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Hypertension



DISCLAIMER: The content of this Website is not influenced by sponsors. The information contained herein should NOT be used as a substitute for the advice of an appropriately qualified and licensed physician or other health care provider. The information provided here is for educational and informational purposes only. In no way should it be considered as offering medical advice. Please check with a physician if you suspect you are ill.

Introduction

Treatment of hypertension is the most common reason for office visits in the United States and for the use of prescription drugs. Approximately 29 to 31 percent of people 18 years and older have hypertension. That means that there are 58 to 65 million people in the United States with hypertension. The number of people with hypertension will likely grow as the population grows older since hypertension occurs in one-half of persons older than 65 years. The increasing number of people who are obese will also increase the number of people diagnosed with hypertension.

Only 34% of people with hypertension have their blood pressure under control. This is defined as a blood pressure < 140/90mmHg.

There are a number of potential reasons for the low rates of blood pressure control. Some reasons include, poor access to health care and medications and lack of adherence to long term therapy in a condition that usually does not have any symptoms.

Hypertension remains the most common risk for factor for heart attack (myocardial infarction) and stroke.

Definitions

Normal blood pressure: systolic (top number) <120 mmHg and diastolic (bottom number) <80 mmHg

Prehypertension: systolic 120-139 mmHg or diastolic 80-89 mmHg

Hypertension:

                Stage 1: systolic 140-159 mmHg or diastolic 90-99 mmHg

`               Stage 2: systolic =160 or diastolic =100 mmHg

Systolic hypertension is considered to be present when the blood pressure is =140/<90 and isolated diastolic hypertension is considered to be present when the blood pressure is <140/=90 mmHg.

The systolic pressure is the greater predictor of risk in patients over the age 50 to 60.

Malignant Hypertension

Malignant hypertension refers to significantly elevated blood pressure along with bleeding vessels in the eye, protein leakage in the eye, and swelling of the fluid within the eyes. These finding may also be associated with hypertensive encephalopathy where in addition to severely elevated blood pressure  a patient may also have confusion, headache, visual disturbances, and seizures. 

Hypertensive Urgency

Severe hypertension (having a diastolic blood pressure >120 mmHg) in a person without any symptoms is referred to hypertensive urgency. There has been no proven benefit in rapid lowering of blood pressure in hypertensive urgency when there is no evidence of organ damage.

Essential Hypertension

The cause of essential hypertension is not well understood. A number of factors have been implicated:

-Increased adrenaline activity along with an over responsiveness to the receptors that recognize it.

- Increased activity of the blood vessels that feed the kidney along with increased salt retention from the kidneys.

-Hypertension is twice as common in people with one or two parents with the disease so there is likely a genetic link.

Risk Factors

The cause of essential hypertension is not well known. A number of risk factors have been associated with it:

-          Hypertension is more common and more severe in blacks.

-          Having parents with hypertension is associated with the development of hypertension over the  
   course of adult life.

-          There is evidence of a relationship between salt intake and hypertension. It is more likely that salt
   contributes to but is not necessarily a cause of high blood pressure.

-          Excess alcohol intake is associated with the development of hypertension.

-          Obesity is also associated with hypertension.

-          Having elevated levels of fat in your blood (dyslipidemia) is also associated with the development
   of hypertension.

-          Hypertension is more common in people with certain personality traits such as hostile attitudes 
   and time urgency/impatient individuals.

Secondary Hypertension

There are a number of identifiable disorders that may be associated with the development of high blood pressure. The cause of the hypertension is usually related to the disorder:

-          Kidney disease, both acute and chronic, especially when it involves the inner aspect of the
   kidneys or the blood vessels that supply the kidneys.

-          Birth control pills can raise blood pressure within the normal range. This change can bring out
   hypertension in individuals who are borderline.

-          Chronic use of anti-inflammatory medications, such as Motrin, and many antidepressants can
   induce high blood pressure. Chronic alcohol intake can also raise blood pressure.

-          Pheochromocytoma is a disorder where an adrenal gland tumor excretes excessive amounts of an
   adrenaline-like hormone. One-half of patients with pheochromocytoma have hypertension.

