Inhalation Techniques for Asthma and COPD

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Questions and Answers

What is a potential adverse effect of β2-agonists related to glucose metabolism?

Hypoglycemia

Increased plasma concentrations of glucose (correct)

Insulin resistance

Decreased blood glucose levels

Why should caution be exercised when using β2-agonists in diabetic patients?

They can raise plasma glucose levels. (correct)

They can cause severe hypoglycemia.

They lead to increased insulin secretion.

They enhance glucose uptake by cells.

What mechanism leads to tachycardia when using β2-agonists?

Reflex stimulation due to peripheral vasodilation (correct)

Direct stimulation of β1 receptors only

Inhibition of adenosine action

Increase in potassium concentration

What adverse effect may β2-agonists cause related to potassium levels?

Hypokalemia Signup and view all the answers

What is the primary reason for the declining use of theophylline in countries where it was once common?

The development of more effective alternatives. Signup and view all the answers

Which of the following describes how theophylline acts as a bronchodilator?

It inhibits phosphodiesterase and increases cAMP. Signup and view all the answers

What common side effect is associated with β2-agonist use due to skeletal muscle stimulation?

Tremor Signup and view all the answers

Which condition would particularly increase the risk of adverse effects when using β2-agonists?

Diabetes Signup and view all the answers

What percentage of the total drug delivered by a metered-dose inhaler typically ends up in the lower airways?

10-20% Signup and view all the answers

Which of the following statements about inhaled drugs is true?

Inhaled drugs may undergo first-pass metabolism after being absorbed. Signup and view all the answers

What is a potential disadvantage of using a metered-dose inhaler (MDI)?

It may be difficult to use. Signup and view all the answers

What advantage do spacer chambers provide when using inhalers?

They reduce the amount of drug inhaled deposited in the oropharynx. Signup and view all the answers

In patients with asthma or COPD, why is inhalation the preferred route for drug delivery?

It reduces systemic side effects. Signup and view all the answers

What may happen to an inhaled drug with a large molecular weight?

It may get retained in the airways. Signup and view all the answers

What is a characteristic of dry powder inhalers (DPIs)?

The powder can act as an irritant. Signup and view all the answers

Why is it important for patients to be taught how to use an inhaler properly?

To ensure maximum drug delivery to the lungs. Signup and view all the answers

What is the primary mechanism by which β2-agonists promote bronchodilation?

Increase in intracellular cAMP levels Signup and view all the answers

Which of the following mechanisms do β2-agonists utilize to induce relaxation in airway smooth muscle cells?

Increased activity of Na+/Ca2+-ATPase Signup and view all the answers

What is one strategy used to minimize β1-mediated adverse effects in β2-agonist development?

Structural modifications to enhance potency Signup and view all the answers

Which of the following compounds is known to constrict the airways?

Adenosine Signup and view all the answers

What role does phosphodiesterase (PDE) play in bronchodilation?

It inhibits cAMP breakdown when inhibited. Signup and view all the answers

Which treatment method is the preferred choice for managing asthma?

Inhalation of β2-agonists Signup and view all the answers

How does activation of β2 receptors affect intracellular calcium levels?

It inhibits the PLC-IP3 pathway, decreasing calcium mobilization. Signup and view all the answers

What is the effect of increased intracellular cAMP on airway smooth muscle cells?

Facilitation of muscle relaxation Signup and view all the answers

What is one effect of corticosteroids on β2-agonists?

They reverse β receptor desensitization in airways. Signup and view all the answers

Which of the following is a systemic side effect of corticosteroid use?

Growth suppression Signup and view all the answers

How do corticosteroids enhance the effects of β2-agonists in asthma therapy?

By increasing the expression of β2-receptors in the lungs. Signup and view all the answers

What potential adverse effect can corticosteroids cause related to bones?

Osteoporosis Signup and view all the answers

What interaction occurs between corticosteroids and glucocorticoid receptors?

Corticosteroids enhance translocation of liganded glucocorticoid receptors. Signup and view all the answers

Corticosteroid use can lead to which psychiatric disturbance?

Euphoria Signup and view all the answers

What is the advantage of using budesonide, fluticasone, and mometasone over beclomethasone dipropionate?

Lower risk of systemic adverse effects Signup and view all the answers

Which of the following possible adverse effects of corticosteroids relates to vision?

Glaucoma Signup and view all the answers

Which corticosteroid is characterized as a prodrug?

Ciclesonide Signup and view all the answers

Which of the following corticosteroids is considered to have the lowest potency?

Flunisolide Signup and view all the answers

What is the primary mechanism by which corticosteroids prevent tolerance to β2-agonists?

