Hypertension Drugs Flashcards
Name some of the risks assosiated with hypertension…
Increased Stroke Risk
Increased Risk of Ischemic heart disease (angina, MI)
Other cardiovascular problems
morbidity/mortality
What level of blood pressure is considered high enough to treat?
Sustained Systolic about 160mm
Sustained Diastolic above 100mm
But if know cardiovascular disease:
sustained systolic 140-159 mm Hg and/or
diastolic BP 90-99 mm Hg
What things do you need to reduce in order to treat blood pressure?
Reduce cardiac output by reducing:
heart rate stroke volume plasma volume
Reduce total peripheral resistance by dilating arterioles
Name some antihypertensives and their basic mode of action
Diuretics- Reduce plasma volume then gradually TPR
vasodilators- Directly lower TPR
b-blockers- Reduce cardiac output & kidney renin secretion
ACE inhibitors- Inhibit endogenous vasoconstrictor production
a-blockers - Reduce TPR by inhibiting noradrenaline action
angiotensin antag -Reduce TPR by inhibiting angiotensin action
Where do diuretics act?
And what is there action?
They act on the kidney to increase urine output.
They method of action is to: Increase Na+ excretion reduce salt re-absorption from glomerular filtrate water loss follows reduce plasma volume reduce cardiac output
Name some types of diuretics…
Thiazides
Loop diuretics
Potassium Sparing Diuretics
What is the most POTENT type of diuretic?
Loop Diuretics
They can make you go ‘loopy’ they’re so strong
What’s the most widley used diuretic?
Thiazide Diuretics.
ie
– chlorothiazide
– hydrochlorothiazide
– bendrofluazide
Where is the sight of action for Thiazide Diuretics?
The Distal Tubule
They inhibit Na and Cl co-transport in the distal tubule. Also have vasodilation properties which have an unknown mechanism.
True or false:
Thiazides Increase Renin release.
True
Thiazide diuretics do increase renin release.
Which may conteract BP as it can increase BP.
What potency are Thiazide Diuretics?
They are moderate potency, so suitable for most patients.
Name some Thiazides:
Derived from Benzothiadiazine:
And Thiazide like structures:
Derived from bensothiadiazine:
– chlorothiazide
– hydrochlorothiazide
– bendrofluazide
Thiazide Like structures:
- Chlorthalidone
- metolazone
Name some Thiazide Side effects…
- More frequent urination
- Hypokalemia
- Diuretic properties reduce over time but vasodilation propeties remain
In what situation would you give loop diuretics over thiazides
- If an emergency
- Patients with renal insufficiency
- Patients with resistant hypertension or heart failure
True or false:
Loop diuretics are more effective at lowering BP than thiazides
FALSE
Loop diuretics are no more effective than thiazides at reducing BP
Name some Vasodilator Drugs in the treatment of BP
- Calcuim Antagonists (Calcium Channel Blockers) MAIN ONE
- Alfa-blockers
Special Circumstances:
- Angiotensin Agonists
- Potassium Channel Activators
- Sodium Notroprusside
- Hydralazine
What is the sight for vasodilator action?
And how do they work?
The sight of action is the Smooth Muscle Cells surrounding the artery.
Action:
Lower intracellular calcium concentration. Cause muscle cell relaxation= vasodilation
How do Calcium Antagonists work?
They block Calcium from entering voltage operated calcium channels in arterial smooth muscle cells.
What categories are there within Calcium Channel Blockers (Calcium Antagonist)? And Name some…
Dihydrophyridines:
- Nifedipine
- amlodipine
- nicardipine
Benzothiazepine
-Diltiazem
Which Calcium Antagonist also blocks calcium channels in conducting tissue of the Heart?
Benzothiazepine
(Diltiazem)
Which can slow the heart down and also potentiate Beta Blocker action
Which Calcium Antagonise is a once daily dose?
Amlodipine
As it’s longer acting
What are some advers effects of Calcium Channel Blockers (Calcium Antagonists)
All:
- Flushing (due to dilation of facial vessles)
- Ankle Oedema
Diltiazem
- Cardiac Depression
- Interaction with Beta Blockers
What is the mechanism of action of Diltiazem?
Blocks voltage-operated calcium channels in cardiac muscle
Oedema (swollen ankles) is a common side-effect of which of the following classes of anti-hypertensive drug?
Calcium channel blockers
True or false…
Alfa 2 receptors are in the Smooth muscle and are a target for Antihyperintensives…
FALSE!!!
Alfa 2 receptors are in nerve endings.
Alfa1 receptors are targets for BP lowering drugs as they are in smooth muscle cells
What are the targets and mode of action for Alfa 1 blocker antihyperintensives?
They act on G proteins within the smooth muscle cells.
They are selective blockers for alfa 1 adrenoceptors
Prevent Vasoconstrictor action of endogenous noradrenaline
Examples of Alfa Blockers
hint SIN
Doxazosin 1xdaily
Terazosin 1xdaily
Prazosin 3xdaily
Name some SE of Alfa Blockers
-Postural Hypotension
(dizzyness/lightheaded)
-Possible severe lowBP after first dose
but generally well tolerated
Name some Beta Blockers
Atenolol
Metoprolol
True or False:
Beta Blockers bind to B1 adrenoceptors in the heart?
TRUE- they bind to sino atrial node + Ventricular muscle in the heart.
B2 receptors are for the airways
How do B1 Blockers Treat high BP?
They block action of Noradrenaline release from the sympathetic Nerves and circulating adrenaline. Do this by binding and blocking B1 adrenoceptors in the heart.
Inital and long term affects of BBlockers….
Initial:
reduces rate&force of heart beat.
After Continued Treatment:
Cardiac output returns to normal but BP remains low.
(Total Periferal resistance resets at lower level)
SE of BBlockers
- Cold Hands
- Fatigue & Difficulty excercisng
Less common
- can provoke asthma attack
- heart failure
- conduction block in heart
- Could affect blood lipids
TRUE or FALSE
Can BB provoke asthma attacks ?
Yes, but only if the patient is asthmatic to begin with
Name some ACE Inhibitors
Catopril 2xdaily
Enalapril 1xdaily
Lisinopril (lysine analogue of enalapril)
Ramipril
Action of ACE Inhibitors
-prevent Conversion of Angiotensin 1 -> Angiotensin 11
(which is a potent vasoconstrictor and inhibits H20 excretion)
-Causes Vasodilation
-Reduces Plasma volume
Name some effects of Angiotensin 11 (the thing that ACE inhibitors block)
Angiotensin 11 is a potent vasoconstrictor and it also stimulates aldosterone secretion (which inhibits salt and H20 excretion)
Some SE of ACE Inhibitors
- Dry Cough
- Hypotension initially, especially if given with diuretic
These effects wear off with time
Losartan is often preferred to enalapril in the treatment of hypertension because it…
Because it …
does not cause a dry cough
Like ACE Inhibitors do!
Name some Angiotensin 11 receptor antagonists
Tan
Losartan
Candesartan
Eprosartan
Valsartan
What do Angiotensin 11 antagonists do?
Block Action of Angiotensin 11 at it’s receptors, therefore blocking the effects of it
(Vasoconstriction + Aldosterone secrion)
When are Angiotensin 11 receptor antagonists used?
- They’re used in combo with ACE inhibitors as they improve the mortality and morbidity compared to ACE inhibitors alone
- They provide an alternative to ACE inhibitors when patients are intolerant (or have SE ie dry cough)
