Drugs affecting cardiovascular system (blood pressure) Flashcards
(33 cards)
High blood pressure is
140/90mmHg
130/80mmHg in diabetics, kidney disease
Chronic BP >140/90mmHg is a risk factor for
- Stroke
- TIA
- MI
- Ischaemic heart disease
- CHF
- Aortic aneurism
- Retinal Haemorrhage
- Renal failure
- Death
BP =
CO x TPR
CO =
HR x SV
What is the major neuronal influence on BP?
Sympathetic tone: releases NA
-P = +SNS tone
How does NA influence BP at the blood vessels?
- activate A1-aR –> vasoconstriction
How does NA affect BP at the heart?
- activates B1-aR, +HR through SA and +contractility through ventricular muscle
How does NA affect BP at the kidneys?
- B1-aR: +Renin release
- Angiotensinogin –> Ang1 –>
- Angiotensin converting enzyme –> AngII
- AngII acts on kidney, heart, and blood vessels
- AngII +fbk to SNS to +BP
- AngII important in remodelling in heart failure
What are the antihypertensive drug classes?
(ABCD)
- Angiotensin system inhibitors (BV, heart, kidney)
- B-aR antagonists (kidney, heart)
- Ca2+ channel blockers (BV, heart)
- Diuretics (kidney)
- (other)
Aldosterone
- Steroid hormone, adrenal cortex
- Rl by angiotensin 1 receptors in kidney
- Causes salt and water retention
- tf +blood volume, +CO, +SV
What are the targets for angiotensin system inhibitors?
Angtiotensin converting enzyme (ACE)
AT1 receptrors (vasoconstriction, aldosterone stimulation)
What are -pril drugs?
Angiotensin converting enzyme inhibitors
e.g. captopril, enalapril, perindopril, ramipril
What is the mechanism of angiotensin converting enzyme inhibitors?
‘-prils’
- block Ang I –> Ang II tf -vascular tone, -aldosterone, -cardiac hypertrophy
- preven bradykinin (vasodilator) breakdown
What are the adverse effects of angiotensin converting enzyme inhibitors?
- First-dose hypotension (must taper dose)
- Dry cough
- Loss of taste (bradykinin?)
- Hyperkalaemia (+K+ in plasma)
- Acute renal failure
- Itching
- Rash
- Angio-oedema
- Foetal malformations
What must usually be prescribed with a ‘-pril’ and/or a ‘-sartan’?
A thiazide diuretic to combat hyperkalaemia (+K+ in plasma)
What are the contraindications for ‘-pril’ drugs?
- Pregnancy
- Bilateral renal stenosis
- Angioneurotic oedema
What type of drugs are ‘-sartan’?
Angiotensin receptor antagonists
e.g. losartan, candesartan
What are the contraindications for angiotensin receptor antagonists?
Same as for angiotensin converting enzyme inhibitors:
- Pregnancy
- Bilateral renal stenosis
- Angioneurotic oedema
What is the mechanism of angiotensin receptor antagonists?
‘-sartan’
- Block AT1 receptor subtype (not known what AT2 does) to:
- Reduce vasoconstriction
- Reduce aldosterone
- Reduce cardiac hypertrophy
- *Reduce SNS activity
What are the adverse effects of ‘-sartan’ drugs?
Angiotensin receptor antagonists
- Hyperkalaemia (Tx thiazide diuretic)
- Headache
- Dizziness
What type of drug are the ‘-olol’s?
B-aR antagonists
e.g. propranalol, atenolol, pindolol, timolol, metoprolol
What is the mechanism of B-aR antagonists?
‘-olol’
- reduce CO (initially), BP stays down
- decreased rate, contractility
- reduce renin release
- LT effects on TPR, blood volume
What is the selectivity of B-aR antagonists?
Beta-1: heart and kidney
Beta-2: vascular smooth muscle, airway smooth muscle
What is sympathomimetic activity?
Mimics transmitters of the SNS e.g. catecholamines, adrenaline, noradrenaline, dopamine
These drugs are used to treat cardiac arrest and hypotension