-          Primary hyperaldosteronism is a disorder where an adrenal tumor causes the kidney to retain
   excessive amounts of salt. This is usually suspected in people who have low potassium levels   
   (hypoklemia) and elevated levels of bicarbonate (HCO3). Symptoms of this disorder are a history
   of weakness, muscle cramps and frequent urination. These symptoms suggest low levels of
   potassium.

-          Having a disorder which involves blood vessels that supply the kidneys. Blood vessels that 
   supply the kidneys can be too narrow, or stenotic, and this can lead to elevated blood pressure.

-         Cushing syndrome is a disorder that is associated with elevated steroid hormone. People usually
   are obese, have large wide faces (“moon facies”), a large hump (“buffalo hump”) over their back,
   and purplish stretch marks over their abdomen.

-          Sleep apnea is a disorder usually associated with obesity and people will usually have a wide
   neck.
   Excessive or redundant tissues in the back of the throat block the wind pipe which causes loud  
  snoring and/or abrupt wakening at night from lack of blood flow to the brain.

-         Coarctation of the aorta is a disorder usually associated with young kids. It is associated with
  abnormal blood vessels exiting the heart.

-         Hypertension can be provoked by having a low thyroid level or elevated parathyroid level. The 
  parathyroid is a bean-sized structure located within the thyroid gland. A doctor is usually clued 
  into this disorder by unexplained elevated levels of calcium.

 

Complications

Hypertension is associated with a number of serious medical conditions. The likelihood of developing these complications varies with the level of blood pressure.

Hypertension is the major risk factor for early heart disease. It is more of a common risk factor than smoking, dyslipidemia, and diabetes.

Hypertension increases the risk of heart failure at all ages.

Left ventricular hypertrophy is a condition that develops in patients with hypertension. One of the main muscles of the heart, the left ventricle, becomes enlarged, similar to that of a weight lifter. This can eventually lead to heart failure or arrhythmias, abnormal heart rhythms, death from a heart attack, and even sudden cardiac death.

Hypertension is an important risk factor for stroke; the incidence can be dramatically reduced with medication used to treat hypertension. 

Hypertension is a risk factor for chronic kidney disease and kidney failure. It can be the cause of kidney disease or it can worsen existing kidney disease.

Diagnosis

Screening for hypertension is recommended every two years for persons with systolic and diastolic below 120 mmHg and 80 mmHg respectively and yearly for people with blood pressure systolic 120 to 139 or a diastolic pressure of 80 to 89.

Measurement

A recent study found no difference in blood pressure readings from a bare arm compared with those measured over a sleeved arm.

Posture

Blood pressure should be screened for “postural changes.” It should be checked with a patient lying supine (on their back) and standing. This is especially important in patients over age 65, diabetics, and those taking blood pressure medications.

Sitting pressures are recommended for routine follow-up monitoring; the patient should sit quietly with the back supported for five minutes and arm supported at the level of the heart.

Circumstances

No caffeine should be ingested the hour before blood pressure is measured and no smoking 30 minutes before the testing.

No stimulant-type products should be ingested, such as Sudafed or eye decongestant, which can affect the blood pressure readings.

Blood pressure should be measured in a quiet, warm setting.

Home reading should be measured in varying circumstances, i.e., in different locations and times of the day.

Cuff Size

The length of the bladder should be 80 percent and the width of the bladder should be at least 40 percent of the circumference of the upper arm.

Technique

Take at least two readings on each visit to the doctor, separated by as much time as possible. If the two readings vary by more than 5 mmHg, then your doctor should take more readings until two consecutive readings are close.

To make the diagnosis of hypertension, take three readings at least one week apart.

When starting, take blood pressure in both arms. If the readings differ than use the reading of the higher arm.            

The diagnosis should not be made until blood pressure has been measured on at least three to six visits, spaced over weeks to months.

White Coat Hypertension

Approximately 20 to 25% of patients with mild office hypertension (diastolic pressure 90 to 104 mmHg) have “white-coat” or isolated office hypertension. In these individuals their blood pressure is normal when measured at home and work. This problem is common in the elderly. It is infrequent in people with diastolic = 105 mmHg.

Ambulatory blood pressure monitoring involves wearing a blood pressure cuff and machine throughout the day. Blood pressure is measured usually every 15 to 20 minutes during the day and every 30 to 60 minutes during sleep. It can be used to confirm or exclude the presence of white-coat hypertension in patients with persistent office hypertension but normal blood pressure readings outside of the office.

