It was not until the late 1800’s and early 1900s that elevated blood pressure was recognized as a contributing factor in cardiovascular disease. Prior to this it was Hippocrates and the Greeks and Romans and others who were honed in on the pulse and its strength and weakness. Leeches were often used to reduce the volume of blood in the body. In the early 1800s Thomas Young gave a lecture on his observations that the pressure of the blood was greater near the aorta and gradually declined as it reached the extremities.
There were experiments involving blood pressure done using horses and dogs. In 1864, basic instruments were developed to measure blood pressure and in 1896 a wrap around rubber cuff for the upper arm was developed to close off the artery and measure the resulting pressure from the first pulse heard after slow deflation. This only recorded the systolic pressure but was the beginning of the more accurate measure of blood pressure.
In 1904 medical students in Paris found that restricting salt would help to reduce blood pressure. However they discovered that this was only effective in milder forms of hypertension.
The first actual drug to treat high blood pressure was an anti-malarial agent, pentaquine in the late 1940’s. The side effects were many but it represents the first in the development of anti-hypertensives. Researchers confirmed the connection between high blood pressure and cardiovascular disease. Prior to the development of the first chlorothiazide (1958) a diuretic developed from the antibiotic sulfanilamide, reserpine and hydralazine were the main antihypertensives in use. Studies using chlorothiazide determined that lowered blood pressure nearly halved the incidence of ischemic heart disease and stroke. From 1972 to 1994 this was verified by an equally impressive continued 50% decline in ischemic heart disease and stroke. From the late 1960’s on many more blood pressure medications have been developed. Below is a list of the most common ones , their actions, and how they are used.
Types of Blood Pressure Medications and their actions and side effects
With one third of Americans afflicted with hypertension (high Blood pressure), many medications over the years have been developed and used to treat this condition. There are several classes of these medications and each lowers blood pressure is a different way. The following is a list of commonly used medications for hypertension.
Diruretics This class of drugs has been in use for probably the longest in treating high blood pressure. It works by preventing the kidneys from reabsorbing salt and water in the urine. This allows for the elimination of sodium through the urine and allows additional water to be excreted. Since this reduces the amount of water in the blood, or reduced blood volume, blood pressure is lowered.
Diruetics carry with them some significant side effects. Loss of too much sodium can cause confusion, fainting and falls. Loss of too much potassium can have serious consequences including fatigue, irritability, and lack of concentration.
More seriously, lowered potassium can cause irregular heartbeat or in rare cases, heart failure. Potassium supplements are usually prescribed to maintain potassium levels.
Another mineral that is depleted by the use of diuretics is magnesium. Reduced magnesium can also cause irregular heartbeat.
Diuretics can also cause an increase in uric acid (especially in elderly patients). Other rare but significant side effects are increase blood cholesterol, poor carbohydrate metabolism, and possible inflammation of the pancreas and gallbladder. Common examples of these drugs include: Hygroton, Diuril, Edicrin, Demadex, Lasix, Bumex, Lozol and Zaroxolyn and others.
There are some diuretics that were developed to address the loss of potassium. These include Midamor, Dyrenium, and Aldactone.
ACE inhibitors (angiotensin-converting enzyme) are the second most often used medications to treat high blood pressure. They act by helping to relax blood vessels. They stop an enzyme in the body from producing angiotensin II, which affects the cardiovascular system by releasing hormones which cause narrowing of blood vessels This increases blood pressure forcing the heart to work harder. Most common examples of ACE inhibitors are Catopril, Vasotec, Lisinopril (Zestril), Benazepril (Lotensin), Acupril, Altace and others.
Beta Blockers are used to treat high blood pressure, arrhythmias, congestive heart failure and angina. Beta blockers block the effects of adrenaline on the body’s beta receptors slowing the nerve impulses that traverse through the heart. Because of this the heart does not have to work as hard due to a decrease in the need for oxygen and blood.
Beta Blockers have more side effects than some of the other blood pressure medications. For instance they may not be indicated for people with allergies, during pregnancy, people over age 60, people with pre-existing heart disease. Individuals with asthma or other chronic respiratory conditions, those with diabetes, hyperthyroidism, or those with kidney or liver disease may not be candidates for this class of anti-hypertensive.
Some examples of beta blockers include: Atenolol (Tenormin), Carvedilol (Coreg, combined alpha/beta blocker), Metoprolol (Lopressor), Nadolol (Corgard), Penbutol sulfate (Levatol), Propranalol (Inderal), and HCTZ and bisprol (Ziac), combination beta blocker and diuretic.
