Module 9 - Respiratory System

Autonomic Control of Airways

Bronchioles

• Lined with smooth muscle that controls amount of air entering lungs

Sympathetic Branch

• Activates beta₂–adrenergic receptors and causes bronchiolar smooth muscle to relax

• The airway diameter increases (bronchodilation)

Parasympathetic Branch

• Causes bronchiolar smooth muscle to contract

• The airway diameter decreases (bronchoconstriction)

Administration of Pulmonary Drugs by Inhalation

Suspension of droplets or particles in a gas.

Rapid and efficient route.

Shorter duration, reduced side effects, difficult to measure dose.

Aerosol Therapy Devices

Nebulizer

• Vaporizes liquid drug into fine mist.

• Uses small machine and face mask.

Metered-Dose Inhaler (MDI)

• Propellant delivers measured dose of drug.

• Patient times inhalation to puffs of drug.

• Can be used with a spacer.

Dry Powder Inhaler (DPI)

• Patient inhales powdered drug.

• Device activated by inhalation.

Soft Mist Inhaler (SMI)

• Propellant-free, soft mist aerosol delivery device.

• Less effort needed to coordinate compared to MDI.

Asthma

Chronic inflammatory disorder of the airways characterized by:

• Paroxysmal or persistent symptoms.

• Dyspnea, chest tightness, wheezing, sputum production & cough.

• Airway hyper-responsiveness to a variety of stimuli (triggers).

Bronchospasm

• Constriction of the muscles in the walls of the bronchioles caused by inflammatory mediators.

Hyper-reactivity

• An exaggerated response of bronchial smooth muscles to trigger stimuli.

Airway remodelling

• Refers to structural changes, including a change in the extracellular matrix in the airway wall, leading to airflow obstruction.

Pharmacologic Therapy - Asthma

Reliever Medication

• Patient should have on hand and take only when needed (during an attack, episode of shortness of breath or before exercising).

Controller Medication

• Prevents asthma attacks and inflammation.

• Take every day, even if no symptoms.

• Acts slowly and works over the long-term.

• Will not help in an asthma attack.

Short-Acting Beta-Adrenergic Agonists (SABA)

A reliever medication.

For quick relief of cough, chest tightening, wheezing, shortness of breath, etc.

Produces bronchodilation by stimulating beta receptors.

Ex. salbutamol, terbutaline

Long-Acting Beta-2 Agonists (LABA)

A controller medication.

Work slowly over a 12-hour period to keep airways open and muscles relaxed.

Similar mechanism of action to SABA.

Should never be used alone.

Ex. salmeterol, formoterol

Inhaled Corticosteroids (ICS)

A controller medication.

Most common and effective type of controller.

Inhibit inflammatory response at all levels.

Ex. fluticasone, budesonide, ciclesonide, beclomethasone, mometasone

Oral Corticosteroids

Used for short periods of time in acute, severe asthma.

Ex. prednisone, prednisolone, dexamethasone.

Leukotriene Receptor Antagonists

A controller medication.

Antagonizes the effects of leukotrienes, eosinophils, and other inflammatory cells.

Ex. montelukast.

Short-Acting Muscarinic Antagonists (SAMA)

A reliever medication.

Blocks muscarinic receptors in smooth muscle, therefore reducing parasympathetic tone, which leads to bronchodilation.

Ex. ipratropium

Long-Acting Muscarinic Antagonists (LAMA)

A controller medication.

Add-on therapy in moderate to severe asthma.

Similar to SAMA.

Ex. glycopyronium, tiotropium, umeclidinium, aclindinium.

Methylxanthines

Use as an ‘add on’ in patients who require high-dose corticosteroids.

Non-specific inhibition of phosphodiesterase, which causes mild bronchodilation.

Ex. theophylline.

Biologics

For severe, uncontrolled asthma despite high-dose ICS and additional controllers.

Reduced airway eosinophilic inflammation by targeting specific pathways.

Ex. anti-immunoglobulin E antibody, IL-5 inhibitors, IL 4 and 13 inhibitors.

Inhaled Combination Products

As effective as separate medication.

More convenient, enhanced adherence.

Chronic Obstructive Pulmonary Disease (COPD)

A progressive, largely preventable lung disease caused mainly by smoking.

Includes chronic bronchitis (inflammation and mucus) and emphysema (destruction of alveoli).

Pharmacologic Therapy - COPD

Bronchodilators

• Short-acting beta-adrenergic agonists (SABA)

• Short-acting muscarinic antagonist (SAMA)

• Long-acting beta-adrenergic agonists (LABA)

• Long-acting muscarinic antagonists (LAMA)

Inhaled corticosteroids (ICS)

Other

• Long-term oxygen therapy

• N-acetylcysteine

• Roflumilast

• Antibiotics for infectious exacerbations.

Short-Acting Bronchodilators (Rescue)

Used for acute symptom relief.

SABA - salbutamol, terbutaline

SAMA - ipratropium

Long-Acting Bronchodilators (Maintenance)

Use every day to keep airways open.

LABA - salmeterol, formoterol, indacaterol, olodaterol

LAMA - tiotropium, umelidinium, glycopyrronium, aclindinium