Title page
Absorption of organic anions (phenol red, bromphenol blue and bromosulphonphthalein) has been studied after their application to rat liver surface in-vivo, employing a cylindrical glass cell (i.d. 9 mm, area 0.64 cm2). Every drug appeared gradually in the blood with the peak level at about 1 h, after which its concentration declined slowly. Absorbed model drug was efficiently excreted into the bile. These observations appear to indicate the possibility of drug absorption from liver surface membrane. Absorption ratios of model drugs were estimated to be more than 59 % in 6 h. As to phenol red, its biliary recovery and metabolism ratio did not change as compared with that of i.v. administration.
Biopharmaceutical study of the hepato-biliary transport of drugs. I. Hepato-biliary transport of non-metabolizing organic anionic compounds in rat.
Bromphenol blue (BPB) and p-acetylaminohippuric acid (PAAH) were studied with rats to understand the basic principles of hepato-biliary transport process. At higher doses of BPB, the hepato-biliary transport capacity appeared to be saturated. At 30 min after the intravenous administration of BPB (5 μmole/300 g body weight), bile/plasma concentration ratio (B/P ratio) was 894±99, liver/plasma concentration ratio (L/P ratio) was 22±5 and bile/liver concentration ratio (B/L ratio) was 42±8. In the case of PAAH (6 μmole/300 g), B/P ratio was 43±15, L/P ratio was 0.47±0.27 and B/L ratio was 12±30. Sulfobromophthalein (BSP) inhibited the L/P and B/L ratios of BPB and BPB inhibited the L/P and B/L ratios of PAAH. With rat liver cell suspensions, BPB was entrapped very rapidly and its cell/medium concentration ratio was about 21 at 30 μg/ml, which was depressed by BSP. With equilibrium dialysis, 95.6±1.5% of BPB and 11.3±3.4% of PAAH were bound to the liver homogenate. These results suggest that these organic anions are transported from blood into bile at least two processes, namely hepatic uptake and biliary excretion, and that the hepatic uptake of these compounds is mainly due to the binding to the substances which exist in the liver cells.
Catalytic removal of tert-butyldimethylsilyl (TBS) ether by PVP-I
Abstract A mild, efficient and rapid protocol the deprotection of alcoholic TBDMS ethers using PVP-1 as catalyst in methanol, the procedure of deprotection of various TBDMS ethers were found to be very convenient, easy work-up, high yielding.