title: Characterization of recombinantly expressed rat and monkey intestinal alkaline phosphatases: in vitro studies and in vivo correlations.
abstract: Intestinal alkaline phosphatases (IALPs) are widely expressed in the brush border of epithelial cells of the intestinal mucosa. Although their physiologic role is unclear, they are very significant when it comes to the release of bioactive parent from orally dosed phosphate prodrugs. Such prodrugs can be resistant to cleavage by IALP, or alternatively undergo rapid cleavage leading to the release and precipitation of the less soluble parent. Because purified IALPs from preclinical species are not commercially available, and species differences have not been investigated to date, an effort was made to recombinantly express, purify, and characterize rat and cynomolgus monkey IALP (rIALP). Specifically, recombinant IALP (rIALP)-catalyzed cleavage of five prodrugs (fosphenytoin, clindamycin phosphate, dexamethasone phosphate, ritonavir phosphate, and ritonavir oxymethyl phosphate) was tested in vitro and parent exposure was assessed in vivo (rat only) following an oral dose of each prodrug. It was determined that the rate of phosphate cleavage in vitro varied widely; direct phosphates were more resistant to bioconversion, whereas faster conversion was observed with oxymethyl-linked prodrugs. Overall, the rat rIALP-derived data were qualitatively consistent with in vivo data; prodrugs that were readily cleaved in vitro rendered higher parent drug exposure in vivo. Of the five prodrugs tested, one (ritonavir phosphate) showed no conversion in vitro and no in vivo parent exposure. Finally, the apparent K(m) values obtained for fosphenytoin and clindamycin phosphate in vitro suggest that IALP is not likely to be saturated at therapeutic doses.
authors: Biocon Bristol-Myers Squibb Research and Development Center, Syngene International Limited, Biocon Park Plot 2 & 3 Bommasandra IV Phase Bangalore-560099, India. murali.subramanian@syngeneintl.com
authors: Murali
authors: M
authors: Subramanian
authors: Sundeep
authors: S
authors: Paruchury
authors: Shashyendra
authors: S
authors: Singh Gautam
authors: Sheelendra
authors: S
authors: Pratap Singh
authors: Rambabu
authors: R
authors: Arla
authors: Sonia
authors: S
authors: Pahwa
authors: Snehasis
authors: S
authors: Jana
authors: Prasannakumar
authors: P
authors: Katnapally
authors: Vadari
authors: V
authors: Yoganand
authors: Basanth
authors: B
authors: Lakshmaiah
authors: Debarati
authors: D
authors: Mazumder Tagore
authors: Kaushik
authors: K
authors: Ghosh
authors: Punit
authors: P
authors: Marathe
authors: Sandhya
authors: S
authors: Mandlekar
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism*; D000818:Animals; D000882:Haplorhini; D007422:Intestines / Q000201:enzymology*; D007700:Kinetics; D008297:Male; D009596:Nitrophenols / Q000378:metabolism; D009943:Organophosphorus Compounds / Q000378:metabolism; D011355:Prodrugs / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000378:metabolism
chemical_list: D009596:Nitrophenols; D009943:Organophosphorus Compounds; D011355:Prodrugs; D011994:Recombinant Proteins; C008644:nitrophenylphosphate; D000469:Alkaline Phosphatase