Diacerein for the treatment of rheumatoid arthritis in patients with inadequate response to methotrexate: a pilot randomized, double-blind, placebo-controlled add-on trial

Rhein methotrexate-decorated solid lipid nanoparticles altering adjuvant arthritis progression through endoplasmic reticulum stress-mediated apoptosis

Methotrexate (MTX) and diacerein (DIA) are two of the most potent disease-modifying anti-rheumatic drugs used for the treatment of rheumatoid arthritis (RA). DIA has reflected some GIT and hepatobiliary manifestations in numerous cases. It undergoes biotransformation in the liver into the active metabolite rhein (RH) which is characterized by its excellent anti-inflammatory activity and lower side effects. However, RH's hydrophobic nature and low bioavailability do not encourage its use in RA. The current study aims to use RH in combination with MTX in targeted solid lipid nanoparticles (RH-MTX-SLNs) for better effectiveness and shadowing light on its possible mechanistic pathways. RH-MTX-SLNs were prepared and assessed for their quality attributes. The effect of the formulation was assessed in-vivo in an adjuvant arthritis animal model investigating the role of the endoplasmic reticulum stress (ERS)-induced apoptosis. Results revealed that RH-MTX-SLNs were in the suitable nanosized range with high negative zeta potential indicating good stability. In-vivo, RH-MTX-SLNs significantly improved all measured inflammatory and arthritic markers, confirmed by electron microscopy and histology examination of the joints. Besides, the formulation was able to alter the ERS-mediated apoptosis. In conclusion, RH-MTX-SLNs can represent a promising therapeutic approach for RA showing significant anti-arthritic activity.

Towards Drug Repurposing in Cancer Cachexia: Potential Targets and Candidates

As a multifactorial and multiorgan syndrome, cancer cachexia is associated with decreased tolerance to antitumor treatments and increased morbidity and mortality rates. The current approaches for the treatment of this syndrome are not always effective and well established. Drug repurposing or repositioning consists of the investigation of pharmacological components that are already available or in clinical trials for certain diseases and explores if they can be used for new indications. Its advantages comparing to de novo drugs development are the reduced amount of time spent and costs. In this paper, we selected drugs already available or in clinical trials for non-cachexia indications and that are related to the pathways and molecular components involved in the different phenotypes of cancer cachexia syndrome. Thus, we introduce known drugs as possible candidates for drug repurposing in the treatment of cancer-induced cachexia.

Diacerein Inhibits Myopia Progression through Lowering Inflammation in Retinal Pigment Epithelial Cell

Myopia is a highly prevalent refractive disorder. We investigated the effect of diacerein on monocular form deprivation (MFD) in hamsters as a possible therapeutic intervention. Diacerein is an anthraquinone derivative drug whose active metabolite is rhein. Diacerein or atropine was applied to the MFD hamsters, and their refractive error and axial length were measured after 21 days. The refractive error (control: −0.91 ± 0.023, atropine: −0.3 ± 0.08, and diacerein: −0.27 ± 0.07 D) and axial length (control: 0.401 ± 0.017, atropine: 0.326 ± 0.017, and diacerein: 0.334 ± 0.016 mm) showed statistically significant differences between control, atropine-treated, and diacerein-treated MFD eyes. Furthermore, we determined the level of transforming growth factor-beta- (TGF-) β1, matrix metalloproteinase- (MMP-) 2, type I collagen, interleukin- (IL-) 6, IL-8, and monocyte chemoattractant protein- (MCP-) 1 in the retina. Atropine and diacerein suppressed levels of the myopia-related TGF-β1 and MMP-2 while increasing type I collagen expression. They also inhibited the interleukin IL-6, IL-8, and MCP-1 levels. Diacerein reduced the IL-6, IL-8, and MCP-1 expression in ARPE-19 cells. Furthermore, diacerein inhibited inflammation by attenuating the phosphorylation of protein kinase B (AKT) and nuclear factor kappa-light-chain-enhancer of activated B (NF-κB) pathway. This suggests that diacerein has a therapeutic effect on myopia and is a potential treatment option.

