Hypertension Flashcards
Describe the guidelines relating to pharmacological anti-hypertensive therapy in different populations
Patients who are younger than 55 y/o can be offered an ACE inhibitor such as ramopril or lisinopril.
Patients who are 55 or over, or black of any age, can be offered a CCB or a thiazide diuretic.
Patients who do not respond to first line treatment can be given ACEI combination therapy with a CCB or diuretic.
Third line treatment can involve a combination of all three.
Beyond this, alpha blockers and beta blockers can be considered.
What is the mechanism of action of ACE inhibitors in hypertension?
ACE inhibitors reduce the synthesis of angiotensin II directly, increase bradykinin directly and reduce aldosterone indirectly.
Overall it therefore reduces Na and H2O reabsorption at the renal tubules and induces peripheral vasodilation. Consequently this reduces total peripheral resistance to lower BP, also reducing afterload on the heart.
What are the main side effects of ACEI therapy?
The most common report is a dry cough (10-15%), which is due to the pulmonary accumulation of bradykinin. This can be alleviated by offering an angiotensin II receptor blocker such as losartan.
Other ADRs include hyperkalaemia (due to the loss of aldosterone), renal failure in patients with compromised renal function due to renovascular disease (due to reduction in GFR secondary to dilation of efferent arteriole), and angio-oedema (due to vasodilator effect).
Name the three classifications of calcium-channel blocker with an example of each.
Dihydropyridines - amilodepine (BP)
Phenylalkylamines - verapamil (arrhythmia)
Benzothiazepines - diltiazam (angina)
Describe the mechanism of action of calcium channel blockers when used for hypertension
Dihydropyredines are mainly used for hypertension (e.g. Amilodepine) due to their selectivity for vascular smooth muscle. They block the entry of calcium into VSMCs to inhibit contraction, thereby mediating vasodilation and a reduction in TPR.
What are the major side effects of dihydropyredine therapy in hypertension?
Reflex tachycardia (baroreceptor mediated response)
Hypotension (over treatment)
Orthostatic (postural) hypotension (blood pooling)
Flushing, redness, oedema (vasodilation)
Describe the main indication for treatment with a phenylalkylamine, such as verapamil
Verapamil is mainly used in the treatment of arrhythmia. Such CCBs can reduce conduction velocity and the AVN and between myocytes by prolonging the action potential duration and ERP. They can also slow heart rate by reducing the slope of phase 4 depolarisation in the pacemaker potential
