Effect of food and gender on the pharmacokinetics of RP 73401, a phosphodiesterase IV inhibitor

OBJECTIVE: Early exploratory clinical pharmacokinetic studies can provide valuable information for the design and control of subsequent phase 2 studies. This philosophy was instituted for the compound RP 73401, a specific phosphodiesterase IV inhibitor, that was being developed simultaneously for delivery by both oral and pulmonary routes of administration. The objective of these studies was to separately evaluate the effect of food and gender on the pharmacokinetics of RP 73401 using small-scale focused pilot studies. METHODS: In the first study, 400 mcg of inhaled RP 73401 were administered to male and female healthy volunteers (n = 8 f, 8 m. In the second study, 400 mcg oral RP 73401 were administered to healthy male volunteers (n = 8) in the fed and fasted state in a crossover fashion. Serial plasma samples were collected for 24 hours and analyzed for RP 73401 using an HPLC method with post-column photochemical reaction and fluorescence detection that had a minimum quantifiable limit of 10 pg/ml. Pharmacokinetic parameters were calculated using non-compartmental techniques. RESULTS: Comparison of male and female pharmacokinetics following inhalation administration showed no statistically significant differences in the absorption and disposition of RP 73401 with respect to AUC, Cmax, tmax, and t1,2 values. Conversely, RP 73401 administered subsequently to a high fat meal showed a 51% reduction in Cmax and a 5-fold prolongation in tmax as compared to the fasted state. However, there was no statistically significant difference in the systemic availability of RP 73401 as assessed through AUC0-infinity comparisons. CONCLUSIONS: These results successfully allowed the uncomplicated inclusion of females in oral and inhalation studies with RP 73401 and indicated the need to address oral drug dosing conditions in order to minimize sources of pharmacokinetic variability in subsequent phase 2 studies.     

Anti-inflammatory and bronchodilator properties of RP 73401, a novel and selective phosphodiesterase type IV inhibitor

1 We have investigated the effects of RP 73401, a novel, potent and highly selective cyclic nucleotide phosphodiesterase (PDE) type IV inhibitor, in guinea-pig and rat models of bronchoconstriction and allergic inflammation. In some models, the effects of RP 73401 have been compared with those of the standard PDE type IV inhibitor, rolipram.

2 RP 73401 (0.4-400 μg kg^-1, intratracheally (i.t.) on lactose) inhibited antigen-induced bronchospasm in previously sensitized conscious guinea-pigs (ID₅₀: 7±1 μg kg^-1) and in anaesthetized rats (ID₅₀: 100±25 μg kg^-1). Rolipram inhibited the antigen-induced bronchospasm in guinea-pigs with an ID₅₀ of 5±1 μg kg^-1. In guinea-pig bronchoalveolar lavage (BAL) fluid, total inflammatory cell and eosinophil numbers were reduced by RP 73401 (ID₅₀S: 3.9±0.8 μg kg^-1 and 3.2±0.7 μg kg^-1, respectively). In the rat, inflammatory cell numbers are less affected. Only the highest dose of RP 73401 (400 μg kg^-1) significantly inhibited eosinophil influx (41±16% inhibition).

3 RP 73401 (0.02-100 μg kg^-1, i.v.) inhibited PAF-induced bronchial hyperreactivity to bombesin in the anaesthetized guinea-pig (ID₅₀: 0.09±0.03 μg kg^-1) and inhibited (0.4-40 μg kg^-1, i.t.) histamine-induced airway microvascular leakage in the anaesthetized guinea-pig by approximately 60% at all doses.

4 RP 73401 relaxed guinea-pig isolated trachea under basal tone (EC₅₀: 9 nM) and when precontracted with histamine (IC₅₀: 2 nM), methacholine (IC₅₀: 29 nM) or leukotriene D₄ (LTD₄, IC₅₀: 4 nM).

5 RP 73401 (0.4-100 μg kg^-1, i.t.) inhibited bronchospasm induced by histamine (ID₅₀: 34±6 μg kg^-1), methacholine (ID₅₀: 66±12 μg kg^-1) and LTD₄ (ID₅₀: <4 μg kg^-1) in the anaesthetized guinea-pig. Against these same bronchoconstrictors, rolipram (i.t.) had ID₅₀ values of 44±4, 72±18 and <4 μg kg^-1 respectively. RP 73401 (4 and 40 μg kg^-1, i.t.) increased the magnitude and duration of bronchodilatation produced by salbutamol in the anaesthetized guinea-pig. At doses producing significant bronchodilatation, RP 73401 was without effect on heart rate or blood pressure in the anaesthetized guinea-pig. RP 73401 (0.01-0.25 mg kg^-1, i.v.) did not affect heart rate and produced only a small fall in blood pressure in the anaesthetized rat.

