Pharmacotherapy/Treatment Of Bronchial Asthma

Bronchial asthma is a chronic inflammatory disease of the airways. The airway narrows and swells, producing extra mucus. It has no cure. It is more common in children and appears more chronic in children than in adults. It is deadly if not managed.

Bronchial Asthma

It is associated with mast cells, eosinophils and T lymphocytes. Mast cells are allergic causing cells that release chemicals like histamine. Histamine is responsible for nasal stuffiness and dripping in a cold or hayfever constituting airways in asthma and itchy areas in a skin allergy.

Eosinophils are white blood cells associated with allergy disease. T lymphocytes are also white blood cells associated with allergy and inflammation.

This along with other inflammatory cells are involved in the development of an airway inflammation in asthma that contributes to the airway hyperresponsiveness, airflow limitation, respiratory symptoms and chronic disease. In certain individuals, the inflammation results in a feeling of chest tightness and breathlessness that is felt often at night or early in the morning. Asthma is always caused by a specific trigger.

Asthma Triggers

1. Smoking

2. Secondhand smoke

3. Infection

4. Colds, flu or pneumonia

5. Allergens such as fruit pudding and moulds

6. Exercise

7. Pollution and toxins

8. Extreme Weather changes

9. Drugs like aspirin, nonsteroidal anti-inflammatory drugs, beta blockers

10. Food additives (MSG)

11. Anxiety and emotional stress

12. Singing or laughing 

13. Acid reflux

14. Perfume and fragrance

Signs And Symptoms

1. Coughing

2. Wheezing

3. Shortness of breath

4. Chest tightness

5. Running nose

6. Swollen nasal passage

7. growth inside the nose

Diagnosis

1. Spirometry is a lung function test to measure breathing capacity. The instrument is connected to the mouth and air is blown into it. The force of the air is measured to determine the breathing capacity of the Lord.

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2. Peak expiratory flow rate uses peak flow metre and air is forcefully exhaled into the tube to measure the force of hair that can be expended through the lungs.

3. Chest x-ray to rule out other diseases

4. Methacholine is an asthma trigger. It is given to the person and reaction to it when inhaled means there is asthma.

5. Listening to wheezing sound from the chest, upper respiratory tract and skin.

6. Allergy test: this is done by skin or blood test to see if you are allergic to anything like pets, dust, mold or pollen. Presence of high T2 is indicative of allergies while less T2 means asthma is not associated with allergies or eosinophils.

7. Nitric oxide test: nitric oxide is always high in asthma patients.

8. Sputum eosinophils: since it is one of the causes of asthma, its presence is an indication of asthma. Saliva or mucus is stained with rose coloured dye which becomes visible to eosinophils.

9. Provocative testing: test of airways obstruction before and after exercise.

Type Of Asthma

There are two different ways asthma is classified. The first is based on triggers.

1. Adult-Onset Asthma

2. Allergic Asthma

3. Asthma-COPD Overlap

4. Exercise-Induced Bronchoconstriction (EIB)

5. Nonallergic Asthma

6. Occupational Asthma

The second classification is based on severity of the condition. These types include:

1. Mild intermittent asthma: define as an attack that affects a person two nights in a month or two days in a week.

2. Mild persistent asthma: two times in a week but not more than once in a day.

3. Moderate persistent asthma: occur once every but less than one night in a week.

4. Severe persistent asthma: as the name implies occur more frequently

Risk Factors

1. Genetic factors

2. Another allergic condition like hay fever or allergic ectopic dermatitis

3. Overweight

4. Smoke

5. Exposure to exhaust fumes or other type of pollution

6. Occupational trigger

Complications

1. Affect sleep and work

2. Permanent narrowing of the tubes that carry air to and from the lungs

3. Effects how well the person breathes

4. Effects long term use of asthma drugs

Prevention

1. Vaccination against influenza and pneumonia

2. Avoid triggers

3. Monitor and treat attacks early

4. Use drugs and observe the one that works best

5. Pace yourself

6. Avoid anger or fear

Lifestyle

1. Always use air condition as it removes irritant or pollutants

2. Decontaminate your decor

3. Maintain optimal humidity

4. Prevent mould spores, reduce pet dander and clean regularly

5. Cover nose and mouth when it is cold

6. Exercise reduce weight

7. Treats ulcer and its related conditions

Pathophysiology Of Bronchial Asthma

Asthma involves many pathophysiologic factors, including bronchial inflammation with airway constriction and resistance that manifests as epi­sodes of coughing, shortness of breath, and wheezing. Asthma can affect the trachea, bronchi, and bronchioles. Inflammation can exist even though obvious signs and symptoms of asthma may not always occur.