Preparation of solid dispersion systems for enhanced dissolution of poorly water soluble diacerein: In-vitro evaluation, optimization and physiologically based pharmacokinetic modeling

Diacerein (DCN), a BCS II compound, suffers from poor aqueous solubility and limited bioavailability. Solid dispersion systems (SD) of DCN were prepared by solvent evaporation, using hydrophilic polymers. In-vitro dissolution studies were performed and dissolution parameters were evaluated. I-Optimal factorial design was employed to study the effect of formulation variables (drug:polymer ratio and polymer type) on the measured responses including; drug content (DC) (%), dissolution efficiency at 15 min (DE _{(15 min)}%) and 60 min (DE _{(60 min)}%) and mean dissolution time (MDT) (min). The optimized SD was selected, prepared and evaluated, allowing 10.83 and 3.42 fold increase in DE _{(15 min)}%, DE _{(60 min)}%, respectively and 6.07 decrease in MDT, compared to plain drug. DSC, XRD analysis and SEM micrographs confirmed complete amorphization of DCN within the optimized SD. Physiologically based pharmacokinetic (PBPK) modeling was employed to predict PK parameters of DCN in middle aged healthy adults and geriatrics. Simcyp^® software established in-vivo plasma concentration time curves of the optimized SD, compared to plain DCN. Relative bioavailability of the optimized SD compared to plain drug was 229.52% and 262.02% in healthy adults and geriatrics, respectively. Our study reports the utility of PBPK modeling for formulation development of BCS II APIs, via predicting their oral bio-performance.

Development of orally disintegrating tablets containing solid dispersion of a poorly soluble drug for enhanced dissolution: In-vitro optimization/in-vivo evaluation

Diacerein (DCN), a potent anti-inflammatory API used to treat osteoarthritis yet, it suffers from poor water solubility which affects its oral absorption. Unabsorbed colonic DCN is converted into rhein, which is responsible for laxation as a main side effect of DCN treatment. Therefore, in this study orally disintegrating tablets (ODTs) loaded with optimized DCN solid dispersion system were prepared using different co-processed excipients (Prosolv^® ODT, Pharmaburst^® 500 and F-melt^®), aiming to achieve improved solubility, rapid absorption and consequently limited amount of rhein reaching the colon. Prepared ODTs were evaluated for physical characteristics, in-vitro drug release, disintegration and wetting times. Dissolution parameters; dissolution efficiency percent at 10 (DE _{(10 min)}%) and 30 (DE _{(30 min)}%) min and mean dissolution time (MDT) were determined. The optimized ODT showed 1.50 and 1.12 fold increase in DE _{(10 min)}% and DE _{(30 min)}%, respectively and 2 fold decrease in MDT, compared to Diacerein^® capsules. In-vivo anti-inflammatory effect of optimized ODT, using rat paw edema revealed significant increase in edema inhibition (p < 0.0465) and promoted onset of action compared to Diacerein^® capsules at 0.5 hr. It could be concluded that optimized ODT could be promising for enhanced dissolution and rapid absorption of DCN from the oral cavity.

Rhein inhibits ATP-triggered inflammatory responses in rheumatoid rat fibroblast-like synoviocytes

Rheumatoid arthritis (RA) is a chronic and systemic inflammatory disorder, which may lead to joint disabilities. So far the pathogenesis of RA remains largely undetermined, and there are still no potent drugs for clinical treatment. Rhein, a natural bioactive anthraquinone derivative, exhibited significant anti-inflammatory activities demonstrated by previous studies. Here we aimed to investigate the effects of rhein on ATP-induced inflammation responses in fibroblast-like synoviocytes isolated from a rat model of collagen induced arthritis (CIA). Our results showed that ATP triggered rapid cytosolic calcium concentration ([Ca²⁺]_c) increase depending on extracellular Ca²⁺ entry. Given the major P2 subtypes expressed in rat synoviocytes were P2X₄ and P2Y₂ receptors, ATP-elicited calcium entry should be mainly resulted from activating P2X₄. Interestingly, rhein could effectively block the ATP-induced [Ca²⁺]_c increases in a dose-dependent manner. Besides, rhein also suppressed the production of intracellular reactive oxygen species (ROS) induced by ATP in synoviocytes that was resulted from P2X₄-mediated Ca²⁺ entry. Brilliant blue G (BBG), which can block P2X₄ receptor at high concentration, showed similar suppressive effects on above responses. Furthermore, in lipopolysaccharide-primed cells, application of ATP synergistically promoted the gene expression of cyclooxygenase-2, interleukin-6 and matrix metalloproteinase-9. Both rhein and BBG attenuated these inflammatory gene expressions enhanced by ATP. Above data together suggested a potential anti-arthritic role of rhein by inhibiting ATP-induced [Ca²⁺]_c increase, ROS production and inflammatory gene expression targeting P2X₄ in CIA rat synoviocytes, which will provide a novel insight in the therapy of RA.