Synthesis and pharmacokinetic and pharmacodynamic evaluation of the forodesine HCl analog BCX-3040

Forodesine HCl is a potent inhibitor of the enzyme purine nucleoside phosphorylase (PNP) and is currently in clinical trials for the treatment of leukemia and lymphoma. Animal models indicated that forodesine HCl would have low oral bioavailability in humans and it was initially developed as an intravenous formulation. We were interested in identifying analogs of forodesine HCl with improved oral bioavailability. The 2'-deoxy analog (BCX-3040) was synthesized and its pharmacokinetic and pharmacodynamic properties compared with forodesine HCl.     

Synthesis of analogs of forodesine HCl,a human purine nucleoside phosphorylase inhibitor—Part II

Forodesine HCl is being investigated as a potential therapeutic target for the control of T-cell proliferation. During the filing process for a New Drug Application (NDA) it became evident that there was a need to synthesize some stereo-isomers of forodesine HCl. Herein we present the synthesis of these three novel compounds (2–4).     

Synthesis of analogs of forodesine HCl,a human purine nucleoside phosphorylase inhibitor—Part I

Forodesine HCl is being investigated as a potential therapeutic target for the control of T-cell proliferation. During our ongoing process development work on forodesine HCl several novel compounds were identified as possible impurities in the process. Herein we present the synthesis of three novel compounds (2–4).     

Enhanced oral bioavailability and anticancer activity of novel curcumin loaded mixed micelles in human lung cancer cells

BackgroundCurcumin has a wide range of pharmacological activities including antioxidant, anti-inflammatory, antidiabetic, antibacterial, wound healing, antiatherosclerotic, hepatoprotective and anti-carcinogenic. However, its clinical applications are limited owing to its poor aqueous solubility, multidrug pump P-gp efflux, extensive in vivo metabolism and rapid elimination due to glucuronidation/sulfation.PurposeThe objective of the current work was to prepare novel curcumin loaded mixed micelles (CUR-MM) of Pluronic F-127 (PF127) and Gelucire^® 44/14 (GL44) in order to enhance its oral bioavailability and cytotoxicity in human lung cancer cell line A549.Study design3² Factorial design was used to assess the effect of formulation variables for optimization of mixed micelle batch.MethodsCUR-MM was prepared by a solvent evaporation method. The optimized CUR-MM was evaluated for size, entrapment efficiency (EE), in vitro curcumin release, cytotoxicity and oral bioavailability in rats.ResultsThe average size of CUR-MM was found to be around 188 ± 3 nm with an EE of about 76.45 ± 1.18% w/w. In vitro dissolution profile of CUR-MM revealed controlled release of curcumin. Additionally, CUR-MM showed significant improvement in cytotoxic activity (3-folds) and oral bioavailability (around 55-folds) of curcumin as compared to curcumin alone. Such significant improvement in cytotoxic activity and oral bioavailability of curcumin when formulated into mixed micelles could be attributed to solubilization of hydrophobic curcumin into micelle core along with P-gp inhibition effect of both, PF127 and GL44.ConclusionThus the present work propose the formulation of mixed micelles of PF127 and GL44 which can act as promising carrier systems for hydrophobic drugs such as curcumin with significant improvement in their oral bioavailability.     

Linaclotide is a potent and selective guanylate cyclase C agonist that elicits pharmacological effects locally in the gastrointestinal tract

AimsLinaclotide is an orally administered 14-amino acid peptide being developed for the treatment of constipation-predominant irritable bowel syndrome (IBS-C) and chronic constipation. We determined the stability of linaclotide in the intestine, measured the oral bioavailability, and investigated whether the pharmacodynamic effects elicited in rodent models of gastrointestinal function are mechanistically linked to the activation of intestinal guanylate cyclase C (GC-C).Main methodsLinaclotide binding to intestinal mucosal membranes was assessed in competitive binding assays. Stability and oral bioavailability of linaclotide were measured in small intestinal fluid and serum, respectively, and models of gastrointestinal function were conducted using wild type (wt) and GC-C null mice.Key findingsLinaclotide inhibited in vitro [¹²⁵I]-STa binding to intestinal mucosal membranes from wt mice in a concentration-dependent manner. In contrast, [¹²⁵I]-STa binding to these membranes from GC-C null mice was significantly decreased. After incubation in vitro in jejunal fluid for 30 min, linaclotide was completely degraded. Pharmacokinetic analysis showed very low oral bioavailability (0.10%). In intestinal secretion and transit models, linaclotide exhibited significant pharmacological effects in wt, but not in GC-C null mice: induction of increased fluid secretion into surgically ligated jejunal loops was accompanied by the secretion of elevated levels of cyclic guanosine-3′,5′-monophosphate and accelerated gastrointestinal transit.SignificanceLinaclotide is a potent and selective GC-C agonist that elicits pharmacological effects locally in the gastrointestinal tract. This pharmacological profile suggests that orally administered linaclotide may be capable of improving the abdominal symptoms and bowel habits of patients suffering from IBS-C and chronic constipation.     

