Pharmacology

1. Hypertension
Hypertension also known as high blood pressure is a long-term medical condition in which the pressure
in the arteries is persistently raised
Antihypertensives
Antihypertensives are class of drugs that are used to treat hypertension.
Antihypertensive therapy seeks to prevent the complication of high BP such as stroke, myocardial
infarction.
There are many classes of antihypertensives, which lower BP by different means most important and
most widely used drugs are:
• Thiazide diuretics
• Ca ion channel blockers
• ACE inhibitors
• Angiotensin II receptors
• Antagonists
• Beta blockers

2. Blood pressure Sytolic Diasystolic
Normal ≤ 120 ≤ 80
Elevated 120-129 ≤ 80
Stage-1 HTN 130-139 80-89
Stage-2 TTN ≥ 140 ≥ 90

3. Stages Systolic Diastolic
Prehypertension 120-139 80-89
Mild Hypertension 140-159 90-99
Moderate Hypertension 160-179 99-109
Severe Hypertension ≥ 180 ≥ 110
There are 4 stages of HTN:

4. Etiology of Hypertension
The exact causes of Hypertension are not
known but several things may play a role including smoking, overweight, lack
of physical activity, much salt in diet, alcohol consumption, stress, old age
and genetic disability.
Mechanism for controlling Blood pressure
Arterial Blood pressure is
directly proportional to the cardiac output and peripheral vascular resistance
Cardiac out put and peripheral resistance in turn are controlled mainly by 2
overlapping mechanisms.
1. Baroreceptor and sympathetic nervous system
2. Renin angiotensin – Aldosterone system

5. Most antihypertensive drugs lower Blood Pressure reducing cardiac output and / or
reducing peripheral resistance.
Baroreceptor and sympathetic Nervous system
Impulses from
baroreflex initiates sympathetic system which causes a fall in Blood pressure
which in turn causes pressure sensitive neurons to send fewer impulses to cardiac
vascular center in the spinal cord. This prompts a reflex response of increase in
sympathetic and decrease in parasympathetic output to heart and vasculature,
resulting in vasoconstriction and increase in cardiac output

6. Renin angiotensin- system
The kidneys provide long term control of BP by
altering the blood volume. Baroreceptors in the kidneys response to the reduce arterial
Blood Pressure by releasing the enzyme Renin low sodium intake and greater sodium
loss also increase renin release Renin converts angiotensin in to angiotensin I which in
turn is converted into angiotensin II. In the presence of angiotensin converting enzyme
ACE.
• Angiotensin is a potent vasoconstrictor, constricting both arteries and veins and
resulting in rise in blood pressure.
• Angiotensin II also exerts pressure on arterioles of glomerulus resulting in rise in
glomerular filtration rate.
• Furthermore angiotensin II stimulates aldosterone secretion leading to increase in
sodium reabsorption and increase in blood volume and eventually increase in blood
pressure.

7. Diuretics:
For all diuretics initial mechanism is to decrease the blood pressure.
Thiazide diuretics
These decrease the Blood pressure by decreasing the peripheral resistance and Cardiac out put.
Loop diuretics
Blocking the reabsorption of Na and Cl