Possible Role of Electrolytes on the Formation of Precipitates during the Infusion of Nafamostat Mesilate in Hemodialysis.

Nafamostat mesilate (NFM) is used as an anticoagulant during hemodialysis in patients who have had complications due to hemorrhages. The formation of precipitates, which could lead to the interruption of hemodialysis has been reported when NFM is infused into blood during hemodialysis. We report herein on an examination of possible factors that could cause this. The effects of electrolytes such as phosphates, citrates or succinates on the formation of precipitates were examined by mixing NFM with aqueous solutions or plasma that contained these electrolytes. The formation of precipitates was observed in all electrolyte solutions when higher concentrations of NFM were mixed at around physiological pH. In the case of plasma, precipitates were observed when solutions containing higher concentrations of NFM were mixed with plasma that contained phosphate and citrate. In addition, the formation of precipitates under dynamic conditions where NFM was infused into flowing electrolyte solutions was also evaluated. The data suggested that such precipitates might be formed and disrupt the blood flow and/or an NFM infusion when NFM is infused into blood flowing in the hemodialysis circuit. The findings presented herein suggest the serum levels of anionic electrolytes (e.g., phosphate), the type of excipients present in pharmaceutical products (e.g., succinic acid or citric acid), the concentration of NFM used for the infusion or the rates of NFM infusion and blood flow are all factors that could affect precipitate formation during NFM infusions for hemodialysis.

Characterization of Bovine Lactoferrin Nanoparticle Prepared by Desolvation Technique.

Lactoferrin (Lf) nanoparticles have been developed as a carrier of drugs and gene. Two main methods, desolvation technique and emulsification method, for preparation of protein nanoparticles have been reported so far, but most of the previous reports of Lf nanoparticles preparation are limited to emulsification method. In this study, we investigated the optimal conditions by desolvation technique for the preparation of glutaraldehyde-crosslinked bovine Lf (bLf) nanoparticles within the size range of 100-200 nm, and evaluated their properties as a carrier for oral and intravenous drug delivery. The experimental results of dynamic light scattering and Transmission Electron Microscope suggested that glutaraldehyde-crosslinked bLf nanoparticles with 150 nm in size could be produced by addition of 2-propanol as the desolvating solvent into the bLf solution adjusted to pH 6, followed by crosslinking with glutaraldehyde. These cross-linked bLf nanoparticles were found to be compatible to blood components and resistant against rapid degradation by pepsin. Thus, cross-linked bLf nanoparticles prepared by desolvation technique can be applied as a drug carrier for intravenous administration and oral delivery.

The Binding of Silibinin, the Main Constituent of Silymarin, to Site I on Human Serum Albumin.

Silibinin is the main constituent of silymarin, an extract from the seeds of milk thistle (Silybum marianum). Because silibinin has many pharmacological activities, extending its clinical use in the treatment of a wider variety of diseases would be desirable. In this study, we report on the binding of silibinin to plasma proteins, an issue that has not previously been extensively studied. The findings indicated that silibinin mainly binds to human serum albumin (HSA). Mutual displacement experiments using ligands that primarily bind to sites I and II clearly revealed that silibinin binds tightly and selectively to site I (subsites Ia and/or Ic) of HSA, which is located in subdomain IIA. Thermodynamic analyses suggested that hydrogen bonding and van der Waals interactions are major contributors to silibinin-HSA interactions. Furthermore, the binding of silibinin to HSA was found to be decreased with increasing ionic strength and detergent concentration of the media, suggesting that electrostatic and hydrophobic interactions are involved in the binding. Trp214 and Arg218 were identified as being involved in the binding of silibinin to site I, based on binding experiments using chemically modified- and mutant-HSAs. In conclusion, the available evidence indicates that silibinin binds to the region close to Trp214 and Arg218 in site I of HSA with assistance by multiple forces and can displace site I drugs (e.g., warfarin or iodipamide), but not site II drugs (e.g., ibuprofen).

