Anti htn drugs

ANTI-HYPERTENSIVE DRUGS

1. Hypertension & Anti-hypertensive Drugs
Presented By : Dr. Vishal
Kr. Kandhway

2. Hypertension
 Hypertension is a very common disorder, particularly past middle
age.
 It is not a disease in itself, but is a important risk factor for cardio-
vascular mortality and morbidity.
 A systolic blood pressure >139 mmhg and a Diastolic blood
pressure >89 mmhg measured on two or more properly seated BP
readings on each of two or more office readings.
 Epidemiological studies have confirmed that higher the pressure
(systolic/diastolic/both) greater is the risk of cardiovascular disease.
 Majority of the cases are of essential (primary) hypertension, i.e.
the cause is not known.

3. Classification
BP classificationSBP DBP Lifestyle
Modification
Drug Therapy
Normal <120 <80 Encourage Not Indicated
Pre-Hypertention120-139 80-89 Yes Not Indicated
Stage I 140-159 90-99 Yes Thiazide type
diuretic needed.
May consider ACEI,
ARBs, CCBs, BBs or
combination
Stage II >160 >100 Yes Two drug
combination for
most- Thiazide type
diuretic, ACEI,
ARBs, CCBs, BBs

4. Types of HTN
•Primary HTN:
 Also known as essential
HTN.
 Accounts for 95% cases of
HTN.

No universally established
cause known.
•Secondary HTN:
 Less common cause of HTN
( 5%).
 Secondary to other
potentially rectifiable causes.

5. Causes of Hypertension
•Chronic kidney disease
•Coarctation of the Aorta
•Cushing’s Syndrome
•Drug induced: Glucocorticoids, Mineralocorticoids,
Sympathomimetics, Nasal decongestants, sudden withdrawal of
antihypertensive drugs
•Obstructive uropathy
•Pheochromocytoma
•Primary aldosteronism and other mineralocorticoid excess states
•Obstructive sleep apnea
•Thyroid (either HYPER or HYPO) or parathyroid disease
•Pregnancy Induced Hypertension

6. Signs and symptoms
Palpitations, dizziness, dyspnoea, decreased exercise
tolerance
Acute HTN causes transient headache and polyuria
Long standing HTN leads to LVH and heaving apical impulse
Left atrial hypertrophy and fourth heart sound (S4)
Very short early diastolic murmur is present
Fundal changes of hypertensive retinopathy are present

7. Lab Investigations
• Ecg.
• Urinalysis.
• Blood glucose and hematocrit; serum potassium,
creatinine ( or estimated GFR), and calcium.
• HDL cholesterol, LDL cholesterol, and triglycerides.
• Optional tests
urinary albumin excretion.
albumin/creatinine ratio.

8. Treatment of HTN
•Step I:- Lifestyle Modification
•Diet, Exercise, limit alcohol and tobacco use,
reduce stress factors.
•STEP II:- If lifestyle changes are not enough, drug
therapy will be introduced.
•STEP III:- If previous steps don’t work, drug dose
or type will be changed or another drug is added.
•STEP IV:- More medications are added until B.P
under control.

9. Anti-hypertensive Drugs
Classification :
1. Diuretics
Thiazides : hydrochlorothiazide, furosemide, spironolactone
2. ACE inhibitors
Captopril, enalapril, ramipril etc.
3. Angiotensin blockers
Losartan, telmisartan etc.
4. Calcium channel blockers
Verapamil, nifedipine, diltiazem, amlodipine etc.
5. Beta-adrenergic blocker
Metoprolol, atenolol, propranolol etc.
6. Beta + alpha adrenergic blocker
Labetalol, carvedilol
7. Alpha adrenergic blocker
Prazocin, phentolamine etc.
8. Central sympatholytics
Clonidine, methyldopa
9. Vasodilators
Minoxidil, Na nitroprusside

10. DIURETICS
 Drugs that increase the rate of urine flow accompanied by an increase
in the rate of Na & Cl excretion.
 Classification : 1. High efficacy (loop) diuretics-
Furosemide,torasemide
2. Medium efficacy diuretics –
a) thiazides – hydrochlorothiazide, benzthiazide
b) thiazide like - chlorthalidone etc.
3. Weak efficacy diuretics :
a) carbonic anhydrase inhibitors – acetazolamide
b) potassium sparing diuretic – spironolactone
c) osmotic diuretic – mannitol, isosorbide, glycerol.
.

