Quinidine Sulfate 200 MG Oral Tablet
Generic Name: QUINIDINE SULFATE
Brand Name: Quinidine Sulfate
- Substance Name(s):
- QUINIDINE SULFATE
WARNINGS
Mortality In many trials of antiarrhythmic therapy for non-life-threatening arrhythmias, active antiarrhythmic therapy has resulted in increased mortality; the risk of active therapy is probably greatest in patients with structural heart disease. In the case of quinidine used to prevent or defer recurrence of atrial flutter/fibrillation, the best available data come from a meta-analysis described under CLINICAL PHARMACOLOGY/Clinical Effects above. In the patients studied in the trials there analyzed, the mortality associated with the use of quinidine was more than three times as great as the mortality associated with the use of placebo. Another meta-analysis, also described under CLINICAL PHARMACOLOGY/Clinical Effects , showed that in patients with various non-life-threatening ventricular arrhythmias, the mortality associated with the use of quinidine was consistently greater than that associated with the use of any of a variety of alternative antiarrhythmics. Proarrhythmic effects Like many other drugs (including all other class IA antiarrhythmics), quinidine prolongs the QT interval, and this can lead to a life-threatening ventricular arrhythmia (see ). The risk of is increased by bradycardia, hypokalemia, hypomagnesemia, hypocalcemia, or high serum levels of quinidine, but it may appear in the absence of any of these risk factors. The best predictor of this arrhythmia appears to be the length of the QT interval, and quinidine should be used with extreme care in patients who have preexisting long-QT syndromes, who have histories of of any cause, or who have previously responded to quinidine (or other drugs that prolong ventricular repolarization) with marked lengthening of the QT interval. Estimation of the incidence of in patients with therapeutic levels of quinidine is not possible from the available data. C torsades de pointes, OVERDOSAGE torsades C torsades de pointes C torsades Other ventricular arrhythmias that have been reported with quinidine include frequent extrasystoles, ventricular tachycardia, ventricular flutter, and ventricular fibrillation. Paradoxical increase in ventricular rate in atrial flutter/fibrillation When quinidine is administered to patients with atrial flutter/fibrillation, the desired pharmacologic reversion to sinus rhythm may (rarely) be preceded by a slowing of the atrial rate with a consequent increase in the rate of beats conducted to the ventricles. The resulting ventricular rate may be very high (greater than 200 beats per minute) and poorly tolerated. This hazard may be decreased if partial atrioventricular block is achieved prior to initiation of quinidine therapy, using conduction-reducing drugs such as digitalis, verapamil, diltiazem, or a ß-receptor blocking agent. Exacerbated bradycardia in sick sinus syndrome In patients with the sick sinus syndrome, quinidine has been associated with marked sinus node depression and bradycardia. Pharmacokinetic considerations Renal or hepatic dysfunction causes the elimination of quinidine to be slowed, while congestive heart failure causes a reduction in quinidine’s apparent volume of distribution. Any of these conditions can lead to quinidine toxicity if dosage is not appropriately reduced. In addition, interactions with coadministered drugs can alter the serum concentration and activity of quinidine, leading either to toxicity or to lack of efficacy if the dose of quinidine is not appropriately modified. (See ) PRECAUTIONS/Drug Interactions . Vagolysis Because quinidine opposes the atrial and A-V nodal effects of vagal stimulation, physical or pharmacological vagal maneuvers undertaken to terminate paroxysmal supraventricular tachycardia may be ineffective in patients receiving quinidine.
