Cardiovascular: Hypertension 2 Flashcards
Give the 3 ways that kidney function is exploited in anti-hypertensive therapy?
- Diuretics increase volume of urine and water loss
- Drugs alter function of sympathetic nervous system
- Drugs that interfere with the renin-angiotensin system
What are the 6 hypertensive drugs that act on the renal system?
- Diuretics (blood volume)
- ACE inhibitors (blood vessels)
- AT-1 receptor inhibitors (blood vessels)
- Beta-adrenoceptor antagonists (centrally and cardiac output)
- D1 dopamine receptor agonists
- Renin inhibitors
How do thiazide diuretics work, give examples of them and the side effects?
- Effective antihypertensive- weak diuretics- drops blood pressure slowly compared to loop diuretics
- Act on Na/Cl simperer of distal tubule
- Examples: Bendroflumethiazide and Chlorothiazide
- 3rd tier Antihypertensive
- Side effects:
- hypokalaemia and metabolic alkalosis (very alkaline condition in body)
How does the baroceptosr reflux work against thiazide like diuretics?
- Body tries to pump blood pressure back up when it intensively drops
- Drop in blood volume goes against baroceptor reflex
What are the other diuretics that are used if thiazide like diuretics do not work and give examples for each one?
- Loop diuretics: Furosemide and bumetanide
- Pottasium sparing diuretics: Spironolactone and amiloride
- Blocks sodium channels and aldosterone receptor
Explain the renin-angiotensin-alderstone system (RAA)?
- Renin is released from juxtaglomerular cells of kidney nephron
- This can be stimulated by many drugs such as vasodilators or diuretics
- RENIN (enzyme) converts ANGIOTENSINOGEN into ANGIOTENSIN I
- ANGIOTENSIN CONVERTING ENZYME (ACE) converts ANGIOTENSIN I to ANGIOTENSIN II
- ANGIOTENSIN II activates AT1
- Leads to constriction of vascular smooth muscle (increase in bp)
- Increased release of aldosterone
What are the drugs that affect the RAA system, give examples of them, how they work and name some side effects?
- ACE inhibitors such as Ramipril and Enalapril prevent conversion of ANGIOTENSIN I to 2
- Reduce blood pressure by decreasing peripheral resistance
- Main side effects include cough rash (occurs as the bradykinin isn’t broken down by ACE) and hypotension
- Contraindicated in pregnancy and NSAID treatment
What are the drugs that antagonise Angiotensin Receptor 1 and how do they work?
- Candesartan and Olmesartan
2. Work by blocking action of angiotensin II on AT-1 receptor
What is the advantage AT-1 receptor antagonists has over ACE inhibitors?
No cough reflex compared to ACE inhibitors
What is the anti-hypertensive drug that works across the whole of the sympathetic nervous system?
Beta adrenoceptor blocking drugs
What are beta adrenoceptor blocking drugs mainly used for now?
- Reduce blood pressure slowly over a series of days
- Ischemic heart disease lecture
- 4th tier anti-hypertensive agent
What do each different types of beta adrenoceptor blocking drug target?
- Bisoprolol: highly selective for Beta 1
- Atenolol: relatively selective for Beta 1
- Propranolol: Mixed block of beta 1 and beta 2
Describe what effect the beta adrenoceptor blocking drugs have?
- Reduce cardiac output by reducing sympathetic stimulation to the heart
- Reduce renin release
- Block of Beta 1 in juxtaglomerular cells (renin release block)
- Central action reduces sympathetic activity
What are the unwanted effects from beta adrenoceptor blocking drugs?
- Bronchoconstriction (beta 2)
- Cardiac failure (beta 1)
- Bradycardia (beta 1)
- Fatigue (beta 1)
- Hypoglycaemia (Beta 1 and 2)
- Cold extremities (beta 2)
What are the contraindications in beta adrenoceptor blocking drugs?
- Asthma patients
- Usually taking another drug that selectively blocks the beta 2 adrenoceptor - Type 1 Diabetic patients
- Hunger leads to blood glucose levels dropping
- Heart rate increases and tremor occurs which is important to know when to use insulin injection
(Beta blockers may prevent this)
