Cardiovascular Drugs Flashcards
what is vascular tone
- the inward pressure of the blood vessels
1) vessel smooth muscle contraction/relaxation
2) vasoconstriction that reflexively occurs in response to stretching
3) neurotrans effects from ANS on receptors
4) hormones from nearby tissues effects on vessels
BP terms
SV = stroke volume, blood amount leaving LV with every contraction (bear) HR = rate of contractions TPR = total peripheral resistance force against which heart pushes to fill arteries, due to vascular tone of vessels in periphery SVR = systemic vascular resistance, includes arteries
– if any of these goes up, BP goes up, if any go down, BP goes down
math BP = CO x TPR CO = SV x HR TPR = SVR + venous tone BP = SV x HR x (SVR + Venous tone)
inotropy and chronotropy
inotropy = ventricular contractility chronotropy = heart rate
vascular tone and relation to vasocontriction/vasodilation
vasocontriction; increases vascular tone
vasodilation: does opposite
one of the most critical things to remember for HTN drugs
DO NOT abruptly discontinue, can cause rebound HTN (sudden very high increase in BP)
Numbers for HTN
Normal: 120/80 Prehypertensive: 120-139/80-89 HTN Stage I: 140-159/90-99 HTN Stage II: >160/>100 HTN Crisis: >180/>110 (emergency care needed)
making HTN diagnosis
1) after 2 readings seated in char
2) confirm in contralateral (opposite) arm to rule our underlying conditions like aortic coarctation
3) use higher reading (systolic or diastolic) to assign the HTN stage
can’t tell everyone same goal for HTN treatment but what’s the most common?
less than 140/90
what’s normal BMI
18.5-24.9 (weight kg/height cm)
lifestyle for HTN
1) physical activity: 30 minutes all/most days, 4 types
2) normal BMI
3) alcohol consumption: limit to one DE per day, 1-2 for men
4) proper diet: low Na+, adequate K+, veggies/fruits, low-fat dairy, low in sat fat (use DASH)
5) hot tub, avoid OTC drugs that raise BP
homeostasis to maintain a normal BP
- combo of neuro (ANS) and endocrine control
1) ANS control - balances - sympathetic - raises BP through catecholamines release
a) agonist beta-1: raise force of vent contraction (inotropy( and raise HR (chronotropy) and raise CO
b) agonist alpha-1: cause vasoconstriction of periph vessels and raises TPR - parasympathetic - lowers BP through CNX (vagus)
a) acetylcholine: on muscarinic receptors lower HR and force of vent contraction
b) nitric oxide NO cause peripheral vasodilation lowers TPR
2) endocrine - hormones change BP
- renin angiotensin system RAS
- natriuretic peptides
RAS
renin angiotensin system - activated when BP is low and kidney has reduced perfusion causing release of 3 hormones
1) angiotensin-II (ang-II): a vasoconstrictor stimulate aldosterone/ADH release, also cardiac effects
2) aldosterone: causes Na+/H2O reabsorption in kidney to increase IV volume
3) antidiuretic hormone ADH: promotes H2O reabsorption in kidney to increase IV volume, called vasopressin or AVP
overall: vasoconstrict periph vessels, increases TPR and increases IV volume (higher SV/CO)
natriuretic peptides
1) atrial natriuretic peptide or ANP
2) brain natriuretic peptide or BNP
- works opposite of RAS, cardiac atria gets stretched when blood volume too high and release ANP to promote diuresis
which hormones retain water and salt of ADH, ANP, and aldosterone?
aldosterone, ADH: retain water/salt
ANP: promotes diuresis
what happens when a person has HTN for a long period of time?
hypothalamus resets its normal and accepts higher BP value as normal
RAS syste’s relation to clotting systems?
if RAS is active patients is more prone to form clots
what would Ang-II cause?