OVERDOSAGE
Overdoses with various oral formulations of quinidine have been well described. Death has been described after a 5-gram ingestion by a toddler, while an adolescent was reported to survive after ingesting 8 grams of quinidine. The most important ill effects of acute quinidine overdoses are ventricular arrhythmias and hypotension. Other signs and symptoms of overdose may include vomiting, diarrhea, tinnitus, high-frequency hearing loss, vertigo, blurred vision, diplopia, photophobia, headache, confusion, and delirium. Arrhythmias Serum quinidine levels can be conveniently assayed and monitored, but the electrocardiographic QT interval is a better predictor of quinidine-induced ventricular arrhythmias. C The necessary treatment of hemodynamically unstable polymorphic ventricular tachycardia (including ) is withdrawal of treatment with quinidine and either immediate cardioversion or, if a cardiac pacemaker is in place or immediately available, immediate overdrive pacing. After pacing or cardioversion, further management must be guided by the length of the QT interval. torsades de pointes C Quinidine-associated ventricular tachyarrhythmias with normal underlying QT intervals have not been adequately studied. Because of the theoretical possibility of QT-prolonging effects that might be additive to those of quinidine, other antiarrhythmics with Class I (disopyramide, procainamide) or Class III activities should (if possible) be avoided. Similarly, although the use of bretylium in quinidine overdose has not been reported, it is reasonable to expect that the α-blocking properties of bretylium might be additive to those of quinidine, resulting in problematic hypotension. C If the post-cardioversion QT interval is prolonged, then the pre-cardioversion polymorphic ventricular tachyarrhythmia was (by definition) In this case, lidocaine and bretylium are unlikely to be of value, and other Class I antiarrhythmics (disopyramide, procainamide) are likely to exacerbate the situation. Factors contributing to QT prolongation (especially hypokalemia, hypomagnesemia, and hypocalcemia) should be sought out and (if possible) aggressively corrected. Prevention of recurrent may require sustained overdrive pacing or the cautious administration of isoproterenol (30 to 150 ng/kg/min). C torsades de pointes. C torsades Hypotension Quinidine-induced hypotension that is not due to an arrhythmia is likely to be a consequence of quinidine-related α-blockade and vasorelaxation. Simple repletion of central volume (Trendelenburg positioning, saline infusion) may be sufficient therapy; other interventions reported to have been beneficial in this setting are those that increase peripheral vascular resistance, including α-agonist catecholamines (norepinephrine, metaraminol) and the Military Anti-Shock Trousers. Treatment To obtain up-to-date information about the treatment of overdose, a good resource is your certified Regional Poison-Control Center. Telephone numbers of certified poison-control centers are listed in the In managing overdose, consider the possibilities of multiple-drug overdoses, drug-drug interactions, and unusual drug kinetics in your patient. Physicians’ Desk Reference (PDR). Accelerated removal Adequate studies of orally-administered activated charcoal in human overdoses of quinidine have not been reported, but there are animal data showing significant enhancement of systemic elimination following this intervention, and there is at least one human case report in which the elimination half-life of quinidine in the serum was apparently shortened by repeated gastric lavage. Activated charcoal should be avoided if an ileus is present; the conventional dose is 1 gram/kg, administered every 2 to 6 hours as a slurry with 8 mL/kg of tap water. Although renal elimination of quinidine might theoretically be accelerated by maneuvers to acidify the urine, such maneuvers are potentially hazardous and of no demonstrated benefit. Quinidine is not usefully removed from the circulation by dialysis. Following quinidine overdose, drugs that delay elimination of quinidine (cimetidine, carbonic-anhydrase inhibitors, thiazide diuretics) should be withdrawn unless absolutely required.
DESCRIPTION
Quinidine is an antimalarial schizonticide and an antiarrhythmic agent with class 1A activity; it is the -isomer of quinine, and its molecular weight is 324.43. d Quinidine sulfate is the sulfate salt of quinidine; its chemical name is cinchonan-9-ol, 6’-methoxy-, (9 )-, sulfate(2:1) dihydrate; its structural formula is: S Its molecular formula is: C H N O •H SO •2H O; and its molecular weight is 782.96, of which 82.9% is quinidine base. 40 48 4 4 2 4 2 Quinidine sulfate occurs as fine needle-like, white crystals, frequently cohering in masses, or fine, white powder. It is odorless, has a very bitter taste, and darkens on exposure to light. It is slightly soluble in water, soluble in alcohol and in chloroform, and insoluble in ether. Each tablet, for oral administration, contains 200 mg and 300 mg of quinidine sulfate (equivalent to 166 mg or 249 mg of quinidine base). In addition, each tablet contains the following inactive ingredients: calcium stearate, microcrystalline cellulose, sodium starch glycolate and starch (corn). Quinidine Sulfate Structural Formula
HOW SUPPLIED