6 These data demonstrate that RP 73401 and rolipram inhibit antigen- and mediator-induced bronchospasm in guinea-pigs with the same potency. Furthermore, RP 73401 administered directly into the airways, protects against allergic airway inflammation. These results indicate the importance of PDE IV in regulating smooth muscle and inflammatory cell activity. At doses suppressing the inflammatory response in the lung, RP 73401 had little effect in the cardiovascular system. RP 73401 may have a role as a bronchodilator and, more importantly, as a prophylactic anti-inflammatory agent in the treatment of asthma.

     

Effects of the phosphodiesterase IV inhibitor rolipram on Th1 and Th2 immune responses in mice

The present study was designed to investigate the effect of the phosphodiesterase IV inhibitor rolipram on Th1 and Th2 immune responses in mice. Mice were immunized subcutaneously at the base of the tail with ovalbumin (OVA) emulsified with complete Freund's adjuvant (day 0) and were treated daily with oral administration of various doses of rolipram from days 0 to 20. On day 21, production of anti-OVA IgG and proliferative responses to the antigen were determined. Anti-OVA IgG2a and interferon-gamma (IFN-gamma), as indicators of Th1 responses, and anti-OVA IgG1 and interleukin-10 (IL-10), as indicators of Th2 responses, were also measured. The results showed that treatment with rolipram failed to affect the production of OVA-specific IgG but decreased the proliferation of spleen cells to the antigen. Its inhibitory effect on these immune responses was correlated with a marked decrease in IFN-gamma but not IL-10 production, although neither anti-OVA IgG2a nor IgG1 production was affected by rolipram. These results suggest that rolipram may preferentially inhibit Th1 responses more effectively than Th2 responses. Administration of rolipram resulted in suppression of antigen (OVA)-induced arthritis in mice. The suppression of joint inflammation by rolipram was associated with the inhibition of the OVA-specific proliferative responses of spleen cells and IFN-gamma secretion. These results indicate that rolipram may be effective in regulating Th1-mediated diseases such as rheumatoid arthritis.     

Effects of RP 73401, a novel,potent and selective phosphodiesterase type 4 inhibitor,on contractility of human,isolated bronchial muscle.

1. The aim of this study was to investigate the smooth muscle relaxant effects of the novel, selective phosphodiesterase (PDE) type 4 inhibitor, RP 73401 in comparison with the classical PDE 4 inhibitor, rolipram, the non-selective PDE inhibitor, theophylline and the beta-adrenoceptor agonist, isoprenaline on the human, isolated bronchus. 2. At resting tone, the rank order of potency (pD2) for the relaxants was RP 73401 > or = rolipram > or = isoprenaline >> theophylline. In terms of maximum relaxation produced (Emax) the PDE 4-selective inhibitors were similar, but the maximal effects (70-75% of theophylline, 3 mM) were lower than that observed with isoprenaline (98% of theophylline, 3 mM) or theophylline itself (100%). 3. On the human isolated bronchus pre-contracted with acetylcholine (ACh, 0.1 or 1.0 mM), the rank order of potency remained the same. The maximal responses to RP 73401 and rolipram were however markedly reduced (Emax 39.9-46.6%) compared with isoprenaline (Emax 79-85%). 4. In tissues pre-contracted with ACh (0.1 mM), RP 73401 and rolipram (10(-9)-10(-7) M) significantly and concentration-dependently increased tissue sensitivity to isoprenaline. RP 73401 and rolipram were similar in potency. Both selective PDE 4 inhibitors also significantly increased the maximal relaxant effects of isoprenaline. These effects were not observed with the PDE 3 inhibitor, siguazodan. 5. In terms of retention by tissues (an index of duration of action), the onset of action of RP 73401 (2.11 +/- 0.53 min) and rolipram (1.70 +/- 0.45 min) was significantly slower than that of isoprenaline (0.33 +/- 0.06 min) or theophylline (1.17 +/- 0.25 min). The retention of RP 73401 (89.0 +/- 21.9 min) on the human isolated bronchial tissues after washing was however dramatically longer than that of rolipram (18.3 +/- 4.5 min), theophylline (3.43 +/- 0.58 min) or isoprenaline (2.81 +/- 0.31 min). 6. These data indicate that RP 73401 is a potent and long acting relaxant of human bronchial muscle in vitro. RP 73401 is more potent than the classical PDE 4-selective inhibitor rolipram and the non-selective PDE inhibitor theophylline and is retained in bronchial tissue for a much longer period of time.     