Evaluation

Once the diagnosis of hypertension is made the next step is to determine if there is any organ damage, what a patients overall heart attack risk is, and to determine if there are factors that can fix or improve the blood pressure readings.

History

A detailed history should be obtained to see if causative or aggravating factors exist- prescription medications, anti-inflammatory pain medications (e.g., Motrin), level of alcohol consumption, determining how it has been progressing, determining of any organ damage exists, and determining if any other risk factors are present.

Laboratory Testing

A blood count to check for elevated blood level (polycythemia), checking for elevated glucose (diabetes), kidney problems (blood creatinine), or checking for any salt or potassium abnormalities (this also can be a screening test for a salt retaining tumor). The lipids should be check fasting (no food for 9 to 12 hours) and an EKG should be done. This can reveal an old heart attack, disease of the blood vessels that supply the heart (coronary artery disease) and/or enlarged left heart from longstanding hypertension, i.e., left ventricular hypertrophy.

Additional tests include testing for protein in the urine; this can be a sign of kidney disease resulting from high blood pressure.

Secondary Hypertension                   

Renovascular Hypertension

Elevated blood pressure can be caused by narrow blood vessels leading to the kidneys. It is the most common correctable cause of secondary hypertension. It probably occurs in less than 1% of patients with mild hypertension and between 10 to 45 percent of white patients with significantly elevated blood pressure.

The follow cases of hypertension should clue in a doctor to check for this condition:

-Severe resistant hypertension in patients with evidence of eye disease and abnormal kidney function (creatinine >1.5 mg/dl).

-Acute rise in blood pressure in someone who has had stable blood pressure for some time.

-Age of onset of hypertension before puberty or over 50.

-An elevation of kidney function (creatinine) that is unexplained or began after starting a blood pressure medication called and ace inhibitor or an ace II blocker.

-Someone who has moderate to severe hypertension with narrowing of the arteries (atherosclerosis) or an incidentally discovered asymmetrically small kidney.

-Someone with abnormal sounding blood vessels, aka bruit, located over one side of the abdomen. The sound of the bruit is similar to water rushing through a tight hose. 

-Someone who does not have a family history of hypertension.

Testing for other causes of secondary hypertension should be done in the appropriate settings:

-In the presence of kidney disease suggested by elevated creatinine or protein in the urine.

-Pheochromocytoma should be expected when there is an episodic elevation in blood pressure that is associated with a headache (usually pounding), palpitations, and sweating.

- Testing for an adrenal tumor causing excessive salt retention and potassium loss is done by measuring the blood level of renin and aldosterone. Your doctor should suspect this disorder when you have unexplained low potassium in the setting of high blood pressure. As mentioned, symptoms included history of weakness, muscle cramps and frequent urination. These symptoms suggest low levels of potassium.

-Cushing syndrome is diagnosed by measuring levels of a steroid hormone in the blood. Again, this should be suspected in someone who is obese with a large moon-like face, buffalo hump, and purplish stretch marks over their abdomen.

-Sleep apnea should be suspected in people who are obese with wide necks and who snore loudly at night and may even wake up from a blockage of their wind pipe. They sometimes have a morning headache and are tired during the day.

-Coarctation of the aorta is seen younger people with decreased pulses over the wrist and a bruit, or a sound similar to rushing fluid in a narrow tube that is usually heard over the back.

-Hypertension can be provoked by a low thyroid level or elevated parathyroid level. Symtoms of hypothyroidism include fatigue, weight gain, constipation, dry skin, being cold when everyone else is normal temperature. Symptoms of hyperparathyroidism is bone pain, stomach ulcers, and recurrent kidney stones.

Treatment

The benefits of blood pressure control have been proven through numerous clinical trials. Controlling elevated blood pressure is associated with 20 to 25 percent reduction in the incidence of stroke, heart failure, and heart attacks. The benefits may be even greater in people who already have diabetes, heart disease, or vascular disease.

Who Should Be Treated?

 All patients should first undergo appropriate lifestyle modification before medication is initiated. Generally, medication to treat high blood pressure should not be started when:

-There is no evidence of organ damage, eye, kidney, heart, blood vessel disease, unless the blood pressure is persistently elevated after 3-6 visits over a several month period.

