Drugs for Hypertension Flashcards
what is primary “essential” hypertension?
- no known cause, represents 90-95% of cases
- genetic predisposition, dietary salt intake, adrenergic tone
what is secondary hypertension?
- known cause; represents 5-10% of cases
- ex. adrenal cortical tumours, drugs
what are the physiological effects of hypertension?
- prolonged force on vessels thickens muscles in the arterial system
- heart constantly works harder to expel blood against a greater force, increasing the workload of the heart
- increase force damages inner lining of arteries (susceptible to atherosclerosis and to narrowing of vessel lumen)
- tiny vessels are damaged and destroyed leading to losses in vision, kidney function and cerebral function
what is hypertension a risk factor for?
- CVA, CAD, CHF, cardiac death, renal failure, peripheral vascular disease, and dementia
what parameters control BP?
- BP=CO X peripheral resistance
- CO: product of heart rate and amount of blood that is ejected with each beat (stroke volume)
- peripheral resistance: arteries possess smooth muscle in the media that responds to alpha 1 receptors. when stimulated they produce contraction of the smooth muscle layer and increase lumen of the vessel increasing peripheral resistance
what is the compensatory action by kidneys to regulate blood pressure?
- engages kidneys to increase urine output, reducing blood volume and stroke volume decreasing blood pressure
what is the compensatory action of the cardiovascular system to regulate blood pressure?
- decreases in heart rate cause decrease in cardiac output, which decreases blood pressure; also causing vasodilation in periphery
what are some lifestyle modifications with hypertension?
- reduce sodium intake
- healthy diet
- low risk alcohol consumption
- regular physical activity
- maintenance of ideal body weight
- smoking cessation
- stress management
why should beta blockers not be used as a mono therapy for hypertension in those 60+?
- do not help to decrease the risk for myocardial infarction or stroke
what is the mechanism of action of thiazide and thiazide- like diuretics?
- first line therapy for management of hypertension
- reduces stroke volume by blocking sodium/chloride transporter in the distal tubule facilitating the excretion of electrolytes
what are some caution precautions when using thiazide diuretics?
- severe renal disease, diabetes, GOUT, liver disease, hyperlipidemia
when are thiazide diuretics contraindicated?
- pregnancy
when should thiazide diuretics be administered?
- during the day to prevent nocturia
what are some adverse effects of thiazide diuretics?
- GI upset, orthostatic hypotension, hyperglycaemia, fluid and electrolyte imbalance
what are some drug to drug interactions with thiazide diuretics?
- lithium, NSAIDs, anti diabetic drugs
what is important to monitor with thiazide diuretics?
- sodium and potassium levels, kidney function and blood pressure within 4-6 weeks of starting therapy
- dizziness and lightheadedness
what is the mechanism of action of angiotensin converting enzyme (ACE inhibitors)?
- decreases peripheral resistance and decrease blood volume
- blocks conversion of angiotensin I to angiotensin II
- increase production of vasodilatory kinins
- inhibits aldosterone secretion
when are ACE inhibitors contraindicated?
- in pregnancy, use caution with potassium-sparing supplements and diuretics
- decreased antihypertensive activity with NSAIDS
what are some adverse effects with ACE inhibitors?
- may induce dry cough
- hyperkalemia
- GI irritation and constipation
- sudden drop in BP (first dose phenomenon)
- allergic reaction of the lips, mouth, and throat occurring during first month of administration
what is the mechanism of action of angiotensin II receptor blockers?
- decrease peripheral resistance and decreases blood volume
- block angiotensin II receptors in arteriolar smooth muscle and in adrenal cortex
- inhibit the release of aldosterone
- no effect on bradykinin
what type of patients are prescribed angiotensin II receptor blockers?
- people who cannot tolerate adverse effects of ACE inhibitor drugs
what are the common adverse effects and drug to drug interactions with angiotensin II receptor blockers?
- similar to ACE inhibitors
what is the mechanism of action for calcium channel blockers?
- block calcium ion channels
- relax vascular smooth muscle, decreasing peripheral resistance
- slow heart rate , reducing cardiac output and cardiac workload
when should you be cautious administering calcium channel blockers?
- in those with liver and kidney impairment
