Uridine 5'-triphosphate (UTP, INS316) is a naturally occurring agonist for P2Y(2) receptors on the apical surface of ciliated respiratory epithelium. INS316, being developed by Inspire Pharmaceuticals, is a short-acting, aerosolized uridine 5-triphosphate (UTP) solution used as a diagnostic aid for lung cancer. INS316 appears to improve sputum expectoration mediated through the P2Y2 receptor, a nucleotide receptor expressed in human airway epithelial cells and some other tissues. UTP binding to the P2Y2 receptor triggers signal transduction that leads to chloride ion secretion, thereby resulting in mucociliary clearance of airway. UTP stimulates salt and water transport and cilia beat frequency in human airway epithelium in vitro. Single, inhaled doses of UTP stimulate mucociliary clearance in conscious, intubated sheep and in patients with mild chronic bronchitis (smokers and former smokers), suggesting that UTP may be useful for obtaining deep-lung sputum specimens suitable for diagnostic purposes. A single dose of INS316 safely improves the ability of patients with mild chronic bronchitis to expectorate a deep-lung sputum specimen suitable for cytologic evaluation.

Uridine 5'-triphosphate (UTP, INS316) is a naturally occurring agonist for P2Y(2) receptors on the apical surface of ciliated respiratory epithelium. INS316, being developed by Inspire Pharmaceuticals, is a short-acting, aerosolized uridine 5-triphosphate (UTP) solution used as a diagnostic aid for lung cancer. INS316 appears to improve sputum expectoration mediated through the P2Y2 receptor, a nucleotide receptor expressed in human airway epithelial cells and some other tissues. UTP binding to the P2Y2 receptor triggers signal transduction that leads to chloride ion secretion, thereby resulting in mucociliary clearance of airway. UTP stimulates salt and water transport and cilia beat frequency in human airway epithelium in vitro. Single, inhaled doses of UTP stimulate mucociliary clearance in conscious, intubated sheep and in patients with mild chronic bronchitis (smokers and former smokers), suggesting that UTP may be useful for obtaining deep-lung sputum specimens suitable for diagnostic purposes. A single dose of INS316 safely improves the ability of patients with mild chronic bronchitis to expectorate a deep-lung sputum specimen suitable for cytologic evaluation.

Bradykinin, a pro-inflammatory mediator is also a neuromediator and regulator of several vascular and renal functions. Bradykinin can act as a vasoactive substance along with histamine in inflammation and swelling as it is a potent vasodilator. In addition, it triggers the release of other mediators such as nitric oxide in inflammatory and cancer tissues. Bradykinin acts via specific cell surface receptors: bradykinin receptor, B1 and B2 that are G-protein coupled receptors of the seven-transmembrane domain family. It was shown that increased plasma levels of bradykinin lead to the angioedema as the common major clinical manifestation. Bradykinin was also studied in heart transplant recipients and in obesity patients, but these studies were terminated or withdrawn for different reasons. Bradykinin is also an important growth factor for many cancers. Bradykinin antagonists showed higher potency than standard anti-cancer drugs, without evident toxicity to the hosts, that is why they have great promise for the development of new anti-cancer drugs.