Effect of absorption promoters on the nasal absorption of drugs with various molecular weights

Abstract

The effect of absorption promoters on the nasal absorption of drugs with different average molecular weights was examined in rats. Phenol red and fluorescein isothiocyanate-dextrans (FITC-dextrans) with various molecular weights were chosen as model drugs while the absorption promoters used in this study were Na glycocholate, Na taurocholate, Na deoxycholate, Na salicylate, EDTA, Na caprylate and Na caprate, all at a concentration of 1%. Of the absorption promoters, bile salts such as Na glycocholate, Na taurocholate, Na deoxycholate, Na caprate and EDTA appeared to be more effective at enhancing the nasal absorption of drugs as compared to Na salicylate and Na caprylate. Na glycocholate, Na caprate and EDTA showed the strongest promoting effect of drugs with an approximate molecular weight 4000, while the maximal effect of Na taurocholate and Na deoxycholate was observed in the nasal absorption of drugs with an approximate molecular weight of 10000. In contrast, Na salicylate and Na caprylate did not affect the absorption of drugs having various molecular weights. These findings indicated that the efficacy of absorption promoters on the nasal absorption of drugs was dependent on their molecular weights.