Drugs for Respiratory System Disorders - PowerPoint Presentation

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Drugs for Respiratory System Disorders

Prepared By I

Gede

Purnawinadi

,

S.Kep

.,

M.Kes

.

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Preview

The respiratory system is

one of the most important organ systems

; a mere

5 to 6 minutes without breathing

may result in

death

.

When

functioning properly

, this system

provides the body with the oxygen critical for all cells

to carry on

normal activities

.

The respiratory system also provides a means by which the body can rid itself of

excess acids and bases

.

This chapter examines drugs used to treat conditions associated with the upper respiratory tract:

allergic rhinitis, nasal congestion, and cough

, pharmacotherapy of

asthma and chronic obstructive pulmonary disease

, conditions that affect the lower respiratory tract.

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Physiology of the Upper Respiratory Tract

The upper respiratory tract (URT) consists of the

nose, nasal cavity, pharynx, and

paranasal

sinuses.

These passageways

warm, humidify,

and

clean

the air before it enters the lungs.

The nasal mucosa is also part of the

first line of body defense

. Up to a quart of nasal mucus is produced daily, and this

fluid is rich with

immunoglobulins

that are able to

neutralize airborne pathogens.

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Allergic Rhinitis

Allergic rhinitis, or hay fever, is

inflammation of the nasal mucosa due to exposure to allergens

.

Although not life threatening, allergic rhinitis is a condition affecting millions of patients, and

pharmacotherapy is frequently necessary to control symptoms and to prevent secondary complications

.

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Allergic Rhinitis

Symptoms of allergic rhinitis resemble those of the common cold:

tearing eyes, sneezing, nasal congestion, postnasal drip, and itching of the throat

. In addition to the acute symptoms, potential complications of allergic rhinitis include

loss of taste or smell, sinusitis, chronic cough, hoarseness, and middle ear infections in children.

As with other allergies, the cause of

allergic rhinitis is exposure to an antigen

. An antigen, or

allergen

, may be defined as

anything that is recognized as foreign by the body’s defense system.

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Allergic Rhinitis

The fundamental pathophysiology responsible for allergic rhinitis is

inflammation

of the

mucous membranes in the nose, throat, and airways

.

The nasal

mucosa is rich with

mast cells

(

a type of connective

tissue cell

) and

basophils

(

a type

of leukocyte

), which

recognize antigens as they enter the body.

Patient with

allergic rhinitis

contain

greater numbers

of mast cells

. An

immediate

hypersensitivity

response

releases

histamine

and other

inflammatory mediators

from the

mast

cells and

basophils

, producing

sneezing, itchy

nasal membranes, and watery eyes

.

A

delayed hypersensitivity

reaction

also occurs

4 to 8 hours after the initial exposure

, causing

continuous inflammation

of the mucosa and adding to the

chronic nasal congestion

experienced by these patients.

Because

histamine is released

during an allergic response,

many

signs and symptoms of allergy are similar to those of inflammation

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Pharmacotherapy of Allergic Rhinitis

The

therapeutic goals

of treating allergic rhinitis are to

prevent its occurrence and to relieve symptoms

.

Thus, drugs used to treat allergic rhinitis may be grouped into two simple categories:

Preventers

are used for

prophylaxis

and include

antihistamines, intranasal corticosteroids,

and

mast cell stabilizers.

Relievers

are used to

provide immediate, though temporary, relief for acute allergy symptoms

once they have occurred. Relievers include the

oral and intranasal decongestants

, usually drugs from the sympathomimetic class.

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Antihistamines

In addition to treating allergic rhinitis with drugs, nurses should help patients

identify sources of the allergies

and

recommend

appropriate interventions.

These may

include

removing pets from the home environment, cleaning moldy surfaces, using

microfilters

on air conditioning units, and cleaning dust mites out of bedding, carpet, or couches

.

The

histamine receptors

responsible for

allergic symptoms

are called

H1 receptors

.

Antihistamines

are drugs that

selectively block histamine from reaching its H1 receptors

,

thereby

alleviating allergic symptoms

.

A

large number of

H1-receptor antagonists

are available

as medications

.

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Intranasal Corticosteroids

Corticosteroids, also known as glucocorticoids, are

applied directly to the nasal mucosa

to

prevent symptoms of allergic rhinitis

.

They are administered with a

metered-spray device

that delivers a

consistent dose of drug per spray

.

When sprayed onto the nasal mucosa, corticosteroids

decrease the secretion of inflammatory mediators

, reduce

tissue edema

, and cause a

mild vasoconstriction

.

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Decongestants

Decongestants are drugs that

relieve nasal congestion

. They are administered by either the

oral or intranasal routes

and are often

combined with antihistamines

in the pharmacotherapy of

allergies or the common cold.

Most decongestants are

sympathomimetics

: drugs that activate the sympathetic nervous system.

Activity

are

effective at relieving the nasal congestion

associated with the

common cold or allergic

rhinitis

.

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COMMON COLD

The common cold is a

viral infection of the upper respiratory tract

that produces a characteristic array of

annoying symptoms

.

Therapies

used to

relieve symptoms

include some of the

same drug classes used for allergic rhinitis

, including

antihistamines

and

decongestants

.

A

few additional drugs, such as those that

suppress cough and loosen bronchial secretions

, are used for symptomatic treatment.