11. Diuretics
•Used with other antihypertensives to enhance effectiveness
•Used: mild to moderate HTN
•Also to treat heart failure or kidney disease
•Few adverse side effects:- Hypokalemia, Hypercalcemia, Impotence, Postural
Hypotension, dehydration, allergic rashes.
•Eg: Furosemide- 20-60 mg PO, IV, IM
Spironolactone- 50-200 mg PO

12. ACEIs
•“ACE” inhibitors:-
•Mainstay of oral vasodilator therapy
•Major breakthrough in treatment of HTN
•More effective when used with diuretics.
•ACTION
• peripheral vascular resistance without increase in
Ø cardiac output
Ø heart rate
Ø cardiac contractility

13. Advantages
•Infrequent orthostatic hypotension
•Lack of aggravation of pulmonary distress.
•Lack of aggravation with DM
•Increase renal blood flow
Side effects
•Headache
•Cough
•GI distress

14. ARBs
•Uses:-
•HTN,MI, Diabetic nephropathy
•Side Effects:-
•Drowsiness, dizziness, cough

15. Circumstances under which ACEI
and ARBs should not be used
Drugs Do not use Use with caution
ACEI •Pregnancy
•H/O angioedema
•Cough/ allergy to ACEI
•Women not practicing
contraception
•Bilateral renal artery
stenosis
•Drugs causing
hyperkalemia
ARB •Allergy
•Pregnancy
•Bilateral renal artery
stenosis
•Drugs causing
hyperkalemia
•Women not practicing
contraception

16. BETA BLOCKERS
•Inhibits adrenergic responses mediated through beta
receptors
•All beta blockers are competitive antagonists.
•Beta blockers should be continued throughout the
perioperative period to maintain desirable drug
effects and to avoid sympathetic system
hyperactivity due to abrupt discontinuation .
•The pharmacology of PROPANOLOL is described
as prototype.

17. CLASSIFICATION
BETA BLOCKERS EXAMPLES
NON SELECTIVE
A.WITHOUT INTRINSIC
SYMPATHOMIMETIC ACTIVITY
B.WITH INTRINSIC
SYMPATHOMIMETIC ACTIVITY
C.WITH ADDITIONAL ALPHA
BLOCKING PROPERTY
Propranolol, Timolol
Pindalol
Labetalol, Carvedilol
CARDIOSELECTIVE (BETA 1)Metoprolol, Atenolol, Esmolol
SELECTIVE BETA 2 Butoxamine

18. PHARAMACOLOGICAL
ACTIONS
1.CVS
A. HEART : Decreases HR, force of contraction,
cardiac output, hence cardiac work and oxygen
consumption reduced
Overall effect in angina patients is improvement
of oxygen supply/demand status and exercise
tolerance is increased

19. PHARAMACOLOGICAL
ACTIONS
1.CVS
B.BLOOD VESSELS : On prolonged administration
BP gradually falls in hypertensive subjects.
Blocks beta mediated vasodilation – total
peripheral resistance increases – cardiac output is
reduced
With continued treatment blood vessels gradually
adapt to reduced cardiac output so that total
peripheral resistance decreases.
BOTH SYSTOLIC AND DIASTOLIC BP FALLS

20. PHARAMACOLOGICAL
ACTIONS
2. Respiratory system :
•Increases bronchial resistance by blocking beta 2
receptors
•In normal individuals sympathetic bronchodilator
tone is minimal hence no effect is seen.
•But in asthmatics the condition is consistently
worsened and a severe attack may be precipitated.

