Question:hard
Mechanism of action of theophylline in bronchial asthma includes all of the following except:
Mechanism of action of theophylline in bronchial asthma includes all of the following except:
Show Hint
Three are real xanthine actions; one belongs to direct beta-2 agonists.
Updated On: Jun 24, 2026
- Phosphodiesterase inhibition
- Adenosine receptor antagonism
- Increased histone deacetylation
- Beta-2 receptor stimulation
Show Solution
The Correct Option is D
Solution and Explanation
This is a true-except question, so the goal is to find the one listed action theophylline does not perform. Theophylline is a methylxanthine, and its real toolkit is well defined.
It blocks phosphodiesterase, so cyclic AMP is not broken down and accumulates, relaxing airway smooth muscle. It also antagonizes adenosine receptors, and since adenosine normally constricts bronchi and triggers mediator release, blocking it helps open the airways. A more modern mechanism is its boosting of histone deacetylase activity at low concentrations, which increases histone deacetylation, switches off inflammatory gene transcription, and even restores steroid responsiveness.
Now the odd one out. Stimulating beta-2 receptors is what direct beta-2 agonists such as salbutamol or formoterol do; they dock onto the receptor itself. Theophylline never works that way, it operates on the PDE, adenosine, and HDAC pathways instead. Therefore beta-2 receptor stimulation is the action that does not belong.
\[\boxed{\text{Beta-2 receptor stimulation}}\]
It blocks phosphodiesterase, so cyclic AMP is not broken down and accumulates, relaxing airway smooth muscle. It also antagonizes adenosine receptors, and since adenosine normally constricts bronchi and triggers mediator release, blocking it helps open the airways. A more modern mechanism is its boosting of histone deacetylase activity at low concentrations, which increases histone deacetylation, switches off inflammatory gene transcription, and even restores steroid responsiveness.
Now the odd one out. Stimulating beta-2 receptors is what direct beta-2 agonists such as salbutamol or formoterol do; they dock onto the receptor itself. Theophylline never works that way, it operates on the PDE, adenosine, and HDAC pathways instead. Therefore beta-2 receptor stimulation is the action that does not belong.
\[\boxed{\text{Beta-2 receptor stimulation}}\]
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