Drugs Affecting Renin-Angiotensin System And Plasmakinins
Question 1. Write A Short Note On Ace Inhibitors.
Or
Discuss The Mechanism Of Action, Uses, And Adverse Effects Of Ace Inhibitors
Answer:
The ACE inhibitors are captopril, enalapril ramipril, lisinopril, perindopril, benazepril and fosinopril.
ACE Inhibitors Mechanism Of Action
- These drugs prevent the conversion of angiotensin I into angiotensin II by inhibiting angiotensin-converting enzyme thus preventing the action of angiotensin II, i.e.
- They cause dilatation of arterioles causes a decrease in peripheral vascular resistance and a decrease in blood pressure.
- These drugs cause a decrease in aldosterone synthesis which leads to a decrease in the retention of sodium ions and water which causes a fall in BP.
- ACE inhibitors decrease the activity of the sympathetic nervous system.
- ACE inhibitors metabolize bradykinin which is a potent vasodilator. ACE inhibitors increase bradykinin levels causing vasodilatation and decrease blood pressure.
- ACE inhibitors cause stimulation of the synthesis of prostaglandins which are vasodilating. This takes place through bradykinin. This causes a decrease in blood pressure.
Read And Learn More: Pharmacology Question And Answers
ACE Inhibitors Adverse Effects
- Dry cough occurs as there is an increase in the level of bradykinin in the lungs.
- Angioedema can occur which causes obstruction of the airway.
- ACE inhibitors can produce a teratogenic effect which is contraindicated in pregnancy.
- Hypotension can occur following the first dose of ACE inhibitors so it is taken in a small dose and then increased simultaneously.
- Neutropenia and proteinuria are rare side effects.
- Presence of rashes and itching.
- There is also a loss of taste sensation.
ACE Inhibitors Therapeutic uses
- Hypertension: ACE inhibitors are fist-line drugs to be used in the treatment of hypertension. They are used alone or in combination with other drugs. These drugs are more effective in renovascular hypertension. These drugs are specially used in patients with diabetes and congestive heart
failure. - Congestive cardiac failure: ACE inhibitors decrease preload and afterload in congestive heart failure.
- Acute myocardial infarction: ACE inhibitors should be started within a day in patients with myocardial infarction. These drugs increase motility in myocardial infarction.
- Diabetic nephropathy: ACE inhibitors are the preferred drugs. They improve renal functions in diabetics.
Question 2. Write A Short Note On Enalapril.
Or
Describe Pharmacological Actions, Therapeutic Uses, And Adverse Effects Of Enalapril.
Answer:
Enalapril is an ACE inhibitor.
Enalapril Mechanism Of Action
- Enalapril prevents the conversion of angiotensin I into angiotensin II by inhibiting angiotensin-converting enzyme thus preventing the action of angiotensin II, i.e.
- They cause dilatation of arterioles causing a decrease in peripheral vascular resistance and decreases blood pressure.
- These drugs cause a decrease in aldosterone synthesis which leads to a decrease in the retention of sodium ions and water which causes a fall in BP.
- It decreases the activity of the sympathetic nervous system.
- Enalapril metabolizes bradykinin which is a potent vasodilator. ACE inhibitors increase bradykinin levels causing vasodilatation and decrease blood pressure.
- Enalapril cause stimulation of the synthesis of prostaglandins which are vasodilating. This takes place through bradykinin. This causes a decrease in blood pressure.
Enalapril Pharmacokinetics
- Enalapril is effective orally.
- The prodrug, i.e. enalapril is converted into an active metabolite, i.e. enalaprilat in the body.
Indications Or Therapeutic Uses
- In hypertension
- In congestive heart failure
- In myocardial infarction
- In diabetic nephropathy
- In scleroderma crisis.
Enalapril Adverse Effects
- Dry cough
- Hypotension
- Angioedema
- Hyperkalemia
- Dysgeusia, i.e. alteration in taste
- Teratogenicity.
Question 3. Write The Basic Use Of Losartan In Hypertension.