21. PHARAMACOLOGICAL
ACTIONS
3. CNS
•No overt central effects
•Subtle behavioural changes, forgetfulness,
increased dreaming and nightmares have been
reported with long term use of high doses.
•Suppresses anxiety in short term stressful
situations.

22. PHARAMACOLOGICAL
ACTIONS
4. METABOLIC
•Blocks lipolysis and gycogenolysis in heart,
skeletal muscle and liver.
•Plasma triglyceride level and LDL/HDL ratio is
increased

23. PHARAMACOLOGICAL
ACTIONS
5. SKELETAL MUSCLE
•Inhibits adrenergically provoked tremors
•This is due to a peripheral action exerted directly
on the muscle fibres through beta 2 receptors.

24. PHARAMACOLOGICAL
ACTIONS
6. EYE
• Reduces aqueous humor secretions and lowers
IOP

25. PHARMACOKINETICS
Well absorbed after oral administration but low
bioavailability due to high first pass metabolism
in the liver.
More than 90% of Propanolol is bound to plasma
proteins.
Metabolism is dependent on hepatic blood flow.
Metabolites are excreted in urine as glucuronides.

26. INTERACTION WITH
ANAESTHETICS
Myocardial depression produced by inhaled or iv
anaesthetics could be additive with depressions
produced by beta blockers.
Additive effects are maximum with enflurane,
intermediate with halothane and least with
isoflurane.
Sevoflurane and Desflurane : no significant
additive effects seen.

27. ADVERSE EFFECTS AND
CONTRAINDICATIONS
Can precipitate CCF by blocking sympathetic
support to the heart.
Bradycardia
Worsens chronic obstructive lung disease, can
precipitate life threatening attack of bronchial
asthma

28. ADVERSE EFFECTS AND
CONTRAINDICATIONS
Withdrawal of Propranolol after chronic use should
be gradual otherwise rebound HTN may occur,
worsening of angina and even sudden death can
occur.
CI in partial and complete heart block.
Cold hands and feet

29. CLINICAL USES
Treatment of essential HTN
Management of angina pectoris
Treatment of Post MI patients
Prophylaxis in patients undergoing non cardiac
surgery
Preoperative preparation of hyperthyroid
patients
Suppression of cardiac dysarrythmias
Migraine prophylaxis
Anxiety
Essential tremor
Glaucoma

30. Management of angina pectoris
•Drug induced decrease in myocardial oxygen demand
secondary to decreased heart rate and myocardial contractility.
•Reduces frequency of attacks and increases exercise tolerance.

31. Treatment of Post MI patients
•Oral treatment with beta blockers after an a/c MI decreases
cardiovascular mortality and reinfarctions and increases the
chances of survival by 20 to 40%.
•Treatment should be instituted 5 days to 4 weeks after MI and
continued for at least 1-3 years.
•Infusion of a beta blocker within 12 hours of onset of MI can
decrease infarct size and ventricular dysrhythmias.

32. Prophylaxis in patients for non
cardiac surgery
•Perioperative myocardial ischemia is the single most
important potentially reversible risk factor for mortality and
cardiovascular complications after non cardiac surgery.
•Administration of atenolol for 7 days before and after non
cardiac surgery in patients at risk for CAD may decrease
mortality and the incidence of cardiovascular complications
for as long as 2 years after surgery.

33. Preop preparation of
hyperthyroid patients
•Thyrotoxic patients can be prepared for surgery in an
emergency by iv administration of propanolol/ esmolol.
•Advantages : rapid suppression of excessive sympathetic
activity and elimination of the need to administer antithyroid
medications and iodine.
•Inhibits peripheral conversion of t4 to t3, highly valuable in
thyroid storm.

34. Attenuated heart rate and BP changes in response to
direct laryngoscopy and tracheal intubation,
esmolol 150mg iv given 2 minutes before
laryngoscopy.
Pheochromocytoma : can be used to control heart
rate but should always be used after an alpha
blocker has been administered otherwise dangerous
rise in BP can occur
Cyanotic episodes in patients with TOF is
minimised by beta blockers.

