Pharmacology, effective drugs in asthma and respiratory diseases.Bronchodilators (smooth muscle dilators), nonsteroidal anti-inflammatory drugs, bronchodilators such as specific sympathetic agonist mimics and muscarinic antagonists, methylxanthines, and anti-leukotropin inhibitors are among the most commonly used inhibitors. Pharmacology of bronchial smooth muscle- Parasympathetic nerves affect the smooth muscles of the terminal bronchioles through the vagus and bronchoconstrictive response, sympathetic and non-adrenergic factors.- Histamine increases vagal afferent activity and bronchoconstriction response.- Muscarinic (M2) presynaptic receptors inhibit the release of acetylcholine and dilate the bronchi.- Stimulation of beta-2 receptors in bronchial smooth muscle causes relaxation due to increased intracellular concentration of CAMP.- The respiratory epithelium releases substances that can regulate the smooth muscle of the bronchi, and removal of the epithelium intensifies the contractile response to acetylcholine, histamine, or serotonin in the large airways and reduces the relaxation response to isoproterenol in the small airways.