Cardiovascular System Pharmacology

Cardiovascular System

The cardiovascular system delivers blood and nutrients to tissues. The heart pumps blood, delivering nutrients and oxygen, and removing waste. It has four chambers: atria (upper) and ventricles (lower), separated by a septum. Valves control blood flow; tricuspid (right) and mitral (left) between atria and ventricles, pulmonic (right ventricle to pulmonary artery), and aortic (left ventricle to aorta).

Unoxygenated blood enters the right atrium via the vena cava, flows through the tricuspid valve to the right ventricle, then through the pulmonic valve to the pulmonary artery for oxygenation in the lungs. Oxygenated blood returns to the left atrium via pulmonary veins, through the mitral valve to the left ventricle, then through the aortic valve to the aorta for systemic circulation. Right and left sides function simultaneously. Heart sounds (S1 and S2) are valve closures.

Electrical Conduction

The sino-atrial (SA) node in the right atrium initiates the heartbeat (60-100 bpm). The electrical current travels across atria to the atrioventricular (AV) node, slowing to allow atrial repolarization. The AV node leads to the Bundle of His, which sends impulses to ventricles via Purkinje fibers causing ventricular contractions. Blood vessels include the aorta, veins, and capillaries.

Congestive Cardiac Failure

Congestive cardiac failure occurs when the heart cannot pump enough blood, leading to fluid accumulation in the lungs. This may result from ventricular pumping issues or diseases. Treatments include:

  • Digitalis Glycosides: Increase myocardial contraction, cardiac output, and urine to reduce congestion (e.g., Digoxin). It acts on the sodium-potassium ATPase pump, reduces impulse conduction, and increases coronary artery circulation. Dosage: 0.5-1mg, maintenance 0.125-0.5mg daily. Side effects include visual disturbances and slow pulse. Contraindicated in ventricular tachycardia.

  • Circulatory Stimulants: Improve blood circulation (e.g., Epinephrine). It constricts peripheral arteries and stimulates the heart. Indications include cardiac arrest and shock. Side effects: hypertension and arrhythmia.

  • LEVOPHED (Noradrenaline): Vasoconstrictor, increases peripheral resistance and blood pressure. Infuse 4mL of 1:1000 solution in 1L saline at 0.5-3mL/minute.

  • METARAMINOL (Aramine): Vasopressor, constricts peripheral blood vessels. Dose: 0.5-5mg IV or 2-10mg IM.

Hypertension

Hypertension is systolic blood pressure greater than 140mmHg and diastolic greater than 90mmHg. It may be caused by increased sympathetic activity or increased renal reabsorption of sodium chloride and water. Treatment includes:

  • Sympathetic Inhibitors (Adrenolytic agents): Inhibit the sympathetic nervous system. Alpha receptors cause smooth muscle contraction, while beta receptors cause relaxation. Beta-blockers (end in -OLOL) prevent excessive nerve stimulation, reducing heart rate and force.

    • Propranolol (Inderal): Beta-blocking agent, reduces plasma renin. Adult dose for hypertension is 160-320mg daily. Side effects: hypotension and nausea. Contraindicated in asthma.

    • ACEBUTOLOL (Sectral): Beta-adrenergic receptor blocking agent. Initial dose is 400mg daily. Side effects: bradycardia and bronchospasm.

  • Vasodilators: Increase the lumen of arteries reducing peripheral vascular resistance (e.g Prazosin).

    • PRAZOSIN (Hypovase): Alpha-adrenoceptor blocking and vasodilator. Dilates arterioles and reduces peripheral resistance. Effective for Hypertension, Congestive Heart failure and Benign prostatic hyperpter. Dose: 500 micrograms b.d/t.d.s.

  • Centrally Acting Antihypertensive Drugs: Act on autonomic centers in the brain.

    • CLONIDINE HYDROCHLORIDE (Catapres): Decreases noradrenaline release, reducing peripheral resistance. Usual dose 0.15mg daily.

    • METHYLDOPA (Aldomet): Blocks renin release, reduces peripheral vascular resistance. Initially 250mg 2-3 times daily, maximum dose is 3gm daily.

    • HYDRALAZINE HYDROCHLORIDE (Apresolute): Relaxes smooth muscles of arterioles. Dose: 25mg b.d. maximum.

    • NIFEDIPINE (Nifecard): Vasodilator and calcium antagonist. Initial 30mg or 60mg once daily

    • RESENPIN (SerpasiL): Reduces concentration of Noradrenaline The maintenance dose is 0.1-0.25mgdly

    • CAPTOPRIL (Capoten): reduces cardiac after - Load and increases cardiac output; Dose - 12.5mg b.d, maintenance of 25mg b.d

    • Sodium Nitroprusside (Nipride): Relaxes smooth muscles; Dose: 3mg per kg per minute

    • LISINOPRIL: inhibits Angiotensin . Dose - for HPN - 2.5ing at bedtime, Maintenace dose is 10-20 mg Once dly.; for Heart failure = 2.5mg maintenance is 5-20mg day

Antirrhythmic Drugs

Antiarrhythmic drugs address heart rate or rhythm disorders by slowing electrical impulses. Classes include:

  • Class I - Sodium-Channel Blockers

  • Class II - Beta Blockers

  • Class III - Potassium-Channel Blockers

  • Class IV - Calcium-Channel Blockers

  • AMLODIPINE (Norvase): Calcium-channel blocker, dilates coronary vessel; Dose Adults = 5-10mg dly.; avoid use in cardiogenic shock.

Antianginal Drugs

Antianginal drugs treat angina (chest pain from reduced blood flow). They include Nitrates and Calcium-Channel Blockers

  • GLYCERYL TRINITRATE (Nitrostat): Vasodilator which help increase oxygenated blood flow to the myocardium and reduce angina pains, Dose: 0.3 - 1mg Sublingually

Anticoagulants

Anticoagulants prevent blood clotting.

