Cardiac failure sympathomimetics

The answer is local anesthetic properties it can block the initiation or conduction of a nerve impulse. It is biotransformed by plasma esterases to inactive products. In addition, cocaine blocks the reuptake of norepinephrine. This action produces CNS stimulant effects including euphoria, excitement, and restlessness Peripherally, cocaine produces sympathomimetic effects including tachycardia and vasoconstriction. Death from acute overdose can be from respiratory depression or cardiac failure Cocaine is an ester of benzoic acid and is closely related to the structure of atropine. 

Intrinsic 3-sympathomimetic activity of some 3-blockers did not appear to prevent the onset of cardiac failure in hearts dependant upon sympathetic drive. It was suggested that 3-blockers with significant 3-sympathomimetic action, such as DCI, might be less likely to precipatate heart failure. The more depressant propranolol lacks 3-sympathomimetic activity. No difference was observed between DCI and propranolol when introduced during the sympathomimetic-dependant phase of experimental heart failure in guinea pigs. ... 

Cardiostimulation. By stimulating Pi-receptors, hence activation of ade-nylatcyclase (Ad-cyclase) and cAMP production, catecholamines augment all heart functions, including systolic force (positive inotropism), velocity of shortening (p. clinotropism), sinoatrial rate (p. chronotropism), conduction velocity (p. dromotropism), and excitability (p. bathmotropism). In pacemaker fibers, diastolic depolarization is hastened, so that the firing threshold for the action potential is reached sooner (positive chronotropic effect, B). The cardiostim-ulant effect of p-sympathomimetics such as epinephrine is exploited in the treatment of cardiac arrest Use of p-sympathomimetics in heart failure carries the risk of cardiac arrhythmias. 

Concomitant use with sympathomimetic drugs, p-adrenoceptor antagonists, calcium channel-entry blockers and other cardioactive drugs may result in bradyarrhythmias, bigemini, or tachyarrhythmias. Cardiac rhythm should be closely monitored and drug dosages carefully adjusted. Digoxin is mainly excreted by the kidneys and plasma levels should be closely monitored in patients with acute renal failure and in those whose renal function is compromised. 

Dobutamine Betai-selective agonist t increases cAMP synthesis Increases cardiac contractility, output Acute decompensated heart failure intermittent therapy in chronic failure reduces symptoms IV only duration a few minutes Toxicity Arrhythmias. Interactions Additive with other sympathomimetics... 

Dopamine Dopamine receptor agonist higher doses activate 13 and a adrenoceptors Increases renal blood flow higher doses increase cardiac force and blood pressure Acute decompensated heart failure shock IV only duration a few minutes Toxicity Arrhythmias Interactions Additive with sympathomimetics... 

Beta-blockers with intrinsic sympathomimetic (ISA) properties are not pure antagonists. These agents partially stimulate the beta-receptors as well. Theoretically, these agents are less likely to cause bradycardia and bronchospasm, increase lipids, decrease cardiac output, and cause peripheral vasoconstriction. However, these agents can still cause bronchospasm or exacerbate heart failure. 

Most of these sympathomimetic drugs tend to be reserved for acute emergencies, including cardiogenic shock, septic shock, in heart surgery and in cardiac infarction or cardiac arrest. Xamoterol is a partial agonist at -adrenoceptors, and is used in mild heart failure only (see P-Adrenoceptor agonists). 

Cocaine is a central nervous system stimulant that inhibits the peripheral re-uptake of catecholamines, leading to increased sympathomimetic activity [115]. Its abuse is associated with a variety of medical problems. These include acute myocardial infarction, cardiac arrhythmias, cerebrovascular accidents, hyperpyrexia and stimulated sympathetic activity, seizures and coma, obstetrical complications, intestinal ischemia, and a variety of psychiatric complications [114-117]. The most prominent renal complication of cocaine abuse is acute renal failure associated with rhabdomy-olysis. 

The Austrian pharmacologist Heribert Konzett (1912-2004) had discovered in 1940 isoprenaUne, which should become the prototype of p-selective sympathomimetics. Due to its bronchodilatory properties, but without causing hyper-tention, it was considered the drug of choice to treat asthmatic attacks. With almost equally strong effect on pj- and p2-receptors, it was of concern, that isoprenaline acts as a very potent cardiac stimulant. Further structural optimisation then led to more selective pj-sympathomimetics, like dobutamine, for the treatment of heart failure and cardiogenic shock, while selective p2-sympathomimetics were aimed at safer therapies of bronchial asthma. 

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