-Blood pressure medication should be started if the systolic pressure is persistently = 140 mmHg and/or the diastolic pressure is persistently =90 mmHg in the office despite attempts at lifestyle modification. Starting two drugs may be considered in patients with an average blood pressure above 160/100 mmHg.

-In patients with diabetes or protein in the urine due to kidney disease, blood pressure medication is indicated when the systolic pressure is persistently above 130 mmHg and/or the diastolic is above 80 mmHg. The goal for these patients should be <120/<80. This often requires 2 or 3 agents to achieve.

In patients with type 2 diabetes, aggressively lowering elevated blood pressure reduces the risk of diabetic complications.

Patients with elevated blood pressure when they go to see their doctor and normal blood pressure readings at home should undergo out of the office 24-hour blood pressure monitoring to see if they are truly hypertensive.

Some conditions such as atrial fibrillation, heart failure, and after a heart attack, require blood pressure medication to improve survival even without the presence of hypertension.

Nonpharmacologic Therapy

Treatment of hypertension begins with lifestyle modification; this includes moderate dietary salt restriction, weight reduction in the obese, avoidance of excess alcohol intake, and regular aerobic exercise.

-A low salt diet will usually lower blood pressure and prevent the onset of hypertension. The recommendation is to reduce dietary intake from the usual 150 to 200meq/day down to 100meq/day (approximately 2.3 gm of sodium or 6 gm of salt).

-Weight loss in obese individuals can lead to a significant drop in blood pressure.

-People that have more than 2 drinks per day have a 1.5 to 2-fold increase in the incidence of hypertension compared to nondrinkers. This effect is related to the amount of alcohol consumed and is most prominent when intake exceeds 5 drinks per day. On the other hand, moderate alcohol intake (1-2 drinks per day) can reduce the risk of heart and blood vessel related problems.

-Engaging in regular aerobic exercise has been shown to have beneficial effects on lowering elevated blood pressure. 

-Adequate potassium may help to control elevated blood pressure. Supplementing with potassium must be done with caution in people with kidney disease.

-Smoking cessation is an important lifestyle modification. Stopping smoking can significantly decrease the chance of heart or blood vessel complications.

Drug Treatment                                                                                                                                       

When starting a single drug in treating uncomplicated hypertension, in the absence of any other disease, there are three main classes of drugs that are used for initial therapy. Thiazide diuretics (usually abbreviated HCTZ), long acting calcium channel blockers, and ACE inhibitors or angiotensin II receptor blockers. The goal is to achieve a specific blood pressure by whatever means. It really does not matter which medication is used to achieve it. Beta blockers are not commonly used for initial therapy since they may have indirect negative effects on heart and blood vessels, particularly in older patients.

Combination Therapy

Single drug therapy may not be enough control the blood pressure over time in some patients who were well controlled when they were initially diagnosed. Over time a number of people who were initially controlled with one medication may require a second agent.

Goal Blood Pressure

The goal of in using blood pressure medication is to lower blood pressure below 140/90 mmHg. There are a number of clinical trials that suggest lowering blood pressure to <130/80 mmHg in people with diabetes, chronic kidney disease who excrete protein in their urine, and in people with atherosclerotic disease (narrowed blood vessels due to fatty build up).

For people who are older, i.e., >65 with isolated systolic blood pressure, lowering blood pressure to systolic <140 and diastolic <65 mmHg is acceptable since lower blood pressures have been associated with an increased risk of stroke and other complications.

Again, it has to be reemphasized, it is important to reduce blood pressure gradually because rapidly lowering blood pressure in someone with severe hypertension can lead to adverse heart and blood-vessel related events.

Resistant Hypertension

Some people’s blood pressure will still be persistently elevated even with the use of blood pressure medication. Resistant hypertension is defined as a diastolic blood pressure above 95 to 100 mmHg despite being on 3 or more blood pressure medications. Some reason for this includes:

-Not being on a high enough dose of medication.

-Having too much circulating excess body fluid.

-Poor compliance with medication or dietary therapy.

-Office or “white-coat” hypertension.                        

-Ingestion of substances that can cause hypertension.

