Supplemental Glossary
By NSCG, Ltd.

Alpha Adrenergic Blocking Agents
Beta Adrenergic Blocking Agents
Bile acid binding agents
Calcium Channel Antagonists
Diuretics
Fibric acid derivatives
Inotropic Drugs
    - Digoxin (digitalis)
    - Catecholamines
    - Phosphodiesterase Inhibitors (amrinone & milrinone)
Niacin
Nitrates
Renin - Angiotensin Inhibitors (ACE inhibitors)
“Statins”
Vasodilators: Hydrazine


Alpha Adrenergic Blocking Agents by NSCG, Ltd.

Stimulation of alpha-1 (1) catecholamine receptors constricts blood vessels thereby increasing blood pressure, and so drugs that block these receptors are used to treat hypertension. Prazosin, terazosin and doxazosin are the most commonly prescribed selective 1 blockers. As urinary bladder outlet smooth muscle is also rich in 1 receptors, the use of these drugs relaxes these muscles, resulting in improved urinary flow, and better bladder emptying, especially in men.

Carvedilol is a unique drug that has both potent beta blockade and 1 blockade and has been used to treat angina as well as hypertension. A recent landmark study has proven this drug to reduce mortality risk in patients suffering heart failure. 2 receptors found in brain tissue, when stimulated result in relaxation of arterial wall smooth muscle and lowering of blood pressure. Drugs that stimulate brain 2 receptors included methyldopa, clonidine, guanabenz, and guanfacine. The main side effect of this class of drugs is sleepiness.

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Beta Adrenergic Blocking Agents by NSCG, Ltd.

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Adrenaline is the most commonly recognized member of a group of drugs (catecholamines) which have potent stimulatory effects throughout the body. Catecholamines stimulate the heart to beat harder and faster, increase the blood pressure, dilate bronchial tubes, dilate some blood vessels while contracting others, alter insulin secretion and sweat production, and contract muscles at the base of the urinary bladder. The varying effects of catecholamines occur because different types of chemical catecholamine receptors are present in different organs. Two distinct types of catecholamine receptors are recognized; alpha () and beta (), and each group has several sub-groups.

Drugs that interfere with catecholamines varying effects work by blocking either the alpha or beta receptor sites, or both, and some may selectively block only one receptor subtype.

A large number of beta blockers are presently clinically available. Some are highly subtype selective (1 or 2) while others are non-selective. Some are able to get into brain tissue - others not, and some actually partially stimulate the beta receptor while simultaneously blocking them. Whether selective or not, beta blockers lower blood pressure, reduce heart rate, reduce cardiac energy requirements, reduce and control certain heart rhythm disturbances, and have been definitively proven to reduce death rates after heart attacks.

Commonly used cardiac selective (1) blockers include Toprol® XL (metoprolol), atenolol, betaxolol, bisoprolol, and esmolol. Commonly used non-selective beta blockers include propranolol, nadolol, carvedilol, sotolol, and timolol. Labetolol has combined non-selective beta and alpha blocking activity, while acebutolol and pindolol are beta blockers with some beta receptor stimulatory effect.

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Bile acid binding agents by NSCG, Ltd.

Bile acids, the major components of bile that are produced in the liver, are created from cholesterol. Once secreted into the small intestine, the majority of bile acids are reabsorbed and re-utilized. Two presently available drugs bind to the bile acids within the small intestine and prevent their reabsorption (bile acid binding resins). The body must then make up for this bile acid loss by manufacturing more and thereby using up more of the bodies cholesterol supply. As these drugs are never absorbed into the body, but just remain inside the intestine, they have few systemic side effects. As with niacin, frequent abdominal bloating, cramping and diarrhea greatly limits the use of these drugs. Bile acid binding resins come as granules that must be thoroughly mixed with water or juices and are taken two to three times daily. These resins may also bind to other medications being taken and a so a carefully planned dosing regimen must be developed by the patient and physician.

Cholestyramine and colestipol are the two currently available compounds in this class of drugs.

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Calcium Channel Antagonists by NSCG, Ltd.

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The past 50 years have witnessed a growing appreciation of the importance of calcium in the control and regulation of many cellular functions, especially in the cardiovascular system. Cardiac muscle contraction, cardiac electrical activity, and blood vessel wall smooth muscle contraction are all calcium dependent processes. Calcium cannot simply diffuse across cellular membranes, but must pass through highly specific and regulated passage ways ("calcium channels"). Different tissues may have different calcium channels. The activity profile of the various calcium channel blocking drugs is related to the specific channel being blocked.