Calcium Channel Blockers relax blood vessels and increase the oxygen and blood to the heart. They also reduce the workload on the heart. About a third of those taking calcium channel blockers experience side effects. These may include flushing and dizziness, slowed heart rate, swelling or bleeding of gums, swelling of the ankles and hands, heartburn and nausea. They should be taken with milk or food. Grapefruit and grapefruit juice cannot be taken with these medications. Alcohol should also be avoided.
Norvasc (amlodipine), Plendil (felodipine), Cardizem (diltiazem), Calan, Covera,-HS, Isoptin, Verelan (verapamil), Adalat, Procardia, Procardia XL (nifedipine), Cardene, Cardene SR (nicardipine) Sular (nisoldipine), and Vascor (bepridil) Caduet (amlodipine) is a combination drug that includes a statin.
Alpha Blockers, also known as alpha-adrenergic antagonists treat enlarged prostate, pheochromocytoma, scleroderma, and Raynaud’s disease as well as high blood pressure. This class of drugs acts by relaxing certain muscles to help blood vessels to remain open. They keep the hormone, norepinephrine from tightening the muscles in the walls of the small veins and arteries. This action results in decreased blood pressure and improved blood flow.
Alpha blockers are not usually a first choice to treat high blood pressure. They are often used in combinations with other medications for difficult to control blood pressure. Side effects include headache, nausea, weight gain, and pounding heart rate. Often when alpha blockers are first taken, they can cause very low blood pressure, resulting in dizziness and fainting especially when going from a sitting to a standing position also known as postural hypotension.
The most commonly used alpha blockers are doxazosin mesylate (Cardura), prazosin hydrochloride (Minipress) and terazosin hydrochloride (Hytrin).
Alpha-2 receptor agonist also known as methyldopa, has been used for over 50 years and is one of the oldest medications for high blood pressure. It was prescribed under the name of Aldomet and is rarely used currently as a primary treatment for high blood pressure. However, in the case of increased blood pressure that can develop during pregnancy, it is considered the first choice to be used.
Angiotensin II receptor blockers aka ARBs. The hormone angiotensin acts to narrow blood vessels by binding to receptors on the vessels. Angiotensin II receptor blockers prevent angiotensin from binding to these receptors and consequently help to lower blood pressure. The ARB’s are specifically contraindicated for use in pregnancy. It is generally well tolerated and is often used when ACE inhibitors are not well tolerated. Some more common examples of ARB’s are: Diovan (Valsartan), Benicar (Olmesartan), Cozaar (Losartin Potassium), Avapro (Irbesarten) and Teveten (Eprosartan mesylate).
Central Agonists (also called central adrenergic inhibitors) are blood pressure medications that work on the central nervous system instead of the cardiovascular system as most others do. They work by preventing the brain from emitting signals to the nervous system to increase heart rate and narrow blood vessels. Consequently the heart does not pump as hard and blood moves more easily through the vessels.
This class of drug has several other uses such as treatment of hot flashes, treatment of alcohol and drug withdrawal, attention deficit/hyperactivity disorder, and Tourette’s syndrome. Side effects include, drowsiness, dizziness, impotence, constipation, headache, dry mouth, weight gain and possible psychological issues like depression.
Central acting agents include Catapres (clonidine), Tenex (guanfacine), and methyldopa (also an Alpha-2 receptor antagonist).
Peripheral adrenergic inhibitors (also called Alpha adrenergic Blockers) reduce high blood pressure by blocking the neurotransmitters to the brain stopping smooth muscles from getting the signal to constrict. This class of drugs was used in the 1950’s when the choice of blood pressure medications was very limited.
This anti hypertensive is used when other drugs are found to be ineffective. They have numerous side effects and drug interactions making them a rare choice for treatment. Examples of peripheral adrenergic inhibitors are Hylorel (guanadrel), Ismelin (guanethidine monosulfate) and Serpasil (reserpine).
Vasolilators act by relaxing the muscles of the artery wall and cause the blood pressure to drop. Often these medications are combined with others to counteract the body’s tendency to retain fluid and increase the heart rate when this class of drugs causes a sudden drop in blood pressure.
Side effects can include difficulty breathing and swelling of tongue, throat or face (these effects are a medical emergency). Common side effects are dizziness or lightheadedness, headache, and increased or irregular heart rate.
Examples of vasodilators used to treat hypertension include Apresazide (hydralazine/hydrochlorothiazide) and Apresoine (hydralazine).
The above is a list of the most commonly used classes of medications prescribed for the treatment of high blood pressure. Also listed are some but not all of the generic and brand names within these major classes of antihypertensives.