Drugs used to treat Hypertension..

1. Hypertension
DR. KAUSHIK MUKHOPADHYAY

3. Blood Volume
ANS –
Sympathetic
RAA Axis
Vascular
mechanism
Blood
Pressure

4. Neuro-humoral Regulation of Hypertension
Heart rate x stroke volume x Peripheral resistance = Blood pressure
*RAAS or RAS: renine angiotensine aldosterone system
Nervous system
Norepinephrine
alpha1
beta1
Humoral RAAS*
Angiotensin II
Cardiac Output x Peripheral resistance = Blood pressure

5. Baroreceptor reflex arc
Postural baroreflex:

6. RAA AXIS
Angiotensinogen
Angiotensin I
Angiotensin II
receptor
Renin
ACE
AT1 AT2
prorenine, catecholamines
Pathway of RAAS in the
Organism (kidney, heart,
Vessels) to maintain
Fluid volume control,
Adjustment of CO and
Resistance.
If regulation fails, high
blood pressure occurs
Pathway of RAAS in the
Tissues: e.g.
Vessel wall
Competition of receptors:
AT1 vasoconstriction
AT2 vasodilatation

7. Classification
1. Diuretics
• Thiazides and related
• Loop Diuretics
• Potassium Sparing
2. Sympatholytics
• Beta Blocker
• Alpha Blocker
• Alpha + Beta Blocker
• Centrally acting
Adrenergic
• Adrenergic Neuron
Blocking

8. Classification3. Calcium Channel Blocker
4. ACE Inhibitor
5. Angiotensin Receptor Blocker
6. Direct Renin Inhibitor
7. Vasodilators
• Arteriolar
• Arteriolar & Venous

9. DiureticsBP
CO
HR
SV
TPR
Beta
Blocker
Centrally
acting
CCB-
Verapamil
• ACEI & ARB
• Renin Inhibitor
• Alpha Blocker
• Centrally acting
• CCB
• Thiazide
• Vasodilators

10. Remember ABCD of HTN
A •ACEI/ARB
B •Beta Blocker
C •Calcium Chnl Blocker
D •Diurtics

11. Diuretics
Drugs causing net loss of Na+ and water in urine
Mechanism of antihypertensive action OF Thiazides:
◦ Initially: diuresis – depletion of Na+ and body fluid volume
– decrease in cardiac output
◦ Subsequently after 4 - 6 weeks, Na+ balance and CO is
regained by 95%, but BP remains low!
◦ Q: Why? Answer: reduction in total peripheral resistance
(TPR) due to deficit of little amount of Na+ and water (Na+
causes vascular stiffness)
◦ Similar effect is seen with sodium restriction (low sodium
diet)

12. Thiazide diuretics – adverse
effects
Adverse Effects:
◦ Hypokalaemia – muscle pain and fatigue
◦ Hyperglycemia: Inhibition of insulin release due to K+
depletion (proinsulin to insulin) – precipitation of diabetes
◦ Hyperlipidemia: rise in total LDL level – risk of stroke
◦ Hyperurecaemia: inhibition of urate excretion
◦ Sudden cardiac death – tosades de pointes (hypokalaemia)
◦ All the above metabolic side effects – higher doses (50 –
100 mg per day)
◦ But, its observed that these adverse effects are minimal
with low doses (12.5 to 25 mg) - Average fall in BP is 10
mm of Hg

13. Thiazide diuretics – current
status
Effects of low dose:
◦ No significant hypokalaemia
◦ Low incidence of arrhythmia
◦ Lower incidence of hyperglycaemia,
hyperlipidemia and hyperuricaemia
◦ Reduction in MI incidence
◦ Reduction in mortality and morbidity

14. Diuretics
K+ sparing diuretics:
◦ Thiazide and K sparing diuretics are combined
therapeutically – DITIDE (triamterene + benzthiazide) is
popular one
Modified thiazide: indapamide
◦ long duration of action (18 Hrs) – orally 2.5 mg dose
◦ It is a lipid neutral i.e. does not alter blood lipid
concentration, but other adverse effects may remain
Loop diuretics:
◦ Na+ deficient state is temporary, not maintained round –
the-clock and t.p.r not reduced
◦ Used only in complicated cases – CRF, CHF marked fluid
retention cases

