Anti-Hypertensives and Hypertension Flashcards
What two factors determine blood pressure?
Cardiac output and periveral vascular resistance.
BP = COTPR
TPR = total peripheral resistance
What circulating factors affect the inotropic state of cardiac muscle, heart rate and filling pressure?
sympathetic and parasympathetic activity, circulating hormones, intrinsic cardiac muscle function, volume regulatory hormones, renal function, volume intake, posture
What are the factors affecting peripheral vascular resistance?
sympathetic and parasympathetic activity, vasoconstrictor and dilator hormones, blood viscosity, blood volume, cardiac function
What do ACEI do in terms of bradykinins?
ACEI inhibit the arm of bradykinins that leads to inactive peptides and thus forces the bradykinin pathway into nitric oxide and prostaglandin production
What are the common ACEI that are in use?
Lisinopril, benazepril, captopril, enalapril, ramipril
How do ACEI drugs work?
inhibit Angiotensin Converting Enzyme, blocking angiotensin-II-mediated vasoconstriction and stimulation of aldosterone release.
*blocks degradation of bradykinin so there is the side effect of bronchoconstriction and stimulation of irritant receptors (cough)
How fast do ACEIs work and how long do they last?
onset of action within an hour. duration of action is 24 hours
What are the Adverse Effects of ACEIs?
Cough Hyperkalemia contraindicated in pregnancy Mild increase in serum creatinine Angioedema (rare) Anemia (rare)
When do you use ACEIs?
HTN, Heart failure, CKD, diabetic nephropathy, polycythemia
What are the commonly used Angiotensin II Receptor Blockers?
ARBs
*losartan, irbesartan, candesartan, valsartan
How do ARBs work?
ARBs = Angiotensin II Receptor Blockers
- irreversibly block angiotensin II action at AT1 receptor (not AT2?)
- prevents vasoconstriction and aldosterone release
Are there any differences in when you would use an ARB or an ACEI?
You use ACEI first, then if there is a cough or hyperkalmia, switch to ARB as the cough isn’t associated with it and the hyperkalemia is less too.
*but you use it in the same hypervolemic states as you would the ACEI
What are the commonly used calcium channel blockers?
Dihydropyridines and Non-dihydropyridines (DHP and NDHP)
DHP = amlodipine, nislodipine, nifedipine, felodipine
NDHP = diltiazem, verapamil
How do calcium channel blockers treat Hypertension?
Cause arterial vasodilation and lower peripheral vascular resistance by blocking L-type calcium channels
- blocking L-type calcium channels will inhibit the influx of extracellular calcium ions through calcium channels in the cellular membranes of myocardial, vascular smooth muscle, or cardiac conduction cells
- loss of extracellular calcium influx leads to decreased phosphodiesterase and increased cGMP levels
- increased cGMP levels leads to less vascular smooth muscle contractility and less cardiac contractility
How does blocking of a calcium channel in vascular smooth muscle result in less constriction?
- blocking L-type calcium channels will inhibit the influx of extracellular calcium ions through calcium channels in the cellular membranes of myocardial, vascular smooth muscle, or cardiac conduction cells
- loss of extracellular calcium influx leads to decreased phosphodiesterase and increased cGMP levels
- increased cGMP levels leads to less vascular smooth muscle contractility and less cardiac contractility
What is the difference between DHP and NHP calcium channel blockers in terms of receptors?
DHPs are more selective for L-type Ca channels in blood vessels (don’t do anything in the heart)
*NDHPs are equally sensitive for peripheral vascular channels AND cardiac channels, thus decrease conduction through AV node and have more modest inotropic and chronotropic actions
Are there any drug interaction concerns associated with calcium channel blockers?
Yes, absolutely. Both are metabolized by P450 enzymes, in particular 3A4.
*However, NDHP are way more inhibitory to the P450 enzymes than the DHP drugs so NDHP are the worrysome ones
What are the adverse effects of NDHP use?
NDHP, Calcium channel blockers
*nausea, headache, constipation, gingival hyperplasia, conduction deficits (can’t even use them in 2 or 3 degree heart blocks)
What are adverse effects in DHP drugs?
peripheral edema, reflex tachycardia, flushing, gingival hyperplasia, headache
what are the Beta blockers selective for Beta 1?
atenolol, metoprolol, bisoprolol
What are the Beta blockers that inhibit both beta-1 and beta-2 adrenergic receptors?
propanolol, timolol
What are the Beta AND alpha adrenergic blockers?
carvedilol, labetalol
How do Beta Blockers work?
compete with catecholamines at peripheral adrenergic neuron sites
- block cardiac receptors to decreased cardiac output
- blocks renin activity
What are the adverse effects of Beta Blocker use?
Fatigue, dyslipidemia, mask symptoms of hypoglycemia, sexual dysfunction, respiratory abnormalities
When might you use a Beta Blocker?
HTN, Angina, Prior MI/CAD (secondary prevention), Heart failure (metoprolol and carvedilol), migraine prophylaxis
Which two Beta blockers in particular were singled out for use in heart failure?
Heart failure Beta blockers = (metoprolol and carvedilol),
What two Direct Vasodilators did we talk about?
hydralazine and minoxidil.
*they act by directly vasodilating vascular smooth muscle
How does hydralazine do it’s work?
function = direct dilation of vascular smooth muscle. Alters calcium metabolism by release of NO from the drug and the endothelium. Calcium isn’t available to maintain contractile state.
How does Minoxidil work?
Potassium channel opener, which hyperpolarizes the cell and makes the membrane less susceptible to depolarization
Direct vasodilation will have what effect on the body?
Overall decreased peripheral vascular resistance (the desired effect in hypertension)
- preferential dilation of arterioles - protects against orthostatic hypotension
- increases HR and stroke volume
- increased renin secretion due to reflex sympathetic discharge
- aldosterone-mediated sodium reabsorption