Pharmacokinetics of indocyanine green in rats with chronic renal failure

Specific assay for the quantitation of indocyanine green in rat plasma using high-performance liquid chromatography with fluorescence detection

A rapid and sensitive reversed-phase HPLC assay employing fluorescence detection was developed for quantitating indocyanine green (ICG) in rat plasma. Sample preparation entailed precipitation of plasma proteins with acetonitrile prior to injection on the column. The assay was linear from 0.4 to 200 micrograms/mL, with a detection limit of 3 ng on column. The plasma concentration-time profile of ICG was characterized by this HPLC method and compared with the traditional spectrophotometric assay following iv bolus and iv infusion administration of 5 mg/kg of ICG to rats. Concentrations of ICG obtained using the spectrophotometric assay were consistently higher than those determined by HPLC. In animals receiving ICG by infusion, the maximum difference between the two assays was observed 1 min post-infusion and became negligible by 5 min post-infusion. The calculated pharmacokinetic parameters for ICG, systemic clearance and apparent volume of distribution, were higher using the HPLC assay as compared with the spectrophotometric procedure. The data suggest that a biotransformation or degradation product of ICG is formed in the rat and interferes with the determination of ICG by the spectrophotometric assay. Since the HPLC assay is specific for the parent dye, it is suggested that this assay method be used when determining pharmacokinetic parameters of ICG in rats.

Relation between renal and hepatic excretion of drugs: X. Excretion of nalorphine in young and adult rats pretreated with hormones or xenobiotics

Different processes are involved in renal and hepatic excretion of organic anions and cations. In contrast to our knowledge of anion excretion, information about cation transport in kidney and liver is relatively scarce. In this study, the elimination of nalorphine was investigated to characterize the relation between renal and hepatic excretion of organic cations. Nalorphine is excreted effectively both via kidney and liver. However, its hepatic excretion dominates in adult rats. In young, 20-day-old animals biliary nalorphine elimination is immature and the excreted amounts are significantly lower. Renal excretion of nalorphine is quite similar in rats of both ages. After bile duct ligation renal excretion of nalorphine increases significantly in adult rats whereas it remains unchanged in young ones. Remarkably, after bilateral nephrectomy hepatic elimination of nalorphine is even diminished in both age groups. In further experiments renal excretion of nalorphine could be stimulated in adult rats after repeated administration of trometamol, triiodothyronine, or dexamethasone; these treatments had no consequences on biliary secretion of nalorphine.

Pharmacokinetics and biliary excretion of rose bengal in rats with acute and chronic renal failure

The effects of glycerol-induced acute renal failure (ARF) and surgically induced chronic renal failure (CRF) on the pharmacokinetics and biliary excretion of rose bengal have been examined in the rat. Both the pharmacokinetics and biliary excretion of rose bengal were unaltered in either ARF or CRF. The latter results in CRF contrast with those of Tse et al (1976, Int. J. Nucl. Med. Biol. 3: 134-137) who reported decreased removal of the dye from blood and reduced biliary excretion. In addition, rose bengal behaves differently from bromosulphophthalein and indocyanine green whose hepatic uptake and initial biliary excretion are known to be decreased in ARF. The results suggest that rose bengal may have a hepato-biliary transport route which differs from that of bromosulphophthalein and indocyanine green, and the findings also emphasize the selective nature of altered organic anion uptake by the liver in ARF.

Relation between renal and hepatic excretion of drugs: I. Phenol red in comparison with p-aminohippurate and indocyanine green

Phenol red is a suitable compound for the simultaneous assay of renal and hepatic excretion in the rat. Its elimination has been compared with those of p-aminohippurate (PAH) and indocyanine green (ICG) which are eliminated nearly exclusively via kidneys or liver, respectively. The interruption of one elimination route one day before the experiment, that means bile duct ligation (DL) in the case of ICG or bilateral nephrectomy (NX) in the case of PAH are followed by a slight increase in the elimination via the alternative pathway, but no effective compensation occurs. On the other hand, the renal excretion of phenol red is significantly increased after DL only following administration of high doses. This intensification is caused by an increase in the unbound amount of phenol red depending on the plasma concentration and reflects an enhanced glomerular filtration fraction. The biliary excretion increases significantly after NX, but only after infusion of low doses. The maximal biliary secretion capacity cannot be exceeded following NX, either. The competitive inhibition of phenol red excretion by probenecid supports the findings of NX or DL experiments. An influence of the three test substances on arterial blood pressure has been excluded. The most important factors influencing the switch over from one to the other elimination route seem to be at least in the case of phenol red the amount of unbound substance, the influence of the administered dose on the glomerular filtration, and disturbances in the volume of distribution, e.g. the possible reduction of hepatic uptake after DL.

Reduced hepatic uptake of propranolol in rats with acute renal failure

The effect of acute renal failure (ARF) on the hepatic uptake and metabolism of propranolol was investigated in relation to the hepatic clearance of the drug. ARF was induced by the subcutaneous injection of uranyl nitrate to rats. The uptake rate of propranolol in the isolated perfused liver was determined by the multiple-indicator dilution method and was found to decrease from 43.6 +/- 2.0 min-1 (mean +/- S.E.) in control to 29.4 +/- 1.7 min-1 in ARF (P less than 0.001). The recovery fraction of propranolol in effluent venous blood increased about twofold in ARF compared to control (P less than 0.05). The metabolic activity for propranolol was examined using the hepatic microsomal fraction prepared from control and ARF rats. There was no significant difference in the kinetics of oxidative metabolism of propranolol between two groups. These results suggest that the previously reported decrease in the hepatic clearance of propranolol in ARF is due to decreased hepatic uptake of the drug from the blood into the liver cells.

Pharmacokinetics and biliary excretion of bromosulphophthalein, [3H]-ouabain and [3H]-taurocholic acid in rats with glycerol-induced acute renal failure

The pharmacokinetics and biliary excretion of bromosulphophthalein (BSP), ouabain and taurocholic acid (TChA) have been studied in rats with glycerol-induced acute renal failure (ARF). In rats with ARF, the hepatic uptake and initial biliary excretion of BSP were decreased. In addition, the rate of BSP conjugation with glutathione by rat liver homogenates was also decreased. This latter change may contribute to the initial decrease in the biliary excretion of BSP. No change was found in the hepatic uptake and biliary excretion of ouabain, but the area under the concentration-time curve was increased and the plasma clearance (Clp) decreased in rats with ARF. This decrease in Clp was not due to reduced renal excretion. The decreased Clp of ouabain in rats with ARF may come from reduced tissue binding and a concomitant decrease in its volume of distribution (Vd). The hepatic handling of TChA appeared unaltered in ARF, but the rate constant for the terminal part of the concentration-time curve (beta) was decreased. This change probably resulted from a large increase in Vd in rats with ARF. It is concluded that the decreased uptake of BSP was not due to a non-specific disturbance of hepatocyte function in ARF because the hepatic handling of ouabain and TChA were unaltered.