Verapamil and diltiazem, while chemically unrelated compounds, each block myocardial calcium channels, cardiac electrical system calcium channels, and arterial wall smooth muscle calcium channels. As such, these drugs are effective in lowering blood pressure, treating angina, and controlling certain heart rhythm disturbances. Their negative effects on heart muscle contractile strength means that heart failure can be aggravated by their use. Many formulations of these two compounds are currently available, but the only significant difference between formulations is their rates of absorption from the intestines. Those formulations that are slowly absorbed can be dosed once to twice daily, while those formulations more rapidly absorbed must be dosed three to four times daily. Intestinal and urinary bladder calcium channels are also affected by these two drugs and so constipation and the slowing of urine flow can be annoying side effects.

The dihydropyridine class of calcium channel antagonists (nifedipine, nisoldipine, nicardipine, felodipine, isradipine and amlodipine) predominantly only block blood vessel wall smooth muscle calcium channels and have their major utility in treating hypertension. The different members of this class may vary in their affinity for heart muscle and in their duration of action.

Beperidil is a unique calcium channel antagonist, as its complex effect on the cardiac tissues make it especially useful in treating angina, while its lack of effect on blood vessel wall smooth muscle calcium channels makes it a poor antihypertensive agent. Unlike all other available CCA, beperidil's effect on the cardiac electrical system may predispose to the occurrence of dangerous heart rhythm abnormalities.

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Inotropic Drugs by NSCG, Ltd.

Only a small handful of drugs are currently available for use which directly increase the contractile strength of the heart muscle (myocardium). These drugs can be separated into three classes depending on their direct modes of action, although, all three classes ultimately function by increasing the amount of calcium brought into or retained within the heart muscle cells.

Digoxin (digitalis) by NSCG, Ltd.
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Digoxin is the most commonly prescribed form of digitalis, a centuries -old drug, and is the only clinically available cardiac stimulant that can be taken by mouth. While digoxin is very well tolerated, and has been shown to greatly and persistently improve cardiac performance, even a small excess of digoxin can cause serious, and even fatal complications. Digoxin is also used to modify various heart rhythm abnormalities.

Catecholamines by NSCG, Ltd.
Catecholamines, another class of drugs known to directly stimulate myocardial contractile strength, occur naturally in the body.. Adrenaline (epinephrine) is produced by the adrenal gland, norepinephrine is predominantly present in nerve endings, and dopamine is found in brain tissue. Each of these chemicals, along with dobutamine, a close relative to dopamine, are used intravenously and are extremely potent cardiac stimulants.

Phosphodiesterase inhibitors by NSCG, Ltd.
Phosphodiesterase inhibitors (amrinone and milrinone) are non-catecholamine, intravenously administered cardiac stimulants. Each of these catecholamine and non-catecholamine drugs is used, short term only, alone or in combination, to improve cardiac function of a seriously failing heart.

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Diuretics by NSCG, Ltd.

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In a general sense, diuretics increase the elimination of sodium (salt) and water from the body via the kidney. Some of their antihypertensive effects are due to decreasing the circulating blood volume, thereby reducing the cardiac output, while additional effect is obtained by reducing the amount of bodily sodium. Diuretics are relatively inexpensive and are especially helpful in the primary treatment of very mild hypertension and also in adjunctive treatment in more severe forms of hypertension. The main side effects common to all diuretics are fluid and electrolyte imbalance (sodium, potassium, chloride, calcium and magnesium problems), and provocation of gout.. As long as kidney function is moderately well preserved, mild diuretics can by used (hydrochlorothiazide, chlorothiazide, triamterene, midamore, spironolactone). When kidney function is impaired, more potent diuretics may be needed ( furosemide, bumetadine, torsemide, ethacrynic acid, metolazone).

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Fibric acid derivatives by NSCG, Ltd.

Only one class of drugs is currently available that specifically lowers severely elevated blood triglyceride levels, fibric acid derivatives. These drugs increase the metabolic breakdown of triglyceride containing lipoproteins (VLDL particles). Although generally very well tolerated, some patients may develop abdominal discomfort and gallstone disease may be aggravated.

The most commonly used fibric acid derivatives presently prescribed are gemfibrizol and fenofibrate. Clofibrate, while still available, is used much less due to its known association with gallstone formation.

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Niacin by NSCG, Ltd.

Nicotinic acid (niacin) is one of the B-complex vitamins, which in high doses, lowers the rate of cholesterol synthesis. Additionally, niacin slows HDL-cholesterol degradation and triglyceride secretion more than the statins, thereby elevating HDL-cholesterol and reducing triglyceride levels, while also lowering LDL-cholesterol. While niacin may sound like a perfect cholesterol-lowering drug, its frequency of minor but very poorly tolerated side effects greatly limits its usefulness. Intense flushing sensations, nausea and bloating are the most common patient complaints, and starting on a very low dose and slowly titrating to a higher, effective dose can sometimes prevent these. As with statin drugs, liver function tests must be monitored. Patients with gout should probably avoid niacin.

