Cardio- Antihypertensives Flashcards
what are the components of the blood pressure formula (BP)?
CO x PVR
what does the term baroreceptors refer to, and where specifically in the cardiovascular system does it apply?
moment to moment regulation of blood pressure.
in carotid artery and aorte- it monitors the stretch of the blood vessles.
how do baroreceptors react to an increase in stretch of blood vessels, as well as a contraction of blood vessels?
^ stretch -> baroreceptor stim. -> ˇ in SNS activity.
ˇ stretch -> ˇbaroreceptor activity -> ˆ SNS activity
how do kidneys control long-term blood pressure in kidneys* and what hormone is responsible for this mechanism?
when BP ˇ -> ˆ [renin]-> ^[angiotensin 2] -> constricts vessels -> ^ [aldosterone] -> ^Na+ retention and ^ in BLOOD VOLUME*
what are the normal levels for BP, as well as the hypertensive, and pre hypertensive?
optimal 115/75
hyper >140/90
pre 120/80
hows does Clonidine regulate BP?
CNS adrenergic neurons regulat BP, and there are alpha2 receptors on adrenergic nerver terminals in CNS. Clonidine is an alpha 2 agonist.
what is the clonidine mechanism in the body?
clonidine -> ˇ NE in CNS -> ˇ SNS and ˆ PSNS activity = ˇ CO & PVR.
what is the toxicity of clonidine?
CNS effects= sedation & impaired concentration
What is the effect of Beta Blockers on BP? (both in heat and kidney)
block of beta1 receptors in heart = ˇCO
block of beta1 receptors in juxta-glomerular region of kidney -> ˇ renin release = ˇPVR
name a non-selective beta blocker for BP, and name its toxicity.
propranolol,
toxicities associated with beta2 blockade (-asthma)
name a selective beta1 blocker.
Metoprolol
what are alpha block (in relation to BP), and their toxicity?
a selective alpha1 drug is prazosin. they block alpha 1 receptors in arterioles and venules. salt and water retention occurs, usually pairs with diuretics or beta blockers. and the toxicity is rare : dizziness, palpitations.
what are vasodilators, ie. what do they do?
they relax smooth muscles of arterioles, which ˇ PVR & ˇBP, some also relax veins. They work best in combination with other antihypertensives that oppose compensatory responses.
name a vasodilator that is a nitric oxide donor.
Sodium nitroprusside given IV for hypertensive emergencies. Its fact acting it dilates arterial and venous vessels. its toxicitiesL hypotension, cyanide accumulation
name a vasodilator that is a calcium channel blocker.
Verapamil used for long-term & emergency inhibits Ca2+ influx -> relaxation ->vasodilation also inhibits cardiac Ca2+ channels toxicity: bradycardia
what is ACE?
Angiotensin converting enzyme
it converts angiotensin 1 to angiotensin 2 by inactivation bradykinin
what is angiotensin 2, and what is its purpose
its a potent vasoconstrictor, and ˆ secretion of aldosterone and ADH
what is bradykinin?
its a vasodilator that increases [NO] and results in relaxation of the muscle.
what is aldosterone?
it increases Na+ reabsorption in distal tubules and collecting tubules (H2O will follow- osmosis)
ADH= antidiuretic hormone (vasopressin) increases the permeability of collecting ducts in kidney and increases the H2O reabsorption.
name an ACE inhibitor and its side effects.
Enalapril: prodrug that metabolized to active drug.
S.E.: cough, hypotension, dizziness, heachache
name an AT1 receptor Blocker (ARB). and its side effects
Losartan: effectiveness similar to ACE inhibitors, parent drug and metabolite active
S.E.: same as ACE inhibitor.
what is a diuretic?
decreases BP by depleting body of Na+
what diuretic could be use for mild-moderate hypertension? and how does it work?
hydrochlorothiazide
inhibits NaCL transport in distal convoluted tubule.
inexpensice and effective
toxicities: hypokalemia, gout, hyponatremia
what diuretic should be used for more powerful hypertensions? and gow dies it work?
Furosemide
inhibits co-transporter of Na+, K+ and Cl- in loop of henle.
rapid and short acting
toxicities: can cause dose dependent ontotoxicity (hearing loss)
what enhances the efficacy of diuretics?
ACE inhibitiors
what are the clinical steps to treat hypertension?
Na+ restriction (low salt diet) weight reduction initial monotherapy: -thiazide diuretic -ACE inhibitor or ARB -beta blocker, or Ca2+ channel blocker -Alpha1 blocker, centrally acting sympatholytics
what is combination step therapy, specifically what are the steps?
use in sever hypertension or if one group of drugs cannot control the hypertension. Done in this order:
- diuretic
- ACE inhibitor/ARB
- Calcium channel blocker
- sympatholytic/Vasodilator
what are the problems associate with the combination therapy?
lack of patient compliance
but there is fixed-dose combinations available, only thing is that you cannot titrate individual drug doses if needed.
