2. Bronchial Asthma
Recurrent and reversible shortness of breath
Occurs when the airways of the lungs become
narrow as a result of:
– Bronchospasm
– Inflammation of the bronchial mucosa
– Edema of the bronchial mucosa
– Production of viscid mucus
Alveolar ducts/alveoli remain open, but airflow
to them is obstructed
Symptoms
– Wheezing
– Difficulty breathing
6. Aerosol delivery of drugs
– Should produce a high local concentration in the
lungs with a low systemic delivery → minimizing
side effects
– Size of the particles: critical determinant
• >10 um – deposited in the mouth & Oropharynx
• <0.5 um – inhaled, subsequently exhaled
• 1-5 um – allow deposition & most effective
7. Bronchodilators:
Xanthine Derivatives
• Plant alkaloids: caffeine, Theobromine, and
Theophylline
• Only Theophylline is used as a bronchodilator
– Examples:
• Aminophylline
• Theophylline
9. Xanthines: Drug Effects
• CNS stimulation
• Cardiovascular stimulation:
– Increased force of contraction
– Increased HR
– Increased cardiac output
– Increased blood flow to the kidneys (diuretic
effect)
10. Xanthines: Indications
• Dilation of airways in asthmas, chronic
bronchitis, and emphysema
• Mild to moderate cases of acute asthma
• Adjunct agent in the management of COPD
12. RT Implications:
Xanthine Derivatives
• Contraindications: history of PUD or GI disorders
• Cautious use: cardiac disease
• Timed-release preparations should not be
crushed or chewed (causes gastric irritation)
13. Bronchodilators: Beta-Agonists
• Large group, sympathomimetic.
• Used during acute phase of asthmatic attacks.
• Quickly reduce airway constriction and restore
normal airflow.
• Stimulate beta2-adrenergic receptors throughout
the lungs.
14. Bronchodilators: Beta-Agonists
Three types
• Nonselective adrenergics
– Stimulate alpha-, beta1- (cardiac), and beta2- (respiratory)
receptors
– Example: epinephrine
• Nonselective beta-adrenergics
– Stimulate both beta1- and beta2-receptors
– Example: Isoproterenol
• Selective beta2 drugs
– Stimulate only beta2-receptors
– Example: Salbutamol
15. Beta-Agonists: Mechanism of Action
• Begins at the specific receptor stimulated.
• Ends with the dilation of the airways.
– relaxes smooth muscles of the airway and results
in bronchial dilation and increased airflow
16. Beta-Agonists: Indications
• Relief of bronchospasm related to asthma, bronchitis,
and other pulmonary diseases.
• Useful in treatment of acute attacks as well as
prevention
• Used in hypotension and shock.
• Used to produce uterine relaxation to prevent
premature labor.
• Hyperkalemia—stimulates potassium to shift into the cell
20. RT Implications
• Monitor for therapeutic effects
– Decreased dyspnea.
– Decreased wheezing, restlessness, and anxiety.
– Improved respiratory patterns with return to normal rate and
quality.
– Improved activity tolerance.
• Decreased symptoms and increased ease of breathing.
21. RT Implications:
Beta-Agonist Derivatives
• Salbutamol, if used too frequently, loses its beta2-
specific actions at larger doses.
• As a result, beta1-receptors are stimulated,
causing nausea, increased anxiety, palpitations,
tremors, and increased heart rate.
22. Anticholinergics:
Mechanism of Action
• Acetylcholine (ACh) causes bronchial constriction
and narrowing of the airways.
• Anticholinergics bind to the ACh receptors,
preventing ACh from binding.
• Result: bronchoconstriction is prevented, airways
dilate.
25. Antileukotrienes
• Also called leukotriene receptor antagonists
(LRTAs).
• Newer class of asthma medications
• Three subcategories of agents.
• Leukotrienes are substances in the body that
cause inflammation, bronchoconstriction, and
mucus production.
