Hypertension + Antihypertensives Flashcards
Equations to work out mean arterial pressure
DBP + PP/3
or
CO x TPR
Blood pressure regulation mechanisms
- autonomic sympathetic activity
- RAAS system
- autacoids e.g. bradykinin, nitric oxide
Response of sympathetic activity in decrease in BP
- activation of B1 adrenoreceptors on heart > increase CO
- activation of a1 adrenoreceptors on smooth muscle > vasoconstriction > increased venous return + peripheral resistance
- activation of B1 adrenoreceptors on kidneys > renin release > RAAS
- increase in BP
Response of RAAS in a decrease in BP
- drop in renal blood flow
- renin released
- angiotensinogen > AngI > AngII > increased peripheral resistance
- increased aldosterone > increased Na+ + H2O retention > increased blood volume > increase CO
- increased ADH > water reabsorption > increased blood volume
- increase in BP
Stages of hypertension
- stage 1: >140/90mmHg
- stage 2: >160/100mHg
- stage 3 > 180 systolic or >110 diastolic
Increase in 20 systolic + 10 diastolic each time
What is target blood pressure for <80 years old?
<140/90mmHg
Range for pre hypertension
120/80mmHg - 140/90mmHg
What advice should be given to pre hypertensive patients?
- promote regular exercise + healthy diet
- reduce stress + promote relaxation
- discourage excessive caffeine consumption
- smoking cessation
- reduce sodium intake
What classifications of drugs are used to treat primary hypertension?
- ACE inhibitors ACEi
- angiotensin recpetor blockers ARB
- calcium channel blockers CCB
- diuretics - thiazide + thiazide like
How do ACEi help hypertension?
- limit conversion of angiotensin I > angiotensin II but inhibiting circulating + tissue ACE
- reduction in AngII activity:
-vasodilation
-reduction in alsoderone release
-reduced ADH release - lower BP
What is target blood pressure for >80 years old?
<150/90mmHg
What is desired blood pressure?
120/80mmHg
Adverse effects of ACEi
- dry cough (bradykinin accumulation)
- hypotension
- hyperkalaemia (lower aldosterone > ^ [K+])
- worsen renal failure
- angioedema
Contradictions of ACEi
Renal artery stenosis
AKD
Pregnancy
Idiopathic angiodema
Why is dry cough a possible side effect of ACEi?
- ACE also converts bradykinin into peptide fragments
- accumulation of bradykinin can cause dry cough
Suffix for ACEi
-pril
Suffix for angiotensin II receptor antagonists
-sartan
Adverse effects of ARBs
- hypotension
- hyperkalaemia (low aldosterone > ^ [K+])
- worse renal failure
What are possible side effects of ACEi that are not an issue with ARBs?
Dry cough
Angioedema
No effect on bradykinin
Contraindications of ARBs
Renal artery stenosis
AKD
Pregnancy
Important drug interactions with ACEi +ARBs
- potassium sparing drugs
- NSAIDs
- other hypertensives
How do angiotensin II receptor antagonists work?
- AngII blockers
- bind to AT1 receptors
- limit action of angiotensin II
- lower BP
Why do ACEi and ARBs precipitate hyperkalaemia?
Lower aldosterone
Causes increase in [K+]
Types of calcium channel blockers
- Dihydropyridines
- Non-dihydropyridines - Phenylalkamines + benzothiazapines
Suffix of dihydropyridine class of CCBs
-ipine
Adverse effects of dihydropyridine class CCBs
- ankle swelling
- flushing
- headaches
- palpitations (due to compensatory tachycardia)
Contraindications of dihydropyridines class CCBs
Unstable angina
Severe aortic stenosis
Cardiogenic shock
Action of dihydropyridine class CCBs
- selective for peripheral vasculature
- inhibits Ca2+ influx to vascular smooth muscles
- causes vasodilation
- decreases peripheral vascular resistance + cardiac workload
Action of phenylalkamines
Depress SA node
Slows Av conduction
Negative inotropy
Example of Phenylalkylamine
Verapamil
Uses of verapamil
Arrhythmias
Angina
Hypertension
Adverse effects of phenylalkyalamines
- Constipation
- Bradycardia
- Heart block
- Cardiac failure
Contraindications of phenylalkylamines
Poor LV function
AV nodal conduction delay
Important drug interactions of dihydropyridine class CCBs
Amlodipine with simvastatin
Important drug interactions of verapamil
B blockers
Other antihypertensives or antiarrhymtics
Examples of thiazide + thiazide like diuretics
Bendroflumethiazide
Indapamide
Adverse effects of thiazide + thiazide like diuretics
- Hypokalaemia
- Hyponatraemia
- Gout
- Arrhythmias
- increase glucose
Contraindications of thiazide + thiazide like diuretics
Hypokalaemia
Hyponatraemia
Gout
How do thiazide + thiazide like diuretics work?
- Inhibit Na+/Cl- co transporter in DCT
- Reduced Na+ + H2O reabsorption
Important drug interactions with thiazide + thiazide like diuretics
NSAIDs
v K+ drugs e.g loop diuretics
Treatment of resistant hypertension
-
spironolactone: aldosterone receptor antagonist if blood K+ <4.5mmol/l
OR - a/B blockers: if blood K+ >4.5mmol/l
Contraindications of spironolactone
Hyperkalaemia
Addison’s
Suffix of B adrenoreceptors blockers
-olol
How can you use the names of beta blockers to know what receptor they act on?
A-N β1
O-Z β1 and β2
Not “olol” ending α and β
Suffix of a adrenoreceptors blockers
-osin
What is the target BP for pregnant women?
135/85mmHg
What is first line treatment of gestational hypertension?
Labetalol hydrochloride
What is the mechanism of action of lebtalol hydrochloride?
Beta blocker
- Blocks B1 receptors in heart > vasodilation > decrease vascular resistance
Order of treating hypertension in patients with(out) type 2 diabetes, <55 or not black
1- ACEi or ARBs
2- ACEi or ARB + thiazide diuretic or CCB
3- ACEi or ARB + thiazide diuretics + CCB
4- add spironolactone (blood K+ <4.5mmol/l) or a/B blocker (blood K+ >4.5mmol/l)
Order of treating hypertension in patients without type 2 diabetes, >55 or black
1- CCB
2- CCBs + ACEi or ARB or thiazide diuretics
3- ACEi or ARBs + CCB + thiazide diuretics
4- add spironolactone (blood K+ <4.5mmol/l) or a/B blocker (blood K+ >4.5mmol/l)
What is first line treatment for hypertension is type 2 diabetes?
ACEi or ARBs
Examples of ACEi
Lisinopril
Ramipril
Examples of ARBs
Candesartan
Losartan
Examples of dihydropyridine CCBs
Amlodipine
Nimodipine
Examples of benzothiazapines
Diltiazem
Examples of B adrenoceptors blockers
Labetalol
Bisoprolol
Metoprolol
Examples of a adrenoceptor blockers
Doxazosin
Why can spironolactone cause gynaecomastia?
It has anti-androgenic effects > reduces action of male hormones > imbalance with oestrogen > breast tissue development
Where aldosterone released from?
Zona glomerulosa in adrenal cortex
