Optimization of Drug Absorption Enhancement Strategies

The major strategies to enhance transmucosal peptide and other drug absorption include (a) coadministration with protease inhibitors, (b) the use of membrane permeation enhancers, (c) coadministration with a combination of absorption enhancers and protease inhibitors, (d) modification of peptide structure to improve metabolic stability or membrane permeation, and (e) use of nano- or microparticles [27], Some of these strategies have been investigated using the in situ rat model. 

Faraj et al. [28] studied the effects of different concentrations of leucine enkephalin, peptidase inhibitors, and sodium glycocholate (GC) on the stability and absorption of leucine enkephalin in nasal cavities of rats. Based on the study, the rate and extent of formation of des-tyrosine leucine enkephalin 

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