CH 11: Anti-hypertensives Flashcards
Hypertension
disease processes that result in a sustained elevation of blood pressure from:
- Renal artery stenosis
- Aortic coarctation
- Pheochromocytoma, Cushing’s or Hyperthyroidism
- Variety of drugs/ chemicals
U- Unknown (called PRIMARY HYPERTENSION” (most cases; 90%))
What is hypertension? (JNC 7)
Normal BP < 120 % < 80 Prehypertensive/elevated 120-129 & <80 Hypertensive * stage 1 = 130-139 or 80-89 * stage 2 = >139 or >89
How do we lower B.P?
with stage 1 or 2 hypertension, we could start with one or two medications
Why should we lower B.P?
If we lower B.P. we decrease morbidity and mortality (health costs, etc)
Hypertension is associated with:
- stroke
- cerebral hemorrhage
- CHF
- renal failure
- hypertensive crisis
- end organ damage
BP data
for every 20 mmHh systolic or 10 mmHg diastolic increase in BP over 115/75, there is a doubling of mortality for both ischemic heart disease and stroke
Hypertension Factoids:
- in 2000, 1 billion people worldwide had hypertension
- hypertension is leading risk factor for cause of death worldwide (51% of strokes and 45% of ischemic heart disease deaths attributable to hypertension
- in U.S., 1 in 3 adults over 20 have it, and estimated 30% are pre-hypertensive
pathophysiology
genetic factors:
we see families and groups where it is more prevalent, and various groups respond to different treatments
environment:
smoking, caffeine, alcohol, obesity, vit. D deficiency
neural effects:
Symp NS, others
renal effects:
reduced sodium excretion
hormonal effects:
RAAS, others
vascular effects:
vasoconstrictors, atherosclerosis, remodeling, etc
Strategies to lowering B.P
REDUCE TOTAL PERIPHERAL RESISTANCE (TPR) BY:
- decrease ANS (automatic nervous system)
- decrease RAAS (renin angiotensin aldosterone system)
- decrease endothelin or vasoactivity (Ca blockers)
REDUCE CARDIAC OUTPUT (CO)
- decrease heart rate (HR)
- decrease blood volume (diuretics)
- increase venous capacitance (alpha blockers)
what are some types of antihypertensives
- Diuretics
- Blockers of Sympathetic N.S
(sympathoplegics) - Blockers of RAS (RAAS)
- Vasodilators
- Calcium Channel Blockers
Diuretics
- increase urine output and reduce blood volume, thus lowering CO
- Can be used alone or * with other anti-hypertensives
- Look at normal kidney functioning
- Glomerulus: forms plasma filtrate
- Proximal tubule:
What are some types of Diuretics?
Carbonic anhydrase inhibitors
Thiazide diuretics
Loop Diuretics/ High Ceiling diuretics
Potassium sparing
Carbonic anhydrase inhibitors
a type of diuretic
NOT VERY efficacious at lowering B.P
ex: Acetazolamide
- work at proximal tubule to block CA
- mostly for glaucoma & metabolic alkalosis
Effects:
decrease HCO3- reabsorption
alkaline urine
increased K+ excretion
Thiazide diuretics
INTERMEDIATE efficacy
- Hydrochlorothiazide, chlorthalidone, and others
- inhibit Na+Cl- symporter in distal tubule
- increase K+ loss (Na-K exchanger in collecting duct)
Side effects:
Hypokalemia
Hyperuricemia (compete with uric acid for prom tubule secretion… can lead to gout)
Loop Diuretics/ High Ceiling Diuretics
MOST efficacious
- Bumetanide, furosemide
- inhibit Na-K-2CL transporter in asc. Loop
- Cal lead to profound diuresis, but also to electrolyte imbalance
Side effects:
Hypokalemia, Hypocalcemia, Hypomagnesemia
Metabolic alkalosis (due to H+ loss)
Potassium Sparing
MILD efficacy
- Amiloride, triamterene, spironolactone
- act in collecting duct to decrease K+ and increase Na+ excretion (some compete with aldosterone)
- Ofter used with Loop or Thiazide diuretics
Side effects:
Hyperkalemia (reduce K+ supplements)