Anti-HTN Drugs Flashcards
(33 cards)
What classes of drugs are used for treating HTN?
Alpha1 blockers, beta-blockers, ACEI, ARBs, renin inhibitors, L-type Ca+ channel blockers, centrally acting alpha2 agonists, direct vasodilators
What are the pharmacological effects of alpha1 receptor blockers?
- decrease TPR & reduce BP
- treat benign prostatic hyperplasia (BPH)
- increase HDL and lower LDL, improve insulin resistance
How are apha1 receptor blockers used to treat hypertension?
Given as an adjunctive therapy. Not recommended as monotherapy by ALLHAT study.
Which patients with hypertension benefit from a beta-blocker?
Effective for all grades of HTN. No salt/water retention, can be taken with diuretic for additive effect.
Very useful in patients with high renin HTN, but work with normal-low renin.
Preferred for patients with MI, IHD, CHF, hyperthyroidism, migraines.
What are the pharmacological effects of beta-blockers (with no ISA)?
- Block beta-1 receptors
- Decrease HR and contractility → decreased CO
- Inhibit renin release from JGA
What are the adverse effects of beta-blockers?
- cold extremities
- bradycardia from decreased AV node conduction
- bronchospasm
- CNS: bad dreams, depression
- block glycogenolysis
- block HSL in adipocytes, increase LDL & TGs, reduce HDL
- must withdraw slowly to prevent tachycardia
What drug is given for hypertensive emergencies?
Labetalol - non-selective beta + alpha1 receptor antagonist
What are the effects of carvedilol?
- Non-selective beta + alpha1 receptor antagonist
- antioxidant
- prevents LDL oxidation, decreases LDL uptake into coronary vessels
- decreased m/m in pts with CHF
What are the effects of Nebivolol?
- highly selective beta1 antagonist
- NO-mediated vasodilation
- significantly increases SV
- antioxidant activity with favorable effects - used for HTN with metabolic syndrome
What is the mechanism of action of ACE inhibitors?
- inhibit conversion of Ang I to Ang II
- prevent degradation of bradykinin
- decreased secretion of aldosterone
- increase renal blood flow
- (captopril increases the synthesis of renal prostaglandins & delays progression of renal disease in diabetics)
What are the pharmacological effects of ACE inhibitors?
- prevent vasoconstrictive effect of AngII - dilate arteries and veins - reduce BP
- reduce AngII-mediate thickening of BV and cardiac hypertrophy
- increases longevity in CHF
What are the side effect of ACE inhibitors?
- hypotension in hypovolemic and/or Na+-depleted pts
- hyperkalemia
- dry cough and angioedema
- fetotoxicity
What is the mechanism of action of ARBs?
Block angiotension II type 1 receptors
What are the pharmacological effects of ARBs?
- vasodilation to decrease TPR and BP
- increase Na+ and water excretion to decrease plasma volume, CO
- no effect on bradykinin
What are the unique properties of Losartan?
- prodrug
- competitive antagonist of TXA2 receptor
- increases uric acid urinary excretion
What is the main side effect of ARBs?
fetotoxicity
What are the selectivities of the different CCBs?
- Verapamil: myocardium
- Diltiazem: intermediate between verapamil & dihydropyridines in selectivity for vascular channels
- Dihydropyridines: blood vessels, used for HTN
What is the mechanism of dihydropyridines?
Decrease BP and TPR by relaxing arteriolar smooth muscle.
Do not cause reflex tachycardia.
Which patients with hypertension benefit from a CCB?
- more effective for pts with low renin - elderly and AA
- for older pts with systolic HTN
- added to ACEI/ARB for diabetics if necessary
What is the mechanism of action of clonidine, guanfacine, guanabenz?
- agonize postsynaptic alpha2-receptors in CNS
- decreases SNS activity to heart & BV
- decrease TPR and HR
- decreases SNS activity to heart & BV
What are the clinical uses for Clonidine?
- analgesic for neuropathy
- ADHD
- tertiary for HTN
What are the side effects of alpha2 agonists?
Sedation, drowsiness, fatigue
Clonidine withdrawal leads to hypertension.
What is the mechanism of action of Hydralazine?
- selective arteriolar smooth muscle relaxer
- triggers reflex SNS activity and leads to increased catecholamine/renin secretion
What are the clinical uses for Hydralazine?
- IV for HTN emergency from eclampsia
- used with beta-blockers and diuretics for HTN
