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Clinical data | |
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Trade names | Norpace |
AHFS/Drugs.com | Monograph |
MedlinePlus | a682408 |
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Routes of administration | Oral, intravenous |
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Pharmacokinetic data | |
Bioavailability | High |
Protein binding | 50% to 65% (concentration-dependent) |
Metabolism | Hepatic (CYP3A4-mediated) |
Elimination half-life | 6.7 hours (range 4 to 10 hours) |
Excretion | Renal (80%) |
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CompTox Dashboard (EPA) | |
ECHA InfoCard | 100.021.010 |
Chemical and physical data | |
Formula | C21H29N3O |
Molar mass | 339.483 g·mol−1 |
3D model (JSmol) | |
Melting point | 94.5 to 95 °C (202.1 to 203.0 °F) |
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Disopyramide (INN, trade names Norpace and Rythmodan) is an antiarrhythmic medication used in the treatment of ventricular tachycardia. [2] It is a sodium channel blocker and is classified as a Class 1a anti-arrhythmic agent. [3] [4] Disopyramide has a negative inotropic effect on the ventricular myocardium, significantly decreasing the contractility. [5] [6] Disopyramide also has general anticholinergic effects which contribute to unwanted adverse effects. Disopyramide is available in both oral and intravenous forms. In 1972, when it was one of the only alternatives to quinidine, it was praised for being more potent and somewhat less toxic. [6] However, a 2012 review of antiarrhythmic drugs noted that disopyramide is among the most toxic agents, with a high burden of side effects and increased mortality (compared to placebo) when used to treat atrial fibrillation. [7]
Disopyramide's Class 1a activity is similar to that of quinidine in that it targets sodium channels to inhibit conduction. [4] [6] Disopyramide depresses the increase in sodium permeability of the cardiac myocyte during Phase 0 of the cardiac action potential, in turn decreasing the inward sodium current. This results in an increased threshold for excitation and a decreased upstroke velocity. [4] Disopyramide prolongs the PR interval by lengthening both the QRS and P wave duration. [6] This effect is particularly well suited in the treatment of ventricular tachycardia as it slows the action potential propagation through the atria to the ventricles. Disopyramide does not act as a blocking agent for beta or alpha adrenergic receptors, but does have a significant negative inotropic effect on the ventricular myocardium. [8] Anesthetized dogs treated with disopyramide (1 mg/kg) had reduced contractile force of 42%, and the decrease in contractile force from 1 mg/kg of disopyramide was roughly double the decrease seen with quinidine in much higher doses of 5, 10, or 15 mg/kg. [6]
Levites proposed a possible secondary mode of action for disopyramide, against reentrant arrhythmias after an ischemic insult. Disopyramide decreases the inhomogeneity between infarcted and normal myocardium refractory periods; in addition to lengthening the refractory period. [5] This decreases the chance of re-entry depolarization, because signals are more likely to encounter tissue in a refractory state which cannot be excited. [2] This provides a possible treatment for atrial and ventricular fibrillation, as it restores pacemaker control of the tissue to the SA and AV nodes. [9]
Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiac disease, occurring in 1:500 individuals in the general population. It is estimated that there are 600,000 individuals in the United States with hypertrophic cardiomyopathy. The most common variant of HCM presents with left ventricular (LV) intracavitary obstruction due to systolic anterior motion of the mitral valve, and mitral-septal contact, diagnosed readily with echocardiography. Pharmacologic treatment with negative inotropic drugs is first-line therapy. Beta-blockers are used first, and while they improve symptoms of shortness of breath, chest pain and exercise intolerance, they do not reduce resting LV intraventricular pressure gradients and often are inadequate to control symptoms. Many investigators and clinicians believe that disopyramide controlled release is the most potent agent available for reducing resting pressure gradients and improving symptoms. [10] [11] [12] [13] Disopyramide has been actively used for more than 30 years. [14] Disopyramide administration for obstructive HCM has a IB recommendation in the 2020 American Heart Association/American College of Cardiology Foundation guidelines for treatment of obstructive HCM. [15] A IB treatment recommendation indicates that a treatment is recommended, and may be useful, and beneficial.
