S4) Hypertension and Heart Failure Flashcards
What is the 1st line pharmacological therapy for treating hypertension in the UK?
- ACE inhibitors / ARBs
- Calcium channel blockers
- Diuretics
Which drug would one prescribe for the following patients presenting with hypertension:
- <55 y/o and not Afro-Caribbean
- > 55 y/o or any age Afro-Carribean
- < 55 y/o and not Afro-Caribbean – ACE inhibitor
- > 55 y/o or any age Afro-Carribean – Ca2+ channel blocker
Describe the action of ACE inhibitors
Competitive inhibitors of Angiotensin Converting Enzyme:
- Reduce formation of angiotensin II
- Arteriole vasodilation
- Reduce circulating aldosterone
Provide two examples of ACE inhibitors
- Lisinopril
- Ramipril
Identify some important side effects of ACE inhibitors
- Dry cough (main)
- Angio-oedema (rare, common in black patients)
- Renal failure (incl. renal artery stenosis)
- Hyperkalaemia
Describe the action of ARBs
Bind to angiotensin AT1 receptor:
- Inhibit vasoconstriction
- Inhibit aldosterone stimulation
Provide two examples of ARBs
- Losartan
- Candesartan
Identify two important side effects of ARBs
- Renal failure
- Hyperkalaemia
Describe the action of CCBs
Bind to alpha subunit of L-type calcium channel, reducing cellular calcium entry:
- Vasodilates peripheral, coronary and pulmonary arteries
- No significant effect on veins
Identify the three main groups of CCBs and provide an example for each
- Dihydropyridines e.g. nifedipine, amlodipine
- Benzothiazepines e.g. diltiazem
- Phenylalkylamines e.g. verapamil
Describe the properties and adverse effects of Dihydropyridines (calcium channel blockers) e.g. amlodipine
- Properties: good oral absorption, protein bound > 90%, metabolised by the liver
- Adverse effects: oedema, SNS activation – tachycardia and palpitations, flushing, sweating
Describe the properties and adverse effects of Phenylalkylamines (calcium channel blockers) e.g. verapamil
- Properties: impedes calcium transport across the myocardial and vascular smooth muscle cell membrane, peripheral vasodilation, ↓ myocardial contractility
- Adverse effects: constipation, bradycardia, can worsen heart failure
Describe the properties and adverse effects of Benzothiazepines (calcium channel blockers) e.g. diltiazem
- Properties: impedes calcium transport across the myocardial and vascular smooth muscle cell membrane, peripheral vasodilation, ↓ myocardial contractility
- Adverse effects: bradycardia, can worsen heart failure
Describe the action of thiazide diuretics
Reduce distal tubular sodium reabsorption:
- Initial blood volume decrease
- Later, total peripheral resistance falls
Identify four adverse effects of thiazide diuretics
- Hypokalaemia
- Increased urea and uric acid levels
- Impaired glucose tolerance
- Increased cholesterol and triglyceride levels
Describe the actions of alpha blockers
Selective antagonism at post-synaptic α-1 adrenoceptors:
- Antagonise contractile effects of NA on vascular smooth muscle
- Reduce peripheral vascular resistance
- Benign effect on plasma lipids / glucose
Provide an example of an alpha blocker
Doxazosin
Identify 3 adverse effects of alpha blockers
- Postural hypotension
- Headache and fatigue
- Oedema
Describe the action of beta blockers
- Reduce HR and CO
- Inhibit renin release
- Initially TPR increases later falls to normal
Provide three examples of beta blockers
- Bisoprolol
- Atenolol
- Nebivolol
Identify five adverse effects of beta blockers
- Lethargy
- Reduced exercise tolerance
- Bradycardia
- Impaired glucose tolerance
- Contraindication – asthma
Provide three examples of centrally acting agents
- Methydopa
- Clonidine
- Moxonidine
Describe the action of the following centrally acting agents:
- Methydopa
- Clonidine
- Moxonidine
- Methydopa: converted to α-methyl-noradrenaline – a potent α2 adrenoceptor agonist
- Clonidine: direct pre-synaptic α2 adrenoceptor agonist
- Moxonidine: imidazoline I1 receptor agonist and some α2 agonist effect
Identify 2 adverse effects of centrally acting agents
- Tiredness/lethargy
- Depression
In four steps, describe the clinical management of heart failure
⇒ Correct underlying cause
⇒ Non-pharmacological measures
⇒ Pharmacological therapy – symptomatic improvement, delay progression of HF, reduce mortality
⇒ Treat complications / associated conditions / CV risk factors e.g. arrhythmias
What are the five main drugs used in the pharmacological management of heart failure?
- Diuretics
- ACE inhibitor
- ARB
- β-blocker
- Spironolactone
Describe the effects of beta blockers on heart failure
- Reduce HR (cardiac beta receptor + myocardial oxygen demand)
- Reduce BP (reduced CO + myocardial oxygen demand)
- Reduce mobilisation of glycogen
- Negate unwanted effects of catecholamines
