@article {Kang55, author = {Y S Kang and R J Boado and W M Pardridge}, title = {Pharmacokinetics and organ clearance of a 3{\textquoteright}-biotinylated, internally [32P]-labeled phosphodiester oligodeoxynucleotide coupled to a neutral avidin/monoclonal antibody conjugate.}, volume = {23}, number = {1}, pages = {55--59}, year = {1995}, publisher = {American Society for Pharmacology and Experimental Therapeutics}, abstract = {The pharmacokinetics and organ uptake of a 3{\textquoteright}-biotinylated, [32P] internally labeled 36-mer phosphodiester oligodeoxynucleotide (PO-ODN) were measured after intravenous injection in the anesthetized adult rat. The PO-ODN was antisense to the tat gene of the human immunodeficiency virus, and was 3{\textquoteright}-biotinylated to a) protect against serum and tissue 3{\textquoteright}-exonuclease activity, and b) facilitate coupling to a neutral avidin-based transcellular drug delivery vector. The latter was comprised of a covalent conjugate of neutral avidin (NLA) and the OX26 murine monoclonal antibody to the rat transferrin receptor. The PO-ODN was internally labeled at the 21-nucleotide position to prevent rapid hydrolysis [32P] label by serum and tissue 5{\textquoteright}-phosphatases. The uptake of the 3{\textquoteright}-bio-[32P21]PO-ODN by brain, heart, kidney, lung, and liver was measured. The studies show that the unconjugated 3{\textquoteright}-bio-[32P21]PO-ODN was rapidly removed from plasma, with a mean residence time of 22 +/- 1 min and a systemic clearance of 9.2 +/- 0.5 ml/min/kg. Large amounts of [32P] radioactivity were recovered in the urine following the injection of the PO-ODN, and when this fraction was included in the calculation of the renal clearance parameter, the renal clearance was 20-fold higher, indicating the principal site of organ clearance of the unconjugated PO-ODN was the kidney. Conjugation of the 3{\textquoteright}-bio-PO-ODN to the NLA-OX26 vector reduced the systemic clearance 50\%, owing to a \> 10-fold reduction in renal clearance. Following conjugation of the 3{\textquoteright}-bio-PO-ODN to the NLA-OX26 vector, the major clearance organ was the liver.(ABSTRACT TRUNCATED AT 250 WORDS)}, issn = {0090-9556}, URL = {https://dmd.aspetjournals.org/content/23/1/55}, eprint = {https://dmd.aspetjournals.org/content/23/1/55.full.pdf}, journal = {Drug Metabolism and Disposition} }