Negative inotropes improve left ventricular (LV) obstruction by decreasing LV ejection acceleration and hydrodynamic forces on the mitral valve. Disopyramide's particular efficacy is due to its potent negative inotropic effects; in head-to-head comparison, it is more effective for gradient reduction than either beta-blocker or verapamil. [16] Disopyramide is most often administered with beta-blockade. When used in patients resistant to beta-blockade, disopyramide is effective in 60% of cases, reducing symptoms and gradient to the extent that invasive procedures such as surgical septal myectomy are not required. [13]
Disopyramide, despite its efficacy, has one main side effect that has limited its use in the US, though it has seen wider application in Canada, UK and Japan. Vagal blockade predictably causes dry mouth, and in men with prostatism, may cause urinary retention. Teichman et al. showed that pyridostigmine used in combination with disopyramide substantially alleviates vagolytic side effects without compromising antiarrhythmic efficacy. [17] This combination has also been shown to be effective and safe in obstructive HCM in a large cohort of patients. [13] Some clinicians prescribe pyridostigmine sustained release (marketed in the US as Mestinon Timespan) to every patient begun on disopyramide. [18] This combination increases acceptance of higher disopyramide dosing, important since there is a dose-response correlation in obstructive HCM, higher doses yielding lower gradients.
Another concern about disopyramide has been the hypothetical potential for inducing sudden death from its type 1 anti-arrhythmic effects. However, a multicenter registry and two recent cohort registries have largely reduced this concern, by showing sudden death rates lower than that observed from the disease itself. [10] [11] [13]
These concerns about the drug must be viewed from the clinical perspective that disopyramide is generally the last agent that is tried for patients before they are referred for invasive septal reduction with surgical septal myectomy (an open-heart operation) or alcohol septal ablation (a controlled heart attack). Both of these invasive procedures have risk of morbidity and mortality.
For selected patients, a trial of oral disopyramide is a reasonable approach before proceeding to invasive septal reduction. Patients who respond to disopyramide are continued on the drug. Those who continue to have disabling symptoms or who experience side effects are promptly referred for septal reduction. Using such a stepped strategy, investigators have reported that survival does not differ from that observed in the age-matched normal United States population. [13]
Disopyramide has the following side effects: [19]
Disopyramide has atropine-like anticholinergic effects. [20]
Additionally, disopyramide may enhance the hypoglycemic effect of gliclazide, insulin, and metformin.[ citation needed ]
Heart murmurs are unique heart sounds produced when blood flows across a heart valve or blood vessel. This occurs when turbulent blood flow creates a sound loud enough to hear with a stethoscope. The sound differs from normal heart sounds by their characteristics. For example, heart murmurs may have a distinct pitch, duration and timing. The major way health care providers examine the heart on physical exam is heart auscultation; another clinical technique is palpation, which can detect by touch when such turbulence causes the vibrations called cardiac thrill. A murmur is a sign found during the cardiac exam. Murmurs are of various types and are important in the detection of cardiac and valvular pathologies.
Hypertrophic cardiomyopathy is a condition in which muscle tissues of the heart become thickened without an obvious cause. The parts of the heart most commonly affected are the interventricular septum and the ventricles. This results in the heart being less able to pump blood effectively and also may cause electrical conduction problems. Specifically, within the bundle branches that conduct impulses through the interventricular septum and into the Purkinje fibers, as these are responsible for the depolarization of contractile cells of both ventricles.
An inotrope or inotropic is a drug or any substance that alters the force or energy of muscular contractions. Negatively inotropic agents weaken the force of muscular contractions. Positively inotropic agents increase the strength of muscular contraction.
Diltiazem, sold under the brand name Cardizem among others, is a nondihydropyridine calcium channel blocker medication used to treat high blood pressure, angina, and certain heart arrhythmias. It may also be used in hyperthyroidism if beta blockers cannot be used. It is taken by mouth or injection into a vein. When given by injection, effects typically begin within a few minutes and last a few hours.
Flecainide is a medication used to prevent and treat abnormally fast heart rates. This includes ventricular and supraventricular tachycardias. Its use is only recommended in those with dangerous arrhythmias or when significant symptoms cannot be managed with other treatments. Its use does not decrease a person's risk of death. It is taken by mouth or injection into a vein.
Pulsus paradoxus, also paradoxic pulse or paradoxical pulse, is an abnormally large decrease in stroke volume, systolic blood pressure and pulse wave amplitude during inspiration. Pulsus paradoxus is not related to pulse rate or heart rate, and it is not a paradoxical rise in systolic pressure. Normally, blood pressure drops less precipitously than 10 mmHg during inhalation. Pulsus paradoxus is a sign that is indicative of several conditions, most commonly pericardial effusion.