Biological Responsiveness and Metabolic Performance of Liposome-Encapsulated Hemoglobin (Hemoglobin-Vesicles) in Apolipoprotein E-Deficient Mice after Massive Intravenous Injection.

The hemoglobin-vesicle (HbV), a vesicle in which a concentrated human hemoglobin solution is encapsulated, was developed as an artificial oxygen carrier. Although HbV has a favorable safety, metabolic, and excretion performance in healthy animals, the effect of a massive amount of HbV, which also contains a large amount of a lipid component including cholesterol, on physiological response and metabolic performance under hyperlipidemic conditions is unclear. The aim of this study was to evaluate whether administration of HbV causes toxicity in apolipoprotein E-deficient mice (hyperlipidemic model mice). Apolipoprotein E-deficient mice were given a single injection of HbV (2000 mg hemoglobin/kg), and physiological responses and metabolic profiles were monitored for 14 d thereafter. All the mice tolerated the massive amount of HbV and survived, and adequate biocompatibility was observed. Serum biochemical parameters indicate that liver and kidney function were not remarkably affected, and morphological changes in the liver and spleen were negligible. Lipid parameters in serum were significantly increased until 3 d after HbV administration, but recovered within 7 d after the administration. In a pharmacokinetic study, HbV was mainly found distributed in the liver and spleen, and disappeared from the body within 14 d. In conclusion, even under conditions of hyperlipidemia, a massive dose of HbV and its components resulted in favorable biological compatibility, metabolic, and excretion profiles. These findings provide further support for the safety of HbV for clinical use.

Bisabololoxide A, one of the constituents in German chamomile extract, attenuates cell death induced by calcium overload.

Bisabololoxide A (BSBO), main constituents in German chamomile extract, is responsible for antipruritic effect. In previous study, the incubation with 30-100 µM BSBO for 24 h exerted cytotoxic and proapoptotic effects on rat thymocytes. To further characterize BSBO cytotoxicity, the effect on the cells suffering from calcium overload by calcium ionophore A23187 was examined. A23187 induced Ca(2+) -dependent cell death. Contrary to our expectation, 1-10 µM BSBO inhibited A23187-induced increase in cell lethality of rat thymocytes. BSBO attenuated A23187-induced increases in populations of shrunken living cells, phosphatidylserine-exposed living cells, and dead cells, without affecting the increase in intracellular Ca(2+) concentration and the Ca(2+) -dependent hyperpolarization. The effect of BSBO on A23187-treated cells may be unique because the activation of Ca(2+) -dependent K(+) channels is required for cell shrinkage, externalization of phosphatidylserine, and cell death in some cells. The cell death induced by A23187 was not inhibited by Z-VAD-FMK, a pan-inhibitor of caspases. Thus, the cell death may be a necrosis with some features observed during an early stage of apoptosis. These results suggest that BSBO at low micromolar concentrations is cytoprotective against calcium overload.

An in-vitro comparative study of the binding of caspofungin and micafungin to plasma proteins.

OBJECTIVES: Echinocandins are widely used for the treatment of invasive fungal diseases. While they bind strongly to plasma proteins, our knowledge of this process is not sufficient to permit their pharmacokinetics and pharmacodynamics targets to be discussed. In this study, we characterized the binding of two echinocandins, caspofungin and micafungin, to plasma proteins, human serum albumin (HSA) and human α 1-acid glycoprotein (AAG). METHODS: The binding parameters, number of binding sites (n) and association constant (K) for caspofungin and micafungin to HSA and AAG were determined by equilibrium dialysis. The binding site on HSA for these echinocandins was identified by conducting inhibition experiments. KEY FINDINGS: Caspofungin was found to bind strongly to a single site on HSA (n = 1.26, K = 0.45 × 106 M-1) and AAG (n = 0.99, K = 0.29 × 106 M-1). Micafungin was found to bind more strongly to HSA (n = 1.35, K = 1.44 × 106 M-1) and AAG (n = 1.32, K = 1.16 × 106 M-1). The binding site for these drugs on HSA appears to be within subdomain IA. CONCLUSIONS: Free fraction of caspofungin and micafungin in patients may not be substantially affected due to the contribution of AAG to the overall protein binding and the binding to subdomain IA on HSA, which is different from the major drug-binding sites within subdomains IB, IIA and IIIA.