Bronchospasms, edema, excessive mucus, and epithelial and muscle damage can lead to bronchoconstriction with broncho­spasm. Defined as sharp contractions of bronchial smooth muscle, bronchospasm causes the airways to narrow; edema from microvascular leakage contributes to airway narrowing. Airway capillaries may dilate and leak, increasing secretions, which in turn causes edema and impairs mucus clearance.

How bronchospasm constricts the airway?

Asthma also may lead to an increase in mucus-secreting cells with expansion of mucus-secreting glands. Increased mucus secretion can cause thick mucus plugs that block the airway. Injury to the epithelium may cause epithelial peeling, which may result in extreme airway impairment. Loss of the epithelium’s barrier function allows allergens to penetrate, causing the airways to become hyperresponsive—a major feature of asthma. The degree of hyperresponsiveness depends largely on the extent of inflammation and the individual’s immunologic response.

Asthma also causes loss of enzymes that normally break down inflammatory mediators, with ensuing reflexive neural effects from sensory nerve exposure. Without proper treatment and control, asthma may cause airway remodeling leading to changes to cells and tissues in the lower respiratory tract; these changes cause permanent fibrotic damage. Such remodeling may be irreversible, resulting in progressive loss of lung function and decreased response to therapy.

Pharmacotherapy Of Bronchial Asthma

Inhaled beta-2 agonists: albuterol (Proventil, Ventolin), pirbuterol (Maxair), terbutaline (Brethaire), or bitolterol (Tornalate) are short acting drugs. They are used for immediate and emergency. They should not be used more than two times a week. In such situations, a switch to long acting is necessary.

Two to four inhalations of the metered dose inhaler can be used when needed for acute symptoms or pre-exercise to block exercise induced bronchospasm. Use an assist device such as the Maxair Autohaler (3M) or AeroChamber (Forest), or one that permits comfortable rebreathing into a holding chamber such as the InspirEase (Schering) for patients with difficulty coordinating inspiration with activation. The albuterol nebulizer solution, 2.5 to 5 mg, depending on severity, can be used via a compressed air driven nebulizer. The 2.5 mg dose of the nebulizer solution delivers a dose approximately equivalent to 10 inhalations of the metered dose inhaler formulation.

Systemic corticosteroids: For interventional therapy, a sufficiently high dose of prednisone or equivalent such that more is unlikely to be beneficial. For prednisone, use the following doses: less than 1 year old, 10 mg bid; 1 to 3 years old, 20 mg bid; 3 to 13 years old, 30 mg bid;>13 years old, 40 mg bid. Higher doses may be justified for impending or actual respiratory failure. For ambulatory use, patients should be instructed to discontinue the evening dose if any side effects develop during the course of therapy. These may include insomnia, mood or behavior changes, musculoskeletal pains, or bloating. Methylprednisolone may be used as a substitute for prednisone at 80% of the prednisone dose if side effects from short courses of prednisone remain troublesome. Dosage should be continued until the patient is free from symptoms and signs of asthma. The mean duration of therapy is 7 days, with a usual range of 5 to 10 days. Dosage should be discontinued without tapering. Oral corticosteroids are as effective as parenteral unless they are not retained.

Shorter-acting oral corticosteroids. When used as maintenance medication, dosages of 20 to 40 mg of prednisone or prednisolone on alternate mornings (16 to 32 mg methylprednisolone) are generally needed and tolerated. Dosing should begin high and then be reduced to the lowest dose consistent with control of asthma.