Piperine and Celecoxib synergistically inhibit colon cancer cell proliferation via modulating Wnt/β-catenin signaling pathway

BackgroundCelecoxib (CXB), a selective COX-2 inhibitor NSAID, has exhibited prominent anti-proliferative potential against numerous cancers. However, its low bioavailability and long term exposure related cardiovascular side effects, limit its clinical application. In order to overcome these limitations, natural bioactive compounds with lower toxicity profile are used in combination with therapeutic drugs. Therfore, in this study Piperine (PIP), a natural chemo-preventive agent possessing drug bioavailability enhancing properties, was considered to be used in combination with low doses of CXB.PurposeWe hypothesized that the combination of PIP with CXB will have a synergistic anti-proliferative effect on colon cancer cells.Study designThe potency of PIP and CXB alone and in combination was evaluated in HT-29 human colon adenocarcinoma cells and mechanism of growth inhibition was investigated by analyzing the players in apoptotic and Wnt/β-catenin signaling pathways.MethodsThe effect of PIP on the oral bioavailability of CXB in mice was investigated using HPLC analysis. The study investigated the synergistic anti-proliferative effect of CXB and PIP on HT-29 cells and IEC-6 non-tumorigenic rat intestinal epithelial cells by SRB cell viability assay. Further, the cellular and molecular mechanism(s) involved in the anti-proliferative combinatorial effect was extensively explored in HT-29 cells by flow cytometry and western blotting. The in vivo efficacy of this combination was studied in CT26.WT tumor syngeneic Balb/c mice model.ResultsPIP as a bioenhancer increased the oral bioavailability of CXB (129%). The IC50 of CXB and PIP were evaluated to select doses for combination treatment of HT-29 cells. The drug combinations having combination index (CI) less than 1 were screened using CompuSyn software. These combinations were significantly cytotoxic to HT-29 cells but IEC-6 were least effected. Further, the mechanism behind CXB and PIP mediated cell death was explored. The co-treatment led to reactive oxygen species generation, mitochondrial dysfunction, caspase activation and enhanced apoptosis in HT-29 cells. Additionally, the combination treatment synergistically modulated Wnt/β-catenin pathway, downregulated the stemness markers and boosted therapeutic response in CT26 syngeneic Balb/c mice.ConclusionThe outcomes of the study suggests that combining CXB and PIP offers a novel approach for the treatment of colon cancer.     

Is the bioavailability index applicable for trace elements in different types of soil?

Abstract

The bioavailability index (BI) is defined as the proportion of reduction in a plant’s accumulation of an element, caused by the removal of the extractable fraction of the element of interest from the soil. The BI and corresponding experimental methods were quantitatively applied to evaluate the bioavailability of trace elements in five Chinese soils. The soil was first extracted with various reagents (DTPA, HCl and NH₂OH.HCI) separately, to remove the extractable elements. The soil, after extraction, was washed with deionised water to eliminate the extractant used in the fractionation analysis. Then the pH of the soil was re-adjusted with CaO. The soil was then fertilised and incubated in a greenhouse for four weeks. Tests showed that after incubation the pH, cation exchange capacity (CEC) and organic matter (OM) of the treated soil were close to their original values. Wheat (Triticum aestivum L.) was planted in both the untreated and treated soil for eight weeks. After harvest the plant concentrations of the elements Cr, Mn, Co, Ni, Zn, Cu, Cd, and Pb were analysed by inductively coupled plasma mass spectrometry (ICPMS). Trace element accumulation by plants grown in the treated soil was reduced significantly compared with that of plants grown in the untreated soil. The results showed that BI values were in the order BI(DTPA)>BI(HCl)>BI(NH₂OH.HCl). This indicated that the DTPA-extractable fraction represented a highly available fraction of the total content. Variations of BI among different trace elements show that Cr, Mn, Zn and Co have a higher BI, in general for the elements tested, whereas, Cu, Cd and Pb have lower values. There are also slight differences in the BI among soils. However, no significant relationship could be found between the BI and the soil characteristics.     

