Anti hypertensives Flashcards
List the main drug classes of antihypertensives
- ACE inhibitors
- Angiotensin receptor blockers
- Beta blockers
- Calcium channel blockers (dihydropyridines)
- Diuretics
Describe the effect of ACE inhibitors
Inhibit the enzyme
=> prevent conversion of angiotensin 1 to 2.
Angiotensin II normally causes blood vessels to constrict, leading to an increase in blood pressure.
=> ACE inhibitors allow for vasodilation
By blocking angiotensin II, ACE inhibitors decrease aldosterone production, reducing fluid retention and lowering blood pressure.
List at least 2 ACE inhibitors
Lisinopril, Captopril, Enalapril
List at least 2 adverse effects of ACE inhibitors and in which group of patients are they contraindicated in.
Contraindicated in PREGNANCY
Adverse effects:
1. severe hypotension
2. acute renal failure
3. dry cough
List at least 2 Angiotension 2 type 1 blockers (AT1 blockers)
Valsartan, losartan, candesartan
What is the MOA of AT1 blockers?
Antagonist to AT1 receptors and hence Angiotension 2 cannot exert its effect
Main adverse effect of AT1 blockers and its contraindication
NO IN PREGNANCY
Less or no dry cough
List 3 beta 1 selective blockers
Atenolol
Bisoprolol
Metoprolol succinate
List a non selective beta blocker
Propranolol
Briefly explain why ACEi causes dry cough
ACE inactivates bradykinins.
When it is inhibited, bradykinin levels increases which causes the dry hacking cough.
List the 3 classes of drugs that are used as second line for hypertension
- Hydralazine
- Mineralocorticoid receptor antagonists
- Alpha-blockers
List 2 adverse effects of beta blockers
- Hypotension
- Bradycardia
- AV nodal block
- Reduced exercise capacity
- Bronchoconstriction
What is one group of patients where beta blockers must be used with caution?
Asthmatic patients as beta blockers can cause bronchoconstriction
Name a diuretic used as an anti-hypertensive
Thiazides:
- Hydrochlorothiazide
- Indapamide
Describe the MOA of thiazides
Inhibit NaCl reabsorption by blocking the sodium-chloride symporter.
Enhance Ca2+ reabsorption
List at least 3 adverse effects of thiazides
Thiazide - loop diuretic
Diuretics make you pee more
= loss of blood volume
= Loss of osmolarity
= all solutes become concentrated
- Hypokalaemia metabolic alkalosis
- Hyponatraemia
- Hyperuricaemia
- Hyperglycaemia
- Hyperlipidaemia
- Hypercalcaemia
** Hint: Since in renal we learnt that most of the reabsorption relies on the sodium electrochemical gradient and cotransport channels, if sodium reabsorption is inhibited, all these other substances don’t get reabsorbed either.
Name 2 alpha adrenergic antagonist
Prazosin
Alfuzosin
Terazosin
Describe the MOA of alpha adrenergic antagonists
Target alpha 1 adrenergic receptors on vascular smooth muscles that mediate vasoconstriction.
Antagonist prevents activation of alpha adrenergic receptors and hence keep the vessel tone lower
This reduces peripheral vascular resistance and hence lower BP.
Which drug can treat both hypertension and benign prostate hyperplasia?
Prazosin
What type of diuretics are likely to lead to hyperuricaemia and precipitate a gout attack?
Thiazide diuretics
Eg. Chlorothiazide
Which group of diuretic agents act preferentially on the collecting duct of the nephron?
ADH antagonists
What is the MOA of loop diuretics?
Inhibit the sodium-potassium-chloride cotransporter (NKCC2) in the thick ascending limb of the loop of Henle.
List at least 2 loop diuretics
Furosemide
Bumetanide
Torsemide
Which part of the nephron does loop diuretics act on?
Thick ascending limb of Loop of Henle
What is the MOA of thiazide diuretics?
Inhibits the Na/Cl co transporter in the DCT and hence block their reabsorption.
List a thiazide diuretic
Chlorothiazide, chlorthalidone
Which part of the nephron do thiazide diuretics act on?
DCT
List at least 2 potassium sparring diuretics
Spironolactone (aldosterone antagonist)
Amiloride (sodium channel blocker)
What is the MOA of spironolactone?
Aldosterone antagonist that acts on its receptors at the distal tubules and collecting duct.
Inhibit aldosterone from exerting its effects
Decrease Na reabsorption and K excretion.
What is the MOA of amiloride?
Potassium sparing diuretic
Act on the DCT and block sodium transport, thereby inhibiting sodium-potassiume exchange
Which part of the nephron does potassium sparing diuretics act on?
Collecting duct and DCT
What is the mechanism of action of ADH antagonist?
Block ADH from binding the vasopressin receptors and hence cannot exert its effect
What is the MOA of carbonic anhydrase inhibitors?
Inhibit the enzyme carbonic anhydrase in the PCT
Hence blocks the conversion of carbonic acid to bicarbonate and hydrogen ions.
This thus increase urinary excretion of bicarbonate, sodium and water.
What is the clinical indication for a carbonic anhydrase inhibitor?
Metabolic alkalosis