Inhaled corticosteroids: beclomethasone dipropionate is available at 42 micrograms (Vanceril, Beclovent) and 84 mcg (Vanceril double strength) per metered inhalation, with 200 metered inhalations per canister; triamcinolone acetonide (Azmacort) is available as a 100 mcg per metered inhalation, with 300 metered inhalations per canister; and flunisolide (Aerobid) is available as a 250 mcg per metered inhalation, 100 metered inhalations per canister. For these 3 inhaled corticosteroids (and budesonide, which is not yet approved in the United States for use in asthma), potency for topical and systemic effect is approximately equivalent. Some data suggests that fluticasone propionate (Flovent) may be twice as potent per mcg as the others, although the drug is associated with a greater degree of systemic effects. Fluticasone is available at concentrations of 44 (Flovent 44), 110 (Flovent 110), and 220 mcg (Flovent 220) per metered dose, each with 120 metered doses per canister Flovent 44 also is available in a canister containing 60 metered doses. Low doses, which are satisfactory for many patients, are < 500 mcg/day (<250 mcg/day for Flovent), but conventional dosage for adults extends up to 1000 mcg/day (500 mcg/day for Flovent).

Higher doses may be needed for some patients. Physicians should determine the lowest dose that maintains control of asthma. Theophylline or salmeterol should be added if more than low doses of inhaled corticosteroids are required. Twice-daily administration is usually sufficient. Once-daily dosing may be adequate for some patients, while others may require more frequent usage. Use an assist device, such as the AeroChamber (Forest) or InspirEase (Schering), to improve delivery if higher than conventional doses are needed. Also, use the assist device for patients having difficulty coordinating inspiration with activation.

Theophylline: Therapy should begin with no more than the lesser of 10 mg/kg/day or 300 mg/day using Theo-Dur or Unidur Tablets or Slo-bid Gyrocaps in 2 divided doses at 12 hour intervals. Slo-bid Gyro Caps can be opened and sprinkled on a spoonful of soft food for children who cannot swallow solid dosage forms. The dose may be increased no more frequently than at 3 day intervals in 2 increments to no more than the lesser of 16 mg/kg/day or 600 mg/day. These values for maximum dosage approximate current observations of the mean dosage necessary to attain serum concentrations of 10 to 20 mcg/mL. It must be noted that the weight adjusted dosage for infants 1 to 6 months old is much lower. Metabolic enzymes for theophylline mature rapidly during the first year of life. This makes theophylline somewhat difficult to use at this age. Initial dosage is described by the regression equation {[(0.2 multiplied by the age in weeks) + 5] mg/kg/day}. Guide final dosage by measurement of serum concentration. Target the lower half of the therapeutic range of serum concentrations, especially for patients with above-average dose requirements. Be aware of the potential for drug interactions with theophylline (see package insert). Do not increase the dose if it is already at the lower end of the therapeutic range in an attempt to reach levels at the upper end of the range. Allow for a degree of biologic flux. Do not maintain any dose that is not tolerated. Do not permit generic substitution.

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Salmeterol (Serevent): Available as a 25 mcg per metered dose, with 120 metered doses per canister. Dosage is limited to 2 inhalations (50 mcg) q 12 h. This should not be used prn. Patients need to be carefully instructed so that salmeterol is not confused with an interventional beta-2 agonist.

Cromolyn and nedocromil (Intal, Tilade): Two inhalations of the standard metered dose inhaler 4 times daily is the recommended dose. Controlled studies demonstrating efficacy have been predominantly with the 20 mg Spinhaler capsules or nebulizer solution administered 4 times daily. The 1 mg per metered dose inhaler (2 mg recommended dose) for cromolyn marketed in the United States provides suboptimal dosage. The 5 mg per metered dose inhaler (10 mg per dose) marketed elsewhere appears to be more effective. The nebulizer solution for cromolyn is used at a standard dose of 20 mg 4 times daily by compressed air driven nebulizer.

Leukotriene antagonists and inhibitors: Zafirlukast (Accolate) is marketed as a 20 mg oral tablet to be administered twice-daily 1 hour before or 2 hours after meals. It has no effect on acute symptoms and is only weakly potent as a maintenance medication , according to study results in package insert. It has no demonstrable additive effects with other maintenance medication.

Zileuton (Zyflo): Zileuton (Zyflo) is marketed as a 600 mg tablet to be administered 4 times daily. Liver function studies are recommended before and during administration. Inhibition of hepatic enzymes can result in slowing of metabolic elimination of medications such as theophylline, warfarin, or propranolol. The clinical efficacy is very modest.

Montelukast. Montelukast is expected to be marketed shortly as a once daily dosage preparation.

Source: WebMD LLC

Others are caffeine, black seed, aspirin, choline and pycnogenol, beta blockers.