In vivo Antiretroviral Efficacy of Oral bis(POM)-PMEA,the bis(Pivaloyloxymethyl)prodrug of 9-(2-Phosphonylmethoxyethyl) adenine (PMEA)

Abstract

The bis-pivaloyloxymethyl(POM)- and diphenyl-ester prodrugs of the broad spectrum antiviral agent 9-(2-phosphonylmethoxyethyl)adenine (PMEA) have been evaluated in vivo for antiviral efficacy upon oral administration in severe combined immune deficiency (SCID) mice infected with Moloney murine sarcoma virus (MSV). Oral bis (POM)-PMEA proved highly efficient in delaying MSV-induced tumor formation and associated death, its effect being equal to that of subcutaneous PMEA at an equimolar dose. Compared to bis(POM)-PMEA, oral diphenyl-PMEA had lower antiviral efficacy, whereas PMEA as such was poorly effective when administered orally. Our studies indicate that bis(POM)-PMEA must have a favorable oral bioavailability and justify its clinical investigation as an oral prodrug of PMEA in the treatment of HIV infections.     

Synthesis,characterization and fluorescent properties of water-soluble glycopolymer bearing curcumin pendant residues

Curcumin is a potential natural anticancer drug with low oral bioavailability because of poor water solubility. The aqueous solubility of curcumin is enhanced by means of modification with the carbohydrate units. Polymerization of the curcumin-containing monomer with carbohydrate-containing monomer gives the water-soluble glycopolymer bearing curcumin pendant residues. The obtained copolymers (P1 and P2) having desirable water solubility were well-characterized by infrared spectroscopy (IR), nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), UV–Vis absorption spectroscopy, and photoluminescence spectroscopy. The copolymer P2 with a molar ratio of 1:6 (curcumin/carbohydrate) calculated from the proton NMR results exhibits a similar anticancer activity compared to original curcumin, which may serve as a potential chemotherapeutic agent in the field of anticancer medicine.     

Synthesis and evaluation of prodrugs of corticotropin-releasing factor-1 (CRF1) receptor antagonist BMS-665053 leading to improved oral bioavailability

A series of phosphate and ester-based prodrugs of anilinopyrazinone 1 (BMS-665053) containing either a methylene or an (acyloxy)alkoxy linker was prepared and evaluated in rat pharmacokinetic studies with the goal of improving the oral bioavailability of the parent (1). The prodrugs, in general, had improved aqueous solubility and oral bioavailability compared to 1. Prodrug 12, which contains an (acyloxy)alkoxy linker, showed the greatest improvement in the oral bioavailability relative to the parent (1), with a seven-fold increase (from 5% to 36%) in rat pharmacokinetic studies.     

Metformin hydrochloride and wound healing: from nanoformulation to pharmacological evaluation

Abstract

Niosomes as drug delivery systems have the ability to decrease drugs' side effects and increase their therapeutic effectiveness. Metformin HCl is an oral antihyperglycemic agent belonging to biguanides. It is the most commonly chosen drug as a startup therapy for patients newly diagnosed with type 2 diabetes. This study aims to encapsulate metformin HCl inside niosomes to be used as a transdermal formulation helping to prolong its antidiabetic effect and investigate its ability to enhance wound healing in diabetic patients. Thin film hydration method was used to prepare metformin HCl niosomes using different proportions of Span 60, Span 40, Tween 80, and cholesterol. All formulations were characterized using transmission electron microscope, zeta potential, and vesicle size. In vitro release studies, stability studies and in vivo evaluation were conducted on selected niosomal formulations. The results of entrapment efficiency ranged from 13% to 32%. Vesicle sizes were determined in nano-range. The in vitro release profile of metformin HCl from niosomes occurred in two consecutive phases. Biological evaluation on diabetic rats revealed that metformin HCl niosomal gel given every 2 days showed a better sustained antidiabetic effect than oral doses given daily. It also showed an improvement in wound healing for diabetic rats given metformin formulations compared to nontreated ones.     

