Indocyanine Green: Observations on Its Physical Properties, Plasma Decay, and Hepatic Extraction*

Abstract

Indocyanine green 1 (ICG) is a tricarbocyanine dye (Figure 1) which has been used in the indicator dilution technique for measuring cardiac output (1, 2). Animal studies (3) and preliminary observations of human subjects (4, 5) have suggested that this dye may have characteristics that could make its uptake, storage, and excretion by the liver helpful indices of hepatic function. The present investigations were carried out to determine whether indocyanine green has properties that may render it suitable for assessing liver function and hepatic blood flow in man.METHODS AND PROCEDURES Physical properties. Indocyanine green was prepared for intravenous administration by dissolving the dye in distilled water to a concentration of 5 mg per ml. Readings of dye concentration were made in a Beckman DU spectrophotometer at 815 m/1.Volume of distribution of radioiodinated human serum albumin 2 was compared with the initial volume of distribution of ICG in 4 normal subjects. Each subject was given approximately 20 /Ac of the I3"-labeled albumin and 50 mg of ICG in a rapid intravenous injection. Venous samples were taken at intervals during the following *

In vivo imaging of hepatic excretory function in the rat by fluorescence microscopy

“…While ICG is an established marker for hepatobiliary excretion and kinetics of ICG are well described [11][12][13], a primarily hepatic clearance of DY635 was confirmed by fluorophotometric determination of the dye in blood, bile and urine. Uptake, intracellular transport and excretion of the two different dyes were assessed by applying IVM.…”

“…ICG was chosen due to its known pharmacokinetics [11][12][13] and its established use in the clinical setting. ICG handling by the liver is predicted from its plasma disappearance curve and represents a widely used method for liver function testing in acute and chronic hepatic disorders [14].…”

“…In plasma, ICG mainly binds to albumin (95%) and lipoproteins and is distributed throughout the plasma without extravascular distribution. ICG is solely hepatobiliary excreted [11]. ICG uptake in the rat is mediated by a mechanism mainly involving the organic anion transporting polypeptide-1 (Oatp1) [21].…”

“…Hepatocellular transport was visualized by use of indocyanine green (ICG), a dye with confirmed hepatobiliary clearance [11]. To optimize visualization and therefore to expand the possibilities of analysis, an additional dye (DY635) was validated for assessing hepatic excretory function.…”

“…Indocyanine green (ICG; Pulsion Medical Systems AG, Munich, Germany) is a well characterized, nearinfrared fluorescent, inert compound [11] which was approved by the United States Food and Drug Administration in 1956. It is widely applied in medical diagnostics.…”