Potential of phosphodiesterase type of IV inhibitors in the treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is a crippling autoimmune disease which afflicts over 1% of the population. Non-steroidal anti-inflammatory drugs are widely used palliatives, but these disease-modifying drugs are of variable and limited efficacy, and are frequently associated with side-effects which restrict their use. Agents that elevate cAMP, including cAMP-specific phosphodiesterase (PDE) inhibitors, possess a profile of anti-inflammatory activities which suggest potential benefit in RA. In several rodent RA models, PDE IV inhibitors reduce the incidence and severity of disease symptoms and histological analysis reveals a significant, beneficial effect on joint pathology. Several potential mechanisms may underpin the anti-arthritic actions of PDE IV inhibitors. These include inhibition of tumor necrosis factor (TNF)-alpha release, increase of interleukin (IL)-10 release, and suppression of T-lymphocyte function, as well as direct, protective effects on cartilage and bone. Although stimulation of the hypothalamic-pituitary-adrenal axis in rodents has previously been suggested as a possible mechanism by which PDE IV inhibitors exert their anti-arthritic effects, recent data question its importance. For example, RP-73401 ameliorates disease severity in Streptococcal cell wall-induced arthritis in Lewis rats, a strain whose susceptibility to this disease has been attributed to a defective HPA response, without affecting either ACTH or corticosterone levels. In a small clinical study, RA patients treated with low doses of RP-73401, showed a positive (non-significant) trend in respect of serum concentrations of IL-6 and CRP. Although levels of TNFalpha and IL-1beta were unaffected, patients reported some symptomatic relief. The administration of higher doses was prohibited due to side-effects and compounds with an improved therapeutic window will have to be identified to further explore the potential of PDE IV inhibitors in the treatment of RA.     

The effect of gene polymorphisms on patient responses to rheumatoid arthritis therapy

Introduction: Rheumatoid arthritis (RA) is a systemic disease leading to joint destruction. The therapy of RA is mainly based on disease-modifying anti-rheumatic drugs (DMARDs) and biological drugs. The response to treatment is different among patients. Therefore, we have searched for factors that may predict the efficacy and toxicity during therapy in individual patients.

Areas covered: This review presents the role of genetic polymorphisms as predictors of the efficacy and toxicity during the therapy of RA patients with DMARDs (methotrexate, leflunomide, sulfasalazine) and biological drugs (anti-TNF-alpha antagonists, Tocilizumab, Rituximab).

Expert opinion: Despite studies having shown an association between genetic polymorphisms and response to therapy in RA patients, the majority of these findings are still inconclusive and inconsistent. We are still far from applying pharmacogenetic tests in routine clinical practice that can predict the outcome of treatment. Several factors, such as small sample size with low statistical power, variability in the outcome definitions and the heterogeneity of the cohorts, limited number of tested single nucleotide polymorphisms (SNPs), small effect for the selected variant, and a lack of consideration of epigenetic factors, may contribute to the inconsistency observed and may lead to limited success in personalizing therapy.     

Effects and mechanisms of melatonin on inflammatory and immune responses of adjuvant arthritis rat

AIM: To study the effects of melatonin on inflammatory and immune responses and its mechanisms. METHODS: The model of adjuvant-induced arthritis (AA) rat was induced by Freund's complete adjuvant (FCA); the thymocyte proliferation and IL-2 production were assayed by 3-(4,5-2dimethylthiazal-2yl)2,5-diphenyltetrazoliumbromide (MTT) and activated mouse splenocytes proliferation, respectively; cAMP and methionine-enkephalin (Met-Enk) level were determined by competitive protein binding assay (CPBA) and radioimmuno-assay, respectively. RESULTS: There was a marked inflammatory response in AA model, which was accompanied by the decreases of thymocyte proliferation and IL-2 production simultaneously. The prophylactic and therapeutic administration of melatonin (1, 10 and 100 microg kg(-1), ig x 7 days) inhibited the inflammatory response and enhanced thymocytes proliferation and IL-2 production significantly in AA rats. In vitro, melatonin, at the concentrations of 10(-7) and 10(-6) mol l(-1) could enhance the thymocyte proliferation in AA rats. The cAMP level stimulated by forskolin (F, a selective adenylate cyclase [AC] activator) in AA rats was higher than that in the control groups. Melatonin (10(-10) or 10(-6) mol l(-1)) had down-regulation on the above increased cAMP levels, which could be abolished by pertussis toxin (PT). Meanwhile, the decrease of thymocyte proliferation in AA rats had a marked relation with the decrease of Met-Enk level in these thymocytes, melatonin (10(-10) or 10(-6) mol l(-1)) could markedly enhance the Met-Enk level, which were blocked by nifedipine, a Ca2+ channel antagonist. CONCLUSIONS: Melatonin possesses anti-inflammatory and immunoregulatory actions, the G protein-AC-cAMP transmembrane signal and Met-Enk release in thymocyte are important mechanisms of this action.     