In Vitro and In Vivo Assessment of Atemoya Fruit (Annona atemoya) for Food-Drug Interactions.

BACKGROUND AND OBJECTIVES: Atemoya (Annona atemoya) is increasingly being consumed worldwide because of its pleasant taste. However, only limited information is available concerning possible atemoya-drug interactions. In the present study, the issue of whether atemoya shows food-drug interactions with substrate drugs of the major drug-metabolizing cytochrome P450s (i.e., CYP1A2, CYP2C9, and CYP3A) is addressed. METHODS: The ability of atemoya juice to inhibit the activities of phenacetin O-deethylase (CYP1A2), diclofenac 4'-hydroxylase (CYP2C9), and midazolam 1'-hydroxylase (CYP3A) was examined in vitro using human and rat liver microsomes. The in vivo pharmacokinetics of phenacetin and metabolites derived from it in rats when atemoya juice or fluvoxamine (a CYP1A2 inhibitor) was preadministered were also investigated. RESULTS: Atemoya juice significantly inhibited CYP1A2 activity in human liver microsomes, but not the activities of CYP2C9 and CYP3A. In spite of this inhibition, preadministration of atemoya had no effect on the pharmacokinetics of phenacetin, a CYP1A2 substrate, in rats. Meanwhile, preadministration of fluvoxamine significantly extended the time needed for the elimination of phenacetin, possibly due to the inhibition of CYP1A2. This suggests that the intake of an excess amount of atemoya juice is necessary to cause a change in the pharmacokinetics of phenacetin when the IC50 values for CYP1A2 inhibition by atemoya and fluvoxamine are taken into account. CONCLUSION: The results indicate that a daily intake of atemoya would not change the pharmacokinetics of CYP1A2 substrates such as phenacetin as well as CYP2C9- and CYP3A-substrate drugs.

Toxicodynamic evaluation of a cisplatin-chondroitin sulfate complex using a perfused kidney and human proximal tubular cells.

Cisplatin (CDDP) is an anticancer drug. The clinical limitations associated with CDDP have stimulated the development of macromolecular drug-carrier systems, in attempts to decrease its toxicity. A complex (CDDP-CSA-23) between CDDP and chondroitin sulfate (CSA), a natural polysaccharide with a mean molecular weight of 23 kDa, proved to have the same anticancer activity as CDDP. A toxicodynamic study was performed on perfused kidneys to determine the effect of CDDP-CSA-23 on renal functions and the extent of platinum accumulation. The results showed that CDDP-CSA-23 attenuates the reduction in urine flow and creatinine clearance induced by CDDP. Moreover, significantly lower amounts of platinum were excreted into the urine in the case of CDDP-CSA-23, compared with CDDP alone. Meanwhile, CDDP-CSA-23 effectively retarded the rapid perfusion of platinum into kidney tissues, as occurs when CDDP is being perfused alone. The cytoprotective effects of CDDP-CSA on human proximal tubular (HK-2) cells were examined by measuring the growth of HK-2 cells in the presence of CDDP or CDDP-CSA-23. Interestingly, CDDP-CSA-23 was found to have a significantly reduced cytotoxicity, compared to CDDP. These results suggest that CDDP-CSA-23 greatly decreased the negative effects of CDDP on glomerular filtration and tubular transport in kidneys at early stages of its administration.

Bisabololoxide A, one of the main constituents in German chamomile extract, induces apoptosis in rat thymocytes.

