Pharmacotherapy of rheumatoid arthritis: an overview

Structural optimization of HPMA copolymer-based dexamethasone prodrug for improved treatment of inflammatory arthritis

Despite their notorious adverse effects, glucocorticoids (GC, potent anti-inflammatory drugs) are used extensively in clinical management of rheumatoid arthritis (RA) and other chronic inflammatory diseases. To achieve a sustained therapeutic efficacy and reduced toxicities, macromolecular GC prodrugs have been developed with promising outcomes for the treatment of RA. Fine-tuning the activation kinetics of these prodrugs may further improve their therapeutic efficacy and minimize the off-target adverse effects. To assess the feasibility of this strategy, five different dexamethasone (Dex, a potent GC)-containing monomers with distinctively different linker chemistries were designed, synthesized, and copolymerized with N-(2-hydroxypropyl) methacrylamide (HPMA) to obtain 5 macromolecular Dex prodrugs. Their Dex releasing rates were analyzed in vitro and shown to display a wide spectrum of activation kinetics. Their therapeutic efficacy and preliminary toxicology profiles were assessed and compared in vivo in an adjuvant-induced arthritis (AA) rat model in order to identify the ideal prodrug design for the most effective and safe treatment of inflammatory arthritis. The in vivo data demonstrated that the C3 hydrazone linker-containing prodrug design was the most effective in preserving joint structural integrity. The results from this study suggest that the design and screening of different activation mechanisms may help to identify macromolecular prodrugs with the most potent therapeutic efficacy and safety for the management of inflammatory arthritis.

Analysis of myosin-V immunoreactive myenteric neurons from arthritic rats

CONTEXT

The inflammatory response itself and the consequent oxidative stress are able to promote neurodegeneration. So, it is possible that enteric nervous system is affected by inflammatory diseases threatening quality of life of patients. However, gastrointestinal symptoms of arthritis are usually attributed to anti-inflammatory drugs rather than neural damage.

OBJECTIVE

To confirm if the general population of myenteric neurons from the ileum and jejunum of rats is affected by arthritis.

METHODS

Twenty Holtzmann rats, 58-day-old male, were used and divided in four groups: control group (C30), arthritic group (Art30), older control group (C60) and older arthritic group (Art60). At 58 days old, the animals in groups Art30 and Art60 received an injection of the complete Freund's adjuvant in order to induce arthritis. The whole-mount preparations of ileum and jejunum were processed for myosin-V immunohistochemistry. Quantitative and morphometric analyses were performed.

RESULTS

Groups Art30 and Art60 presented, respectively, a reduction of 2% and 6% in intestinal area when compared to their control groups. No significant differences were observed in general neuronal density among the four groups (P>0.05). Group C60 presented a reduction of 14.4% and 10.9% in mean neuronal cell body area when compared to group C30 (P<0.05), for the ileum and jejunum, respectively. The other groups had a similar mean neuronal cell body area (P>0.05).

CONCLUSION

Arthritis does not promote quantitative or morphological damages in general myenteric population. However, studies in progress have revealed some significant alterations in myenteric neurons subpopulations (nitrergic and VIP-ergic neurons).

Appraisal of anti-inflammatory and free radical scavenging activities of ethanol extract of Ilex ficoidea Hemsl and Ilex centrochinensis S.Y. Hu

This study was to appraise the anti-inflammatory and free radical scavenging activities of ethanol extracts of Ilex ficoidea Hemsl (EIFH) and Ilex centrochinensis S.Y. Hu (EICC). Anti-inflammatory activities were evaluated using xylene-induced ear edema and the cotton pellet granuloma tests. Some antioxidants produced during chronic inflammation were quantitated and the DPPH, superoxide anion and hydroxyl free radicals scavenging activities in vitro were also investigated. EICC showed a significant anti-inflammatory effect during the acute inflammation and chronic inflammation without any acute oral toxicity. However, EIFH exhibited a negligible anti-acute inflammatory and a moderate anti-chronic inflammatory activity. EICC significantly inhibited the formation of MDA and markedly raised the activities of SOD, CAT and GSH-Px. EIFH could reduce the level of MDA and elevate the activity of SOD only at the high dose. The free radical scavenging activities of EICC are higher than that of EIFH. These results suggest that EICC possesses significant anti-inflammatory and free radical scavenging activities. The anti-inflammatory mechanism is attributed, in part, to enhance the activities of antioxidant enzymes.

The incidence of pancytopenia in patients taking leflunomide alone or with methotrexate

PURPOSE

To estimate the incidence of pancytopenia in patients taking leflunomide with or without methotrexate in Australia.

METHODS

Review of spontaneous reports to the Australian Adverse Drug Reactions Advisory Committee (ADRAC); estimation of incidence using national prescription reimbursement data; concomitant exposure to methotrexate was estimated using three sources of information.

RESULTS

ADRAC received 11 reports of pancytopenia (meeting predefined criteria) associated with the use of leflunomide during its first 31 months of marketing. In nine reports, the patients were also taking methotrexate. Estimates of incidence in patients taking leflunomide alone ranged from 1 in 3698 to 1 in 4582 patients exposed; for patients also taking methotrexate the estimates ranged from 1 in 575 to 1 in 822.

CONCLUSIONS

Use of methotrexate with leflunomide increases the risk of pancytopenia compared with use of leflunomide alone. The haematological toxicity of the combination requires further study.

Biological mediators of acute inflammation

Inflammation may be defined as the normal response of living tissue to injury or infection. It is important to emphasize two components of this definition. First, that inflammation is a normal response and, as such, is expected to occur when tissue is damaged. Indeed, if injured tissue did not exhibit signs of inflammation this would be considered abnormal. Secondly, inflammation occurs in living tissue, hence the need for an adequate blood supply to the tissues in order for an inflammatory response to be exhibited. The inflammatory response may be triggered by mechanical injury, chemical toxins, invasion by microorganisms, and hypersensitivity reactions. Three major events occur during the inflammatory response: the blood supply to the affected area is increased substantially, capillary permeability is increased, and leucocytes migrate from the capillary vessels into the surrounding interstitial spaces to the site of inflammation or injury. The inflammatory response represents a complex biological and biochemical process involving cells of the immune system and a plethora of biological mediators. Cell-to-cell communication molecules known collectively as cytokines play an extremely important role in mediating the process of inflammation. An extensive exposition of this complex phenomenon is beyond the scope of this article. Rather, the author provides a review of inflammation, an overview of the role of certain biological mediators in inflammation, and a discussion of the implications of certain biological response modifiers in clinical practice.