ASTHMA and COPD: Pharmacology Flashcards
What are the most potent spasmogens in Asthma ?
cysteinyl-leukotrienes LTC 4 and LTD 4
What is the significance of drug particle size in inhaled drug delivery systems ?
The size determines the location in which the drug will be distributed in the airway. Particles larger than 10 µm impact on the upper airways and will be swallowed. Whereas particles smaller than 1 µm will be distributed to the alveoli and can enter systemic circulation.
What are the requirements for optimal delivery of drugs through Pressurised Metered-Dose Inhaler?
- adequate inspiratory airflow rate;
- gentle, slow, long inspiration preceded by full expiration;
- a breath hold of at least 5 seconds.
How does Pressurised Metered-Dose Inhaler deliver drugs ?
The propellant in the device is a pressurised hydrofluoroalkane (HFA) and activation delivers a measured dose of aerosol via an atomisation nozzle.
A variant of it generates two fine jets of liquid that converge and release a soft mist when they collide, with 60% to 80% of the particles at optimal size
How does breath-actuated pMDI works ?
breath actuation requires air to be drawn through the mouthpiece at a flow rate of at least 30 L/min and people who have severe airflow obstruction cannot achieve this.
What is the advantage of Pressurised Metered-Dose Inhaler with a Spacer
?
A spacer device (a plastic reservoir) can be attached to the pMDI to act as a chamber from which the suspended aerosol particles can be inhaled. The use of a spacer removes the need to coordinate aerosol activation and inspiration.
How does β 2 -Adrenoceptor agonists work.
β 2 -Adrenoceptors are widely distributed in the lung and the receptor density is higher in bronchial smooth muscle than in other cell types. Stimulation of these receptors by an agonist stabilises the receptor in its active configuration, resulting in increased generation of cAMP by adenylyl cyclase and activation of PKA. This phosphorylates myosin light chain proteins that are central to the regulation of smooth muscle tone.β 2 -Adrenoceptor agonists also reduce Ca 2+ entry into muscle cells and activate K + channels that hyperpolarise the smooth muscle cell.
what is the adverse effect of beta 2 agonist frequent use in Asthma ?
Frequent use of a β 2 -adrenoceptor agonist in asthma can enhance Th2 inflammatory pathways and will downregulate β 2 -adrenoceptors. Monotherapy with LABA is associated with worse asthma control and more frequent exacerbations. LABAs should therefore not be used without an inhaled corticosteroid.
What is the pharmacological synergy of LABA and ICS?
The LABA enhance the gene-transcription effects of corticosteroids, and corticosteroids increasing β 2 -adrenoceptor gene transcription and enhancing coupling of the receptor to adenylyl cyclase. Therefore, they are synergic potentiators.
What is the effect of beta-2 agonist on skeletal muscles ?
It cause Fine skeletal muscle tremor from stimulation of β 2 -adrenoceptors.
What are the indications for muscaranic receptor antagonists ?
The main benefit of muscarinic antagonists is in COPD. They are of less value for bronchodilation in acute mild to moderate asthma, but ipratropium has a place when added to a β 2 -adrenoceptor agonist in severe exacerbations of asthma.