Stopping Therapy

Some people who have maintained normal blood pressure levels after a period of years can have their medication gradually diminished or discontinued. Gradual discontinuation of therapy is most likely to be effective in patients with mild hypertension who are well controlled on a single drug and who can be maintained on lifestyle modification such as weight loss and salt restriction. 

Medications Used to Treat Hypertension

There are many classes of antihypertensive medications. Six medications (diuretics, beta-blockers, rennin inhibitors, ACE inhibitors, calcium channel blockers, and ARBs) are acceptable for use as initial therapy.

Diuretics                              

Thiazide diuretics lower blood pressure by decreasing the volume of fluid in the body. They work by decreasing the uptake of salt (sodium) by the kidneys. Thiazide diuretics are usually administered once daily. Diuretics are more potent in blacks, older individuals, and the obese. They are more effective in smokers than in nonsmokers. Long-term thiazide use also prevents loss of bone mineral content in women at risk for osteoporosis.

Some adverse effects of diuretics include potential abnormalities in potassium and sodium levels, elevating levels of uric acid (this is important in people with gout), elevating glucose levels (important in diabetes), worsening lipids such as LDL and triglycerides, rashes, and erectile dysfunction. 

Beta-Blocking Agents

These drugs are effective in hypertension because they decrease heart rate and the amount of blood that is ejected from the heart, this ultimately decreases the pressure in the entire system. They are especially important in people that have heart-related chest pain (angina), or in people who have had a heart attack (myocardial infarction), or stable heart failure (congestive heart failure), as well as those with migraine headache and physical symptoms of anxiety such as shaking or nervousness.

Beta blockers work on 2 different receptors in the heart, beta 1 and beta 2 receptors. Beta 1 receptors are selective only for the heart and beta 2 receptors are receptive for both the blood vessels and the lung. At higher doses both agents will work on both receptors.

Side effects of all beta-blockers include provoking and/or worsening lung spasms in patients with asthma and COPD (chronic obstructive pulmonary disease), they can effect electrical currents of the heart which can result in slowing of the heart rate or even blocking electrical transmissions, nasal congestion, causing CNS symptoms such as nightmares, depression, and confusion. Fatigue and lethargy, and impotence may occur. All beta-blockers increase levels of triglycerides.

Beta-blockers previously were not used in heart failure. Recent evidence has shown that they can have beneficial effects in people with this condition. Beta-blockers are used cautiously in people who have type 1 diabetes since they can mask symptoms of low blood sugar. These drugs should also be used with caution in people with vascular disease especially those with leg pain related to vascular problems at rest or in people with nonhealing ulcers.

Beta-blockers used to be considered one of the first drugs that are used when hypertension is first diagnosed but are now used more as add-on therapy when a single drug is not enough to control blood pressure. There are some conditions though where beta-blockers are definitely indicated such as when there is coronary heart disease (clogging of the blood vessels that supply the heart) and heart failure.

Caution should be used when stopping beta-blockers. They should not be abruptly discontinued because they can bring on adverse heart events or cause a severe increase in blood pressure.

Renin Inhibitors

Renin inhibitors are relatively new on the market. Drugs such as Aliskiren, have recently been approved by the FDA. This drug can be used as solo therapy or in combination with other medications. It works by blocking rennin which in turn blocks angiotensin I and II. Angiotensin I and II are responsible for sending blood flow to the kidneys. Altering the level of blood flow to the kidneys can change the pressure in the entire system and can also effect sodium retention.

There is no clinical trial data for this new drug so its effect on hypertension, diabetes, or heart disease remains unknown.

Angiotensin-Converting Enzyme Inhibitors

ACE inhibitors are increasing being used as the initial medication used in mild to moderate hypertension. They work by inhibiting the rennin-angiotensin-aldosterone system. As previously mentioned, inhibiting this system causes reduced blood pressure to the kidneys which in turn effects the entire pressure throughout the body. It also decreases salt uptake. ACE inhibitors are more effective in younger white patients. They are relatively less effective in blacks and older persons and people with predominately systolic hypertension. Used alone ACE inhibitors control only about 40 to 50% of patients. The combination of an ACE inhibitor and a diuretic or a calcium channel blocker is very effective.

