Lecture 5.6 Drugs influencing CVS Flashcards
What are the hypertensive drugs?
Angiotensin system inhibitors
Beta adrenoceptor antagonists
Calcium channel blockers (can also affect blood vessels as L-type are found there).
Diuretics
Describe briefly the effects of the RAS.
Fall in BP stimulates SA to release renin, converting angiotensinogen to angiotensin 1. ACE then converts that to angiotensin 2 and we get cell growth and remodelling of heart. Via AT1 receptors can also lead to vasoconstriction and aldosterone which retains water via Na.
Briefly go through ACE inhibitors.
The “prils”. Blocks the conversion of Ang1 to Ang2. Reduces vasoconstriction and water retention (via aldosterone decrease). Can also reverse cardiac hypertrophy. Which is why it is a staple drug used for patients who have had MI.
Adverse effects include first dose hypotension, dry cough, loss of taste, itch, foetal malformations. Contraindicated for pregnant women, and those with bilateral renal stenosis.
E.g. Captopril, Enalapril
Briefly go through angiotensin receptor antagonists.
The “sartans”. Block AT1 receptors resulting in reduction of vasoconstriction, aldosterone level, cardiac hypertrophy, sympathetic activity. Pretty much the same as ACE inhibitors, but they also have fewer side effects.
Only hyperkalaemia and headaches. Contraindications same as per ACE inhibitors.
E.g. Losartan, candersartan.
Briefly go through b-adrenoceptor antagonists.
The “olols”. Works to reduce CO. Reduces renin release, so also decreases blood volume and TPR. Varies with respect to selectivity, that is, some selective for B1,2, or both.
They can pass BBB, so can cause hallucinations/insomnia.
Cannot be used for diabetics as can cause fatigue, confused for hypoglycaemia.
Reflex alpha-1 constriction and blockade of dilatory B2 adrenoceptor can result in feeling very cold.
Even B1 selective (heart) can bronchoconstrict, so cannot be used for asthmatics.
E.g Propranolol, atenolol, pindolol.
Briefly go through calcium channel blockers.
Inhibits voltage gated L-type calcium channels in myocardium and vessels. They reduce cardiac and vascular contractility.
Two types: Dihydropyridines, which only act on vessels. They are felodipine and nifedipine. Adverse effect is tachycardia.
Verapamil and diltiazem affect myocardium. Adverse effect is bradycardia
Briefly go through thiazide diuretics.
They inhibits Na/Cl cotransporter in distal convoluted tubule. That results in decreased absorption of water and salt.
Loss of K+ as well through collecting duct occurs. Results in lower blood volume and reduction in blood pressure.
Adverse effects include gout, hyperglycaemia and allergic reactions.
Most common drug is hydrochlorothiazide.
