Antihypertensive Agents

By: Sami Barghshoon, BioFiles v7 n5, 2012, 5–20

BioFiles Volume 7, Number 5 – Pharmaceutical Drugs and Drug Candidates

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Angiotensin-Converting Enzyme (ACE) Inhibitors

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Agents that inhibit angiontensin-converting enzymes (ACE) and angiotensin II formation are essential to cardiovascular medicine.1 These inhibitors are used not only to treat essential hypertension and complications associated with it, but also to prevent cardiovascular, cerebrovascular, and renal complications.2,3

The first oral ACE inhibitor therapeutic was developed in the 1970s,4 and was soon followed by other ACE inhibitors with more attractive pharmacodynamic effects.

Millions of people use ACE inhibitors on a daily basis to manage hypertension. In the U.S., roughly 163 million prescriptions were filled in 2009, making this class of therapeutics the country’s fourth most widely prescribed medicine.5

The U.S. Food and Drug Administration (FDA) has approved 10 ACE inhibitors for the treatment of hypertension and there are 15 ACE inhibitors approved worldwide.

Sigma® Life Science offers you all 15 approved ACE inhibitors at competitive prices. We strive to provide you with the highest quality of approved therapeutics available. Look no further than Sigma Life Science for precision and control over your research experiments.

For more information and a complete list of small molecules and related products, visit sigma.com/therapeutics.

 

ACE Inhibitors References

  1. Gradman et al. 2010. American society of hypertension writing group. Combination therapy in hypertension. J Am Soc Hyperten 4:42–50.
  2. Ferguson et al. 1977. A specific orally active inhibitor of angiotensin-converting enzyme in man. Lancet 1:775–8.
  3. Re, RN. 2001. The clinical implication of tissue renin angiotensin systems. Curr Opin Cardiol 16:317–327.
  4. Ondetti et al. 1977. Design of specific inhibitors of angiotensin-converting enzyme: new class of orally active antihypertensive agents. Science 196:441–4.
  5. Consumer Reports. 2011. Using ACE Inhibitors to treat high blood pressure and heart disease. http://consumerreportshealth.org

 

Angiotensin II Receptor Blockers (ARBs)

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Hypertension can result from excessive activity of the renin-angiotensin-aldosterone system (RAAS) and this overactivity can injure critical organs such as the heart and blood vessels.1

In the 1990s, angiotensin II receptor blockers (ARBs) became commercially available to block the activity of RAAS.2

Unlike ACE inhibitors which prevent angiotensin I conversion to II, ARBs bind to the angiotensin II AT1 receptor, blocking the cellular actions triggered by angiotension II.3

Over the past two decades, studies in the pressure in animals and humans.4

The pharmacological differences among ARBs are how they exert their effects. Some ARBs compete with angiotensin II in a concentration-dependent manner for AT1 receptor binding while others irreversibly bind to the receptor.5

At Sigma Life Science, you will find six approved therapeutics in this target class. We strive to provide you with a comprehensive selection of approved therapeutics so you don’t have to spend a lot of time and effort to find them.

Visit sigma.com/therapeutics for a listing of all approved drugs and drug candidates.

 

ARBs References

  1. Savoia C, Schiffrin EL. 2007. Vascular inflammation in hypertension and diabetes: molecular mechanisms and therapeutic interventions. Clin Sci 112:375–384.
  2. Ferrario, CM. 2006. Role of angiotensin II in cardiovascular disease therapeutic implications of more than a century of research. J Renin Angiotensin Aldosterone Syst 7:3–14.
  3. Oparil, S. 2000. Newly emerging pharmacologic differences in angiotensin II receptor blockers. Am J Hypertens 13:18S–24S.
  4. Addison et al. 2011. Angiotensin receptor blockers: Pharmacology, efficacy, and safety. J Clin Hypertens 13:677–86.
  5. Munger, MA. 2011. Use of angiotensin receptor blockers in cardiovascular protection: current evidence and future directions. Pharmacy & Therapeutics 36:22-40.

 

α1-Adrenoreceptor Blockers

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α1-Antagonists (α-blockers) selectively block post-synaptic α1-adrenoreceptors and prevent catecholamine-induced constriction of arteries and venous vascular beds, thereby lowering blood pressure.1

However, α-blockers administered over time increase an individual's extracellular fluid and plasma volumes.2 This expansion typically manifests as weight gain and an attenuation of blood pressure. Therefore, these therapeutics are contraindicated in persons with heart failure because of their ability to expand extracellular and plasma volumes.3

One therapeutic strategy to counter the induced expansion is the administration of α1-adrenoreceptor antagonists with diuretics such as chlorthalidone or hydrochlorothiazide.4 The diurectics mitigate the expansion of the extracellular and plasma volumes, providing significant incremental reductions in blood pressure. Diuretics available from Sigma Life Science are discussed in a subsequent section.

