Drugs affecting cardiovascular system Flashcards
Division of drugs used to treat heart and blood disorders:
- Positive inotropes
- Antihypertensives and vasodilators
- Antianemic agents
- Agents influencing the blood coagulation
Positive inotropes function:
increase the strength of cardiac muscle contraction by increasing the quantity of intracellular calcium available for binding by muscle proteins.
Positive inotropes division:
I. Cardiac glycosides: digoxin
II. Phosphodiesterase inhibitors: pimobendan - congestive heart failure due to dilated cardiomyopathy and chronic degenerative mitral valvular disease in dogs
III. Catecholamines (b-adrenergic agonists): dopamine, dobutamine, epinephrine and isoproterenol
Antihypertensives and vasodilators division:
I. Angiotensin converting enzyme (ACE) inhibitors
II. Calcium channel blockers
III. beta-blockers
IV. alpha-blockers
V. Diuretics
ACE inhibitors
enalapril, benazepril, captopril, lisinopril, ramipril
- chronic congestive heart failure in dogs
- manage systemic hypertension in dogs and cats
Calcium channel blockers
amlodipine, diltiazem
- vasodilators
Beta-blockers
atenolol (propranolol, metoprolol, esmolol)
- slow heart rate and reduce myocardial O2 consumption
Alpha-blockers
prazosin (a1-adrenergic receptor blocker)
- mixed vasodilator
Diuretics
- Congestive heart failure characterized by cardiogenic pulmonary edema, pleural effusion, ascites or combination of these signs
Four classes of diuretics used to treat congestive heart failure in dogs and cats
I. loop diuretics - furosemid
II. thiazide diuretics - chlorothiazide
III. potassium-sparing diuretics - spironolactone
IV. other hypotensives - vasodilators - nitroglycerin
Antianemic agents
Treat anemia by providing components needed for red blood cells production, including hemoglobin synthesis, and by stimulating bone marrow formation of RBC
- vitamin B12, folic acid and iron (ferrum)
Agents influencing the blood coagulation:
Anticoagulants
- affect blood clotting
- interfere with clotting cascade by blocking synthesis of clotting factor VII (prothrombin, thrombin) or block the formation of fibrinogen
Name phases of the coagulation process:
- Activation of prothrombin
- The own clotting phase
- The retraction phase
Characterize first phase of the coagulation process
Activation of prothrombin:
- response to trauma on blood vessels and tissues
- releasing of thrombokinase from platelets and damaged vascular endothelium, with calcium ions catalyzes conversion of prothrombin into thrombin
Characterize the second phase of the coagulation cascade
The own clotting phase:
Thrombin converts fibrinogen into a meshwork of fibrin, forming a clot
Characterize the third phase of the coagulation cascade:
The retraction phase:
The fibrin chains are stabilized and strengthened. Final clot retraction and serum extrusion.
Name the two ways in which anticoagulants are used?
- In vivo - directly into the body or on body surface
- In vitro - added to blood in laboratory to facilitate experimental and diagnostic investigations
How are blood samples examined?
- the coagulated blood
- serum - serological surveys for diagnostic identification of antibodies that are formed as a response to disease - the uncoagulated blood and plasma
- laboratory examinations and determination
What do we determine with uncoagulated blood and plasma?
Noncellular blood components: concentration of catecholamines, hormones, vitamins, mineral substances, enzymes
Cellular blood components: blood cell counts and hematogrammes, agglutination, hemagglutination, various tests
Plasma components: enzyme activities, coenzymes, mineral substances, metabolites and protein etc.
Anticoagulants are necessary!
Divide anticoagulants:
- Inhibitors of clotting factors
- Vitamin K antagonists
- Calcium chelators - in vitro anticoagulants
- Enzymes
Inhibitors of clotting factors:
Heparin
- antithrombin III inhibits the proteolytic action of clotting factors IX, X, XI, XII and thrombin
- binds to the wall of endothelial cells and interferes with platelet aggregation and their adhesion
- prevents thrombosis and embolism
- obtained from bovine liver and lung tissue or porcine intestinal mucosa
D: 50-100 IU/kg up to 400 IU/kg
Name anticoagulants in the heparin group (6):
dalteparin, enoxaparin, nadroparin, parnaparin, reviparin and sulodexide
Vitamin K antagonists:
- Vitamin K is responsible for blood clotting, to stop bleeding!
Antagonists interfere with vitamin K-dependent clotting factors (II, VII, IX, X) in hepatic synthesis of vit K
- in vivo
- coumarin anticoagulants
- indandione anticoagulants
Name types of coumarin anticoagulants
- Vit. K antagonist
- warfarin - sodium warfarin is most commonly used! - prevention
- dicumarol
- phenprocoumon
- acenocoumarol
- ethyl tioklomarol
- biscoumacetate - ethyl biscoumacetate for prophylaxis of thrombosis and embolism
Name types of indandione anticoagulants
- Vit. K antagonists
- phenindione
- klorindion
- diphenadione
Characterize and name types of calcium chelators - (In vitro anticoagulants)
- chelated calcium + coagulation factors catalyze conversion of prothrombin into thrombin
- Sodium citrate - bind calcium ions required for the conversion of prothrombin into thrombin
- Sodium oxalate
- Edetate Calcium disodium (EDTA)
Enzymes function and examples:
- dissolve blood clots
- inactivate fibrinogen and fibrin
- streptokinase, alteplase, urokinase, fibrinolysine
What is the function of enzyme streptokinase?
Catalyze the conversion of plasminogen to plasmin - prevent formation of blood clots or dissolve already formed clots
Drugs used to treat bleeding:
Hemostatics - help the blood clot
- Lyophilized concentrates - skin
- Adstringents - site of bleeding
- Epinephrine and norepinephrine constrict blood vessels and decrease blood flow to tissues