  • HEPARIN: Prevents fibrin formation. Dose: 5000-10,000 Units IV or Subcutaneously. Watch out for bleeding.

  • ENOXAPARIN SODIUM (Clexane): Dose for DVT or puimentary Embolisen = 1.5eng/kg body weight

  • PHENINDIONE (Dindevan): Prevents formation of prothrombin of other blood clothing; Dose 100ing furce daily and followed by song twice daily;; stop administration.

Haematinics

Haematinics (aka anti-anemic drugs) aid in blood formation, treating anemia.

  • FOLIC ACID (folvite): Aids in red blood cell maturation. Dose:5-20mg daily, ; use alone to Heat megaloblastic aremia.

  • FERROUS SULPHATE (fresol): Iron salt for hemoglobin formation. Dose:200-400 tds for adults and children,;; Avoid Tetracyclines.

  • CHEMIRON: For the synthesis of heremoglabire; Dose Adults 2-3 teaspoonsfuls or one capsule tds.;Administer the correct dose

  • ASTYMIN It provides Amino Acid for protent synthesis; Dessap - 2-6 years = 5nL twice daily

Cardiovascular System

The cardiovascular system delivers blood and nutrients. The heart pumps blood via 4 chambers: atria and ventricles, separated by a septum. Valves control blood flow: tricuspid, mitral, pulmonic, and aortic. Unoxygenated blood enters the right atrium via the vena cava, flows to right ventricle, then the pulmonary artery for oxygenation. Oxygenated blood returns to the left atrium, to the left ventricle, then to the aorta for circulation. Heart sounds are valve closures.

Electrical Conduction

The SA node initiates heartbeat (60-100 bpm). Electrical current travels to the AV node, slowing for atrial repolarization. The AV node leads to the Bundle of His, sending impulses to ventricles via Purkinje fibers. Blood vessels: aorta, veins, capillaries.

Congestive Cardiac Failure

Heart can't pump enough blood, causing lung fluid accumulation. Treatments:

  • Digitalis Glycosides: Increase myocardial contraction, cardiac output, and urine. E.g., Digoxin. Dosage: 0.5-1mg, maintenance 0.125-0.5mg daily. Side effects: visual disturbances, slow pulse. Contraindicated in ventricular tachycardia.
  • Circulatory Stimulants: Improve circulation. E.g., Epinephrine. Side effects: hypertension, arrhythmia.
  • LEVOPHED (Noradrenaline): Vasoconstrictor, increases BP. Infuse 4mL of 1:1000 in 1L saline at 0.5-3mL/minute.
  • METARAMINOL (Aramine): Vasopressor. Dose: 0.5-5mg IV or 2-10mg IM.

Hypertension

Systolic BP > 140mmHg, diastolic > 90mmHg. Treatment:

  • Sympathetic Inhibitors: Alpha receptors cause muscle contraction, beta receptors cause relaxation. Beta-blockers (end in -OLOL) reduce heart rate. E.g., Propranolol, ACEBUTOLOL.
    -Propranolol (Inderal): Adult dose for hypertension is 160-320mg daily. Side effects: hypotension and nausea. Contraindicated in asthma.
    -ACEBUTOLOL (Sectral): Initial dose is 400mg daily. Side effects: bradycardia and bronchospasm.
  • Vasodilators: Increase artery lumen. Prazosin.
  • PRAZOSIN (Hypovase): Dose: 500 micrograms b.d/t.d.s.
  • Centrally Acting Antihypertensives: Act on brain centers. Clonidine, Methyldopa.
    -CLONIDINE HYDROCHLORIDE (Catapres): Usual dose 0.15mg daily.
    -METHYLDOPA (Aldomet): Initially 250mg 2-3 times daily, maximum dose is 3gm daily.
  • Other drugs: Hydralazine, Nifedipine, Resenpin, Captopril, Sodium Nitroprusside, Lisinopril.

Antirrhythmic Drugs

Address heart rhythm disorders. Classes: Sodium-Channel Blockers, Beta Blockers, Potassium-Channel Blockers, Calcium-Channel Blockers. Amlodipine.

  • AMLODIPINE (Norvase): Calcium-channel blocker; Dose Adults = 5-10mg dly.; avoid use in cardiogenic shock.

Antianginal Drugs

Treat angina. Nitrates and Calcium-Channel Blockers. Glyceryl Trinitrate.

  • GLYCERYL TRINITRATE (Nitrostat): Dose: 0.3 - 1mg Sublingually

Anticoagulants

Prevent blood clotting. Heparin, Enoxaparin, Phenindione.

  • HEPARIN: Dose: 5000-10,000 Units IV or Subcutaneously. Watch out for bleeding.
  • ENOXAPARIN SODIUM (Clexane): Dose for DVT or puimentary Embolisen = 1.5eng/kg body weight
  • PHENINDIONE (Dindevan): Prevents formation of prothrombin of other blood clothing; Dose 100ing furce daily and followed by song twice daily;; stop administration.

Haematinics

Aid in blood formation, treating anemia. Folic Acid, Ferrous Sulphate, Chemiron, Astymin.

  • FOLIC ACID (folvite): Dose:5-20mg daily, ; use alone to Heat megaloblastic aremia.
  • FERROUS SULPHATE (fresol): Dose:200-400 tds for adults and children,;; Avoid Tetracyclines.
  • CHEMIRON: Dose Adults 2-3 teaspoonsfuls or one capsule tds.;Administer the correct dose
  • ASTYMIN It provides Amino Acid for protent synthesis; Dessap - 2-6 years = 5nL twice daily