Sigma Life Science is your definitive source for all approved α-blockers that are available at competitive prices. This includes the first generation of nonselective α-receptor antagonists, phentolamine and phenoxybenzamine, as well as the quinazoline-selective α1-adrenoreceptor blockers.

Visit sigma.com/therapeutics for a listing of approved drugs and drug candidates.

 

α1-Adrenoreceptor Blockers References

  1. Neaton et al. 1993. Treatment of mild hypertension study. JAMA 270:713–24.
  2. Wright et al. 2008. Clinical outcomes by race in hypertensive patients with and without metabolic syndrome. Arch Intern Med 168:207–17.
  3. David et al. 2008. Heart failure with preserved and reduced left ventricular ejection fraction in antihypertensive and lipid-lowering treatment to prevent heart attack trial. Circulation 118:225E–67E.
  4. Barzillay et al. 2004. Cardiovascular outcomes using doxazosin vs chlorthalidone for the treatment of hypertension in older adults with and without glucose disorders. J Clin Hypertens 6:116–25.

 

β-Adrenergic Blockers

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The first β-adrenergic blockers (β-blockers) were identified as antihypertensive agents in the early 1960s.1,2 The first approved drug, propranolol, was used as an adjunct therapy to phentolamine in the treatment of pheochromocytoma.3,4

In the U.S. and Europe, β-blockers are recommended as a first-line treatment for hypertension. This recommendation is based on reduced mortality and morbidity in large clinical trials. Most of the benefit from β-blockers stems from secondary vascular protection in established disease instead of primary prevention.5

There is no consensus regarding how β-blockers lower blood pressure and it is probable that several mechanisms are at work. Mechanisms to account for the antihypertensive actions of β-blockers include reduction in peripheral vascular resistance and inhibition of renin release.3

β-blockers are not uniform in their various pharmacologic effects. Some of the differences between β-blockers include sympathomimetic and membrane-stabilizing activities, β1 selectivity, α1-adrenergic-blocking, duration of action.6 This variation contrasts with other classes of antihypertensive drugs and may be important in the selection of a drug for clinical or research use.

β-blockers are taken by tens of millions of Americans everyday. In 2009, these therapeutics were the fifth most widely prescribed class of medicines in the United States with 128 million prescriptions filled.7

To date, the Food and Drug Administration (FDA) has approved 15 β-blockers for oral use in patients with systemic hypertension. Sigma Life Science is your only source for all 15 approved β-blockers. You’re more likely to find the β-blockers for your research needs at Sigma Life Science than anywhere else.

For a complete listing of all approved drugs and drug candidates, visit sigma.com/therapeutics.

 

β-Adrenergic Blockers References

  1. Prichard BNC.1964. Hypotensive action of pronethalol. Br Med J 1:1227–8.
  2. Prichard BNC, and Gillam PMS. 1964. Use of propranolol (Inderal) in the treatment of hypertension. Br Med J 2:725–7.
  3. Frishman WH. 2011. α- and &bdeta;-adrenergic blocking drugs. In: Frishman WH, Sica DA (eds.). Cardiovascular Pharmacotherapeutics, 3rd ed. Minneapolis, MN:Cardiotext Inc. Pg 57–86.
  4. Frishman WH, Sica DA. 2008. &bdeta;-Adrenergic blockers. In: Izzo JL Jr, Sica D, Black HR (eds.). Hypertension Primer, 4th ed. The Essentials of High Blood Pressure. Philadelphia, PA: Wolters Kluwer Lippincott Williams & Wilkins Pg 446–50.
  5. Chobanian et al. 2003. The Seventh report of the joint report. JAMA 289:2560–72.
  6. Frishman WH. 2008. &bdeta;-Adrenergic blockers: a 50-year historical perspective. Am J Ther 15:565–76.
  7. Consumer Reports. 2011. Using &bdeta;-blockers to treat high blood pressure and heart disease. http://consumerreportshealth.org

 

Calcium Channel Blockers (CCBs)

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Calcium channel blockers (CCBs) inhibit the movement of extracellular calcium across the cell membrane through ion-specific channels. Although several types of channels exist, CCBs target the L-type channels in humans. Inhibition of the inward calcium flux causes smooth vascular muscle cell relaxation, resulting in vasodilation and lowering of blood pressure.1

There are two groups of approved therapeutics that target L-type calcium channels, dihydropyridine and nondihydropyridine compounds. The two types bind to different sites on the channel.2 However, nondihydropyridine calcium channel blockers differ from the dihydropyridine subclass in that they are more negatively chronotropic and inotropic. This difference is important for patients who also require β-blockers to manage their hypertension.

