Monoketocholate can decrease transcellular permeation of methotrexate across Caco-2 cell monolayers and reduce its intestinal absorption in rat

Plasma Distribution of Methotrexate and Its Polyglutamates in Pediatric Acute Lymphoblastic Leukemia: Preliminary Insights

BACKGROUND AND OBJECTIVE

High-dose methotrexate (HD-MTX) is the mainstream therapy of current acute lymphoblastic leukemia (ALL) regimens, but frequent intra- and interindividual differences in the clinical response to HD-MTX lead to chemotherapeutic interruption or discontinuation. The exact mechanism of transport across the cell membrane and the disposition of active methotrexate metabolites-methotrexate polyglutamates (MTXPGs)-are not well described in the literature. The aim of this study was to gain more insight into the plasma distribution of methotrexate and MTXPGs in pediatric patients with ALL and to clarify the obscure pathways of MTXPGs.

METHODS

We prospectively measured the concentrations of MTXPG_1-7 in plasma samples from three male pediatric patients treated with HD-MTX and leucovorin rescue according to the IC-BFM 2009 protocol using liquid chromatography-mass spectrometry (LC-MS). Blood samples were obtained at 24, 36, 42, and 48 h after the start of HD-MTX treatment.

RESULTS

Noticeable plasma concentrations of MTXPGs with a 2.2-fold interpatient variability were detected. The highest interindividual variability in total plasma MTXPG concentration was observed at 36 h, and ranged from 13.78 to 30.82 μmol/L. Among all patients, the predominant polyglutamate types in relation to the total plasma MTXPG concentration at each time point were MTXPG₃ (16.71-30.02%) and MTXPG₅ (26.23-38.60%), while MTXPG₇ was the least abundant MTXPG (3.22-5.02%).

CONCLUSION

The presence of MTXPGs in plasma of patients with ALL could be related to the action of ABC efflux transporters on blood cells and hepatocytes resulting from the administration of high doses of methotrexate. This study may not draw definitive conclusions, but it does reduce uncertainty about the dynamics of methotrexate and its active metabolites, which may be of vital importance for achieving a clinical response.

Bile acids as novel enhancers of CNS targeting antitumor drugs: a comprehensive review

Despite a relatively low prevalence of primary brain tumors, they continuously attract scientific interest because of the complexity of their treatment due to their location behind the blood-brain barrier. The main challenge in treatment of brain tumors is not the efficacy of the drugs, per se, but the low efficiency of drug delivery to malignant cells. At the core of the problem is the complex structure of the blood-brain barrier. Nowadays, there is evidence supporting the claim that bile acids have the ability to cross the blood-brain barrier. That ability can be exploited by taking a part in novel drug carrier designs. Bile acids represent a drug carrier system as a part of a mixed micelle composition, bilosomes and conjugates with various drugs. This review discusses the current knowledge related to bile acid molecules as drug penetration modifying agents, with the focus on central nervous system antitumor drug delivery.

Semisynthetic bile acids: a new therapeutic option for metabolic syndrome

Bile acids are endogenous emulsifiers synthesized from cholesterol having a peculiar amphiphilic structure. Appreciation of their beneficial effects on human health, recognized since ancient times, has expanded enormously since the discovery of their role as signaling molecules. Activation of farnesoid X receptor (FXR) and Takeda G-protein receptor-5 (TGR5) signaling pathways by bile acids, regulating glucose, lipid and energy metabolism, have become attractive avenue for metabolic syndrome treatment. Therefore, extensive effort has been directed into the research and synthesis of bile acid derivatives with improved pharmacokinetic properties and high potency and selectivity for these receptors. Minor modifications in the structure of bile acids and their derivatives may result in fine-tuning modulation of their biological functions, and most importantly, in an evasion of undesired effect. A great number of semisynthetic bile acid analogues have been designed and put in preclinical and clinical settings. Obeticholic acid (INT-747) has achieved the biggest clinical success so far being in use for the treatment of primary biliary cholangitis. This review summarizes and critically evaluates the key chemical modifications of bile acids resulting in development of novel semisynthetic derivatives as well as the current status of their preclinical and clinical evaluation in the treatment of metabolic syndrome, an aspect that is so far lacking in the scientific literature. Taking into account the balance between therapeutic benefits and potential adverse effects associated with specific structure and mechanism of action, recommendations for future studies are proposed.

Self-association of sodium isoursodeoxycholate and sodium isohenodeoxycholate in water

Bile salts (BS) form hydrophobic Small's primary micelles at concentrations above the critical micelle concentration (CMC), while at concentrations above 3CMC they form secondary micelles (by the association of primary micelles via H-bonds). In this paper the self-associations of the anions of isohenodeoxycholic acid (3-epimer of henodeoxycholic acid, ICD) and the anions of isoursodeoxycholic acid (3-epimer of ursodeoxycholic acid, IUD) are examined, since the thermodynamic parameters of their self-association have not yet been published. Forming of IUD aggregates with two or three building units is slightly more favorable via α sides of steroid skeletons, regarding hydrophobicity, while regarding steric repulsive interactions it is more favorable to associate via β sides. Due to this, IUD in the vicinity of the CMC can form primary micelles by association of IUD particles both from the convex side and from the concave side of the steroid ring system. Therefore, IUD is significantly more prone to initial micellization than bile salt derivatives whose steroidal skeletons contain equatorially oriented OH groups.