By increasing β2 receptor expression. Signup and view all the answers

What common characteristic do budesonide, fluticasone, and mometasone share regarding hepatic metabolism?

They undergo first-pass metabolism Signup and view all the answers

Which corticosteroid is indicated as lung-selective with lower systemic adverse effects?

Ciclesonide Signup and view all the answers

What is the reason for preferring inhaled corticosteroids in pediatric patients?

Reduced first-pass metabolism and adverse effects Signup and view all the answers

Among the following corticosteroids, which one has a higher risk of systemic adverse effects due to its first-pass metabolism?

Beclomethasone dipropionate Signup and view all the answers

What factor primarily influences the development of systemic adverse effects from corticosteroids?

First-pass metabolism extent Signup and view all the answers

Study Notes

Inhalation for Asthma and COPD

Inhalation is the preferred method for drug delivery in asthma and COPD due to lower risks of adverse effects.
Only 10-20% of the drug delivered via a metered-dose inhaler reaches the lower airways.
The rest is absorbed through the gut and undergoes first-pass metabolism before entering systemic circulation.
Proper inhaler technique is essential to optimize drug delivery.

Inhalation Drug Delivery Devices

Spacer Chambers: Reduce drug deposition in the oropharynx.
Dry Powder Inhalers (DPI): Can be irritating to the mouth.
Metered-Dose Inhalers (MDI): May be difficult to use.
Nebulisers: Easier to use than MDIs.

Bronchodilation Mechanisms

cAMP: promotes bronchodilation.
β-agonists: Increase cAMP synthesis by activating adenylyl cyclase (AC).
Phosphodiesterase (PDE) inhibitors: Slow cAMP breakdown (e.g., theophylline).
Acetylcholine and adenosine: Constrictor agents, inhibited by muscarinic and adenosine antagonists.

β2-Selective Agonists

Strategies for minimizing β1-mediated adverse effects:
- Develop drugs with β2 selectivity.
- Modify structure for reduced metabolism by COMT and increased bioavailability.
- Administer via inhalation (aerosol or dry powder).
Treatment of choice in asthma.
Primary mechanism: bronchodilation through cAMP elevation.

Molecular Actions of β2-agonists

Activation of β2 receptors leads to:
- Increased intracellular cAMP through Gs protein activation.
- Activation of PKA.
PKA phosphorylation of target substrates promotes:
- Opening of KCa channels for smooth muscle relaxation.
- Inhibition of PLC-IP3 pathway, reducing cellular Ca2+.
- Increased Na+/Ca2+ exchange.
- Increased Na+,Ca2+-ATPase activity.

Adverse Effects of β2-agonists

Tachyphylaxis: Rapid tolerance to bronchodilator effects.
Tremor: Stimulation of β2 receptors in skeletal muscle.
Tachycardia: Reflex cardiac stimulation due to β2-mediated vasodilation and direct activation of cardiac β1 and β2 receptors.
Hyperglycemia: Increased plasma concentrations of glucose, lactate, and free fatty acids.
Hypokalaemia: Promotes entry of K+ ions into skeletal muscle, potentially dangerous in cardiac disease.

Theophylline

Structurally similar to caffeine.
Inexpensive, widely used in developing countries.
Declining use due to side effects and less effectiveness compared to inhaled β2-agonists or corticosteroids.
Mechanisms:
- Bronchodilation: inhibits PDE, increases cAMP.
- Antagonises adenosine action.

Synergism Between Corticosteroids and β2-agonists

Corticosteroids:
- Enhance β2 responsiveness.
- Prevent tolerance to β2-agonists.
β2-agonists:
- Increase translocation of liganded GR receptors.
- Enhance binding of GR to DNA.
The combination enhances each other's effects in asthma therapy.

Corticosteroids: Adverse Effects

Local: Dysphonia, oropharyngeal candidiasis, cough.
Systemic: Adrenal suppression, growth supression, bruising, osteoporosis, cataracts, glaucoma, metabolic abnormalities, psychiatric disturbances, pneumonia.

Corticosteroids: Pharmacokinetics and Choice

First-Pass Metabolism: Influences systemic adverse effects.
Low Oral Bioavailability: Budesonide, fluticasone, and mometasone are preferred due to reduced systemic effects.
Ciclesonide: Lung-selective prodrug with lower risk of systemic adverse effects.

Corticosteroids: Potency Comparison

Least potent: Triamcinolone, flunisolide.
Intermediate: Beclomethasone dipropionate, budesonide.
Most potent: Fluticasone propionate.

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Description

Explore the essential inhalation techniques and drug delivery devices used in the treatment of asthma and COPD. Learn about the mechanisms of bronchodilation and the importance of proper inhaler technique to optimize drug efficacy. This quiz will assess your understanding of inhalation therapy and its application.