ISSN:
1573-904X
Keywords:
esterase-sensitive prodrugs
;
peptide delivery
;
opioid peptides
;
Caco-2 cells
;
membrane permeability
;
chemical and enzymatic stability
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Purpose. To evaluate the cellular permeation characteristics and the chemical and enzymatic stability of phenylpropionic acid-based cyclic prodrugs $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{1} $$ and $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{2} $$ of opioid peptides [Leu5]-enkephalin (H-Tyr-Gly-Gly-Phe-Leu-OH) and DADLE (H-Tyr-D-Ala-Gly-Phe-D-Leu-OH), respectively. Methods. The rates of conversion of cyclic prodrugs $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{1} $$ and $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{2} $$ to [Leu5]-enkephalin and DADLE, respectively, in HBSS, pH 7.4 (Caco-2 cell transport buffer) and in various biological media having measurable esterase activity were determined by HPLC. The cell permeation characteristics of [Leu5]-enkephalin, DADLE, and cyclic prodrugs $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{1} $$ and $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{2} $$ were measured using Caco-2 cell monolayers grown onto microporus membranes and monitored by HPLC. Results. In HBSS, pH 7.4, cyclic prodrugs $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{1} $$ and $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{2} $$ degraded to [Leu5]-enkephalin and DADLE, respectively, in stoichiometric amounts. In 90% human plasma, the rates of disappearance of cyclic prodrugs $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{1} $$ and $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{2} $$ were slightly faster than in HBSS, pH 7.4. These accelerated rates of disappearance in 90% human plasma could be reduced to the rates observed in HBSS, pH 7.4, by pretreatment of the plasma with paraoxon, a known inhibitor of serine-dependent esterases. In homogenates of Caco-2 cells and rat liver, accelerated rates of disappearance of cyclic prodrugs $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{1} $$ and $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{2} $$ were not observed. When applied to the AP side of a Caco-2 cell monolayer, cyclic prodrug $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{1} $$ exhibited significantly greater stability against peptidase metabolism than did [Leu5]-enkepha-lin. Cyclic prodrug $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{2} $$ and DADLE exhibited stability similar to prodrug $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{1} $$ when applied to the AP side of the Caco-2 cell monolayers. Prodrug $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{1} $$ was 1680 fold more able to permeate the Caco-2 cell monolayers than was [Leu5]-enkephalin, in part because of its increased enzymatic stability. Prodrug $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{2} $$ was shown to be approximately 77 fold more able to permeate a Caco-2 cell monolayer than was DADLE. Conclusions. Cyclic prodrugs $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{1} $$ and $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{2} $$ , prepared with the phenylpropionic acid promoiety, were substantially more able to permeate Caco-2 cell monolayers than were the corresponding opioid peptides. Prodrug $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{1} $$ exhibited increased stability to peptidase metabolism compared to [Leu5]-enkephalin. In 90% human plasma but not in Caco-2 cell and rat liver homogenates, the opioid peptides were released from the cyclic prodrugs by an esterase-catalyzed reaction that is sensitive to paraoxon inhibition. However, the rate of this bioconversion appears to be extremely slow.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1018802324759
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