Structure-Property Relationships in Sodium Muricholate Derivative (Bile Salts) Micellization: The Effect of Conformation of Steroid Skeleton on Hydrophobicity and Micelle Formation-Pattern Recognition and Potential Membranoprotective Properties

It is known that β-muricholic acid anions prevent membrane toxicity of hydrophobic bile acids, which are being used in therapy for solubilization of the cholesterol type bile stone. Better knowledge of these derivative micelles is very important for understanding their physiological and pharmacological effects. β-Axial (a) oriented hydroxyl group from the steroid skeleton decreases the hydrophobic surface of the convex side of the steroid skeleton. Therefore, the critical micellization concentration (CMC) for steroid surfactants with β-a-OH group should increase, but in the case of OH groups of different orientations forming H-bonds in the hydrophobic phase of the micelle, it has the opposite effect; the CMC decreses, and aggregation is more favored. The set of muricholic acids (MCs) is composed by α-MC, β-MC, γ-MC, and ω-MC, where α-MC and β-MC have β-axial-OH groups. The aggregation numbers (n) are determined using the Moroi-Matsuoka-Sugioka thermodynamic method. CMC, enthalpy of demicellization, and ΔC_p are determined by isothermal titration calorimetry (ITC). This report pioneers in the study of MC derivatives micellization. Micelles of β-MC and γ-MC belong to the linear congeneric group (LCG) and their micelles above 85 mM have constant aggregation numbers n = 4-5. Micelles of α-MC and ω-MC are outliers in relation to the LCG, their aggregation number constantly increases; at 85 mM n = 6.8 (α-MC) and 6.5 (ω-MC). In micelles of derivatives β-MC and γ-MC, there is a low probability for the existence of hydrogen bonds. A micelle of α-MC probably has hydrogen bonds in its hydrophobic domain.

Pathways and progress in improving drug delivery through the intestinal mucosa and blood-brain barriers

One of the major hurdles in developing therapeutic agents is the difficulty in delivering drugs through the intestinal mucosa and blood-brain barriers (BBB). The goal here is to describe the general structures of the biological barriers and the strategies to enhance drug delivery across these barriers. Prodrug methods used to improve drug penetration via the transcellular pathway have been successfully developed, and some prodrugs have been used to treat patients. The use of transporters to improve absorption of some drugs (e.g., antiviral agents) has also been successful in treating patients. Other methods, including blocking the efflux pumps to improve transcellular delivery, and modulation of cell-cell adhesion in the intercellular junctions to improve paracellular delivery across biological barriers, are still in the investigational stage.

Wittig reaction (with ethylidene triphenylphosphorane) of oxo-hydroxy derivatives of 5β-cholanic acid: Hydrophobicity, haemolytic potential and capacity of derived ethylidene derivatives for solubilisation of cholesterol

Bile acid salts are biosurfactants which form mixed micelles with phospholipids in vertebrates. These mixed micelles are suitable for solubilisation of cholesterol. For therapeutic purposes some bile acid salts as sodium ursocholate are used. However, bile acid anions possess low capacity for solubilisation of cholesterol. Thus, synthesis of more hydrophobic and less membranotoxic bile acid derivatives is of the great interest. In this paper Wittig reaction between ethylidene triphenylphosphorane and different bile acids oxo derivatives is examined. Wittig reaction of bile acids has not been studied much. C12 oxo group is inert in this reaction. If Wittig reaction happens on C7 oxo group stereospecifically E ethylidene stereoisomer is obtained, while the same reaction on C3 oxo group leads to more reactive not sterospecific product. In this paper stereochemical course of investigated Wittig reactions is thoroughly analysed. Hydrophobicity of derived products is determined over the temperature (T) dependence on retention coefficients (k) in reversed phase high resolution chromatography. Using method of principle components on k=f(T) matrix it is found that values of first principle components best describe hydrophobicity of analysed bile acids, while the second principal component is responsible for their hydrophilicity. By in silico molecular descriptors: valence connectivity index of order 3 (X3v) and packing density index (PDI), linear regression equations are obtained that can be used to predict hydrophobicity (over retention coefficient) of bile acids that belong to set of more congeneric groups. Membranotoxicity is determined by haemolytic potential. Monoethylidene derivatives of bile acids (in the form of anions) have lower membranotoxicity than deoxycholic acids anion. Sodium salt of deoxycholic acid 7-ethylidene derivative has 11% greater capacity for solubilisation of cholesterol monohydrate than sodium salt of deoxycholic acid.

Modulated pharmacokinetics and increased small intestinal toxicity of methotrexate in bilirubin-treated rats

OBJECTIVES

The effect of bilirubin treatment on the pharmacokinetics and small intestinal toxicity of methotrexate was evaluated in rats, since bilirubin and its glucuronide conjugates can suppress multidrug resistance-associated protein-mediated transport.

METHODS

Rats were treated intravenously with bilirubin and the various clearances and tissue distribution of methotrexate were estimated under a steady-state plasma concentration. Intestinal toxicity induced by methotrexate was also evaluated by measuring the leakage of alkaline phosphatase (ALP) activity. Probenecid, an inhibitor for multidrug resistance-associated protein and organic anion transporters, was used for comparison.

KEY FINDINGS

The treatment with bilirubin increased the steady-state plasma concentration and reduced biliary excretion clearance, urinary excretion clearance and intestinal exsorption clearance of methotrexate, as did treatment with probenecid. The intestinal absorption and jejunum distribution of methotrexate also significantly increased in bilirubin- and probenecid-treated rats. A greater leakage of ALP activity to the luminal fluid, with a lower ALP activity in the intestinal mucosal membrane after intestinal perfusion of methotrexate, was observed in bilirubin- and probenecid-treated rats.

CONCLUSIONS

Hyperbilirubinemia, which is involved under various disease states, may increase the small intestinal accumulation and toxicities of methotrexate, since high plasma concentrations of conjugated bilirubin can suppress the function of multidrug resistance-associated proteins, which facilitate the efflux of methotrexate out of cells.