Enzymatic Degradation of Leuprolide in Rat Intestinal Mucosal Homogenates

Abstract

The purpose of this study was to evaluate in vitro enzymatic degradation and protection of leuprolide acetate in the mucosal homogenates of rat small intestine. When leuprolide was incubated at 37 degrees C with the homogenates, it was degraded quickly. The apparent Michaelis-Menten constant, K(m), and the maximal reaction velocity, Vmax, for leuprolide were 898 mM and 3.4 nmol/min/mg protein, respectively. At least four metabolites of leuprolide were observed in HPLC chromatograms, which were related to cleavages by some serine proteases. In the presence of protease inhibitors in the incubation medium, degradation of leuprolide was significantly suppressed by antipain and 3,4-dichloroisocoumarin (DCI), whereas bestatin and p-hydroxymercuribenzoic acid (PCMB) showed weaker protection than antipain and DCI, and alpha 2-macroglobulin (MG) exhibited no protection. When a w/o/w emulsion formulation was used, rapid degradation of the drug in intestinal homogenates was also inhibited. Therefore, the present study with representative protease inhibitors and a w/o/w formulation revealed that the enzymatic degradation of leuprolide is preventable in the rat intestinal mucosal homogenates.

In vivo evaluation and in vitro metabolism of leuprolide in mice—mass spectrometry‐based biomarker measurement for efficacy and toxicity

“…1(A), is a synthetic nonapeptide and potent analog of GnRH that inhibits gonadotropin secretion, when given continuously, achieving castrate levels for testosterone in prostate cancer patients. As a peptide, leuprolide is susceptible to the action of proteolytic enzymes,6, 7 while proteases and peptidases act as barriers limiting its intestinal absorption 8. Leuprolide's bioavailability is low (less than 1%) following either oral or intraduodenal injections in male rats 9.…”

In vivo βιολογική αξιολόγηση και φαρμακοκινητική μελέτη με χρήση HPLC-MS-MS του Leuprolide και αναλόγων του που εμπλέκονται στη θεραπεία του καρκίνου

“…Δζδζηυηενα, δ απμοζία D -αιζκμλζημφ ηαηαθμίπμο ζηδ εέζδ 6, υπςξ οπμζηδνίγεηαζ ηαζ αζαθζμβναθζηά (Berger et al, 1991;Matsoukas et al, 1997;Keramida et al, 1998;Keramida et al, 2006) Sealfon et al, 1997;Laimou et al, 2010 (Claassen, 1994) ηαζ (ii) θυβς απυηθζζδξ ηδξ πμνήβδζδξ απυ ημο ζηυιαημξ, ηαεχξ δ LHRH ηαζ ηα ακάθμβα αοηήξ παναηηδνίγμκηαζ απυ ζδζαίηενα παιδθή αζμδζαεεζζιυηδηα. Δίκαζ αθδεέξ πςξ δ πεπηζδζηή θφζδ ηδξ LHRH ηαζ ηςκ ακαθυβςκ αοηήξ ηαεζζηά ηα οπυ ιεθέηδ ιυνζα εοάθςηα οπυ ηδ δνάζδ εκυξ πθήεμοξ ζζημ -εζδζηχκ πνςηεμθοηζηχκ εκγφιςκ (Haviv et al, 1992;Zheng et al, 1999a).…”