Mechanism of action of theophylline in bronchial asthma is:: (A) Phosphodiesterase 4 inhibition, (B) Beta2 agonism, (C) Anticholinergic action, (D) Inhibition of mucociliary clearance
Answer is A. Ans. (A) Phosphodiesterase 4 inhibition(Ref: Katzung 11th/e p345; KDT 8th/e p245)Theophylline is used in bronchial asthma. Its mechanism of action is:Inhibition of phosphodiesterases particularly PDE-4.Antagonism of adenosine receptors.Enhancement of histone deacetylation. Acetylation of histone is required for activation of inflammatory gene transcription. By inhibiting this process, low-dose theophylline may restore responsiveness to corticosteroids.