15. RAS - Physiology
Vasoconstriction
Na+ & water
retention
(Adrenal cortex)
Kidney
Increased
Blood Vol.
Rise in BP

16. ACE inhibitors in Hypertension
Captopril
Pharmacokinetics:
◦ Available only orally, 70% - 75% is absorbed
◦ Partly absorbed and partly excreted unchanged in urine
◦ Food interferes with its absorption
◦ Half life: 2 Hrs, but action stays for 6-12 Hrs

17. Captopril – Pharmacological actions
1. In Normal:
◦ Depends on Na+ status – lowers BP marginally on single
dose
◦ When Na+ depletion – marked lowering of BP
2. In hypertensive:
◦ Lowers PVR and thereby mean, systolic and diastolic BP
◦ RAS is overactive in 80% of hypertensive cases and
contributes to the maintenance of vascular tone –
inhibition causes lowering of BP
◦ Captopril decreases t.p.r on long term – arterioles dilate –
fall in systolic and diastolic BP
◦ No effect on Cardiac output

18. Captopril – Adverse effects
Cough – persistent brassy cough in 20% cases – inhibition of bradykinin and substanceP
breakdown in lungs
Hyperkalemia in renal failure patients with K+ sparing diuretics, NSAID and beta blockers
(routine check of K+ level)
Hypotension – sharp fall may occur – 1st dose
Acute renal failure: CHF and bilateral renal artery stenosis
Angioedema: swelling of lips, mouth, nose etc.
Rashes, urticaria etc
Dysgeusia: loss or alteration of taste
Foetopathic: hypoplasia of organs, growth retardation etc
Neutripenia
Contraindications: Pregnancy, bilateral renal artery stenosis, hypersensitivity and
hyperkalaemia

19. ACE inhibitors - Enalapril
It’s a prodrug – converted to enalaprilat
Advantages over captopril:
◦ Longer half life – OD (5-20 mg OD)
◦ Absorption not affected by food
◦ Rash and loss of taste are less frequent
◦ Longer onset of action
◦ Less side effects

20. ACE inhibitors – Ramipril
It’s a popular ACEI now
It is also a prodrug with long half life
Tissue specific – Protective of heart and kidney
Uses: Diabetes with hypertension, CHF, AMI and
cardio protective in angina pectoris
Dose: Start with low dose; 2.5 to 10 mg daily

21. ACE inhibitors – uses
Hypertension
Congestive Heart Failure
Myocardial Infarction
Prophylaxis of high CVS risk subjects
Diabetic Nephropathy
Schleroderma crisis

22. Losartan
Theoretical superiority over ACEIs:
◦ Cough is rare – no interference with bradykinin
and other ACE substrates
◦ Complete inhibition of AT1 – alternative remains
with ACEs
◦ Result in indirect activation of AT2 –
vasodilatation (additional benefit)
◦ Clinical benefit of ARBs over ACEIs – not known

23. Beta-adrenergic blockers
Advantages:
◦ No postural hypotension
◦ No salt and water retention
◦ Low incidence of side effects
◦ Low cost
◦ Once a day regime
◦ Preferred in young non-obese patients, prevention of
sudden cardiac death in post infarction patients and
progression of CHF

24. Beta-adrenergic blockers
Drawbacks:
◦ Fatigue, lethargy (low CO?) – decreased work capacity
◦ Loss of libido – impotence
◦ Cognitive defects – forgetfulness
◦ Difficult to stop suddenly
Therefore cardio-selective drugs are preferred now
◦ In asthma
◦ In diabetes mellitus
◦ In peripheral vascular disease

25. Vasodilators-site of action

26. Calcium Channel Blockers -
Classification

27. CCB – First Line Anti-HT
CCBs block L-Type channel:
Smooth Muscle relaxation
Negative chronotropic, ionotropic and chronotropic
effects in heart
Advantages:
• Unlike diuretics no adverse metabolic effects
• Can be given to asthma, angina and PVD patients
• No renal and male sexual function impairment
• Can be given in pregnancy
• Preferred in elderly and prevents stroke

28. Αlpha-adrenergic blockers
Non selective alpha blockers are not used in
chronic essential hypertension
(phenoxybenzamine, phentolamine), only used
sometimes as in pheochromocytoma
Specific alpha-1 blockers like prazosin, terazosin
and doxazosine are used
Advantages: improvement of carbohydrate
metabolism – diabetics, lowers LDL and increases
HDL, symptomatic improvement in BHP
But not used as first line agent