One aspect of CCBs that differentiate them from other antihypertensive agents is their ability to reduce blood pressure across all patient groups, regardless of sex, race/ethnicity, age, and dietary sodium intake.3

Currently, there are eight dihydropyridine and two nondihydropyridine approved therapeutics. These therapeutics are for individual use or in combination with other antihypertensive drugs, including statins.3

In 2009, CCBs were the ninth most widely prescribed class of medicines in the United States with 92 million prescriptions. CCBs not only help people manage their high blood pressure, angina, and certain heart rhythm abnormalities, they can also be used to treat migraines, poor circulation to the hands and feet, and certain psychiatric disorders.4

Sigma Life Science currently offers all the dihydropyridine approved therapeutics except for clevidipine, which is not available for research purposes. The two nondihydropyridine approved therapeutics, diltiazem (Cat. No. D2521) and verapamil (Cat. No. V4629), can also be obtained from Sigma Life Science.

There are other approved CCBs that are useful tools in hypertension research. These research therapeutics are listed below and include the two drug candidates azelnidipine (Cat. No. A7106) and cilnidipine (Cat. No. C1493).

At Sigma, we strive to provide you with the largest selection of approved therapeutics available. You’re more likely to find the CCBs for your research needs at sigma.com/therapeutics than anywhere else.

 

CCBs References

  1. Abernethy DR and Schwartz JB. 1999. Calcium-antagonist drugs. N Engl J Med 341:1447-57.
  2. Materson BJ. 1995. Calcium channel blockers: is it time to split the lump? Am J Hypertens 8:325-9.
  3. Elliott et al. 2011. Calcium channel blockers. J Clin Hypertens 13:687-9.
  4. Consumer Reports. 2011. Using calcium channel blockers to treat high blood pressure and heart disease. http://consumerreportshealth.org

 

Diuretics

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First-line agents in the treatment of hypertension are the thiazide-type diuretics. These therapeutics are proven to reduce cardiovascular mortality and morbidity. This reduction occurs in both systolic and diastolic forms of hypertension.1

Hydrochlorothiazide (HCTZ) is the thiazidetype diuretic used most often. Another proven thiazide-type therapeutic is chlorthalidone, which resembles HCTZ structurally but differs in its pharmacology.2 These compounds are well tolerated antihypertensive agents with respect to symptomatic and adverse side effects.3

Loop diurectics such as fuorsemide, bumetanide, and torsemide are less effective than the thiazide-type drugs in reducing blood pressure. However, loop diuretics are important in hypertensive patients with significant fluid overload or advanced renal failure.4

Diuretics can be successfully combined with β-blockers, ACE inhibitors, ARBs, and CCBs. The combination of a diuretic with any one of these antihypertensive agents provides the best effect in lowering blood pressure when compared to combinations without a diuretic.5

You can obtain HCTZ and many of the loop diurectics from Sigma Life Science at competitive prices. There are biomolecules and peptides also available at Sigma. We strive to provide you with the largest selection of products so you can focus more on your research.

You’re more likely to find the agents for your research needs at Sigma Life Scienve than anywhere else.

 

Diuretics References

  1. Ernst et al. 2010. Meta-analysis of dose-response characteristics of hydrochlorothiazide and chlorthalidone: effects on systolic blood pressure and potassium. Am J Hypertens 23:440-6.
  2. Carter et al. 2004. Hydrochlorothiazide versus chlorthalidone: evidence supporting their interchangeability. Hypertension 43:4-9.
  3. Psaty et al. 1997. Health outcomes associated with antihypertensive therapies used as first-line agents. A systematic review and meta-analysis. JAMA 277:739-45.
  4. Vargo et al. 1995. Bioavailability, pharmacokinetics, and pharmacodynamics of torsemide and furosemide in patients with congestive heart failure. Clin Pharmacol Ther 57:601-9.
  5. Materson et al. 1993. Single-drug therapy for hypertension in men: A comparison of six antihypertensive agents with placebo. N Engl J Med 328:914-21.

 

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