Antihypertensives Flashcards
What regulates Blood pressure
- barorerceptor reflex
- kidneys
- adrenal gland
- hypothalamus and pituitary glands
What is the baroreceptor reflex
- as blood pressure increases heart rate decreases
or - as blood pressure decreases heart rate increases
How can blood pressure by modified
- lifestyle
- stress
- diet
- fluid and electrolyte levels
- organ function (heart failure means you have a harder time maintaining BP)
What is normal blood pressure
- <120/<80 mmHg
What is pre-hypertensive BP?
- 120-139/80-89mmHg
What is hypertensive BP
- > 140/>90 mmHg
What is BP a product of
- total peripheral resistance and cardiac output
- BP (HRxSV)xTPR
what makes up cardiac output
- heart rate and stroke volume
what are the classes of drugs for hypertension
- diuretics
- sympatholytics
- vasodilators
- ACE inhibitors
- calcium channel blockers
Diuretics:
- often the first drug used to reduce hypertension if lifestyle changes do not work
- reduce fluid load in the vascular system
- reduced fluid reduces the Total peripheral resistance
Types of diuretics
- Thiazide
- loop
- potassium-sparing
Thiazide diuretics:
- proximal tubule of the kidney
- inhibit rreabsorption of sodium into vasculature
- Na and water retained in nephron and excreted from body
Loop diuretics
- work on the loop of henle
- inhibit reabsorption of Na and Cl into circulation
- retains water in the nephron and excretes it from the body
- stronger than thiazide - loses the most water
- can be used long/short term
Potassium-sparing diuretics
- distal tubule
- prevent secretion of K+ into the distal tubule
- Na and water are retained and excreted
- less diuretic effect but reduces potassium loss
- does not reduce peripheral resistance as much
What are the side effects of diuretics
- electrolyte imbalance:
1. hypokalemia: can cause heart arrhythmia
2. hyponatremia: can cause muscle cramping - dizziness, orthostatic hypotension
- muscle weakness
- may cause reflex increase in cardiac output due to reduced BP
What are examples of sympatholytics and when are they used
- 2nd line of defense
- beta blockers (B1)
- alpha-1 blockers to reduce constriction
vasodilators:
- reduce peripheral vascular resistance using second-messenger system
- cause a change within the cell to increase vasodilation
side effects of vasodilators
- dizziness
- orthostatic hypotension
- reflex tachycardia due to the drop in BP
- weakness
- nausea, headache
- hair growth
Renin-angiotension system inhibitors
- next step and affect the kidneys and adrenal gland
- ACE inhibitors
- Angiotensin II receptor blockers
ACE inhibitors
- block conversion of angiotensin 1 to angiotensin II
- example: end in =pril
Angiotensin II receptor blockers
- bind so that angiotensin II cannot bind
- decrease vasooconstriction
- decrease aldosterone release and retention of salt and water
- decrease the affects of angiotensin
ACE inhibitor side effects
- dry cough (angiotensin is also in the lungs)
- rash
Angiotensin II blockers as a BP medication
- very few side effects
- not as affective as other BP medications and usually taken with other BP meds
Calcium-channel blockers
- reduce contractile process in smooth vasculature and causes vasodilation
- also used to teat angina due to myocardia ischemia
- used with caution due to possible increase risk of heart attack and cancer
Calcium-channel blockers side effects
- orthostatic hypotension
- reflex tachycardia
- these are reduced with extended release forms which have different layers that when digested it releases small doses over time