Answer:
Losarton is a competitive antagonist of angieotensin II.
- It blocks AT1 receptors.
- It blocks all actions of angiotensin II like vaso- constriction and aldosterone synthesis and decreases blood pressure.
- Losartan does not inhibit ACE and so bradykinin level is not increased so it decreases hypertension.
- Losartan is used as a first-line drug for hypertension.
Question 4. Classify Antihypertensive Drugs.
Answer:
Classification Of Antihypertensive Drugs
- ACE inhibitors: Captopril, enalapril, lisinopril, perindopril, ramipril, lisinopril, benazepril and fosinopril B Losartan, candesartan, irbesartan, valsartan, telmisartan
- Calcium channel blockers: Veraparnil, diltiazam, nifedipine, felodipine, amlodipine
- Diuretics
- Thiazides: Hydrochlorthiazide, chlorthalidone, indapamide
- High ceiling: Furosemide, Bumetanide, torsemide
- K+ sparing: Spironolactone, Amiloride, triamterene
- Beta adrenergic blockers: Propranolol, atenolol, temolol, nadolol
- Beta + Alpha-adrenergic blockers: Labetalol, carvedilol
- Alpha adrenergic Blockers: Prazosin, Terazosin, Doxazosin, Phentolamine, Phenoxybenxamine
- Central sympatholytics: Clonidine and Methyldopa
- Vasodilators
- Arteriolar: Hydralazine, Minoxidil, and Diazoxide
- Arteriolar + Venous: Sodium nitroprusside.
Question 5. Write In Short About Losarton.
Answer:
It is an angiotensin antagonist.
- It is a competitive antagonist and inverse agonist of angiotensin II.
- It is more selective for AT1 as compared to AT2 receptors and does not block any other receptor or ion channel, except the thromboxane A2 receptor.
- It blocks all overt actions of angiotensin II.
- Losartancauses fall in blood pressure in hypertensive patients which lasts for 24 hours, while heart rate remains unchanged and cardiovascular reflexes are
not interfered.
Losarton Mechanism Of Action
Losarton blocks AT1 receptors. It blocks all actions of angiotensin II like vasoconstriction and aldosterone synthesis and decreases blood pressure.
It does not inhibit ACE and so bradykinin level is not increased so it decreases hypertension.
Losarton Adverse Effects
- It can cause hypotension and hyperkalemia
- Dry cough sometimes is present
- Angioedema is reported in fewer cases
- Headache, dizziness, weakness, and upper gastrointestinal side effects are mild and occasional
- Dysguesia, i.e. taste alteration
- Teratogenicity.
Losarton Uses
- Hypertension: Losartan is the first-line drug, comparable in efficacy and desirable features to ACE inhibitors.
- Congestive heart failure: The ARBs afford clear-cut symptomatic relief as well as survival benefits in CHF.
- Myocardial Infarction
- Diabetic nephropathy.
- Scleroderma crisis.
Question 6. Mention The Basis Of Use Of Ace Inhibitors In Various Cardiac Conditions.
Answer:
The use of ACE inhibitors in various cardiac conditions is as follows:
- Congestive heart failure: ACE inhibitors cause both arteriolar and vasodilatation in CHF patients. They reduce afterload as well as preload, so there are fewer congestive symptoms and more effective pumping of the heart.
- Myocardial infarction: ACE inhibitors are administered while myocardial infarction is evolving and is continued for 6 weeks to reduce early as well as
long-term mortality. They decrease reinfarction. - It acts as a prophylactic agent in high cardiovascular-risk subjects. The protective effect is exerted both on the myocardium as well as vasculature.
Question 7. Discuss Contraindications For The Use Of Ace Inhibitors.
Answer:
- Ace Inhibitors Contraindications
- ACE inhibitors are contraindicated in pregnancy as they produce teratogenic effects.
- A high dose of ACE inhibitor is contraindicated in beginners as it leads to severe hypotension.
- In patients with angioedema, these drugs can cause airway obstruction.
- ACE inhibitors are contraindicated in patients with single or bilateral renal artery stenosis.
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