Enhancement of in situ intestinal absorption of an insoluble NO-donating drug ZLR-8 in rats by spray-dried emulsion / 中国药科大学学报

ABSTRACT

Aim: To explore the in situ intestinal absorption in rats of ZLR-8, an insoluble NO-donor drug, and to compare the intestinal absorption enhancement by spray-dried emulsion. Methods: Intestine of rats was cannulat-ed for in situ perfusion. UV and HPLC methods were used to monitor phenolsulfonphthalein and ZLR-8, respec-tively. The effects on ZLR-8 absorption of the intestinal segments, the concentration of ZLR-8 and the pH of the circulating perfusate were studied. The absorption of ZLR-8 suspension was compared to that of the spray-dried emulsion. Results: 1-h in situ intestinal perfusion of the spray-dried emulsion allowed the estimation of the absor-tion percentage to be (23. 54 ± 1. 40) %, (15. 95 ± 0. 09) %, (12. 30 ± 0. 74) %, (3. 98 ± 0. 12) %, respec-tively; the absorption rate constants in duodenum, colon, jejunum and ileum to be (0.248 6 ±0.046 0) h~(-1), (0. 143 7 ±0. 036 0) h~(-1), (0. 069 2 ±0. 001 3) h~(-1), (0. 020 8 ±0. 000 4) h~(-1), respectively. Significant differ-ences in absorption characteristics were found among intestinal segments. In the range of 3. 4-9. 4, pH of the per-fuate had significant influence on the absorption of ZLR-8, and better absorption appeared at pH of 5. 4 to 7. 4. It was found that the absorption rate constant was unaffected by ZLR-8 concentration. However, the absorption amount was proportional to ZLR-8 concentration. Compared to the ZLR-8 suspension, the in situ intestinal absorption of ZLR-8 in rats given the spray-dried emulsion increased significantly. Conclusion: It was only found that ZLR-8 administered in suspension has minor absorption in rat duodenum while no apparent absorption occurred in other segemnts. ZLR-8 in spray-dried emulsion was fairly absorbed in the rat intestinal segments. Passive diffusion was invloved in the absorption of ZLR-8. Spray-dried emulsion significantly enhanced the intestinal absorption of ZLR-8 in rats.