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Medical College National Medical University.docx
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Cardiovascular Drugs

Cardiovascular drugs may be divided into three groups: drugs that affect the heart; drugs that affect blood pressure; and drugs that pre­vent blood clotting.

Drugs that affect the heart. Drugs may affect the heart in two ma­jor ways: changing the rate and forcefulness of the heartbeat.

The most common drugs used to change the rate and forcefulness of the heartbeat are the digitalis glycosides (cardiac glycosides). These drugs are used to treat patients in heart failure (when the heart is not contracting with sufficient force). Most of the digitalis glycosides are obtained from the leaf of the digitalis (foxglove) plant. The important effects of the digitalis glycosides are the strengthening of the myocar­dium (heart muscle) and the slowing of the rate of the heart contrac­tion. Examples of digitalis are digoxin, and digitoxin.

Other drugs, which belong to the general class of sympathomimetics are used to increase heart rate and the force of contraction. These include isoproterenol and epinephrine.

Drugs used to correct abnormal heart rhythm are called antiar­rhythmics. Examples of these drugs are quinidine, procainamide, lido-caine and propranolol.

Drugs that affect blood pressure. Vasodilators are drugs which relax the muscles of vessel walls. Blood flows more freely and blood pressure falls as blood vessels open and become dilated. Examples of nitrite drugs are nitroglycerin and amylnitrite. Nitroglycerin dilates all smooth muscles in the body including the muscles of the coronary blood ves­sels. The pain (angina pectoris) caused by a lack of adequate blood flow to the heart is relieved by placing nitroglycerin under the tongue.

A third type of drugs used to lower blood pressure is called a di­uretic, an agent which promotes excretion of fluid. An example of this type of drug is chlorothiazide (Diuril).

Vasoconstrictors are drugs which constrict muscle fibers around blood vessel opening. Vasoconstrictors are needed to raise blood pres­sure, increase the force of heart action and stop local bleeding. Ex­amples of vasoconstrictor drugs are epinephrine (adrenaline), vaso­pressin and aramine (metaraminol).

Drugs that prevent blood clotting. These drugs are called antico­agulants. They are used to prevent the formation of clots in veins and arteries. Heparin is an anticoagulant chemical substance. When given intravenously, heparin prevents the formation of clots within vessels. Aspirin is the most widely used anticoagulant.

Language development

І. Complete the sentences using the words and word combinations from the list below.

Similar, leaf, clots, the heart muscle, blood, tongue, flow

  1. The _______ may cause occlusion of blood supply to a vital organ.

  2. Digitalis is obtained from the _______ of the digitalis.

  3. Quinidine decreases the number of times _______ can contract in a given period of time.

4. Other nitrite drugs work in a manner _______ to that of nitroglycerin.

5. _______ and lymph are the liquid tissues of the body.

6. _______ moves food around during chewing.

7. Obstruction of the _______ of blood can lead to the back flow of blood.

ІІ. Choose the correct preposition.

  1. Absorption of a drug is the process of movement of the drug to/ from the site of/in its application towards the general circulation.

  2. In this process, physiochemical properties of/in drugs, their for­mulations, and route of administration are all important.

  3. A prerequisite to absorption is that the drug must be able to enter into/at solution.

  4. Thus, for example, in/on case of solid drug products (e.g. tablets) the ingredients must undergo disintegration, deaggregation, and dissolution.

ІІІ. Replace the underlined words with their synonyms from the list.

comprises, origin, influenced by, powerful, cultivation, entire, handling, recognized, position, obtained

  1. Digitalis is an important cardiotonic drug, official in most phar­macopoeias of the world since the eighteenth century.

  2. The drug contains a large number of glycosides, of which the most important from medicinal viewpoint are digitoxin, giditoxin and gitaloxin.

  3. The total concentration of these three glycosides varies appreciably with the plant source and the conditions of growth.

  4. Also, since all are the secondary glycosides derived by hydrolysis of some of sugars from the primary or parent glycosides occurring in the leaf, their concentration is dependant upon'the manner of treatment of the plant material following harvesting.

  5. Nearly 30 other glycosides have been identified in the drug.

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