Treating hypertension Flashcards
What are some complications of hypertension?
Stroke
Kidney disease
Diabetes
What is the difference btw primary and secondary hypertension?
Primary hypertension has no obvious cause and/or is not related to any other diseases.
What are some causes of secondary hypertension?
Renal/renal disease
Endocrine disease (Cushing’s)
Iatrogenic - NSAIDS/hormonal oral contraceptive.
What is the equation for BP?
BP = CO x TPR
What is the equation for CO?
CO = HR x SV
What are 4 drug types usually used to control blood pressure?
ACE inhibitors
Angiotensin II receptor blockers
Calcium channel blocker
Diuretics
Name 2 ACE inhibitors
Captopril
Enalapril
How do ACE inhibitors work?
They inhibit angiotensin I converting enzyme, to stop the formation of angiotensin II which has effects on the renal system which increase H20 absorption, causes vasoconstriction, increases aldosterone production.
However due to there being no angiotensin II, less Na and water is reabsorbed, less aldosterone produced and less vasoconstriction occurs meaning more water lost via urine - lowering blood volume and therefore reducing blood pressure.
What is a side effect of ACE inhibitors?
Hyperkalemia
Cough due to inhibition of bradykinin breakdown.
What is an example of an ATII receptor blocker?
Losartan
What is a benefit of using an ATII blocker compared to an ACE inhibitor?
No cough
Better tolerated
What are some side effects of ATII antagonists
Hyperkalaemia
What are some calcium channel blockers which we would use to cause peripheral vasodilation?
Dihydropyridines such as nifedipine - they are more selective for the periphery which makes them better for lowering blood pressures.
They also reduce preload of the heart (filling pressure).
What are some effects of using dihydropyridines (such as nifedipine)
Peripheral oedema (due to vasodilation)
Dizziness
Constipation (lack of gut smooth muscle contraction)
May worsen GORD (due to relaxation of the smooth muscle in the lower oesophageal sphincter).
What are the different classes of diuretics?
Loop agents - such as furosemide
- potent - up to 30% of filtered Na
Thiazide - hydrochlorothiazide
- mild diuretic effect
- direct vasoconstrictor
K+ sparing - spironolactone
- weak diuretic
- useful to control K+ loss due to other diuretics.
What is the method of action of thiazides?
Blocks Na+-Cl- symporter in the first part of DCT, leading to an increase Na+ load and therefore Increased water content in the nephron of the kidney.
Also had a vasodilation effect therefore more water filtered into the nephron.
When are B blockers useful in treating hypertension?
B blockers are useful in hypertension where ACD has failed to achieve sufficient BP control.
- b1 selective antagonists decrease cardiac output and also decrease renin secretion.
Name a B1- selective B blocker?
atenolol
Name a a1 selective B blocker?
Carvedilol - improves coronary perfusion.
What are some side effects of B blockers
constipation
indigestion
hypotension
Give an example of an alpha blocker?
Prazosin
Doxazosin
When would we use alpha blockers to treat bp?
When bp has not been adequately controlled by ACD.
Aldosterone antagonism method.
Studies show that primary aldosteronism is common in patients with resistive hypertension.
Spironolactone can help with resistant hypertension.
Blocks the effect of aldosterone at DCT.
What are some side effects of spironolactone.
hyperkalemia - anti androgenic effect
When would we use A2 agonists?
A2 adrenoceptor agonist action inhibits NE release - primary act via SNS
Not very selective due to CNS effects
Reserved for extreme resistant hypertension
When can’t we use direct vasodilators to treat hypertension?
pregnancy
What are some direct vasodilators we can use to treat hypertension?
NO donors (glyceroltrinitrate) Hydralazine K+ channel activators.