Tachycardia-induced cardiomyopathy (TIC) is a disease where prolonged tachycardia or arrhythmia causes an impairment of the myocardium, which can result in heart failure. People with TIC may have symptoms associated with heart failure and/or symptoms related to the tachycardia or arrhythmia. Though atrial fibrillation is the most common cause of TIC, several tachycardias and arrhythmias have been associated with the disease.
Restrictive cardiomyopathy (RCM) is a form of cardiomyopathy in which the walls of the heart are rigid. Thus the heart is restricted from stretching and filling with blood properly. It is the least common of the three original subtypes of cardiomyopathy: hypertrophic, dilated, and restrictive.
Acecainide is an antiarrhythmic drug. Chemically, it is the N-acetylated metabolite of procainamide. It is a Class III antiarrhythmic agent, whereas procainamide is a Class Ia antiarrhythmic drug. It is only partially as active as procainamide; when checking levels, both must be included in the final calculation.
Amrinone, also known as inamrinone, and sold as Inocor, is a pyridine phosphodiesterase 3 inhibitor. It is a drug that may improve the prognosis in patients with congestive heart failure. Amrinone has been shown to increase the contractions initiated in the heart by high-gain calcium induced calcium release (CICR). The positive inotropic effect of amrinone is mediated by the selective enhancement of high-gain CICR, which contributes to the contraction of myocytes by phosphorylation through cAMP dependent protein kinase A (PKA) and Ca2+ calmodulin kinase pathways.
Septal myectomy is a cardiac surgery treatment for hypertrophic cardiomyopathy (HCM). The open-heart surgery entails removing a portion of the septum that is obstructing the flow of blood from the left ventricle to the aorta.
Alcohol septal ablation (ASA) is a minimally invasive heart procedure to treat hypertrophic cardiomyopathy (HCM).
Noncompaction cardiomyopathy (NCC) is a rare congenital disease of heart muscle that affects both children and adults. It results from abnormal prenatal development of heart muscle.
The following outline is provided as an overview of and topical guide to cardiology, the branch of medicine dealing with disorders of the human heart. The field includes medical diagnosis and treatment of congenital heart defects, coronary artery disease, heart failure, valvular heart disease and electrophysiology. Physicians who specialize in cardiology are called cardiologists.
Sodium channel blockers are drugs which impair the conduction of sodium ions (Na+) through sodium channels.
Hypertrophic cardiomyopathy screening is an assessment and testing to detect hypertrophic cardiomyopathy (HCM).
AH-1058 is a lipophilic antiarrhythmic calcium channel blocker synthesized by the Pharmaceutical Research Laboratories of Ajinomoto Co., Inc in Kawasaki, Japan. It is derived from cyproheptadine, a compound with known antiserotonic, antihistaminic and calcium channel blocking properties. The IUPAC name of AH-1058 is: 4-(5H-dibenzo[a,d]cyclohepten-5-ylidene)-1-[E-3-(3-methoxy-2-nitro) phenyl-2-propenyl]piperidine hydrochloride.
Heart failure with preserved ejection fraction (HFpEF) is a form of heart failure in which the ejection fraction – the percentage of the volume of blood ejected from the left ventricle with each heartbeat divided by the volume of blood when the left ventricle is maximally filled – is normal, defined as greater than 50%; this may be measured by echocardiography or cardiac catheterization. Approximately half of people with heart failure have preserved ejection fraction, while the other half have a reduction in ejection fraction, called heart failure with reduced ejection fraction (HFrEF).
Istaroxime is an investigational drug under development for treatment of acute decompensated heart failure
Tissue Doppler echocardiography (TDE) is a medical ultrasound technology, specifically a form of echocardiography that measures the velocity of the heart muscle (myocardium) through the phases of one or more heartbeats by the Doppler effect of the reflected ultrasound. The technique is the same as for flow Doppler echocardiography measuring flow velocities. Tissue signals, however, have higher amplitude and lower velocities, and the signals are extracted by using different filter and gain settings. The terms tissue Doppler imaging (TDI) and tissue velocity imaging (TVI) are usually synonymous with TDE because echocardiography is the main use of tissue Doppler.
Compared with controls, patients treated with disopyramide had a significantly higher mortality, with a Peto odds ratio (i.e., pooled odds ratio) of 7.56.