Antihypertensives Flashcards
What determines blood pressure?
CO X TPR = mAP
CO= HR X SV
What defines pre-hypertension?
120/80-140/90 mmHg
What is the first line treatment for a pre-hypertensive patient?
Lifestyle modification: exercise and weight loss
What is the first line treatment offered to a Caucasian male with hypertension?
ACEi or AG II receptor inhibitor
What is the first line treatment offered to a hypertensive Afro-Caribbean male?
Calcium channel blocker
What numerical changes define the hypertensive categories?
140/90- stage 1
160/100- stage 2
>180 systolic or >120 diastolic - stage 3
How does an ACEi work?
It prevents ACE (angiotensin I converting enzyme) from cleaving Ag-I into Ag-II, decreasing the amount of Ag-II present and therefore its effects on water homeostasis.
(Ag-II is cleaved by chymases also and therefore there is still some present).
How do ARB’s work?
They prevent Ag-II from binding to its target sites (AT1) and therefore decrease its homeostatic effects.
How do calcium channel blockers work?
They bind to VOCC in smooth muscle and prevent them from opening, resulting in the vasculature remaining dilated.
What is the target blood pressure for a hypertensive under 80?
140/90
What is the target blood pressure for a hypertensive >80?
150/90
What is the target blood pressure for a type I diabetic with hypertension?
135/85
Why might a hypertensive be prescribed diuretics?
To decrease water reabsorption and therefore reduce SV, reducing BP. Additionally, it will help relieve oedema
Why might a hypertensive be placed on beta-blockers?
To reduce HR and therefore reduce BP. Useful in those with cardiac failure.
What side effects are experienced by those taking ACEi?
Dry, non-productive cough due to accumulation of bradykinins (usually cleaved by ACE).
Why are the first line treatments different between ethnicities?
Typically individuals of Black ethnicity have lower renin levels and therefore giving a drug which works on the RAAS pathway isn’t as beneficial as a CCB.
What is the pathophysiology of hypertension?
Remodelling and hypertrophy Increased vasoactive substances Hyperinsulinemia and hyperglycaemia Resulting in end organ damage Hypertensive heart disease - LVH
Give the name of an ACEi
Lisinopril or ramipril
What are the side effects of ACEi?
Hypotension Dry cough Hyperkalaemia Renal failure Angioedema
What population of patients would not receive an ACEi?
Renal artery stenosis AKD Pregnancy Breastfeeding CKD- caution
What drugs have interactions with ACEi?
K increasing drugs
NSAIDs
Other antihypertensives
Why would a ARB be selected over an ACEi?
No effect on bradykinin and therefore there is no dry cough
Angioedema is decreased because ARBs are less effective in low renin individuals
Name an ARB
Lorsartan or candesartan
Name contraindications for use of ARBs
Renal artery stenosis
AKD
Pregnancy and breastfeeding
CKD caution
