An ester compound (Ada-Enk) of [D-Ala2] Leuenkephalin (Enk) with 1-adamantanol was evaluated as a prodrug for the improved brain delivery using rats as the experimental animal. The tissue-to-plasma concentration ratio(Kp)of Ada-Enk at steady state dining the intravenous infusion was 4.5 times larger than that of Enk, indicating the improved delivery to the brain. The distribution of Ada-Enk to the other organs was also increased in comparison with Enk, but the degree of the enhanced distribution was much higher in the brain. The distribution of Ada-Enk was similar in all the regions in the brain. In addition, Enk was found in the brain during the intravenous infusion of Ada-Enk. The in vitro metabolic study showed that Ada-Enk was metabolized in both plasma and brain while Enk was formed in the brain homogenates much more than in the plasma.
|Number of pages||11|
|Journal||Drug Delivery System|
|Publication status||Published - 1993|
- [D-Ala] Leu-enkephalin
- brain-directed delivery
ASJC Scopus subject areas
- Pharmaceutical Science