Lecture 3 Step Treatment of Hypertension Flashcards
What is the mechanism of action of ACE inhibitors?
Inhibits the angiotensin-converting enzyme in the renin-angiotensin system
What is an example of an ACE inhibitor?
Lisinopril
What is the bioavailability of Lisinopril after oral administration?
25%
What is the half-life of Lisinopril?
12 hours
How is Lisinopril excreted?
Not metabolised in liver, undergoes renal excretion unchanged
What does ARB stand for?
Angiotensin II Receptor Blocker
What is an example of an ARB?
Losartan
What is the mechanism of action of ARBs?
Selective competitive blockers of angiotensin II at the AT1 receptor
What is the bioavailability of Losartan after oral administration?
32%
What is the amount of first pass metabolism of Losartan?
14% - to active metabolite, more potent
What is the half-life of Losartan?
2 hours; 3-9 hours for active metabolite
How is Losartan metabolised?
Cytochrome P450 metabolism
How is Losartan excreted?
In urine and bile
What is an example of a calcium channel blocker?
Amlodipine
What is the mechanism of action of calcium channel blockers?
Inhibit the influx of calcium ions by blocking the calcium channel
What do calcium channel blockers act on?
Myocardial muscle (contractility), myocardial conducting system(inhibit formation, propagation of depolarisation), vascular smooth muscle (coronary/systemic vascular tone reduced - vasodilation)
What is the bioavailability of Amlodipine after oral administration?
60%
What is the half-life of Amlodipine?
30-50 hours
How long does it take to reach steady-state plasma concentrations of Amlodipine?
7 to 8 days of daily dosing
How is Amlodipine metabolized?
Liver CYP450 - slowly metabolised
What is the effect of poor renal function on the elimination of Amlodipine?
Not significantly reduced
What are the different drug targets to reduce mean arterial blood pressure?
Renin-angiotensin-aldosteron pathway
AT2 receptors
Na reabsorption mechanisms (kidney)
α1 receptors
β1 receptors
Ca2+ receptors
Which drug classes are prescribed for <55y/o non-black African or African-Caribbean family origin without diabetes?
ACE inhibitor or Angiotensin II receptor blocker
What other pathway is blocked which ACE inhibitors?
Kininase II enzyme from Bradykinin to inactive form
Allows for vasodilation, decreased peripheral resistance and decreased blood pressure
Name 4 common side effects of ACE inhibitors
Cough, diarrhoea, dizziness, vomiting
What is the main common side effect of Lisinopril?
Postural disorder
What is hyperkalaemia?
High K+ levels
What drug class is prescribed for patients >55y/o with black African/Caribbean family origin without diabetes?
Calcium channel blockers
What pathway do CCBs block?
They block the contraction by stopping the muscle from forming crossbridges