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Antitussives

Antitussives are drugs used to

dampen the cough reflex

. They are of

value in treating coughs due to allergies or the common cold

.

Cough is a

natural reflex mechanism

that serves to forcibly

remove excess secretions and foreign material from the respiratory system

.Dry, hacking, nonproductive cough

, however,

can be irritating to the membranes of the throat

and can deprive a patient of much-needed rest. It is these types of conditions in which therapy with medications that control cough, known as

antitussives

, may be warranted.

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Expectorants and Mucolytics

Several drugs are available to control excess mucus production.

Expectorants

increase bronchial secretions

, and

mucolytics

help loosen thick bronchial secretions.

Expectorants

are drugs that

reduce the thickness or viscosity of bronchial secretions

, thus

increasing mucus flow that can then be removed more easily by coughing.

Drugs

available to directly

loosen thick, viscous bronchial secretions

. Drugs of this type, which are called

mucolytics

,

break down the chemical structure of mucus molecules

. The mucus

becomes thinner and can be removed more easily by coughing.

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Physiology of the Lower Respiratory Tract

The primary function of the respiratory system is to

bring oxygen into the body and to remove carbon dioxide

. The process by which gases are exchanged is called

respiration

.

Ventilation

is the

process of moving air into and out of the lungs

. As the

diaphragm contracts and lowers in position

, it creates a negative pressure that draws

air into the lungs

, and

inspiration

occurs.

During

expiration

, the

diaphragm relaxes

and

air leaves the lungs

passively with no energy expenditure required.

Ventilation

is a purely mechanical process that occurs approximately

12 to 18 times per minute in adults.

This

rate may be modified by a number of factors, including

emotions, fever, stress, the pH of the blood, and certain medications.

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Bronchiolar Smooth Muscle

Bronchioles are muscular,

elastic structures

whose diameter, or lumen, varies with the

contraction or relaxation

of smooth

muscle.

Bronchodilation

opens the lumen

, allowing

air to enter the lungs

more freely, thus

increasing the supply of oxygen to the body’s tissues

.

Bronchoconstriction

closes the

lumen

, resulting in

less airflow.

Bronchodilation

and bronchoconstriction

are largely

regulated

by the

two branches of the autonomic nervous

system

:

The

sympathetic branch

activates beta2-adrenergic receptors

, which causes

bronchiolar smooth muscle to relax

, the airway diameter to increase, and

bronchodilation

to occur.

The

parasympathetic branch

causes

bronchiolar smooth muscle to contract

, the airway diameter to narrow, and

bronchoconstriction

to occur.

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Administration of Pulmonary Drugs Via Inhalation

Drugs

that

enhance

bronchodilation

will

enable the

patient

to breathe easier

. Drugs that stimulate beta2- adrenergic receptors, commonly called

bronchodilators

, are some of the most frequently prescribed

drugs for treating pulmonary disorders

.

The

enormous

surface area of the bronchioles and alveoli

, and the

rich blood supply

to these areas, results in an almost

instantaneous onset of action for

inhaled

substances.

Medications

are delivered to the respiratory system by

aerosol therapy

. An

aerosol

is a

suspension of minute

liquid droplets or fine solid particles suspended in a gas

.

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ASTHMA

Asthma

is a

chronic pulmonary disease with inflammatory and

bronchospasm

components

. Drugs may be given

to decrease the frequency of asthmatic attacks

or to terminate attacks in progress.

Characterized by

acute bronchospasm, asthma can cause

intense breathlessness, coughing, and gasping for air

.

Along with

bronchoconstriction

, an

acute inflammatory response

stimulates

histamine secretion

, which

increases mucus

and

edema

in the airways

.

As in allergic rhinitis, the airway becomes

hyper-responsive to allergens

. Both

bronchospasm and inflammation

contribute to airway

obstruction.

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BRONCHODIALATORS FOR TREATING ASTHMA

Beta-Adrenergic Agonists

Beta2-adrenergic agonists (or simply beta agonists) are

effective bronchodilators

for the management of asthma and other pulmonary diseases. They are first-line drugs

for the treatment of acute bronchoconstriction.

Anticholinergics

Anticholinergics

(also called cholinergic blockers or antagonists) are

alternative bronchodilators

for patients who are

unable to tolerate the

beta2-adrenergic

agonists.

Methylxanthine

The

methylxanthines

were considered drugs of choice for treating asthma 30 years ago. The

methylxanthines

, theophylline (Theo-

Dur

, others) and aminophylline (

Truphylline

), are

bronchodilators chemically related to caffeine

.

Corticosteroids

Corticosteroids, also known as glucocorticoids, are the most potent natural

anti-inflammatory substances known.

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Pharmacotherapy of COPD

Chronic obstructive pulmonary disease (COPD)

is a

progressive pulmonary disorder

characterized by

chronic and recurrent obstruction of airflow

.

COPD

is a major cause of death and disability. The three specific COPD conditions are

asthma, chronic bronchitis

, and

emphysema

.

The goals of pharmacotherapy of COPD are to

relieve symptoms and avoid

complications

of the condition.

Various classes of drugs are used to

treat infections, control cough, and relieve bronchospasm

. Most patients receive

bronchodilators such as ipratropium (

Atrovent

), beta2 agonists, or inhaled corticosteroids.

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