respiratory 2[1]

7/31/2019 Respiratory 2[1]

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Plants Used for RespiratoryProblems - II

Theophylline


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Two types of bronchodilators

Adrenergic agents

Increase the volume and diameter of

bronchial smooth muscles by relaxing them Include norepinephrine, epinephrine, and

ephedrine

Theophylline drugs Act on the bronchial muscles to relieve air

way obstruction, increase coronary bloodflow and stimulate respiration


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Theophylline

Natural component in tea that findspharmaceutical use as a bronchodilator,

vasodilator, and a smooth musclerelaxant


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Tea

From tip leaves of Camellia sinensis

Shrub or small tree native to Tibet,

India, China, and Burma.

Still largely grown in this region of theworld

Caffeine, theophylline, tannins andtheol contribute to flavors andstimulating properties


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Botanical print

of tea plant,

Camellia sinensis


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Workers at tea plantation in

the Darjeeling region of India


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Value of tea

Stimulating effects of tea due to caffeine andtheophylline present

Although there is some concern aboutcaffeine intake, people who drink largeamounts of green tea have low rates ofcancer

Animal studies have shown that rates ofbreast and prostate cancer reduced byconsumption of green tea - attributed to

polyphenols in green tea


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Theophylline

When caffeine metabolized in body, a smallamount is actually converted to theophylline

Theophylline used to treat asthma since1930s by directly relaxing the smoothmuscles of the bronchial airways - therebyopening constricted airways

This bronchodilating action helps relievewheezing, coughing, etc


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Theophylline

Purine alkaloid

Also called a methyl

xanthine alkaloid Originally extracted

from tea

Now chemicallysynthesized


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Theophylline

Popular asthma drug for many years

One of first long term bronchodilators

Several trade names and is available ina variety of forms: Theo-Dur, Slo-Bid,Aminophylline are a few of the

commonly known medications


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Side Effects

Theophylline can become toxic

Difference between a therapeutic level and a

toxic level is narrow Side Effects include tachycardia, palpitations,

nausea, GI upset, headache, insomnia,arrhythmias, convulsions, urticaria, erythema,dermatitis

Theophylline must also be used with cautionin patients with cardiovascular disease,

hypertension, or hepatic or renal insufficiency


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History of theophylline use

Became standard treatment in 1930s

Use declined substantially since 1980s upon

realization of the importance of theinflammatory component of asthma

Use of a Beta-2 agonist coupled with steroidsbecame standard management tools

Also concerns about side effects

Theophylline removed from OTC oralmedications - inhaled still allowed in 1995


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Treatment options

Anti-inflammatory effects of inhaled steroidsbecame preferred treatment

For many patients these reduced need forother drugs

However long-term effects of inhaled steroidsstill unknown

Recent studies show that when used withinhaled steroids, theophylline improves lungfunction - not just brochodilation


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Theophylline back in picture??

Study involved patients with persistent cough,wheeze, or breathlessness despite daily use

of inhaled steroids Patients who received theophylline improved

peak flow rates and other measures of lungfunction

Results showed that therapy combining lowdose theophylline with low-dose inhaledsteroids is as effective as using high dose

steroids alone and avoided side effects


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How theophylline works

Dilation and relaxation of constrictedairways

Increased contraction strength of thediaphragm

Increased beat frequency of the

respiratory cilia

Central Nervous System stimulation

Diuretic effects


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Dilation and relaxation of

constricted airways Main reason for using theophylline

By relaxing the airway muscles, airways

enlarge

In asthma, breathing becomes easier

In conditions where fluid or othermaterial has accumulated in airways,dilation of the airways can suppresscoughing


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More on dilation and relaxation

Smooth muscles surround the small airwaysand, when constricted, narrow airways

Theophylline inhibits cAMPphosphodiesterase, which causes thebreakdown of cyclic AMP

Cyclic AMP causes smooth muscle relaxation

By inhibiting cAMP phosphodiesterase,there's more cyclic AMP around to relaxsmooth muscles


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Increased contraction strength of

the diaphragm The diaphragm forms the muscular floor of

the chest cavity and its contractions

correspond to the strength of breathingmotions

When breathing becomes difficult, this muscleworks harder against the resistance created

by disease Theophylline can strengthen the diaphragm


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Increased beat frequency of the

respiratory cilia Cells secrete a layer of mucus which captures

debris we have inhaled and move debris

formed by disease lower down in the lungs Mucus is moved to throat by cilia on epithelial

cells lining respiratory tract - cilia move themucus and its trapped debris

Once the mucus reaches the throat it is eithercoughed up or swallowed

Theophylline helps cilia to beat faster and

thereby more rapidly clear respiratory debris


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Central Nervous System

stimulation Stimulating effects of theophylline

similar to caffeine, a closely related

cmpd While this can considered be a negative

side effect, it can be helpful in infants

who suffer from sleep apnea


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Diuretic

Increased urinary output that may be aproblem for some individuals - however

the effect is usually mild May help dry excessive respiratory

secretions thus help suppress coughing

respiratory 2[1]

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