German chamomile (Matricaria recutita L.), one of the popular ingredients in herbal teas, has been traditionally used for medicinal purposes. Bisabololoxide A (BSBO) is one of the main constituents in this herb. BSBO is supposed to be principle in some bioactivities of German chamomile such as anti-inflammatory, gastrointestinal, and antipruritic actions. Although the use of German chamomile has spread, the information related to toxicity of BSBO is very limited. In present study, the cytotoxic effect of micromolar BSBO was cytometrically examined on rat thymocytes by using appropriate fluorescent dyes. When the cells were incubated with BSBO for 24 h, BSBO at concentrations of 30 microM or more significantly increased populations of dead cells, shrunken cells, and cells with phosphatidylserine exposed on membrane surface. Both cell shrinkage and externalization of membrane phosphatidylserine are general features in an early stage of apoptosis. In addition, BSBO significantly increased population of cells containing hypodiploid DNA, and the increase was completely attenuated by Z-VAD-FMK, a pan-inhibitor for caspases, indicating an involvement of caspase activation. Thus, it is likely that the type of cell death induced by BSBO is apoptosis. The significant changes in cellular parameters of rat thymocytes by BSBO were not observed when the concentration was 10 microM or less. Furthermore, the short incubation (3 h) of cells even with 30-100 microM BSBO did not significantly affect the cells. Therefore, it may be suggested that BSBO is practically safe when German chamomile is conventionally used.

Characterization of the Interaction of Daptomycin With Site II on Human Serum Albumin.

Daptomycin, a cyclic lipopeptide antibiotic, is clinically used for the treatment of infections caused by Gram-positive bacteria, including the methicillin-resistant Staphylococcus aureus and the vancomycin-resistant Enterococci. While daptomycin shows high plasma protein binding (90-93%), our knowledge of the binding process is not extensive. To address this issue in more detail, we characterized the binding of daptomycin to plasma proteins and the findings indicate that the association constant for the binding of daptomycin to human serum albumin (HSA) is much higher than that for α1-acid glycoprotein, another plasma protein. Daptomycin was also found to bind to a single site on HSA, which was identified as site II. The findings also suggest that the n-decanoyl moiety of daptomycin penetrates into the hydrophobic pocket of site II and that this acyl moiety interacts with Tyr411 at the entrance to site II. Due to this selective interaction with site II, daptomycin binding was significantly inhibited by drugs (ibuprofen or diazepam) and endogenous compounds (uremic toxins or fatty acids) which also strongly bind to site II. In diseased states, such an inhibition in the binding could result in the pharmacokinetics and therapeutic action of daptomycin being substantially altered.

Processing grapefruit juice with γ-cyclodextrin attenuates its inhibitory effect on cytochrome P450 3A activity.

OBJECTIVES: Grapefruit (Citrus paradisi) juice enhances the oral bioavailability of drugs that are metabolized by intestinal cytochrome P450 3A4 (CYP3A4). Patients are advised to avoid drinking grapefruit juice to prevent this drug-grapefruit juice interaction. The aim of this study was to investigate whether processing grapefruit juice with cyclodextrins (CDs) would result in preventing or inhibiting this interaction. METHODS: Grapefruit juice and the major furanocoumarins found in grapefruit, bergamottin (BG) and 6', 7'-dihydroxy bergamottin (DHBG) were mixed with α, ß and γCDs. The effects of these processed juice samples and furanocoumarins on CYP3A activity were compared with the corresponding values for unprocessed juices and furanocoumarins. Interactions between CDs and these furanocoumarins were also investigated by phase solubility and 1 H NMR studies. KEY FINDINGS: The inhibition of CYP3A by grapefruit juice was significantly attenuated by processing particularly with γCD. Similar attenuation effects by γCD were observed in the cases of BG and DHBG. Furthermore, BG and DHBG were suggested to be strongly encapsulated in the cavity of γCD. CONCLUSION: The encapsulation of BG and DHBG by γCD and the resulting attenuation of the inhibition of CYP3A activity by grapefruit juice may be applicable to juice processing for preventing drug-grapefruit juice interactions.