Solid Dispersion as an Approach for Bioavailability Enhancement of Poorly Water-Soluble Drug Ritonavir

Ritonavir is an antiretroviral drug characterized by low solubility and high permeability which corresponds to BCS class II drug. The purpose of the study was to develop solid dispersion by different methods and investigate them for in vitro and in vivo performance for enhancing dissolution and bioavailability, respectively. Since the drug possesses food-related absorption, the effect of biorelevant media (FaSSIF and FeSSIF state) on dissolution behavior was also studied. The solid dispersion was prepared using Gelucire as carrier in 1:4 ratio by different methods and were characterized for differential scanning calorimetry (DSC), X-ray diffractometry, scanning electron microscopy, and FT-IR. Oral bioavailability of 10 mg of ritonavir in solid dispersion prepared by solvent evaporation (SE1) and melt method (MM1) was compared with pure drug after oral administration of solid dispersion and pure drug to Albino Wistar rats of either sex. The results suggested formation of eutectic solid dispersion. In vitro dissolution studies was performed in 0.1 N HCl and biorelevant media showed enhanced dissolution rate as compared to pure drug in both FeSSIF media and 0.1 N HCl. The apparent rate of absorption of ritonavir from SE1 (C _max 20221.37 ng/ml, t _max 0.5 h) was higher than that of MM1 (C _max 2,462.2, t _max 1 h) and pure drug (C _max 1,354.8 ng/ml, t _max 0.5 h). On the basis of the result obtained, it was concluded that solid dispersion is a good approach to enhance solubility and bioavailability of poorly water-soluble ritonavir.     

Therapeutic strategies of Moringa oleifera Lam. (Moringaceae) for stomach and forestomach ulceration induced by HCl/EtOH in rat model

BackgroundThe drumstick tree Moringa oleifera Lam. (Moringaceae), distributed in many parts of the world, is an important food plant with high nutritional value and used in medical applications and pharmaceutical industries. The aim of this study was to highlight the gastroprotective effect of Moringa oleifera in hydrochloric acid/Ethanol (HCl/EtOH) in a rat model.MethodsMoringa phytocompounds were characterized by infrared spectra (FTIR). Rats were induced for gastric ulcer with 150 mmol/L HCl/60% EtOH solution and pretreated orally with the edible infusion extract of the leaves of Moringa oleifera at a single dose of 100 mg/kg body weight (bw). Antioxidant parameters and lipid peroxide levels were measured and the pathological damage was histologically analysed.ResultsThe FTIR analysis showed the presence of several chemical biocompounds. The methanolic extract is the potent radical-scavengers with an estimated value of 87.54% at the higher concentration used (500 µg/ml) and antibacterial agent. Further, the DPPH inhibition value of the M. oleifera infusion was 80.58%. For in vivo analysis, mucus was highly produced in gastric mucosa of plant-treated rats, thereby pH were elevated in rats pretreated with M. oleifera compared to ulcerated animals. Whereas, lesion index was markedly reduced (79%) in stomach protected with plant. Interestingly, oral administration of M. oleifera protected gastric mucosa through decreasing MDA levels as well as increasing antioxidant enzyme activities (CAT, SOD, GPx).ConclusionOverall, the therapeutic value against acidified ethanol induced gastric and ulcer ability of M. oleifera might be due to its biocompounds.     

