Antihypertensive drug

The rationale underlying the treatment of chronic HTN concerns its association with atherosclerosis and the increased risk of stroke, heart failure, renal diseases, peripheral vascular disease, and coronary artery disease. Except in severe HTN, there is no rash to start drug Rx prior to lifestyle changes because the goals are long term. Factors in hypertension include decreases in vagal tone, increases in sympathetic tone, increased renin-angiotensin activity, and water retention. 

Strategies underlying drug Rx include reduction in blood volume, reduction in sympathetic one, reduction in vagal tone, and relaxation of vascular smooth muscle. Note that depending on the anti-HTN drug used, homeostatic mechanisms may lead to compensatory responses of salt and water retention and/or reflex tachycardia. 

CO—heart rate 1 Vagal tone Beta blockers, some Ca channel antagonists (CCBs) 

CO—contractile force T Sympathetic tone Beta blockers 

Peripheral resistance t Sympathetic tone Sympathoplegics, CCBs, direct-acting vasodilators, diuretics 

CO—contractile force t sympathetic tone Beta blockers 

Sodium nitrite or amyl nitrite can be used in cyanide poisoning. They promote formation of methemoglobin, which binds CN ions, forming cyanomethemoglobin. This prevents the inhibitory action of CN on complex IV of the electron transport chain. Cyanomethemoglobin is then reconverted to methemoglobin by treatment with sodium thiosulfate, forming the less toxic thiocyanate ion (SCN ). 

Arteriolar Ca -channei blockers, hydralazine, K -channel openers 

Orthostatic (postural) hypotension results from venular dilation (not arteriolar) and mainly results from a, blockade or decreased sympathetic tone. 

Thiazide and loop diuretics are commonly used in the management of hypertension. 

ANGIOTENSIN-CONVERTING INHIBITORS (ACEIs) AND ANGIOTENSIN-RECEPTOR BLOCKERS (ARBs) 

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Another quinazoline, prazosin (1040), is now a widely used antihypertensive drug, acting by vasodilation (77MI21300, B-81MI21301) its preparation is outlined in the patent literature (72NEP7206067). 

As we have had occasion to note more than a few times previously, the guanidine function forms the basis of a family of hypotensive agents active by reason of their activity as blockers of the peripheral sympathetic system. Condensation of tetra-hydroisoquinoline with the S-methyl ether of thiourea affords the antihypertensive drug debrisoquin (135). ... 

Anti hypertensive Drugs. Table 1 Common side effects of antihypertensive drugs... 

Lipoprotein Metabolism Antihypertensive Drugs Antiobesity Drugs... 

If 50% of Europeans with essential hypertension are affected by this disease because of an elevated secretion of endogenous ouabain, then there might be a chance to block its interaction at the cardiac glycoside binding site of Na+/K+-ATPase and thus lower blood pressure. This therapeutic approach seems to be successfiil. Recent studies provide evidence that the cardenolide analogue Rostafuroxin (PST 2238 Fig. 4) at very low concentrations can overcome the ouabain-induced tise of hypertension in experimental animals [6]. This compound has recently entered the phase I of clinical trials and is certainly a prototype of a new class of antihypertensive drugs. 

VMATs are irreversibly inhibited by the potent antihypertensive drug reserpine. The depressive effects of reserpine helped to formulate the original monoamine hypothesis of affective disorders. Reseipine also appears to interact with the transporters near the site of substrate recognition. Tetrabenazine, which is used in treatment of movement disorders, inhibits VMAT2 much more potently than VMAT1, consistent with the less hypotensive action of this agent. 

The NSAIDs prolong bleeding time and increase the effects of anticoagulants, lithium, cyclosporine, and the hydantoins. These dru may decrease the effects of diuretics or antihypertensive drug >. Long-term use of the NSAIDs with acetaminophen may increase the risk of renal impairment. 

Discuss the general drug actions, uses, adverse reactions, contraindications, precautions, and interactions of the antihypertensive drugs. 

Discuss important preadministration and ongoing assessment activities the nurse should perform on the patient taking an antihypertensive drug. 

In addition to these antihypertensive drugs, many antihypertensive combinations are available, such as Ser-Ap-Es, Timolide 10-25, Aldoril, and Lopressor (Table 42-2). Most combination antihypertensive drug are a combination of an antihypertensive and a diuretic. 

Many antihypertensive drug lower the blood pressure by dilating or increasing the size of the arterial blood vessels (vasodilatation). Vasodilatation creates an increase in the lumen (the space or opening within an arteiy) of the arterial blood vessels, which in turn increases the amount of space available for the blood to circulate Because blood volume (the amount of blood) remains relatively constant, an increase in the space in which the blood circulates (ie, the blood vessels) lowers the pressure of the fluid (measured as blood pressure) in the blood vessels. Although the method by which anti-hypertensive drug dilate blood vessels varies, the result... 

Another type of antihypertensive drug is the diuretic. The mechanism by which the diuretics reduce elevated blood pressure is unknown, but it is thought to be based, in part, on their ability to increase the excretion of sodium from the body. The actions and uses of diuretics are discussed in Chapter 46. 

Antihypertensives are used in the treatment of hypertension. Although many antihypertensive drugs are available, not all drag may work equally well in a given patient. In some instances, the primary care provider... 

Diaz oxide (Hyperstat IV) and nitroprusside (Nitropress) are examples of intravenous (IV) drugs that may be used to treat hypertensive emergencies. A hypertensive emergency is a case of extremely high blood pressure that does not respond to conventional antihypertensive drug therapy. 

When any antihypertensive drug is given, postural or orthostatic hypotension may be seen in some patients, especially early in therapy. Postural hypotension is the occurrence of dizziness and light-headedness when the individual rises suddenly from a lying or sitting position. Orthostatic hypotension occurs when the... 

Additional adverse reactions that may be seen when an antihypertensive drug is administered are listed in the Summary Drug Table Antihypertensive Drugs. For the adverse reactions that may be seen when a diuretic is used as an antihypertensive drug, see the Summary Drug Table Diuretics in Chapter 46. 

The hypotensive effects of most antihypertensive dru are increased when administered with diuretics and other antihypertensives. Many dnigp can interact with the antihypertensive drugs and decrease their effectiveness (eg, antidepressants, monoamine oxidase inhibitors, antihistamines, and sympathomimetic bronchodilators). When the ACE inhibitors are administered with the NSAIDs, their antihypertensive effect may be decreased. Absorption of the ACE inhibitors may be decreased when administered with the antacids. Administration of potassium-sparing diuretics or potassium supplements concurrently with the ACE inhibitors may cause hyperkalemia. When the angiotensin II receptor agonists are administered with... 

Risk for Deficient Fluid Volume related to administration of a diuretic as an antihypertensive drug (when appropriate)... 

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