RAS hormones are agonists mainly, would bind to AT1 receptor and cause a rise in BP/other cardio effects
Steps in the activation of RAS
1) first angiotensinogen is produced in the liver, this enzyme is inactive
- > 2) angiotensinogen is broken down by tPA and renin enzyme
3) angiotensinogen becomes angiotensin I (partially active)
- > 4) ACE (angiotensi converting enzymes) and enzymes in the tissue like chymase break down angiotensin I
5) angiotensin I becomes angiotensin II (highly active)
6) then angiotensin II works as an agonist on AT1 receptors to increase BP
*** during this time vasodilators (bradykinins) are being degraded, ACE1 drugs may prevent this and improve vasodilation but can cause cough/angioedema
overall:
a) produces hormones that are vasoconstrictors and volume expanders (salt retention eg)
b) destruction of vasodilators
c) causes overall vasoconstriction and icreased blood volume hence higher BP
AT1 vs AT2 receptors
these are receptors that hormones in the RAS bind to as agonists
AT1: causes vasoconstriction, endothelial mitotic effects, and release of ADH/aldosterone (salt/water retention, increased blood volume)
AT2: causes vasodilation, opposite of AT1
essential (primary) vs secondary HTN
primary: don’t have underlying medical condition causing HTN, most common in ADULTS
secondary: underlying med condition, more likely in CHILDREN
hypertensive urgency vs hypertensive emergency
1) URGENCY
- SBP: >180, DBP: >110
- no organ damage
sx: severe headache, SOB, nosebleed, severe anxiety
tx: readjust meds, no hospitalization/parenteral drugs
2) EMERGENCY
- SBP >180, DBP >120
- could occur at lower leve,s MAIN SIGN is organ damage
examples: stroke, LoC, memory loss, MI, eye/kidney damage, renal failure, aortic dissection, angina, pulmonary edema, eclampsia
tx: in hospital - nursing care ECG tracing
- parenteral meds: nitroprusside IV or substitute nitroglycerin IV, nicardipine IV (postop HTN), fenoldopam/Corlopam IV (vasodilator)
ADPIE of pediatric HTN
A/D: look up child’s age sex on table of normal values and if >95th %tile on 3> occasions (preHTN = >90%tile but
How are drugs for HTN classified?
by their MOA
INTRO
1) arterioles as site of MOA: drugs working as vasodilators
- review: if arterioles are vasoconstricted, TPR increases, TPR is the force against which the heart pumps when filling arteries, TPR sometimes called afterload, if arterioles are vasodilated then VP will lower
2) capacitance venules as MOA site: drugs here are vasodilators
- review: capacitance venules are veins in lower extremities and viscera capable of storing large amounts of blood; normally blood returned to heart by venous system and provides blood for SV, called preload
- this reduces SV and CO
3) heart site of MOA: drugs here are negative chronotropes and inotropes (remember chronotropy = heart rate, so negative chronotrope means slow the heart rate; inotropy means forceful contraction so negative inotropes make the contractions less forceful)
- lower SV and BP
4) kidney as MOA site: work as RAS blockers and diuretics
- review: if RAS inhibited then no release of Ang-II, aldosterone, ADH
- since RAS causes vasoconstriction/volume retention, these result in vasodilation and reduced blood volume and thus lower BP
what are some common drug clases used to treat HTN?
1) Ca+ channel blockers (CCB): vasodilators
2) RAS blockers like ACEIs (ACE inhibitors), ARBs (angiotensin receptor blockers) and DRI (direct renin inhibitors): basodilators and reduce blood volume
3) alpha-blockers: vasodilators
4) beta-blockers: negative chronotropes/negative inotropes
5) diureticsL reduce blood volume and thus SV
6) other: older drugs like clonidine work on CNS site to affect ANS function
Diuretics overview and categories
Overview of DIUR
- diuresis: loss of body water through urination
- DIUR reduce ECF volume by stimulation natriuresis (salt in urine that drags out water)L urine production reduces blood volume
- vary by MOA site in kidney
remember: K+ wasting DUR may need supplements, K+ sparing can lead to hyperkalemia
Categories
1) thiazide diuretics
2) loop DIUR
3) aldosterone antagonists (aldoANT)
4) osmotic diuretics
5) carbonic anhydrase inhibitors
6) AVP (arginine vasopressin) (ADH) antagonists)
7) synthetic hyman B-type ANP
thiazide DIUR
- K+ wasting though very mild so may not need K+ supplements
- don’t work in patients with kidney disease (creatinine >1.5)
MOA: site in proximal nephrone (proximal tubule) to inhibit Na+ reabsorption - allows natriuresis (Na+ exretion and diuresis)
DRUGS
1) hydrochlorthiazide (HCTZ, Diuril)
2) chlorthalidone (Hygroton)
3) metolazone (Zaroxolyn, Mykrox, unsual/powerful)
4) methyclothiazide (Enduron)
5) indapamide
Usefulness: treat HTN, treat edema; reduce calciuria so prevent Ca+ kidney stones
AEs: aside from mild a) hypokalemia b) high dose AE on cholesterol c) patients with sulfa allergy may be allergic d) increased blood glucose and could develop DM2 e) gout may develop since thiazides may raise uric acid levels
Loop DIUR
