Mechanisms of Peptide Absorption after Pulmonary Delivery

Mechanism of Peptide Absorption after Pulmonary Delivery 

The co-transport of di- and tripeptides with protons has been well studied in the small intestine and kidneys, and showed enhanced absorption of peptides by the 

Hoover et al. [47] assessed the absorption of a series of model D-phenylalanine analogues that were resistant towards enzymatic hydrolysis, after intrapulmonary administration of aerosolized peptide solution into the rat lung. Compared to oral administration, all peptides showed better absorption from the lung than from the gut, with pulmonary absorption ranging from 55.1 to 68.5% for the methylated series of these model peptides. However, some members of the non-methy-lated peptide series were metabolized during the absorption process, which was not observed in the intestinal absorption studies. Therefore, the advantage of pulmonary over oral administration must be examined on a case-by-case basis. 

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