4 - Hypertension and Heart Failure Drugs Flashcards
What are the effects of hypertension and how is bp regulated?
- Increases arterial wall thickness by remodelling and hypertrophy. Stiffens the walls so they are less compliant
- Organ damage from lack of blood flow
- Regulated by RAAS, autonomic NS, bradykinin, NO and natriuretic peptides
What are the values that define hypertension and what are some of the causes?
>140/90
primary, secondary (conn’s, diabetes), isolated diastolic/systolic, white coat
What are target blood pressure targets (clinically and ambulatory) for different groups of people?
- <140/90 if less than 80 inc type II diabetes
- <150/90 if greater than 80
- <135/85 if type I diabetic
What is best practice when diagnosing hypertension?
- Sitting relaxed and arm supported
- Both arms should be within 15mm/Hg of each other, if not then repeat. Take highest reading
- Measure over a period of time including ambulatory and hoe machines
- CVD and organ damage should be assessed whilst waiting for hypertension confirmation
What are the stages of hypertension?
- Resistant hypertension at stage 3
- Emergency if >180/20 and clinical signs
What is prehypertension and how can progression of this be limited
>120/80 but less then 140/90
- Promote regular exercise
- Healthy balanced diet
- Reduce stress and increase relaxation
- Limit alcohol and caffiene intake
- Smoking cessation
- Reduce salt in diet
In general what are some classes of drugs that are used to treat primary hypertension?
- ACE inhibitors
- ARBs
- Calcium channel blockers
- Diuretics
- Alpha and Beta blockers
What is the mechanism of action of ACEi’s to treat hypertension?
Competitive inhibitors of Angiotensin Converting Enzyme:
- Reduce formation of angiotensin II
- Arteriole vasodilation
- Reduce circulating aldosterone so less ADH
- Build up of bradykinin which is a vasodilator as makes NO, good for low renin hypertensives
What are some examples of ACEi’s?
- Ramipril
- Lisinopril
What are some side effects of ACEi’s?
Side effects:
- Dry cough*
- Hypotension
- Hyperkalaemia* as loss of aldosterone
- Renal failure especially due to renal artery stenosis as efferent arteriole needs to constrict
- Angiooedema* due to BK, especially black population
What are some contraindications of using ACEi’s?
- Pregnancy (along with ARBs, can cause CVS and CNS defects and growth restriction and oligohydraminos)
- Hyperkalaemia
- NSAIDs, K+ raising drugs, antihypertensives
- AKD
- Breastfeeding
- Renal artery stenosis
What is the mechanism of action of ARBs?
- AngII mainly binds to AT1 receptor
- Inhibits vasoconstriction* better than ACEis as the AT1 receptor blocked so any AngII made from chymases can not work either
- Inhibits aldosterone stimulation*
- Less effective in low renin hypertensives as no effect on bradykinin
What are some examples of ARBs?
- Candesartan
- Losartan
What are some side effects and contraindications of ARBs as antihypertensives?
Side effects:
- No dry cough and angiooedema like ACEi
- Renal failure
- Hyperkalaemia
Contraindications:
- AKD
- Pregnancy and breast feeding
- Renal artery stenosis
- K+ raising drugs, NSAIDs, other antihypertensives
What is the mechanism of action of calcium channel blockers?
- Bind to alpha1 subunit of L-type calcium channel (VOCC), reducing cellular calcium entry causing vasodilation, reducing preload on the heart
- LTCC in vascuar smooth muscle, cardiomyocytes, SA and AV node. Different classes selective for different areas
If a patient had hypertension with low renin levels, what class of drug would be best to prescribe them first?
- CCB as doesn’t target RAAS
- ACEi as increases bradykinin