Evaluation for antioxidant and renoprotective activity of olmesartan using nephrectomy rats.

Angiotensin II type 1 receptor blockers, which inhibit the rennin-angiotensin system, are used in the treatment of hypertension. In addition to their ability to lower blood pressure, these compounds have also been reported to protect organs, such as kidney and heart. Although the mechanisms of these protective effects are not fully understood, it is generally thought that their antioxidant effects likely play a role. The aim of the present study was to characterize the relationship between the antioxidant activity of olmesartan and its pharmacological actions such as renoprotective or blood pressure lowering effects, using 5/6 nephrectomy rats. In 5/6 nephrectomy rats, the potential antioxidant power, the ratio of oxidized to unoxidized albumin, as a marker of protein oxidation in blood, both systolic and diastolic blood pressure, plasma creatinine concentration, and amounts of protein excreted into the urine were significantly higher than the corresponding values for sham operated rats. However, olmesartan significantly suppressed these parameters within 8 weeks after oral administration in 5/6 nephrectomy rats. The oxidized albumin ratio was significantly decreased 4 weeks after the administration of olmesartan and these lower levels were maintained at 8 weeks. Furthermore, olmesartan improved radical scavenging activity of isolated albumin from rat plasma. Interestingly, a good correlation was found between the oxidized albumin ratios and renal function, whereas no correlation was found in the case of blood pressure. Based on those findings, we conclude that the antioxidant properties of olmesartan may be related to its renoprotective action rather than an antihypertensive effect.

Enhanced dissolution and oral bioavailability of praziquantel by emulsification with human serum albumin followed by spray drying.

The goal of this study was to enhance the oral bioavailability of praziquantel through its conjugation with human serum albumin (HSA). Praziquantel-HSA particles were produced by spray drying an emulsion of an aqueous solution of HSA and a solution of praziquantel in oil. The particles were agglomerates of multiple smooth corrugated particles containing amorphous praziquantel nearly equivalent to the theoretical doses. The solubility of praziquantel in an aqueous medium was enhanced in both the produced particles and the physical mixture. In addition, the dissolution rate in an aqueous medium was enhanced in the case of particles, but not in a physical mixture. Thus, the inclusion of HSA by emulsification followed by spray drying appeared to contribute to the enhanced dissolution rate. In a pharmacokinetic study, the maximum plasma concentration (Cmax) and the area under the concentration-time curve (AUC) for the produced particles (HSA/praziquantel = 1/1 w/w) were approximately two times higher than the corresponding values for raw praziquantel. This increased oral bioavailability of the particles was considered to be due to the enhanced dissolution rate. This process for producing praziquantel-HSA particles could be useful in terms of improving the oral bioavailability of the other hydrophobic drugs.

[Some problems for dosage form based on questionnaire surveying compliance in patients taking tamsulosin hydrochloride].

After the dosage form of tamsulosin hydrochloride was changed from a capsule to on orally disintegrating tablet (ODT, Harnal D), we often received patient complaints and noted an increase in noncompliance with medication regimens. The change in dosage form appeared to cause poor compliance by patients who had become accustomed to the light pink/white capsule over many years. Therefore, we carried out a questionnaire survey of patients taking the ODT form to determine the effects of changing the dosage form and the usefulness of the ODT. Most (92%) of respondents took the ODT with water. In addition, 16% missed taking the medicine after the change in dosage form. ODT is a dosage form that is easy to take for patient with dysphagia, or those on restricted water intake. However, it appears that elderly men and patients with visual disorders cannot distinguish the ODT from other medicines and this affects patient compliance. In conclusion, all pharmaceutical companies should consider the design of medications in terms of coloration, indications, or shape in anticipation of the aging society in future, so that patients can distinguish them. Furthermore, sufficient pharmaceutical care is needed to improve both compliance and safety management for the elderly.

