Ibopamine in chronic congestive heart failure: hemodynamic and neurohumoral effects

Article Abstract:

The output of the heart is decreased in patients with congestive heart failure. While 60 percent of the blood or more may be expelled from the heart during a healthy heart beat, less than 30 percent might be expelled in a patient with serious heart failure. In addition, the resistance of the peripheral blood vessels is increased in heart failure, resulting in both a decrease in the blood flow through the muscles and organs, and an increase in the workload of the heart. A number of dopamine agonists have properties that may be useful in treating heart failure. Dopamine agonists are drugs that stimulate receptors for dopamine (DA) on various tissues, including heart muscle and peripheral blood vessels. Ibopamine is an unusual dopamine agonist in that, although it acts primarily on both the DA-1 and DA-2 receptors, it also acts on all four adrenoreceptors as well, alpha-1, alpha-2, beta-1, and beta-2. The action of any individual drug is determined by the relative degree of stimulation of the different receptors. Alpha receptors tend to constrict the peripheral blood vessels and beta receptors tend to relax and dilate them. Ibopamine is metabolized into its active form, epinine, by enzymes called esterases in the blood plasma; this active epinine causes an increase in the output of the heart and a relaxation of the blood vessels, improving blood flow. In addition, ibopamine decreases the amounts of aldosterone and renin in the blood; these hormones help regulate blood pressure and the retention of water in the body. Their reduction helps to further reduce the workload of the heart. Research on ibopamine suggests that long-term treatment does not result in tolerance. For some drugs, long-term treatment results in a decrease in the corresponding receptors, which results ultimately in decreased effectiveness of the drug. While the effectiveness of ibopamine does diminish somewhat over long-term use, this has been a consequence of the progression of the heart failure itself, and not the development of tolerance to the drug. (Consumer Summary produced by Reliance Medical Information, Inc.)

Dopamine, Dopamine agonists, Dopamine receptors, Adrenergic mechanisms

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Congestive heart failure in coronary artery disease

Article Abstract:

This review discusses congestive heart failure (CHF), a condition in which the heart becomes unable to pump enough blood for the body's needs, in patients with coronary artery disease (CAD), disease of the arteries that supply the heart with blood. CHF is the only cardiovascular disorder whose prevalence in the US is increasing. It is caused by hypertension (high blood pressure) and by CAD, which is likely to become the main cause of CHF in the future because antihypertensive therapy is increasingly effective. As patients with CAD receive better treatment and survive longer, CHF is becoming increasingly common among them. Twelve ways that CAD can cause CHF are presented in a table; most cases result from obstructive disease of the coronary arteries or from complications of myocardial infarction (heart attack). These complications include infarct expansion (dilatation and thinning of the infarcted area not due to necrosis) and extension (new foci of necrotic tissue near a previous infarct), as well as 'stunning' or 'hibernation' of the heart muscle (temporarily impaired function without cell death). CHF has traditionally been treated with diuretics, dilators, and digitalis, which relieve symptoms, but rarely prevent death from CHF. Recently acquired knowledge about the pathophysiology of CHF should prompt different approaches. Some of these include early treatment after infarction with drugs to limit infarct expansion, such as those that inhibit acetylcholinesterase (an enzyme involved in muscle contraction and vessel dilatation); clearing blocked arteries by thrombolytic (clot-dissolving) drugs or by surgery; and proper drug therapy for diastolic dysfunction of the left ventricle (beta-blockers, calcium channel blockers, and nitrates). Certain drugs, such as diltiazem or digitalis, that are commonly prescribed to treat CAD can cause CHF. The slow rate of progress in treating impairments of heart muscle function contrasts with the rapid advances in recent years in treating CAD and its complications. (Consumer Summary produced by Reliance Medical Information, Inc.)

Complications and side effects, Coronary heart disease

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Ibopamine in the treatment of heart failure

Article Abstract:

In congestive heart failure, the heart cannot keep up with the needs of the body and the constriction of peripheral blood vessels both decreases the flow of blood and increases the workload of the heart. For decades, the primary treatment has been digoxin, which stimulates the heart, or diuretics, which decrease the blood pressure and hence, the workload of the heart. Drugs that inhibit the alpha receptors for adrenalin, the alpha adrenergic antagonists, inhibit the constriction of peripheral blood vessels and can reduce the workload of the heart. Inhibitors of angiotensin-converting enzyme may be used to reduce blood pressure and the retention of water and sodium. New drugs are being introduced that may add to the choices available to the physician. Ibopamine is a drug that is likely to become important in treating congestive heart failure. The drug is similar to the naturally occurring substance dopamine, and acts primarily on the dopamine receptors. The drug, which is metabolized in the blood to its active form epinine, also stimulates all types of adrenoreceptors. The net effect is that ibopamine relaxes the peripheral blood vessels and increases the strength of the heart. Unlike many drugs of closely related structure, ibopamine also improves the flow of blood through the kidneys. Extensive studies have failed to identify any serious adverse cardiovascular effects of ibopamine. There have been no observed increases in the likelihood of abnormal heart beats among patients that have been treated with ibopamine. The results of studies indicate that ibopamine is safe and does not aggravate some of the conditions that may lead to death in the patient with heart failure. An important finding is that the effects of ibopamine are additive to the effects of the commonly used drugs digoxin and the diuretics. Therefore, it may be possible to improve the efficacy of treatment by using both drugs before heart failure progresses beyond its earliest stages. (Consumer Summary produced by Reliance Medical Information, Inc.)

Similar abstracts:

• Abstracts: Receptor function in heart failure. Clinical pharmacology of ibopamine. Cardiovascular pharmacology of adrenergic and dopaminergic receptors: therapeutic significance in congestive heart failure
• Abstracts: Coupling between the heart and arterial system in heart failure. Circulatory abnormalities and compensatory mechanisms in heart failure

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