ACE inhibitors are the ideal agent in people with diabetes especially when there is protein in the urine or evidence of kidney disease. ACE inhibitors also delay kidney disease in people without diabetes. It has been shown through clinical trials to reduce the number of heart related deaths, heart attacks (myocardial infarctions), strokes, and has decreased the incidence of new-onset heart failure, kidney impairment, and new-onset diabetes.

ACE inhibitors are the drugs that should be used (in combination with a diuretic and beta-blocker) in patients with heart failure.

One big advantage of ACE inhibitors is their lack of troublesome side effects. Severe low blood pressure (hypotension) can develop in people with narrow blood vessels leading to the kidneys (renal artery stenosis). This condition becomes evident when kidney failure  develops after an ACE inhibitor is started.  This can be reversed by stopping the medication. Elevated potassium levels can occur in patients with kidney disease and in the elderly. A chronic dry cough is common and is seen in 10% of people or more. Skin rashes have been observed with any ACE inhibitors. Swelling, also called angioedema, is an uncommon and potentially dangerous side effect of ACE inhibitors. ACE inhibitors should not be used during pregnancy because they have been associated with a number of birth defects due to low blood pressure and lack of blood flow to the kidneys.

Angiotensin II Receptor Blockers

There is growing data that suggests that ARBs are similar to ACE inhibitors in their ability to improve heart outcomes in patients with hypertension along with patients with heart failure and diabetics with kidney problems.

Their effects in lowering blood pressure are similar to ACE inhibitors. Unlike ACE inhibitors, ARBs do not cause cough and are less likely to be associated with rashes or swelling. However, similar to ACE inhibitors, elevated potassium levels can be a problem in patients with narrowing of the blood vessels that lead to the kidney (bilateral renal artery stenosis). With this condition people may develop low blood pressure and kidney impairment.

Aldosterone Receptor Antagonists

Spironolactone and eplerenone work by decreasing sodium levels and are effective in heart failure and cirrhosis. They are somewhat weak in treating hypertension. These drugs are a good addition in patients with resistant hypertension who are already on other blood pressure lowering medications.

Aldosterone receptor antagonist work by preventing the uptake of sodium by the kidney. Hypertension plays an important role in causing organ damage including heart muscle enlargement (left ventricle hypertrophy) and kidney scarring (renal fibrosis). Aldosterone receptor antagonists counteract these consequences of hypertension independent of their blood pressure lowering effects.

Spironolactone can cause breast pain and breast enlargement (gynecomastia) in men. Elevated potassium levels (hyperklemia) can be a problem especially in people with kidney disease.

Calcium Channel Blocking Agents

These agents work by causing the dilation of blood vessels and cause less reflexive elevation in heart rate and fluid retention then other blood vessel dilators. They are effective as solo therapy in 60% of people in all groups of people and all grades of hypertension. For these reasons they may be preferable to beta-blockers and ACE inhibitors in blacks and older persons. Verapamil and diltiazem should be used with caution with beta-blockers because of their potential in effecting the electrical circuit of the heart as well as its contraction.

Recent studies have shown that calcium channel blockers are similar or equivalent to ACE inhibitors and thiazide diuretics in the prevention of coronary heart disease, major cardiovascular events, and related deaths and over mortality. A protective effect against strokes with calcium channel blockers is well established.

The most common side effects of calcium channel blockers are headache, swelling of the extremities, slow heart rate (bradycardia), and constipation (especially verapamil in the elderly). The dihydropyridine agents- nifedipine, felodipine, and amlodipine- are more likely to produce headache, flushing, palpitations, and swelling of the extremities. Calcium channel blockers can affect the strength of heart contractility so they should be used cautiously in people with heart problems. Amlodipine is the only calcium channel blocker with proven safety in  patients with heart failure.

Alpha-Adrenoceptor Antagonists

Prazosin, terazosin, and doxazosin block alpha receptors which relaxes vascular smooth muscle (muscles within blood vessels). They decrease blood pressure by increasing blood vessels that are constricted and under high pressure. These agents are effective as solo agents but side effects are common which limit their use as monotherapy agents.

Side effects include marked low blood pressure (hypotension) and fainting (syncope) after the first dose so it should therefore be given at bedtime. Other side effects that occur include palpitations, headache, and nervousness. These symptoms are less severe and frequent with doxazosin because of its slower onset.

Unlike beta-blockers and diuretics, the alpha-blockers have no adverse effect on lipids. On the contrary, they actually increase HDL (good cholesterol) and reduce total cholesterol.