Pharmacokinetic synergy from the taxane extract of Taxus chinensis improves the bioavailability of paclitaxel

BackgroundTaxus chinensis (Pilger) Rehd is widely distributed in China and the northern hemisphere, and the most popular medicinal component isolated from Taxus chinensis is paclitaxel (PTX), which has now become the first-line chemotherapeutic drug for breast cancer and ovarian cancer. Oral administration of pure PTX as a potential anti-cancer agent is compromised by low bioavailability.Hypothesis/purposeIn the clinical practice of traditional Chinese medicine, drug co-administration in the form of mixtures or formula could achieve pharmacokinetic/pharmacodynamic synergies. In this study, we aimed to investigate whether there exist any ‘inherent’ phytochemical synergy from Taxus chinensis extract that could improve PTX bioavailability.Study designPharmacokinetic study of PTX after oral administration of Taxus chinensis extracts or single PTX was performed. In addition, comparative cytotoxic studies were carried out on the MCF-7 breast cancer cell lines.MethodsThe plasma concentrations of PTX were determined using a validated high performance chromatography tandem mass spectrometry method. The cytotoxicity was compared using the MTT assay.ResultsOral administration of taxane fractions isolated from Taxus chinensis (containing 17.2% PTX) could achieve remarkably higher blood concentration and systemic exposure of PTX in rats, while the retention of PTX was significantly improved. Further tissue distribution analysis revealed that the penetration of PTX into major tissues was drastically increased compared with that of single PTX. In addition, in MCF-7 cells, the co-existing components in taxane mixtures could strengthen the inhibitory effects of PTX on tumor cell proliferation.ConclusionTogether, these results support that administration of PTX in the form of taxane mixtures may become a novel approach to improve the poor bioavailability of PTX. Moreover, the inherent synergy from Taxus chinensis taxane extracts promises a novel strategy to strengthen PTX efficacy.     

Enhanced Solubility and Bioavailability of Naringenin via Liposomal Nanoformulation: Preparation and <Emphasis Type="Italic">In Vitro</Emphasis> and <Emphasis Type="Italic">In Vivo</Emphasis> Evaluations

This study was aimed at preparing orally administered naringenin-loaded liposome for pharmacokinetic and tissue distribution studies in animal models. The liposomal system, consisting of phospholipid, cholesterol, sodium cholate, and isopropyl myristate, was prepared using the thin-film hydration method. Physicochemical characterization of naringenin-loaded liposome such as particle size, zeta potential, and encapsulation efficiency produced 70.53?±?1.71 nm, ?37.4?±?7.3 mV, and 72.2?±?0.8%, respectively. The in vitro release profile of naringenin from the formulation in three different media (HCl solution, pH 1.2; acetate buffer solution, pH 4.5; phosphate buffer solution, pH 6.8) was significantly higher than the free drug. The in vivo studies also revealed an increase in AUC of the naringenin-loaded liposome from 16648.48 to 223754.0 ng·mL^?1 h as compared with the free naringenin. Thus, approximately 13.44-fold increase in relative bioavailability was observed in mice after oral administration. The tissue distribution further showed that the formulation was very predominant in the liver. These findings therefore indicated that the liposomal formulation significantly improved the solubility and oral bioavailability of naringenin, thus leading to wider clinical applications.     

Preparation and <Emphasis Type="Italic">In Vitro</Emphasis>–<Emphasis Type="Italic">In Vivo</Emphasis> Evaluation of Sustained-Release Matrix Pellets of Capsaicin to Enhance the Oral Bioavailability

Capsaicin has multiple pharmacological activities including antioxidant, anticancer, and anti-inflammatory activities. However, its clinical application is limited due to its poor aqueous solubility, gastric irritation, and low oral bioavailability. This research was aimed at preparing sustained-release matrix pellets of capsaicin to enhance its oral bioavailability. The pellets comprised of a core of solid-dispersed capsaicin mixed with microcrystalline cellulose (MCC) and hydroxypropyl cellulose (HPMC) and subsequently coating with ethyl cellulose (EC) were obtained by using the technology of extrusion/spheronization. The physicochemical properties of the pellets were evaluated through scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffractometry (XRD). Besides, the in vitro release, in vivo absorption, and in vitro–in vivo correlation were also assessed. More importantly, the relative bioavailability of the sustained-release matrix pellets was studied in fasted rabbits after oral administration using free capsaicin and solid dispersion as references. The oral bioavailability of the matrix pellets and sustained-release matrix pellets of capsaicin was improved approximately 1.98-fold and 5.34-fold, respectively, compared with the free capsaicin. A good level A IVIVC (in vitro–in vivo correlation) was established between the in vitro dissolution and the in vivo absorption of sustained-release matrix pellets. All the results affirmed the remarkable improvement in the oral bioavailability of capsaicin owing to the successful preparation of its sustained-release matrix pellets.