Cardiac arrhythmias drugs causing

The side-effects of cardiac glycosides are mostly caused by electrophysiological/neuronal phenomena. Gastro-intestinal adverse reactions are probably triggered by effects on the central nervous system. Various types of cardiac arrhythmias are caused by the influence of the drugs on nodal tissues in the heart. The risk of arrhythmia is strongly enhanced by low plasma potassium concentrations. 

Alterations in the serum potassium level are hazardous because they can result in cardiac arrhythmias. Drugs that may cause hyperkalemia despite normal renal function include potassium itself, 13 blockers, digitalis glycosides, potassiumsparing diuretics, and fluoride. Drugs associated with hypokalemia include barium, 13 agonists, caffeine, theophylline, and thiazide and loop diuretics. 

Miscellaneous toxidties Visual impairment caused by retinal deposits has occurred with thioridazine at high doses, this drug may also cause severe conduction defects in the heart that result in fatal ventricular arrhythmias. Sertindole prolongs the QT interval of the ECG the underlying myocardial effect may lead to cardiac arrhythmias. Clozapine causes a small but important (1—2%) incidence of agranulocytosis and at high doses has caused seizures. 

Ca2+ is an important intracellular second messenger that controls cellular functions including muscle contraction in smooth and cardiac muscle. Ca2+ channel blockers inhibit depolarization-induced Ca2+ entry into muscle cells in the cardiovascular system causing a decrease in blood pressure, decreased cardiac contractility, and antiarrhythmic effects. Therefore, these drugs are used clinically to treat hypertension, myocardial ischemia, and cardiac arrhythmias. 

Optimal therapy of cardiac arrhythmias requires documentation, accurate diagnosis, and modification of precipitating causes, and if indicated, proper selection and use of antiarrhythmic drugs. These drugs are classified according to their effects on the action potential of cardiac cells and their presumed mechanism of action. 

Hypersensitivity to the drug or any other component of the product (cross-sensitivity between phenothiazines may occur) comatose or greatly depressed states caused by CNS depressants or from any other cause (phenothiazines, clozapine, loxapine, molindone, pimozide, haloperidol) coadministration with other drugs that prolong the QT interval and in patients with congenital long QT syndrome or history of cardiac arrhythmias (mesoridazine, thioridazine, pimozide, ziprasidone see Drug..Interactions). 

Do not administer saquinavir mesylate concurrently with drugs listed in the Drug Interactions section. Inhibition of CYP3A4 by saquinavir could result in elevated plasma concentrations of these drugs, potentially causing serious or life-threatening reactions such as cardiac arrhythmias or prolonged sedation. 

Fatalities Fatalities caused by severe hypotension, hypoglycemia, and cardiac arrhythmias have been reported, both by the IM and IV routes. Severe hypotension may result after a single dose. Limit administration of the drug to patients in whom P. carinil has been demonstrated. 

The acute effects of psychomotor stimulant overdoses are related to their CNS stimulant properties and may include euphoria, dizziness, tremor, irritability, and insomnia. At higher doses, convulsions and coma may ensue. These drugs are cardiac stimulants and may cause headache, palpitation, cardiac arrhythmias, anginal pain, and either hypotension or hypertension. Dextroamphetamine produces somewhat less cardiac stimulation. Chronic intoxication, in addition to these symptoms, commonly results in weight loss and a psychotic reaction that is often diagnosed as schizophrenia. 

Thus, diuretics that act on one portion of the nephron may produce much greater excretion of fluid and electrolytes than diuretics that act elsewhere. In addition, the practical efficacy of a drug for achieving a therapeutic end point (eg, increased cardiac contractility) may be limited by the drug s propensity to cause a toxic effect (eg, fatal cardiac arrhythmia) even if the drug could otherwise produce a greater therapeutic effect. 

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