Alpha-blockers should not be used as initial agents to treat hypertension except in men who have symptoms related to an enlarged prostate (BPH) because they can serve two purposes, both in lowering blood pressure and in treating an enlarged prostate.

Drugs with Central Sympatholytic Action  

Methyldopa and clonidine lower blood pressure by stimulating alpha-adrenergic receptors in the central nervous system. These agents are effective as single therapy but they are usually used as second or third-line add-on agents because of high frequency of adverse reactions such as sedation, fatigue, dry mouth, low blood pressure on standing, and impotence.

There is an important concern for rebound hypertension after stopping the medication. Methyldopa also causes liver inflammation (hepatitis) and breakdown of red blood cells (hemolytic anemia). Methyldopa would be a good choice in women who are pregnant. Clonidine is available in patches. This can be particularly helpful in people who have problems remembering to take their medications.

Arteriolar Dilators

Hydralazine and minoxidil relax blood vessel smooth muscle which produces dilation of the blood vessels. When given alone they can cause reflexive heart racing (tachycardia), increase in the strength of heart muscle contraction, and cause headache, palpitations, and fluid retention. They are usually given in combination with diuretics and beta-blockers in patients who are resistant to multiple blood pressure lowering medications. Hydralazine can produce gastrointestinal upset and may produce symptoms similar to lupus. Minoxidil causes excessive hair growth (hirsutism) and marked fluid retention; this agent is reserved for only the most difficult cases of hypertension.

Peripheral Sympathetic Inhibitors

These agents are used infrequently, usually only in the most resistant cases. Reserpine is a cost-effective blood pressure lowering medication. Some side effects include, mental depression, sedation, nasal stuffiness, sleep disturbances, and stomach ulcers. Guanethidine and Guanadrel prevent adrenaline release and frequently cause low blood pressure on standing, diarrhea, and fluid retention.

Choosing an Anti-Hypertensive Medication

Drugs used to treat high blood pressure can be divided into two complementary groups easily remembered as AB and CD (ACE/ARB and Beta-Blockers and Calcium Chanel Blockers and Diuretics). Combining drugs between the two groups are likely to be more potent in lowering blood pressure than combining within groups. Drugs A/B are more effective in young, white persons. Drugs C/D are more effective in old or black persons. Again, there has been a trend to not use beta-blockers as first-line agents because of the side effects already discussed. Most people require two or more medications and even then a number of people fail to achieve the systolic blood pressure goal of <140 mmHg. Three or four drugs are usually required to reduce systolic blood pressures to <130 mmHg in diabetic patients.

Since one agent is usually not enough to bring the blood pressure into the target range, the debate is usually not which medication to start first, rather, it is which combination of medication should be used. In people requiring the initiation of two blood pressure medications (because of blood pressure >160/100 mmHg) a good first choice would be the combination of an ACE inhibitor and a diuretic. In light of the many side effects of other agents, some experts believe that starting a calcium channel blocker might be preferable to using a thiazide diuretic in a younger patient with high blood pressure.

The initial use of lose dose combinations allow for faster blood pressure lowering with the side effects that come with higher doses of medication. Improved blood pressure control can be achieved with combining an ACE with an ARB.

When the initial selection is made patients should be warned about common side effects and the importance of taking the medication on a daily basis. Treatment should start at a low dose, unless the blood pressure is very high (>160/100 mmHg), follow-up visits should be at 4 to 6 week intervals to allow for the full effect of the medication.

If after the medication has been increased to its maximal dosage and the patient is not yet at their target blood pressure then a second medication should be added. As a rule of thumb, a blood pressure reduction of 10 mmHg can be expected for each antihypertensive medication added to the regimen.

Hypertension can be controlled in most patients with one or two drugs from the 2 complimentary categories. Patient who are compliant with their medication and who do not respond to these combinations should be tested for secondary causes to their hypertension before moving on to more complex regimens.

 

DISCLAIMER: The content of this Website is not influenced by sponsors. The information contained herein should NOT be used as a substitute for the advice of an appropriately qualified and licensed physician or other health care provider. The information provided here is for educational and informational purposes only. In no way should it be considered as offering medical advice. Please check with a physician if you suspect you are ill.