35. METOPROLOL
•Cardioselective beta blocker
•Less likely to cause adverse effects in asthmatics
and patients with PVD.
•Available as IV preperation also.

36. ATENOLOL
Most selective beta 1 blocker
Antihypertensive effect of atenolol is prolonged
permitting OD admisistration of the drug.
Administration of atenolol for 7 days before and
after non cardiac surgery in patients at risk for CAD
may decrease mortality and the incidence of
cardiovascular complications for as long as 2 years
after surgery.

37. ESMOLOL
Rapid onset short acting selective beta 1 blocker that
is administered iv only.
Initial dose of 0.5mg/kg IV over 1 minute, full
therapeutic effect is seen within 5 min, action ceases
with 10-30 min after discontinuing the drug.
Attenuates pressor response, prevention of periop
tachycardia and HTN with 100-200 mg IV esmolol
15 seconds before induction.
Also used during resection of pheochromocytoma,
peri-op management of hyperthyroidism, PIH

38. ESMOLOL
Available for iv administration only.
pH – 4.5 -5.5
Pain on injection
Rapid hydrolysis in the blood by plasma esterases that
is independent of liver, renal and hepatic function.

39. LABETALOL
Combined alpha + beta blocking activity
5 times more potent in blocking beta than alpha
receptors
Reduces CO, HR, Systolic and diastolic BP.
Most important side effect : postural hypotension

40. LABETALOL
Safe and effective treatment of hypertensive
emergencies – 20-80mg iv every 10 min until desired
response is attained
Labetalol 0.1-0.5mg/kg iv can be used to attenuate
increase in heart rate and BP that results from
increased surgical stimulation
Can also be used in rebound HTN after clonidine
withdrawal, angina pectoris
Oral : 100-600 mg BD

41. CALCIUM CHANNEL
BLOCKERS
Diverse group of structurally unrelated compounds
that selectively interfere with inward calcium ion
movement across myocardial and vascular smooth
muscle cells

42. CLASSIFICATION
GROUP EXAMPLES
Phenylalkylamines Verapamil
1,4 DihydropyrimidinesNifedipine, nicardipine,
nimodipine, felodipine,
Amlodipine
Benzothiazepines Diltiazem

43. MECHANISM OF ACTION
Voltage gated Ca ion channels – Cell membranes of
skeletal muscle, vascular smooth muscle, cardiac
muscle, mesentric muscle, glandular cells and neurons
2 types – L type and T type ion channels
L type is the main channel for slow and sustained Ca
entry into vascular smooth muscle cells
L channel has 5 subunits – alpha1,2 ; beta; gamma;
delta
Alpha 1 subunit forms the central part of the channel
and provides main pathway for Ca entry.

44. MECHANISM OF ACTION
Phenylalkylamines – binds to intracellular portion of
L type channel alpha 1 subunit when the channel is in
an open state and physically occlude the channel.
1,4 dihydropyridimines : Prevents calcium entry by
causing Extracellular allosteric modulation of the L
type voltage gated ion channels.
Benzothiazepines : MOA not well understood. 2
additional effects – acts on Na : K pump decreasing
amount of intracellular sodium available for exchange
with calcium

45. PHARMACOLOGICAL
EFFECTS
1.Decreased myocardial contractility
2.Decreased HR
3.Decreased SA node activity
4.Decreased rate of AV node conduction
5.Vascular smooth muscle relaxation with associated
vasodilation and decrease in BP
6.Dilates coronary arteries – hence relieves coronary
vasospasm.

