In this 5 part series on cardiac drugs, we look at the "Sartans".
Sartans are anti hypertensives in a class of drugs known as Angiotensin2 receptor blockers or ARBs for short.
Recapping our physiology, low blood flow through the kidneys initiate a humoral cascade where ACE in lungs converts inactive Angiotensin into Angiotensin 2.
This potent substance increases blood pressure by stimulation arterial vasoconstriction, and stimulation of the Aldosterone secretion.
Receptors in vessels called AT-1 receptors are activated by Angiotensin 2 causing constriction, and hence , hypertension.
Sartan drugs are a family of drugs which compete at the AT1 receptor and effectively block the action of Angiotensin 2 from working.
Their direct effects are vasodilation, which reduces pressure inside the blood vessel. Used therefore as an anti hypertensive, Sartan drugs are a powerful weapon in the management of chronic heart failure.
Indirectly Sartans also inhibit Vasopressin (ADH) and promote sodium excretion by inhibiting aldosterone. Where sodium is excreted via the kidneys, water (urine) follows. This effect prevents venous overload (preload) which makes the hearts job to pump more efficient.
Examples of these drugs include Irbesartan, Telmisartan, and Losartan.
They are usually second line after ACE inhibitors. Side effects include headache and dizziness especially when standing up quickly. They don't tend to have the irritating cough that ACE inhibitors have, but a potentially worrying issue is the unconfirmed reports that ARBs increase risk of MI.
To date, there is no consensus and further investigations are underway.
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Our next edition will be beta blockers.
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