Advances in antiarthritic therapeutics

Nanoemulgel, an Innovative Carrier for Diflunisal Topical Delivery with Profound Anti-Inflammatory Effect: in vitro and in vivo Evaluation

Purpose

Rheumatoid arthritis is an autoimmune disorder that directly affects joints. However, other body organs including heart, eyes, skin, blood vessels and lungs may also be affected. The purpose of this study was to design and evaluate a nanoemulgel formulation of diflunisal (DIF) and solubility enhanced diflunisal (DIF-IC) for enhanced topical anti-inflammatory activity.

Methodology

Nanoemulsion formulations of both DIF and DIF-IC were prepared and incorporated in three different gelling agents, namely carboxymethylcellulose sodium (CMC-Na), sodium alginate (Na-ALG) and xanthan gum (XG). All the formulations were evaluated in term of particle size, pH, conductivity, viscosity, zeta potential and in vitro drug release. The formulation 2 (NE2) of both DIF and DIF-IC which expressed optimum release and satisfactory physicochemical properties was incorporated with gelling agents to produce final nanoemulgel formulations. The optimized nanoemulgel formulation was subjected to three different in vivo anti-inflammatory models including carrageenan-induced paw edema model, histamine-induced paw edema model and formalin-induced paw edema model.

Results

DIF-IC-loaded nanoemulgel formulations yielded significantly enhanced in vitro skin permeation than DIF-loaded nanoemulgel. The nanoemulgel formulation of DIF-IC formulated with XG produced improved in vivo anti-inflammatory activity.

Conclusion

It was recommended that DIF-IC-based nanoemulgel formulation prepared with XG could be a better option for effective topical treatment of inflammatory conditions.

Evaluation of Antiarthritic Potential of Methanolic Extract of Gentiana kurroo Royle

Rheumatoid arthritis is a systemic disorder which involves the activation of immune system against the self-tissues. The main targets of this disease are the joints. Being systemic the development of this disease involves different mechanisms and thus the exact cause of this disease remains unknown. Although different drugs have been developed, none has been found to be the cure for this disease. In the current study the rat carrageenin paw was used as a model for acute inflammation and mycobacterium induced adjuvant arthritic model was used for exploring the antiarthritic potential of methanolic extract of Gentiana kurroo. In this study the different extracts tested showed less inhibition of acute inflammation than methanolic extract. The methanolic extract was further used in different doses and the anti-inflammatory efficacy was found to be dose dependent. The results obtained were significant with the control and the standard groups. In the arthritic model the methanolic extract showed decrease in the paw volume of arthritic animals and also in the arthritic symptoms. Again the results obtained were found to be significantly dose dependent. From the results obtained it can be concluded that this extract may serve as a source of drug against the rheumatoid arthritis.

Antinociceptive and antiarthritic activity of Cissampelos pareira roots

In the present study, 50% aqueous ethanolic extract of Cissampelos pareira (Menispermaceae) roots (C. pareira) at the dose levels of 100-400 mg/kg, once daily for 3 days exhibited significant (P < 0.001) resistance against mechanical pain after 30 min in analgesymeter induced pain in mice. In acetic acid (0.6%; i.p.) inducing writhing, Cissampelos pareira significantly (P < 0.05) decreased the writhing episodes; the degree of percent protection at 200 and 400 mg/kg was 22.73 and 51.63. The hot plate reaction time was increased by 2.07 (P < 0.05) and 2.70 (P < 0.001) folds. respectively. Further Cissampelos pareira showed the dose dependent significant protective effect against complete Freund's adjuvant induced arthritis. The percentage protection on the 18th day was 40.54 (P < 0.01) and 71.52 (P < 0.001) at 200 and 400 mg/kg respectively. Lysosomal enzymes (acid phosphatase and N-acetyl glucosaminidase) were decreased by 50% (P < 0.01) and 26.26% (P < 0.05) by using Cissampelos pareira, dextramethasone decreased them 56.56% (P < 0.01) and 31.82% (P < 0.01) and the glycoprotein contents (total hexose and sialic acid) were increased by 1.55-folds (P < 0.01) and 1.51-folds (P < 0.05) by using Cissampelos pareira while dextramethasone increases them by 1.51-folds (P < 0.001) and 1.60-folds (P < 0.01) respectively in stomach homogenate with respect to arthritic group. The increased pain threshold and protective effect against CFE by Cissampelos pareira vindicated its medicinal value in treatment of pain and arthritis.