Analysis of the Binding of Aripiprazole to Human Serum Albumin: The Importance of a Chloro-Group in the Chemical Structure.

Aripiprazole (ARP), a quinolinone derivative, is an atypical antipsychotic drug that is used in the treatment of schizophrenia. ARP has an extensive distribution and more than 99% of the ARP and dehydro-ARP, the main active metabolite, is bound to plasma proteins. However, information regarding the protein binding of ARP is limited. In this study, we report on a systematic study of the protein binding of ARP. The interaction of ARP and structurally related compounds with human serum albumin (HSA) was examined using equilibrium dialysis, circular dichroism (CD) spectroscopy, fluorescent probe displacement, and an X-ray crystallographic analysis. The binding affinities (nK) for ARP and its main metabolite, dehydro-ARP with HSA were found to be significantly higher than other structurally related compounds. The results of equilibrium dialysis experiments and CD spectral data indicated that the chloro-group linked to the phenylpiperazine ring in the ARP molecule plays a major role in the binding of these ligands to HSA. Furthermore, fluorescent probe displacement results indicated that ARP appears to bind at the site II pocket in subdomain III. A detailed CD spectral analysis suggests that the chloro-group linked to the phenylpiperazine ring may control the geometry of the ARP molecule when binding in the site II binding pocket. X-ray crystallographic analysis of the ARP-HSA complex revealed that the distance between the chlorine atom at the 3-positon of dichlorophenyl-piperazine on ARP and the sulfur atom of Cys392 in HSA was 3.4-3.6 Å. A similar halogen bond interaction has also been observed in the HSA structure complexed with diazepam, which also contains a chloro-group. Thus, the mechanism responsible for the binding of ARP to a protein elucidated here should be relevant for assessing the pharmacokinetics and pharmacodynamics of ARP in various clinical situations and for designing new drugs.

Species Differences in the Binding of Sodium 4-Phenylbutyrate to Serum Albumin.

Sodium 4-phenylbutyrate (PB) is clinically used as a drug for treating urea cycle disorders. Recent research has shown that PB also has other pharmacologic activities, suggesting that it has the potential for use as a drug for treating other disorders. In the process of drug development, preclinical testing using experimental animals is necessary to verify the efficacy and safety of PB. Although the binding of PB to human albumin has been studied, our knowledge of its binding to albumin from the other animal species is extremely limited. To address this issue, we characterized the binding of PB to albumin from several species (human, bovine, rabbit, and rat). The results indicated that PB interacts with 1 high-affinity site of albumin from these species, which corresponds to site II of human albumin. The affinities of PB to human and bovine albumins were higher than those to rabbit and rat albumin, and that to rabbit albumin was the lowest. Binding and molecular docking studies using structurally related compounds of PB suggested that species differences in the affinity are attributed to differences in the structural feature of the PB-binding sites on albumins (e.g., charge distribution, hydrophobicity, shape, or size).

Long chain fatty acids alter the interactive binding of ligands to the two principal drug binding sites of human serum albumin.

A wide variety of drugs bind to human serum albumin (HSA) at its two principal sites, namely site I and site II. A number of reports indicate that drug binding to these two binding sites are not completely independent, and that interactions between ligands of these two discrete sites can play a role. In this study, the effect of the binding of long-chain fatty acids on the interactive binding between dansyl-L-asparagine (DNSA; site I ligand) and ibuprofen (site II ligand) at pH6.5 was examined. Binding experiments showed that the binding of sodium oleate (Ole) to HSA induces conformational changes in the molecule, which, in turn, changes the individual binding of DNSA and ibuprofen, as well as the mode of interaction between these two ligands from a 'competitive-like' allosteric interaction in the case of the defatted HSA conformer to a 'nearly independent' binding in the case of non-defatted HSA conformer. Circular dichroism measurements indicated that ibuprofen and Ole are likely to modify the spatial orientation of DNSA at its binding site. Docking simulations suggest that the long-distance electric repulsion between DNSA and ibuprofen on defatted HSA contributes to a 'competitive-like' allosteric interaction, whereas extending the distance between ligands and/or increasing the flexibility or size of the DNSA binding site in fatted HSA evokes a change in the interaction mode to 'nearly independent' binding. The present findings provide further insights into the structural dynamics of HSA upon the binding of fatty acids, and its effects on drug binding and drug-drug interactions that occur on HSA.