Many non-prescription, short and long acting formulation of niacin are available, although several sustained release, prescription-only versions, purporting to be better tolerated, are also available.

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Nitrates by NSCG, Ltd.

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Nitrates form a group of drugs that rapidly and predictably relax the smooth muscle of blood vessel walls causing significant dilatation of both veins and arteries. Whether due to reduced blood return to the heart via venous dilatation or reduced blood pressure from arterial dilatation, cardiac performance is improved while cardiac energy requirements are reduced by nitrates. Via a complex mechanism, the body easily builds up an insensitivity to nitrate effectiveness, and for this reason, nitrate free period must be built into any dosing regimen. The predominant limiting side effect of all nitrate formulations is a pounding headache.

Nitroglycerine is the most well known nitrate, is remarkably effective, rapidly acting, but even more rapidly metabolized. As it is immediately inactivated if swallowed, it must be absorbed directly through the oral mucosa (lining of the mouth),, absorbed through the skin via a patch or paste, or given intravenously.

Isosorbide mononitrate or isosorbide dinitrate, nitrates which are much more slowly metabolized than nitroglycerine, are taken by mouth, and can be dosed once or twice daily.

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Renin - Angiotensin Inhibitors (ACE inhibitors) by NSCG, Ltd.

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Angiotensin II is one of the most potent naturally occurring constrictors of arteries in the body and is intimately involved in blood pressure regulation. The body manufactures angiotensin II by a series of chemical steps, one of the first of which is the creation of a precursor chemical, angiotensin I. This step requires the action of an enzyme - Renin, which is manufactured by the kidneys. Angiotensin I is then altered by a converting enzyme, that is predominantly locate in the lungs, into angiotensin II. Any drug that interferes with the production or activity of angiotensin II will lower blood pressure.

All beta blockers reduce the production of renin by the kidneys and thus secondarily reduce angiotensin production.

Angiotensin converting enzyme inhibitors (ACE inhibitors) prevent the conversion of angiotensin I to its active form, angiotensin II. ACE inhibitors are remarkably effective antihypertensive drugs and they have also been shown to reduce mortality after heart attacks and to reduce heart enlargement after heart attacks. The major differences between the various marketed ACE inhibitors are their duration of action and their routes of elimination from the body. The major side effects shared by all ACE inhibitors include a dry, irritative cough, elevation of blood potassium levels, decreased sense of taste, and these drugs are specifically contraindicated if the arteries to both kidneys are significantly blocked. The more commonly prescribed ACE inhibitors include: benazapril, captopril, enalapril, fosinopril, lisinopril, moexipril, quinapril, ramipril and trandolapril.

Drugs that block the effect of angiotensin II on its arterial wall smooth muscle receptor (ARB drugs) similarly reduce blood pressure and are effective in the control of symptoms of heart failure. These drugs share nearly all of the side effects of ACE inhibitors but do not appear to cause a cough. The most commonly prescribed drugs in this class include: Atacand® (candesartan), irbesartan, losartan, and valsartan.

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“Statins&148; by NSCG, Ltd.

Today, the most frequently prescribed class of cholesterol lowering drugs, the HMG-CoA reductase inhibitors, a.k.a. “statins,” act by inhibiting an enzyme which plays an important role in cholesterol synthesis. By in large, the statins are the easiest of the cholesterol lowering drugs to use as their response rate is highly predictable and their side-effect rate is low. Occasional muscle aches or nausea are the most common reasons for stopping these drugs, but severe muscle or liver inflammation can occur and therefore these drugs must be closely monitored.

While all presently available statins are closely chemically related, the different members of this group may vary significantly in cholesterol lowering power and price. Some of the most commonly used statins include atorvastatin, lovastatin, cerivastatin, pravastatin, fluvastatin, and simvastatin.

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Vasodilators: Hydrazine by NSCG, Ltd.

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Hydralazine is the only presently used drug in this class. It is a potent drug that acts directly to relax the smooth muscle cells in the walls of arteries, causing arterial dilatation and a brisk reduction in blood pressure. Successful use of this drug usually requires aggressive dosing and because of the drugs rapid metabolism, it must be given three to four times daily. Fluid retention is commonplace as is tachycardia. As many as 20% of patients taking hydralazine chronically develop a lupus syndrome.

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