This document summarizes different classes of antihypertensive drugs and their mechanisms of action. It discusses: 1) Diuretics like thiazides and loop diuretics which decrease blood volume and cardiac output. 2) ACE inhibitors and ARBs which inhibit the renin-angiotensin-aldosterone system to reduce vasoconstriction and sodium retention. 3) Calcium channel blockers which relax blood vessels by blocking calcium channels. Each class is described along with examples, mechanisms, and potential adverse effects. The document provides an overview of the major pharmacological approaches for treating hypertension.

1. Anti-Hypertensive Drugs
Pharmacology
A.Jersita Sherley
3 rd year
Biomedical science
BMS18471

2. Hypertension
• Persistent increase in systemic arterial blood pressure.
• Blood pressure = Cardiac output × Systemic vascular resistance.
• Increase in blood pressure =Hypertension.
• Normal blood pressure =120/80 mm Hg

3. • Systolic – Heart contracts
Diastolic – Heart Relaxes

4. Complications of hypertension:

5. Differences:

6. Mechanism which controls the blood
pressure:
1. Baro receptor reflexes ( baro – pressure )
2. Renin Angiostenin Aldosterone System (RAAS)
Both the mechanism increase the Blood pressure of the person .

9. Mechanism for baroreceptor reflex :

10. Mechanism for RAAS:

11. Mechanism of Angiostenin 2 :
• It constructs both arteries&veins

12. Anti – Hypertensive drugs:

17. 1.Diuretics :
• Currently recommended as first line drug for hypertension.
• Low –dose diuretics is safe and effective in preventing stroke ,
myocardial infraction &congestive heart failure .
• Recent data suggest diuretics are superior to beta blockers in older
adults.

18. Thiazides :
Decreases the” BP” by increasing sodium &water
excretion.This causes decrease in Blood volume
resulting in decrease in cardiac output.

19. Loop diuretics: • Potassium – sparing diuretics:
• Spironolactone &eplerenone
(aldosterone receptor
antagonist) It reduce the
potassium loss in the urine.
• The exchange of Na+ for K+ in
the distal nephron is mediated
by the actions of the epithelial
Na+ channel (ENaC).
• Aldosterone receptor:
• Corticosteroid hormone which
stimulates absorption of sodium
by the kidneys and so regulates
water and salt balance.
• It is used for poor renal function
or who have not responded to
thiazides .
• Mechanism :
• loop diuretics prevent water
reabsorption. The decrease in
plasma volume that occurs in
response to an increased sodium
excretion reduces venous return
and lowers cardiac output.

20. • Thiazides –Distal convulated
tubule .
• Loop diuretics- ascending
loop of Henle
• Potassium sparing (K+ )- end
of the distal tubule and
collecting duct .

21. Adverse Effect of Diuretics:

22. 2.Angiotensin converting Enzyme
(ACE)Inhibitor:

23. Mechanism of ACE inhibitors:

24. Adverse effect of ACE inhibitors:
• Cough – breakdown in lungs
• Angioedema – swelling of lips ,nose ,mouth etc
• Rashes &allergies
• Dysguesia – loss or alteration of taste .

25. 3.Angiotensin Receptor(AT1) Blocker :
• It blocks all the actions of A -2 mediated by vasoconstriction,
aldosterone release and renal actions of salt and water reabsorption.
Result in reducing the blood pressure.
• Adverse effect is similar to the ACE Inhibitors.

26. 4.Direct Renin Inhibitors:

27. MECHANISM:
• Inhibiting the activity of renin that is responsible for hydrolyzing
angiotensinogen to angiotensin I, which in turn reducing the
formation of angiotensin II that facilitates blood pressure.
• Uses:
• This medication is used to treat high blood pressure (hypertension).
Lowering high blood pressure helps prevent strokes, heart attacks,
and kidney problems. Aliskiren works by relaxing blood vessels so
blood can flow more easily. It belongs to a class of drugs known as
direct renin inhibitors.
• Adverse Effect : cough , diarrhoea, dizziness, trouble breathing.

28. 5.Calcium Channel Blockers (CCB):

29. Mechanism of CCB:(L – type channel):

30. Adverse effect of CCB:

31. 6.Beta Blockers :
• Beta blockers works by blocking the actions of hormones called
adrenaline and nor- adrenaline.
• These hormones make the heart beat faster and with more force .
• Blocking the action makes the heart beat more slowly and with less
force .
• Thus it reduces the Blood pressure in the heart.

33. Adverse effect of Beta blockers:

34. 7.Alpha Blockers :

35. Adverse effect of Alpha blockers:

36. 8.Alpha – Beta adrenergic Blockers:
• Labetalol & Carvedilol having antagonisic activity at both adrenergic
receptors .
• Controlling hypertension in pheochromocytoma.
• A hormone-secreting tumour that can occur in the adrenal glands.
• Phaeochromocytomas usually develop in the small glands on top of
the kidneys (adrenal glands).

37. 9.Centrally acting Drugs:
1.”Alpha – methyl Dopa” – acts in
alpha 2 receptors in Brain & cause
inhibition of adrenergic discharge and
fall in BP.
• Used in the time of pregnancy.
2.”Clonidine” –Agonist of central Alpha
-2 receptor
Adverse effect of these drugs:
1. Dryness of mouth and eyes.
2. Bradycardia
3. Sedation

38. Mechanism :
1. Peripheral sympatholytic drugs ( alpha – beta adreno receptor
)block the influence of Nor –epinephrine at the effector organ (
heart).
2. Gangolic blockers – block the transmission at sympathetic ganglia .
3. Blocks the sympathetic activity within the brain.
4. Centrally acting sympatholytics block sympathetic activity by
binding to and activating alpha2 (α2)-adrenoceptors. This reduces
sympathetic outflow to the heart thereby decreasing cardiac output
by decreasing heart rate and contractility.

39. 10.Vasodilators :
• Vasodilation generally occurs in our body due to low oxygen level ,a
decrease in available nutrients & increase in temperature.
• It cause the widening of the Blood vessels ,which in turn increase the
blood flow and lowers the blood pressure.

40. Arteriolar:
• Hydralazine :
• Combines with receptors in the endothelium of arterioles .
• It release NO and relaxes the vascular smooth muscles thus falls in BP.
• Increase the renin secretion .
• Adverse effect : Tachycardia .
• Minoxidil :
• Relaxation of smooth muscles.
• Powerful vasodilator.
• Used in hypertension and alopecia.
• Adverse effect : Edema .

41. Arteriolar + venous :
• Sodium Nitroprusside:
• Relaxes both resistance and capacitance vessels and reduces cardiac
output .
• Reacts with sulfhydryl groups in erythrocytes ,albumin and some
protiens release NO ( nitrous oxide).
• NO – Stimulates guanyl cyclase to produce cyclic GMP and inhibit
cellular contraction
• Adverse effect : palpitation & abdominal pain .

42. Drugs to be avoided in Pregnancy:

44. Health is wealth – Thank You