Tyrosine411 and Arginine410 of Human Serum Albumin Play an Important Role in the Binding of Sodium 4-Phenylbutyrate to Site II.

Sodium 4-phenylbutyrate (PB) has many pharmacological activities; therefore extending its clinical use to the treatment of a wider variety of diseases would be desirable. However, our knowledge of the binding of PB to plasma proteins is not extensive. To address this issue in more detail, we characterized the protein binding of PB. Binding experiments showed that PB mainly binds to human serum albumin (HSA) in plasma. PB was also found to bind to a single site on HSA, which was identified as site II by fluorescent probe displacement experiment. Furthermore, an appropriate alkyl chain length and a carboxylic group in the PB structure were required for PB binding to HSA, suggesting that hydrophobic (and van der Waals) and electrostatic interactions are involved as binding modes. The contributions of hydrogen bonding and/or van der Waals interactions were also indicated by thermodynamic analyses. Tyrosine411 and arginine410 were identified as being involved in the binding of PB to site II, based on binding experiments using chemically modified- and mutant-HSA preparations. In conclusion, the available evidence indicates that PB binds to site II of HSA with assistance by multiple forces and that tyrosine411 and arginine410 both play important roles in this phenomenon.

Potential Use of Biological Proteins for Liver Failure Therapy.

Biological proteins have unlimited potential for use as pharmaceutical products due to their various biological activities, which include non-toxicity, biocompatibility, and biodegradability. Recent scientific advances allow for the development of novel innovative protein-based products that draw on the quality of their innate biological activities. Some of them hold promising potential for novel therapeutic agents/devices for addressing hepatic diseases such as hepatitis, fibrosis, and hepatocarcinomas. This review attempts to provide an overview of the development of protein-based products that take advantage of their biological activity for medication, and discusses possibilities for the therapeutic potential of protein-based products produced through different approaches to specifically target the liver (or hepatic cells: hepatocytes, hepatic stellate cells, liver sinusoidal endothelial cells, and Kupffer cells) in the treatment of hepatic diseases.

Cross-linked human serum albumin dimer has the potential for use as a plasma-retaining agent for the fatty acid-conjugated antidiabetic drugs.

OBJECTIVES: The half-life of fatty acid-conjugated antidiabetic drugs are prolonged through binding to albumin, but this may not occur in diabetic patients with nephropathy complicated with hypoalbuminemia. We previously showed that human serum albumin (HSA) dimerized at the protein's Cys34 by 1,6-bis(maleimido)hexane has longer half-life than the monomer under high permeability conditions. The aim of this study was to investigate the superior ability of this HSA dimer as a plasma-retaining agent for fatty acid conjugated antidiabetic drugs. METHODS: The diabetic nephropathy rat model was prepared by administering a single injection of streptozotocin (STZ) intravenously, and the pharmacokinetic properties of HSA monomer and dimer were evaluated. Site-specific fluorescent probe displacement experiments were performed using warfarin and dansylsarcosine as site I and site II specific fluorescent probes, respectively. KEY FINDINGS: The half-life of the HSA dimer in STZ-induced diabetic nephropathy model rats was 1.5 times longer than the HSA monomer. The fluorescent probe displacement experiment results for HSA monomer and dimer were similar, where fatty acid-conjugated antidiabetic drugs displaced dansylsarcosine but not warfarin in a concentration-dependent manner. CONCLUSIONS: The HSA dimer shows potential for use as a plasma-retaining agent for antidiabetic drugs due to its favourable pharmacokinetic properties.