OF CONVERSION (E.G., DIRECT-CURRENT CARDIOVERSION) ARE CONSIDERED.
ii. REDUCTION IN THE FREQUENCY OF RELAPSE INTO ATRIAL FIBRILLATION/FLUTTER
THERAPY WITH QUINIDINE GLUCONATE SHOULD BEGIN WITH ONE TABLET (324 MG; 202 MG OF QUINIDINE BASE) EVERY EIGHT OR TWELVE HOURS. IF THIS REGIMEN IS WELL TOLERATED, IF THE SERUM QUINIDINE LEVEL IS STILL WELL WITHIN THE LABORATORY'S THERAPEUTIC RANGE, AND IF THE AVERAGE TIME BETWEEN ARRHYTHMIC EPISODES HAS NOT BEEN SATISFACTORILY INCREASED, THEN THE DOSE MAY BE CAUTIOUSLY RAISED. THE TOTAL DAILY DOSAGE SHOULD BE REDUCED IF THE QRS COMPLEX WIDENS TO 130% OF ITS PRE-TREATMENT DURATION; THE QTC INTERVAL WIDENS TO 130% OF ITS PRE-TREATMENT DURATION AND IS THEN LONGER THAN 500 MS; P WAVES DISAPPEAR; OR THE PATIENT DEVELOPS SIGNIFICANT TACHYCARDIA, SYMPTOMATIC BRADYCARDIA, OR HYPOTENSION.
Iii. SUPPRESSION OF LIFE-THREATENING VENTRICULAR ARRHYTHMIAS (ITS USE WITH VENTRICULAR ARRHYTHMIAS OF LESSER SEVERITY IS GENERALLY NOT RECOMMENDED):
DOSING REGIMENS FOR THIS IS SIMILAR TO THE SYMPTOMATIC ATRIAL FIBRILLATION/FLUTTER TREATMENT. WHERE POSSIBLE, THERAPY SHOULD BE GUIDED BY THE RESULTS OF PROGRAMMED ELECTRICAL STIMULATION AND/OR HOLTER MONITORING WITH EXERCISE.