The therapeutic potential of PDE4 inhibitors

Phosphodiesterase enzymes are responsible for the inactivation of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Phosphodiesterase 4 (PDE4) is a cAMP specific phosphodiesterase expressed in inflammatory cells such as eosinophils. Inhibition of PDE4 results in an elevation of cAMP in these cells, which in turn downregulates the inflammatory response. The anti-inflammatory effects of PDE4 inhibitors have been well documented both in vitro and in vivo in a variety of animal models. The potential use of PDE4 inhibitors as anti-inflammatory agents for the treatment of asthma and other inflammatory disorders has received considerable attention from the pharmaceutical industry, but to date, there are no selective PDE4 inhibitors on the market. Early PDE4 inhibitors, typified by rolipram, suffered from dose-limiting side effects, including nausea and emesis, which severely restricted their therapeutic utility. Second generation compounds, including CDP840 and SB207499 (Ariflo), have been identified with reduced side effect liability. Recent evidence suggests a correlation between side effects and the ability of compounds to bind at the so-called high affinity rolipram binding site (HPDE), whilst beneficial effects appear to correlate with binding at the catalytic site. A number of companies are actively pursuing compounds which exhibit improved affinity for the catalytic site and reduced affinity for the HPDE, in the expectation that this will provide compounds with an improved therapeutic index.

Anti-inflammatory effects of triptolide loaded poly(D,L-lactic acid) nanoparticles on adjuvant-induced arthritis in rats

Triptolide (TP), which has potent immunosuppressive effects, anti-inflammatory and severe toxicity on digestive, urogenital, blood circulatory system, was used as a model drug in this study. The aim of this study was to investigate the anti-inflammatory effect of complete Freund's adjuvant-induced arthritis in rats treated with TP-loaded poly(D,L-lactic acid) (PLA) nanoparticles (TP-PLA-NPs) by gavage. TP-PLA-NPs were prepared by the modified spontaneous emulsification solvent diffusion method (modified-SESD). Nanoparticles were shown to be small particle size (149.7 nm), low polydispersity index (0.088), a fine spherical shape with smooth surfaces determined by dynamic light scattering (DLS) and transmission electron microscope (TEM). Encapsulation efficiency and the in vitro release of TP from nanoparticles were measured by the reverse phase high-performance liquid chromatography (RP-HPLC). The in vitro release profile of TP from nanoparticles exhibited a typical biphasic release phenomenon, namely initial burst release and consequently slow release. The potential therapeutic arthritic method of TP-PLA-NPs was established. The results obtained in experiments indicated that TP-PLA-NPs significantly inhibited the adjuvant-induced arthritis, and had preferable anti-inflammatory effect with the long-time administration.

Superoxide dismutase entrapped in long-circulating liposomes: formulation design and therapeutic activity in rat adjuvant arthritis

The aim of this study was to investigate whether long-circulating liposomes can improve the anti-inflammatory activity of superoxide dismutase (SOD). Small-sized poly(ethyleneglycol) (PEG)-liposomes containing SOD were prepared via different preparation protocols and characterized in terms of encapsulation efficiency (EE), size, enzymatic activity and protein structure, to establish conditions where high EE can be combined with preservation of enzyme activity and structure. It was observed that structural information from circular dichroism analyses does not correlate with data on enzyme activity. SOD-containing PEG-liposomes prepared by the dehydration-rehydration method appeared to represent the most attractive formulation for in vivo evaluation. The therapeutic potential of selected SOD-containing PEG-liposomes was established and compared with SOD entrapped in stearylamine (SA)-liposomes and 'free' SOD upon intravenous (i.v.) injection in an arthritic rat model. Both small PEG-liposomes and SA-liposomes showed a superior therapeutic activity compared to 'free' SOD, with PEG-liposomes inducing stronger anti-inflammatory effects than SA-liposomes.