46. Verapamil
•Synthetic derivative of Papaverine
•Phenylalkylamine calcium channel blocker
•Dosage
Oral : 80-160mg every 8 hours
IV : 75-150mcg/kg
•Onset of action : oral - <30min, IV – 1-3 min
•90% drug is bound to plasma proteins
•70% drug is cleared by the kidneys
•Elimination half time : 6-12 hours

47. Verapamil
Uses :

•SVT
•Angina pectoris
•Essential HTN
•Treatment of maternal and fetal tachydysrhythmia as
well as premature labor

48. Verapamil
SIDE EFFECTS
•Nausea,constipation, bradycardia are common
•Headache
•CI in 2
nd
and 3
rd
degree heart block and may
precipitate CHF
•Should not be given with beta blockers – additive
sinus depression

49. Nifedipine
•Dihydropyridine calcium channel blocker
•Dosage
Oral : 10-20mg every 8 hours
IV : 5-15mcg/kg

•Onset of action : oral - <20min, IV – 1-3min,
sublingual - <3min
•80% drug is bound to plasma proteins
•70% drug is cleared by the kidneys
•Elimination half time : 2-5 hours

50. Nifedipine
•Greater coronary and peripheral arteriolar vasodilator
properties than verapamil.
•Little or no direct depressant effect on SA/AV node
activities.
•Peripheral vasodilation causes decrease in BP-
activates baro-receptors leading to increased
peripheral sympathetic activity resulting in increased
HR

51. Nifedipine
USES
•Angina pectoris : 10-20mg TID orally, especially in
patients with coronary vasospasm
•Sublingual nifedipine : Treatment of hypertensive
emergencies

52. Nifedipine
SIDE EFFECTS
•Palpitation, flushing, ankle edema, hypotension,
headache,drowsiness,nausea

53. Diltiazem
•Benzothiazepine Ca channel blocker
•Blocks Ca channels in the AV node and is therefore
the first line medication for SVT
•Can also be used for control of HTN and
management of angina pectoris.
•Oral : 60-90mg 8 hourly
•IV : 0.25mg/kg over 2 min and is repeated every
15min or after initial dose can be given as continuous
infusion as 10mg/hour for upto 24 hours
•70-80%plasma bound
•Excreted in bile (60%) and in urine (35%)
•Elimination half life : 3-5hours

54. Drug interactions
•Ca channel blockers must be administered with
caution to patients with impaired left ventricle
function or hypovolemia because of their inherent
myocardial depressant activity.
•These drugs potentiate effect of depolarizing and non
depolarizing NM blocking agents.
•Verapamil has potent local anaesthetic action which
may increase the risk of LA toxicity when regional
anaesthesia is administered to patients being with this
drug.

55. Risks of chronic treatment
•Increased perioperative bleeding and an increased
risk of GI bleed have been reported in patients
receiving dihydropyridimines.
•Risk of developing cardiovascular complications are
more with DHP’s
•Hence treatment with Ca channel blockers especially
DHP derivatives should be reserved for second step
rather than initial therapy.

56. Central Sympatholytics
•Eg: Clonidine is a partial agonist with high affinity and high intrinsic
activity at alpha-2A receptors in brainstem.
•Decreases the sympathetic outflow- cause fall in BP and bradycardia
(due to enhanced vagal tone)
•USES:-
•In treatment of HTN
•Adjuvant in spinal and epidural anaesthesia
• Administered preop- reduces anaesthetic requirement and improves
cardiovascular stability
•SIDE EFFECTS:-
•Sudden hypotention, sedation, mental depression, disturbed sleep,
bradycardia, salt and water retention, alarming rise in BP if dose is
missed for 1-2days.
•Dose:- oral-0.2-0.3 mg daily
• IV- 0.1-0.2 mcg/kg I/O

57. Vasodilators
•Venous-
Relax the smooth muscles in systemic venous bed
 Reduce preload by pooling blood in venous bed-reducing venous return-
resulting in reduction in ventricular end diastolic volume.
Eg: NTG given in dose of: 10-200 mcgs/min IV
 0.3-0.6mg/dose SL
•Arteriolar-
Relax the smooth muscles of arteriols-reduce the left ventricular afterload-
increase the stroke volume
Eg: Hydralizine in dose of 25-100mg TID PO
 Minoxidil in dose of 2.5-10mg TID PO

58. •Arteriolar + Venous
Have generalised relaxing effect on both the
venous and arterial beds.
Reduce both preload and afterload
Eg: Sodium Nitroprusside in dose of 10-300
mcgs/min IV

59. Thank You
59