29. Vasodilators - Hydralazine
Directly acting vasodilator
MOA: hydralazine molecules combine with receptors in the endothelium of
arterioles – NO release – relaxation of vascular smooth muscle – fall in BP
Subsequenly fall in BP – stimulation of adrenergic system leading to
◦ Cardiac stimulation producing palpitation and rise in CO even in IHD and
patients – anginal attack
◦ Increased Renin secretion – Na+ retention
◦ These effects are countered by administration of beta blockers and
diuretics
Uses: 1) Moderate hypertension when 1st line fails – with beta-blockers and
diuretics
2) Hypertension in Pregnancy, Dose 25-50 mg OD

30. Vasodilators - Minoxidil
Prodrug and converted to an active metabolite which acts
by hyperpolarization of smooth muscles and thereby
relaxation of SM – leading to hydralazine like effects
Rarely indicated in hypertension
More often in alopecia to promote hair growth
Topically as 2-5% lotion/gel and takes months to get effects
MOA of hair growth:
◦ Enhanced microcirculation around hair follicles and also by direct
stimulation of follicles
◦ Alteration of androgen effect of hair follicles

31. Sodium Nitroprusside
Relaxes both resistance and capacitance vessels and reduces t.p.r
and CO (decrease in venous return)
Improves ventricular function in heart failure by reducing preload
MOA: RBCs convert nitroprusside to NO – relaxation also by non-
enzymatically to NO by glutathione
Uses: Hypertensive Emergencies, 50 mg is added to
500 ml of saline/glucose and infused slowly with 0.02 mg/min
initially and later on titrated with response (wrap with black
paper)
Adverse effects: All are due release of cyanides (thiocyanate) –
palpitation, pain abdomen, disorientation, psychosis, weakness
and lactic acidosis.

32. Centrally acting Drugs
Alpha-Methyldopa: a prodrug
◦ Precursor of Dopamine and NA
◦ MOA: Converted to alpha methyl noradrenaline which
acts on alpha-2 receptors in brain
◦ Various adverse effects – cognitive impairement, postural
hypotension, positive coomb`s test etc. – Not used
therapeutically now except in Hypertension
during pregnancy
Clonidine: Partial agonist of central alpha-2 receptor
◦ Not frequently used now because of tolerance and
withdrawal hypertension

34. Eighth Joint
National Committee
(JNC 8)

37. Therapeutic Problem- 1
An overweight middle aged man is found to
be hypertensive while attending a clinic for
medical checkup. His BP is 170/110 mm of
Hg on 2 successive observations.
What will be the treatment of this patient?

38. 1. Presenting Features - His BP is 170/110 mm of Hg
on 2 successive observations
2. Relevant Information - overweight middle aged
man
3. Inference – The patient is suffering from moderate
Hypertension
4. Treatment –
a) General Measures –
1. Salt Restriction (5mg/day)
2. Life style modification – Physical exercise
3. Cessation of smoking/restriction of alcohol intake
4. Basic Laboratory Testing

39. b) Drugs –
i. Amlodipine tablet
(5mg) – Once daily
or
ii. Enalapril Tablet (5mg)
– once daily
or
iii.Losartan tablet
(50mg) – once daily
or
iv.Hydrochlorothiazide
tablet (25mg) – once
daily
If target BP (SBP<140,
DBP<90) not reached
within one month of
treatment with single
drug,
1. dose should be
increased of the initial
drug
or
2. another drug is added
from other class.
ARB is not combined
with ACEI.

40. Therapeutic Problem - 2
A 58-year-old man presented with history of severe
hypertension for 20 years which was well controlled
with medication. He stopped taking drugs for a
prolonged period. His BP is found to be 240/130
mm of Hg with papilloedema.
What will be the management of this case?

41. 1. Presenting Features - BP is 240/130 mm of Hg with
papilloedema
2. Relevant Information –
1. Severe HTN for 20 yrs
2. Stopped medication for prolonged period
3. Inference – The patient is suffering from hypertensive
emergency and needs prompt t/t
4. Treatment –
a) General Measures –
1. Admission in Hospital and iv catheterisation

42. b) Drugs –
i. Injection Sodium Nitroprusside –
It is diluted in 5% Dextrose and infused at 0.3
mcg/Kg/min initially and titrated to reach
desirable target BP upto a maximum dose of
10mcg/Kg/min
or
ii. Injection Enalaprilat–
Usual 0.625 mg-1.25 mg over 5 min every 6-8
hr, maximum 5mg/ dose.
Reduction should be no more than 25% within minutes
to 2 h or to a blood pressure in the range of 160/100-
110 mmHg