02/01/16 Flashcards
USA HTN Stats
- >20 years old: ~33% hypertensive
- >40 million ambulatory care visits
- >50% nursing home patients
- ~30% unaware
HTN Diagnosis
- Hypertension: an elevation of arterial blood pressure above an arbitrarily defined normal value
HTN Symptoms
- Stage 1:
- No symptoms
- Stage 2:
- Headache
- Somnolence
- Confusion
- Vision disturbances
- nausea
- vomiting
Consequences of chronic hypertension
- peripheral vascular disease
- myocardial infarction
- heart failure
- aneurysm
- renal failure
- retinopathy
- stroke
- atherosclerosis
Primary (or Essential) HTN
- ~90-95%: causes unknown
- Due to multiple genetic/environmental factors:
- nutrition
- SNPs
- age
- obesity: 85% in BMI>25
- renin levels
- substance abuse
Secondary HTN
- ~5% of all cases of hypertension
- Due to identifiable secondary conditions
- renal disease: nephritis
- anatomical CVS defects
- CAD
- adrenal disorders
- tumors
Mean Arterial Pressure equation
- MAP=CO*(TPR/SV)
Strategies to treat HTN
- Decrease cardiac output
- Beta adrenergic receptor antagonists
- Cardiac Ca2+ channel blockers
- alpha-2 adrenergic receptor agonists
- Decrease plasma volume
- thiazides
- loop diuretics
- ACE inhibitors/angiotensin II receptor antagonists
- Decrease TPR
- alpha-2 adrenergic receptor agonists
- ACE inhibitors/angiotensin II receptor antagonists
- Vasodilators
- alpha-1 adrenergic receptor antagonists
- endothelin receptor antagonists
- vascular smooth muscle Ca2+ channel blockers
HTN Drug Summary: Figure
Thiazides: Name, MOA, toxicity
- Hydrochlorothiazide: Microzide
- MOA:
- inhibit apical Na+/Cl- transporter (NCC) in DCT
- Toxicity:
- hypokalemic metabolic alkalosis
Thiazides use in HTN
- Initial therapy for Stage 1 HTN
- Decrease SBP ~10-15 mmHg
- Advised for patients with normal renal function
- Combination therapies
- Aldactazide: HCT, spironolactone
- Zestoretic: HCT, lisinopril
- Diovan HCT: HCT, valsartan
Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT)
- 42,418 participants
- Thiazide>>>ACE-I/ARB>>>Ca2+ channel blocker>>>alpha 1 blocker
- Thiazide for stage I/II HTN
- Diuretic intolerant patients: Ca2+ channel blocker or RAAS blockers
- Use>1 drug
- Exercise, change diet, stress
Loop Diuretics: Name, MOA, toxicities
- Furosemide: Lasix
- MOA:
- inhibit apical Na+/K+/2Cl- transporter (NKCC2) in TALOH
- Toxicity:
- hypokalemic metabolic alkalosis
Loop use in HTN
- Moderate to severe HTN
- Decrease SBP ~30 mmHg
- HTN crisis
- begin with low dose
- shorter duration of action than thiazides
- enhance urinary Ca2+ loss- consideration when treating elderly
RAAS Inhibitors: MOA Figure
Macula Densa regulates Renin release: Big Picture Figure
Macula Densa regulates Renin Release: Up Close Figure
Macula Densa regulates renin release
- Decrease BP→Decrease GFR→Decrease [Na+Cl-] in distal tubule→Increase PGE2/I2
- Stimulate EP2/EP4/IP receptors→increase renin→increase BP
- Increase BP→Increase GFR→Increase [Na+Cl-] in distal tubule→increase ATP/adenosine
- Stimulate A1 receptors→decrease renin→decrease BP
- Angiotensin-II inhibits renin release in JG cells (negative feedback loop)
Renin release mechanisms in JG cells: Figure
Renin levels in HTN
- Renin levels can vary between patients
- Important for therapy decision
- ~60%: normal renin
- ~15%: increased renin
- young, caucasian, males
- increase SNS activity, stress
- treat with ACE-I, ARBS
- ~25%: decreased renin
- old, AA, females
- increase Na+ retention
- treat with diuretics, Ca2+ channel blockers
ACE-I: Drug names
- Captopril: Capoten
- Fosinopril: Monopril
- Enalapril: Vasotec
- Lisinopril: Prinivil
- Ramipril: Altace
ACE-I: MOA
- inhibit ACE
- Decrease conversion of ATI→ATII
- Decrease TPR→decrease BP
- decrease aldosterone/VP→decrease plasma volume→decrease BP
- decrease CVS remodeling
ACE-I: PK
- Oral; most are pro-drugs
- captopril t1/2=2 h, lisinopril=12-24 h
- excreted in urine
ACE-I: Toxicity
- severe hypotension/acute renal failure
- decrease ACE=increase BK/substance P→cough reflex
- angioedema
- hyperkalemia
- teratogenic
ARBs: Drugs
- Losartan: Cozaar
- Omesartan: Benicar
- Telmisartan: Micardis
- Valsartan: Diovan
ARB: MOA
- 2 ATII GPCR subtypes;
- ATII-1→Gq/11→vasocontriction
- ATII-2→Gi2/3→vasodilation
- ARBs antagonist ATII-1
- decrease TPR, decrease BP
- ATII-2 active
- Increase vasodilation
- Decrease TPR, decrease BP
- Decrease aldosteron/VP
- Decrease plasma volume, decrease BP
- Decrease CVS remodeling
ARB: PK
- Oral; some are pro-drugs
- losartan t1/2= 2 h, telmisartan= ~24 h
- excreted in urine
ARB: toxicity
- severe hyoptension/acute renal failure
- no cough!
- less angioedema
- hyperkalemia
- teratogenic
Renin Inhibtors: Drug Name
- Aliskiren: Tekturna
- Remikiren
Renin Inhibitors: MOA
- inhibit renin
- decrease ATII production