• Result: coughing, wheezing, shortness of breath.
26. Antileukotrienes (cont'd(
Currently available agents
– montelukast (Singulair)
– zafirlukast (Accolate)
– zileuton (Zyflo)
Mechanism of Action
– Prevent inflammation in the lungs so asthma symptoms
are relieved
28. Antileukotrienes: Indications
• Prophylaxis and chronic treatment of asthma in
adults and children older than age 12.
• NOT meant for management of acute asthmatic
attacks.
• Montelukast (Singulair) is approved for use in
children ages 2 and older.
30. Corticosteroids
• Anti-inflammatory.
• Used for chronic asthma.
• Do not relieve symptoms of acute asthmatic attacks.
• Oral or inhaled forms.
• Inhaled forms reduce systemic effects.
• May take several weeks before full effects are seen.
31. Corticosteroids:
Mechanism of Action
• Stabilize membranes of cells that release harmful
bronchoconstriction substances.
• These cells are leukocytes, or white blood cells.
• Also increase responsiveness of bronchial smooth
muscle to beta-adrenergic stimulation
33. Inhaled Corticosteroids:
Indications
• Treatment of bronchospastic disorders that are
not controlled by conventional bronchodilators.
• NOT considered first-line agents for management
of acute asthmatic attacks or status asthmaticus
34. Inhaled Corticosteroids:
Side Effects
• Pharyngeal irritation
• Coughing
• Dry mouth
• Oral fungal infections
• Systemic effects are rare because of the low
doses used for inhalation therapy
35. Inhaled Corticosteroids:
Nursing Implications
• Cautious use in patients with diabetes, glaucoma,
osteoporosis, PUD, renal disease, HF, edema.
• Teach patients to gargle and rinse the mouth with
water afterward to prevent the development of oral
fungal infections
37. Mast Cell Stabilizers (cont'd(
• Indirect-acting agents that prevent the release of the
various substances that cause bronchospasm.
• Stabilize the cell membranes of inflammatory cells (mast
cells, monocytes, macrophages), thus preventing release
of harmful cellular contents.
• No direct bronchodilator activity.
• Used prophylactically.
38. Mast Cell Stabilizers:
Indications
• Adjuncts to the overall management of asthma.
• Used solely for prophylaxis, NOT for acute asthma
attacks.
• Used to prevent exercise-induced bronchospasm.
• Used to prevent bronchospasm associated with exposure
to known precipitating factors, such as cold, dry air or
allergens.
40. Other Respiratory Agents
Mucolytic Agents
1. Acetylcysteine
- reduce the thickness and stickiness of purulent and non-purulent
pulmonary secretions
- antidote for paracetamol poisoning
2. Carbocysteine
- act by regulating and normalizing the viscosity of secretion from
the mucus cell of respiratory tract
- decrease the size and number of mucus producing cells
3. Bromhexine
- depolymerization of mucopolysaccharides, direct effect on
bronchial glands
- liberation of lysosomal enzymes producing cells which digest
mucopolysaccharide fibers
Aminophylline is a compound of the bronchodilator theophylline with ethylenediamine in 2:1 ratio. The ethylenediamine improves solubility, and the aminophylline is usually found as a dihydrate.
Aminophylline is less potent and shorter-acting than theophylline
Aminophylline: competitive nonselective phosphodiesterase inhibitor[3] which raises intracellular cAMP, activates PKA, inhibits TNF-alpha[4][5] and leukotriene[6] synthesis, and reduces inflammation and innate immunity[6]and nonselective adenosine receptor antagonist.[7]
Reference ranges of theophylline in the treatment asthma vary by age, as follows:
Adults: 5-15 µg/mL
Children: 5-10 µg/mL
The reference range of theophylline in the treatment of acute bronchospasm in adults is 10-15 µg/mL.
The reference range of theophylline in the treatment of neonatal apnea is 6-11 µg/mL.