NDC:68151-1991-0 in a PACKAGE of 1 TABLETS
INDICATIONS AND USAGE
Conversion of atrial fibrillation/flutter In patients with symptomatic atrial fibrillation/flutter whose symptoms are not adequately controlled by measures that reduce the rate of ventricular response, quinidine sulfate is indicated as a means of restoring normal sinus rhythm. If this use of quinidine sulfate does not restore sinus rhythm within a reasonable time (see ), then quinidine sulfate should be discontinued. DOSAGE AND ADMINISTRATION Reduction of frequency of relapse into atrial fibrillation/flutter Chronic therapy with quinidine sulfate is indicated for some patients at high risk of symptomatic atrial fibrillation/flutter, generally patients who have had previous episodes of atrial fibrillation/flutter that were so frequent and poorly tolerated as to outweigh, in the judgment of the physician and the patient, the risks of prophylactic therapy with quinidine sulfate. The increased risk of death should specifically be considered. Quinidine sulfate should be used only after alternative measures ( use of other drugs to control the ventricular rate) have been found to be inadequate. e.g., In patients with histories of frequent symptomatic episodes of atrial fibrillation/flutter, the goal of therapy should be an increase in the average time between episodes. In most patients, the tachyarrhythmia during therapy, and a single recurrence should not be interpreted as therapeutic failure. will recur Suppression of ventricular arrhythmias Quinidine sulfate is also indicated for the suppression of recurrent documented ventricular arrhythmias, such as sustained ventricular tachycardia, that in the judgment of the physician are life-threatening. Because of the proarrhythmic effects of quinidine, its use with ventricular arrhythmias of lesser severity is generally not recommended, and treatment of patients with asymptomatic ventricular premature contractions should be avoided. Where possible, therapy should be guided by the results of programmed electrical stimulation and/or Holter monitoring with exercise. Antiarrhythmic drugs (including quinidine sulfate) have not been shown to enhance survival in patients with ventricular arrhythmias. Treatment of malaria Quinidine sulfate is also indicated in the treatment of life-threatening malaria. Plasmodium falciparum
DOSAGE AND ADMINISTRATION
Treatment of P. falciparum malaria Quinidine sulfate tablets are used in one of the approved regimens for the treatment of life-threatening malaria. The central component of the regimen is Quinidine Gluconate Injection, and the regimen is described in the package insert of Quinidine Gluconate Injection. P. falciparum Conversion of atrial fibrillation/flutter to sinus rhythm Especially in patients with known structural heart disease or other risk factors for toxicity, initiation or dose-adjustment of treatment with quinidine sulfate should generally be performed in a setting where facilities and personnel for monitoring and resuscitation are continuously available. Patients with symptomatic atrial fibrillation/flutter should be treated with quinidine sulfate only after ventricular rate control ( with digitalis or ß-blockers) has failed to provide satisfactory control of symptoms. e.g., Adequate trials have not identified an optimal regimen of quinidine sulfate for conversion of atrial fibrillation/flutter to sinus rhythm. In one reported regimen, the patient first receives two tablets (400 mg; 332 mg of quinidine base) of quinidine sulfate every six hours. If this regimen has not resulted in conversion after 4 or 5 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 QT 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 sulfate is discontinued, and other means of conversion ( direct-current cardioversion) are considered. C e.g., Reduction of frequency of release into atrial fibrillation/flutter In a patient with a history of frequent symptomatic episodes of atrial fibrillation/flutter, the goal of therapy with quinidine sulfate should be an increase in the average time between episodes. In most patients, the tachyarrhythmia during therapy with quinidine sulfate, and a single recurrence should not be interpreted as therapeutic failure. will recur Especially in patients with known structural heart disease or other risk factors for toxicity, initiation or dose-adjustment of treatment with quinidine sulfate should generally be performed in a setting where facilities and personnel for monitoring and resuscitation are continuously available. Monitoring should be continued for two or three days after initiation of the regimen on which the patient will be discharged. Therapy with quinidine sulfate should be begun with 200 mg (equivalent to 166 mg of quinidine base) every six 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 QT 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. C Suppression of ventricular arrhythmias Dosing regimens for the use of quinidine sulfate in suppressing life-threatening ventricular arrhythmias have not been adequately studied. Described regimens have generally been similar to the regimen described just above for the prophylaxis of symptomatic atrial fibrillation/flutter. Where possible, therapy should be guided by the results of programmed electrical stimulation and/or Holter monitoring with exercise.