17-Drugs for Hypertension Flashcards
Primary “essential” hypertension
- No known cause, can be caused due to a genetic predisposition, dietary salt intake, adrenergic tone
- represents 90 - 95% of cases
Secondary hypertension
- high blood pressure caused by the effects of another disease (known cause)
- represents 5 - 10% of cases
- examples: pheochromocytoma, adrenal cortical tumours, drugs
Physiological effects of hypertension (3)
- loss of responsiveness –> prolonged force thickens arterial muscles (heart recieves less blood)
- L ventricle thickens –> bc heart has to pump blood against a greater force (increases workload)
- Narrowing of lumen/atherosclerosis –> bc increased force damages inner lining of arteries
How can HTN lead to a loss in vision, kidney + cerebral function?
Tiny vessels are damaged, leading to these diseases.
3 factors that affect blood pressure (and what causes them)
- Blood volume: due to fluid loss + fluid retention
- TPR/diameter of vessels: due to SNS activity, renin/angiotensin 2, increased viscosity
- CO: affected by SV & HR
What 3 factors affect the stroke volume?
preload, contractility, afterload
What systems of the ANS affects HR?
SNS, PSNS, and epinephrine
Describe how the CV system & kidneys work to regulate high blood pressure.
CV system:
- vasodilation
- decreased SV and HR (both of these will decrease CO & BP)
Kidneys:
- increases urine output –> less BV –> decreased BP
Describe a high risk, moderate to high risk & low risk patient for hypertension.
High risk: has DM
Moderate to high risk: multiple CV risk factors, target organ damage, OVER 75
Low risk: No CV risk factors or organ damage
What is the reccommended amount of alcohol consumption to be considered “low risk”?
Men: < 14 drinks/week
Women: < 9 drinks/week
What is the minimum reccommended amount of physical activity?
4 days/week for 30-60 mins & moderate cardio
Start pharmacotherapy if BP is ____________ or more for a diabetic patient.
130/80
Which type of diuretic is preferred? Long-acting or short acting?
long-acting
Give an example of a short-acting diuretic
Hydroclorothiazide
T or F: Beta blockers are a first-line therapy for those 60 and above.
FALSE!
T or F: RAS inhibitors are contraindicated in pregnancy.
True
What class of drugs are first-line therapy for reducing HTN?
Diuretics
Describe the mechanism of action of diuretics for reducing blood pressure.
Reduces SV by blocking Na/Cl transporters in kidneys –> electrolytes & water are excreted –> BV decreases (and BP)
T or F: Diuretics are safe to use in pregnancy.
FALSE - diuretics are contraindicated in pregnancy bc the loss of fluid + electrolyte imbalances can have a damaging effect on the fetus.
What are some side effects/consequences of diuretics?
Orthostatic hypotension, hypokalemia, GI upset, hyperglycemia
What is the onset and duration of thiazide diuretics?
Onset: 2 hrs
Duration: 6-12 hrs
What are some nursing considerations for patients on diuretics? What should patients monitor/report?
- Monitor Na/K levels, kidney function & BP (w/in 4-6 wks of starting therapy)
- Monitor fluid output & weight gain/loss, report lightheadedness/dizziness
How does angiotensin 2 affect BP? (2 ways)
- Increases TPR in vasculature (vasoconstriction)
2. Stimulates secretion of aldosterone/ADH
Pharmacological inhibition of RAAS (which class of drugs are used & what does it result in?)
- ACE inhibitors & ARBs
- decreases TPR & BV
Describe the mechanism of action of ACE inhibitors.
- prevents conversion of angiotensin 2
- increases production of vasodilatory kinins
- inhibits aldosterone secretion (reduces Na & water retention)
*All these things decreases TPR & BV
T or F: ACE inhibitors should be combined with NSAIDs to manage HTN.
FALSE! Using them in conjunction w/ NSAIDs decreases the antihypertensive activity.
What is the first dose phenomenon?
A sudden drop in BP leads to reflex tachycardia (more likely to pass out/fall).
Angioedema
Allergic rxn of the lips, mouth and throat (medical emergency)
Side effects of ACE inhibitors
- persistent dry cough
- hyperkalemia
- constipation/GI irritation
- angioedema
- first dose phenomenon
Describe the mechanism of action of ARBs.
- blocks angiotensin 2 receptors in arteries + adrenal cortex
- inhibits release of aldosterone
- no effect on bradykinin
*These things decrease TPR & BV
T or F: ACE inhibitors are more efficacious than ARBs.
False, they are equal in efficacy!
Describe the mechanism of action of CCBs.
- Relaxes vascular smooth muscle & decreases TPR by blocking Ca channels (no contractions).
- It slows the HR and reduces CO.