Vasodilators, specific agents

Currently, a number of beta blockers are used clinically the selection of a specific agent depends on factors such as cardioselectivity, duration of action (half-life), and several other ancillary properties of each drug.110 Certain beta blockers, for instance, produce added effects such as mild peripheral vasodilation or stabilization of cardiac membranes that can be beneficial in treating certain cardiovascular condi-... 

Other bothersome side effects are related to specific agents. Niacin, for instance, is often associated with cutaneous vasodilation and a sensation of warmth when doses are administered, but administering an extended-release form of this drug can reduce these sensations.71 99 Some fairly serious problems, including liver dysfunction, gallstones, and pancreatitis, can occur with many antihyperlipidemia drugs, but the incidence of these side effects is rare. Cardiovascular problems such as arrhythmias, blood dyscrasias, and angioneurotic syndrome may also occur with fibric acids. 

A number of compounds have been reported which have coronary dilator properties or other activities which have culminated in their clinical trial for use in angina pectoris. Lidoflazlne (IV) is claimed to be a specific, long acting coronary vasodilator. This agent appears to reduce coronary vascular resistance in dogs and causes an Increase in coronary venous pO. ... 

Tonic- an agent used to increase energy and vigor in a specific part of the body. Vasodilator- an agent used to dilate the blood vessels. 

Dipiridamol is known as a coronary vasodilating agent, although it also possesses specific antiaggregant activity. It is used for preventing thrombo-formation after cardiac valve replacement in combination with warfarin. The mechanism of dipiridamoTs antiaggregant action is not completely clear, and its efficacy is questionable. 

Because of the wide range of specificity of sulpiride and other substituted benzamides, it is possible to administer these drugs intravenously and differentiate renal or mesenteric vasodilation produced by DA from non-specific vasodilating agents such as bradykinin (18,Jj)). However, we disagree with Shepperson et al 20) who estimated the relative potency of less specific antagonists by the intravenous route. 

Examples of specific drugs used in the treatment of chronic heart failure include digitalis glycosides (e.g., digoxin, positive inotropic agent), diuretics (hydrochlortiazide and furosemide), and vasodilators (nitrates such as nitroglycerin, ACE inhibitors, such as captopril, and hydralazine). 

Four categories of calcium channel blockers can be defined based on their chemical structures and actions diphenylalkylamines, benzothiazepines, dihydropyridines, and bepridil. Both diphenylalkylamines (verapamil) and benzothiazepines (diltiazem) exhibit effects on both cardiac and vascular tissue. With specificity for the heart tissue, these two types of calcium channel blockers can slow conduction through the AV node and are useful in treating arrhythmias. The dihydropyridines (nifedipine is the prototypical agent) are more potent peripheral and coronary artery vasodilators. They do not affect cardiac conduction, but can dilate coronary arteries. They are particularly useful as antianginal agents. Bepridil is unique in that it blocks both fast sodium channels and calcium channels in the heart. All calcium channel blockers, except nimodipine and bepridil, are effective in treating HTN. 

Inhibitors of a heart-specific subtype (type III) phosphodiesterase, which are positive inotropics, may be used in the short-term treatment of severe congestive cardiac failure, e.g. amrinone, enoximone and milrinone. However, developments of oral formulations of drugs of this type have been halted by the results of the PROMISE trial (Prospective Randomised Milrinone Survival Evaluation trial) which documented a paradoxical increase in mortality in class IV heart failure patients randomised to receive milrinone. However, some benzimidazole derivatives with class III phosphodiesterase inhibitor actions seem to be beneficial in heart failure. The agent vesnarinone is an orally active compound that may act as a class III phosphodiesterase inhibitor but appears to be a vasodilator with multiple mechanisms. See HEART FAUURE TREATMENT INOTROPIC AGENTS. 

Nitrates and similar vasodilators are used particularly to treat angina attacks, but are not specific coronary vasodilators. They work by redistributing blood flow in the periphery and so beneficially reduce load on the heart. There is a perceived need for cerebral vasodilators that may have a potential use in certain neurological disorders (dementia), and some agents are thought to be active here, e.g. nimodipine and co-dergocrine mesylate. 

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