Antihypertension / dental courses

INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
Antihypertensive Drugs
www.indiandentalacademy.com

Hypertension - Definition
 Hypertension can be defined as the level of blood pressure
at which there is risk to the organs or vasculature.
 Based largely on epidemiological studies.

Hypertension- Definition
Category Systolic (mmHg) Diastolic (mm Hg)
optimal <120 < 80
normal < 130 < 85
high-normal
Hypertension
stage 1
stage 2
stage 3
130-139 85-89
140-159 90-99
160-179 100-109
> 180_ >110_

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Primary Hypertension - Definition
 The category of hypertension when the cause is unknown.
 There are probably several different genetic causes as well
as a complex interplay of polygenetic and environmental
factors.
 Includes approximately 90% of cases.
 Also referred to as essential hypertension.
Approximately 20% of all adults in US are affected.
Even though the underlying cause usually is not known,
hypertension can usually be very effectively treated.

Secondary Hypertension - Definition
 The category of hypertension when the cause is secondary
to renal, endocrine, anatomic disorders etc.
Includes approximately 10% of cases.

Hypertension - Clinical Significance
1. Heart disease
2. Stroke
3. Kidney failure
4. Blindness
 Effects usually are not apparent until after 10 or more years of
sustained high blood pressure.

Treatment Strategies
A. Lifestyle Modifications
 low fat diet rich in vegetables and fruit
 reduction of excess body weight
 limited alcohol consumption
 daily aerobic exercise
 smoking cessation
 reduction of sodium uptake
B. Drug Therapy

. Additional Risk factors for cardiovascular disease
smoking
dyslipidemia
diabetes mellitus
age older than 60
sex (men and postmenopausal women)
family history of cardiovascular disease

Risk Group A
 No risk factors
 No cardiovascular disease
 No Target organ damage
Risk Group B
 At least one risk factor not including diabetes mellitus
 No cardiovascular disease
 No target organ damage
Risk Group C
 Cardiovascular disease
 Target organ damage
 Diabetes mellitus

Treatment Strategy
Blood Pressure Risk group A Risk group B Risk group C
High-normal
Stage 1
Stage 2
lifestyle
modification
lifestyle
modification
lifestyle
modification
lifestyle
modification
lifestyle
modification
(up to 6 months)
drug therapy drug therapy
drug therapy
drug therapy
(140-159/90-99)
(130-139/85-89)
(160-179/100-109)

Blood Pressure Regulation
Renin-angiotensin system

Sympathetic nervous control

Fluid retention by the kidney

Drugs Used To Decrease Blood Pressure
 Very effective at lowering blood pressure
Usually do not correct the underlying defect
Drug therapy is usually life-long

Diuretics
 One of the most common, effective and inexpensive drug classes
for the treatment of hypertension.
 Several different classes of diuretics are effective including the
thiazides, loop diuretics and K+
sparing diuretics.
Prototype: hydrochlorthiazide

Diuretics
 Inhibit renal tubular reabsorption resulting in a reduction of
body salt and water.
The mechanism of long-term blood pressure reduction still
is not completely clear.

Drugs Acting on the Angiotensin System
A. Angiotensin Converting Enzyme (ACE) Inhibitors
X

ACE Inhibitors - Mechanism
 Inhibit conversion of angiotensin I to angiotensin II
 Potentiate actions of bradykinin by inhibiting its degradation
bradykinin degradation products
ACE
(bronchoconstriction)

ACE Inhibitors - Characteristics
 Little or no increase in heart rate
 Reduces ventricular hypertrophy
 Side effects: cough, angioedema and rash
 Over-all a very safe class of drugs
 Prototype: captopril

Angiotensin II
receptor
Gq
GTP GDP
Βγ
phospholipase C
PIP2
IP3
+
+
protein kinase C
Ca+2[ ]
+
+
diacylglycerol
Angiotensin I
ACE
Angiotensin II

Drugs Acting on the Angiotensin System
B. Angiotensin Receptor Antagonists
 Inhibit the action of angiotensin II by antagonizing one of its
receptors
 Similar effects as the ACE inhibitors
 Lack the effect on the kinins which results in a lower
incidence of cough and rash
Prototype: losartin

Beta Blockers
 Competitively antagonizes the effects of the sympathetic
effectors norepinephrine and epinephrine.

Beta Blockers
 Blockade of B1-adrenergic receptors in ventricle decreases
contractility and the SA node decreases the rate of contraction.
Blockade of B-Blockers inhibit renin release which also
contributes to a decrease in blood pressure.

Beta Blockers
Prototype: propanolol
 Side effects: Causes bronchoconstriction due to B-2 receptor
blockage.
 Over-all well tolerated
 Beta blockers should not be discontinued abruptly

Calcium Channel Blockers
 Bind to receptors of calcium channels in cardiac and vascular
smooth muscle.
 Prevent Ca+2
influx into the smooth muscle cells which reduces
the contraction of the blood vessels and heart rate.
 The different calcium channel blockers differ in their relative
effects on vascular and cardiac tissue.

Calcium Channel Blockers
Side effects are generally mild.
Can cause a reflex increase in heart rate (tachycardia) in
response to the vasodilation.
 Representative drug: felodipine
 Since they act on arterioles, not veins postural hypotension is
rare.
 Frequently combined with a B-blocker

Alpha1-Adrenergic Blockers
 Alpha1-adrenergic receptors are found on vascular smooth
muscle where they mediate vasoconstriction.

 Side effects: orthostatic (postural) hypotension and
reflex tachycardia
 Prototype: prazosin.
 Blockade of the alpha1-adrenergic receptors results in
vasodilation of both the arterial and venous beds .

 It is usually necessary to take a diuretic with these drugs.
B-blockers are also frequently co-administered with these drugs.

Direct-Acting Vasodilators
 Directly relaxes the vascular smooth muscle
 Several drugs in this category are very quick acting and
are mainly used for hypertensive emergencies
 Side effects include reflex tachycardia and edema. As a result
these drugs are frequently combined with a B-blocker and a
diuretic

 Nitrovasolators release nitric oxide (NO)
activation of guanylate cyclase
[cGMP]
stimulation of a cGMP-dependent kinase and a
decreased cytosolic [Ca+2]
relaxation of vascular smooth musclewww.indiandentalacademy.com

 Several other direct-acting vasodilators that work through
poorly defined mechanisms
 Examples of nitrovasolators include nitroglycerin and sodium
nitroprusside

Centrally Acting Drugs
 Antihypertensive effect results from action in the CNS causing
a reduced sympathetic nerve firing rate.
 Prototype: clonidine

 Clonidine activates alpha2 and imidazoline receptors in the
vasomotor center of the medulla which inhibits the sympathetic
nervous system.
 Considered a second-line drug or for special cases
(ie methyldopa in pregnant hypertensive patients).
 A reduced heart rate and cardiac output account for reduction
in blood pressure.

 An advantage of these drugs is that they do not cause
postural hypotension
 Side effects - hypertensive rebound if there is an abrupt
withdrawal
-dry mouth, sedation

Additional Considerations
 Different ethnic groups have a greater probability of
responding to the different drug categories
 Approximately two thirds of the US population aged 65 or
older have hypertension.

 Hypertension during pregnancy poses a risk for both mother
and fetus.
 preclampsia
 Hypertension is a major risk factor for kidney and
cardiovascular problems in patients with diabetes

(December 18, 2002)

Antihypertension / dental courses

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