title: Altered pharmacokinetics of recombinant human deoxyribonuclease in rats due to the presence of a binding protein.
abstract: Preclinical pharmacokinetic studies with recombinant human DNase (rhDNase) following a single intravenous injection of 0.01, 0.1, or 1.0 mg/kg in male rats demonstrated that clearance and steady-state volume of distribution increased at the 1.0 mg/kg dose, whereas the mean exit time from the serum remained unchanged. To characterize the molecular form of 125I-rhDNase in serum, rats were intravenously injected with approximately 300 microCi (5 micrograms)/kg 125I-rhDNase or approximately 300 microCi (5 micrograms)/kg 125I-rhDNase with 1 mg/kg unlabeled rhDNase, and blood samples were taken at 2 min. Urine was collected from one rat in each group from 0-6 and 6-24 hr after injection. Serum samples were analyzed by trichloroacetic acid precipitation and native PAGE; urine samples were analyzed by size exclusion HPLC. Native PAGE results indicate that there is a protein present in the serum that binds rhDNase specifically. The presence of excess unlabeled rhDNase decreases the 125I-rhDNase-binding protein complex level relative to free 125I-rhDNase. In contrast, a high-molecular weight peak of radioactivity was seen after size exclusion HPLC of the urine from the animal that received 125I-rhDNase with unlabeled rhDNase rather than the animal that received 125I-rhDNase alone. In addition to its effects on disposition, a specific serum binding protein for rhDNase may play a role in modulating the bioactivity of circulating rhDNase.
authors.affiliation: Genentech, Inc., San Diego, CA.
authors.forename: M
authors.initials: M
authors.lastname: Mohler
authors.forename: J
authors.initials: J
authors.lastname: Cook
authors.forename: D
authors.initials: D
authors.lastname: Lewis
authors.forename: J
authors.initials: J
authors.lastname: Moore
authors.forename: D
authors.initials: D
authors.lastname: Sinicropi
authors.forename: A
authors.initials: A
authors.lastname: Championsmith
authors.forename: B
authors.initials: B
authors.lastname: Ferraiolo
authors.forename: J
authors.initials: J
authors.lastname: Mordenti
mesh_terms: D000818:Animals; D001798:Blood Proteins / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003851:Deoxyribonucleases / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D011485:Protein Binding; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000493:pharmacokinetics
chemical_list: D001798:Blood Proteins; D007457:Iodine Radioisotopes; D011994:Recombinant Proteins; D003851:Deoxyribonucleases