- more powerful DIUR, work even in kidney disease
- K+ wasting and may cause more severe hypokalemia -> supplements
MOA: in loop of Henle of kidney and block Na+ reabsorption promoting atriuresis
Drugs 1) furosemide (Lasix) 2) ethacrynic acid (Edecrin) 3) bumetanide (Bumex, shorter acting) 4) torsemide (Demadex) (available PO and IV/IM)
Usefulness: not just for HTN, also for severe edema
AEs aside form hypokalemia
a) sulfa allergy except for ethacrynic acid
aldoANT
alodsterone antagonists
- K+ sparing can severe hyperkalemia causing life-threatening cardiac arrhythmias
MOA: distal nephrone as aldosterone antagonists so Na+ ot reabsorbed and natriuresis occurs
Drugs
1) amiloride (Midamor)
2) spironolactone (Aldactone)
3) triamterene (Dyrenium)
4) combos
5) newer = eplerenone (Inspra): used only for severe cardiac failure
Other uses: tumors producing aldosterone (Conn’s syndrome); off-label - treatment of hirsutism (excessive facial hair)
Combo drugs
1) often combined with K+ wasting diuretics such as triamterene + HCTZ or spirinolactone + HCTZ etc
AEs
a) severe hyperkalemia - never add K+ supplements and CAUTION with RAS blockade drugs
Osmotic Diuretics
- not usually for HTN
MOA: act as a particle in the renal tubules to to drag water out of body in urine
Drugs
1) mannitol (Resectisol, Osmitrol)
usefulness: edema syndromes, intra-cranial pressure, keep blood flowing in transplanted kidneys
carbonic anhydrase inhibitors
- also not usually for HTN
- mildly K+ wasting
MOA: bocks enzyme needed for sodium bicarbonate (NaHCO3) reabsorbtion promoting natriuresis - ALSO reduces aqueous humor formation in anterior chamber of eye
Drug
1) acetazolamide (Diamox)
Usefulness: managing glaucoma since drug reduces IOP
- others based on other effects, metabolic alkalosis, aspirin overdose, prevent acute mountain sickness, catamenial epilesy
AEs
a) kidney stones
b) hypokalemia
c) sulfa allergy may
d) may worsen liver failure encephalopathy (increases serum ammonia)
AVP antagonsists
what is ADH
- has 2 names: both ADH and AVP
when AVP: thinking ability to cause vasoconstriction
when ADH: thinking of action on kidney to cause reabsorption of water
MOA: antagonize ADH and promote water excretion in urine
Usefulness: treating SIADH (syndrome of inappropriate ADH secretion) which can occur after head trauma or from ANY CNS lesion; treating hyponatremia
Drugs
OLDER
1) demeclocycline (tetracycline derivative, Declomycin)
2) lithium salts (Lithonate, Lithotabs, Eskalith)
NEWER
3) conivaptan (Vaprisol) IV: for severe hyponatreia
Synthetic Human B-type atrial natriuretic Peptide (ANP)
- IV infusion of the same hormone that the atria normally make in conditions of volume overload
Usefulness: in severe edematous heart failure
potential AE: hypotension
drugs
1) nesitiride (Natrecor IV)
types of adrenergic antagonists
also called blockers, block sympathetic nervous sytem
1) beta-blockers (BB)
2) alpha-blockers
Beta-blockers (BB)
MOA: block catecholamine (sympathetic effects at the beta receptors
phys review
beta-1: receptors on heart, positive chronotropy and positive inotropy (some beta-1 on kidney and can activate RAS)
beta-2 receptors on lung, bronchodilate
beta-3: metabolic effects on glucose and lipids
THING TO KNOW
1) blockade can be non-selective or selective
selective: for beta-1 only
non-selective: for beta-1 and 2
2) some BB also block alpha-1, called alpha-beta blockers
AEs of beta-blockade:
1) bronchoconstriction due to beta-2 blockade
2) adverse metabolic effects on glucose and lipids (beta-3 blockade)
which beta receptor is blocked when treating HTN?
beta-1
causes negative chronotropy, negative inotropy
and blockade of renin release (reduce RAS activity)
which BB crosses the BBB? what implication does this have? list the two examples of BB’s that don’t cross the BBB
1) lipophilic BB
2) can cause CNS side effects
3) non-lipophilic: atenolol (Tenormin), nadolol (Corgard)
selective BBs do what? what’s the benefit of them? name the main example
1) beta-1 blockade
2) less chance of pulmonary bronchoconstriction
3) metoprolol (Lopressor) and atenolol (Tenormin); another is the ocular glaucoma drug betaxolol (Betopic)
what’s a big side effect of non-selective BBs? examples?
1) bronchoconstriction
2) propranolol (Inderal), nadolol (Corgard), glaucoma ocular BB timolol (Timoptic)
adverse _____ effects may occur with BBs, what are some that pertain
1) lipid effects
2) lipid neutral: pindolol (Visken)&acebutolol (Sectral), and metoprolol (Lopressor)
ISA
intrinsic sympathomimetic activityL means drug can stimulate as well as block the beta-1 receptor, may cause raised HR and BP and hurt cardiac patients
examples: pindolol (Visken)&acebutolol(Sectral) and the ocular glaucoma drug careteolol (Ocupres)
what’s a long-acting BB that allows once-daily dosing
propranolol-XL
what’s special about nadolol (Corgard)?
can be used in liver failure since not hepatically degraded
what’s special about the alpha-beta blockers?
can improve HTN by periph vasodilation
ex: carvedilol (Coreg, Coreg-CR), labetolol (Normodyne, Trandate)