G protein coupled receptors signaling pathways implicate in inflammatory and immune response of rheumatoid arthritis

G protein coupled receptors(GPCRs)are transmembrane receptor proteins,which allow signals to transfer across membrane.GPCRs include a large number of receptors,different receptors mediated different signaling pathways of GPCRs-adenylyl cyclase(AC)-cyclic adenosine 3',5'-monophosphate(c AMP),including β2 adrenergic receptors(β2-ARs)-AC-c AMP signaling pathways,E-prostanoid2/4(EP2/4)-AC-cA MP signaling pathways.Regulatory proteins,such as G protein coupled receptor kinases(GRKs)andβ-arrestins,play important modulatory roles in GPCRs signaling pathway.GPCRs signaling pathway and regulatory proteins implicate the pathogenesis process of inflammatory and immune response.Rheumatoid arthritis(RA)is an autoimmune disease characterized by synovitis and accompanied with inflammatory and abnormal immune response.This article review the advances on GPCRs signaling pathway implicating in the inflammatory and immune response of RA.     

Disparity between clinical and immune responses in a controlled trial of azathioprine in rheumatoid arthritis

Summary Drugs that interfere with the immune responsein vitro, such as azathioprine (AZ), have been used extensively since 1964 in clinical therapeutic trials of autoimmune diseases. However, few adequately controlled studies are available concerning the concurrent effect of AZ on the immune and clinical responses to treatment of rheumatoid arthritis (RA). Thirty patients suffering from classical seropositive RA received AZ (1.5 – 2.0 mg/kg/day) and placebo in a controlled clinical cross-over study for two 12-week periods. Other treatments were kept constant throughout the entire 6 months. In terms of the clinical responses of joint count and grip strength patients receiving AZ improved markedly, in contrast to the placebo group. After 2 months, joint scanning revealed no progress of the disease in patients undergoing AZ treatment. Corresponding with the remarkably beneficial clinical effect of AZ, a significant drop in immunoglobulins was observed. However, since AZ failed to suppressin vivo specific antibody synthesis in RA, the question remains as to whether this drug actually does interfere with the autoimmunogenesis of the disease.Presented in preliminary form at the 8th European Rheumatology Congress, Helsinki, June 1975     

Inhibitory effect of saponin fraction from Codonopsis lanceolata on immune cell-mediated inflammatory responses

Saponin components are known to be pharmaceutically, cosmetically and nutraceutically valuable principles found in various herbal medicine. In this study, we evaluated the inhibitory role of saponin fraction (SF), prepared from C. lanceolata, an ethnopharmacologically famous plant, on various inflammatory responses managed by monocytes, macrophages, lymphocytes and mast cells. SF clearly suppressed the release of nitric oxide (NO) and tumor necrosis factor (TNF)-α, but not prostaglandin E₂ (PGE₂). While this fraction did not scavenge the reactivity of SNP-induced radicals in RAW264. 7 cells, it negatively modulated the phagocytic uptake of macrophages treated with FITC-dextran. Interestingly, SF completely diminished cell-cell adhesion events induced by both CD29 and CD43, but not cell-fibronectin adhesion. Concanavalin (Con) A [as well phytohemaglutinin A (PHA)]-induced proliferation of splenic lymphocytes as well as interferon (IFN)-γ production were also clearly suppressed by SF treatment. Finally, SF also significantly blocked the degranulation process of mast cell line RBL-2H3 cell as assessed by DNP-BSA-induced β-hexosaminidase activity. The anti-inflammatory activities of SF on NO production seemed to be due to inhibition of nuclear factor (NF)-κB activation signaling, since it blocked the phosphorylation of inhibitor of κB (IκB)α as well as inducible NO synthase (iNOS) expression. Therefore, these results suggest that SF may be considered as a promising herbal medicine with potent anti-inflammatory actions.     

Hormone mediation of immune responses in the progression of diabetes,rheumatoid arthritis and periodontal diseases

The crucial role of the immune response is common to diabetes mellitus (DM), rheumatoid arthritis (RA) and periodontal disease. This review identifies advances in this field and exciting paradigms in their management. Uncontrolled hyperglycaemia in diabetic patients results in the formation of advanced glycation end products (AGEs), which are detrimental to cell structure and function. Altered host resistance such as defective migration of PMN, impaired phagocytosis and an exaggerated inflammatory response to microbial products also compromises healing in uncontrolled diabetic patients, further compromised in smokers. Nicotine has well documented effects on the immune response, cell adhesion proteins and apoptosis which affect the severity of disease presentation and response to treatment. Rheumatoid arthritis is a multifactorial disease that results in severe destruction of synovial cartilage and bone. Local secretion of large amounts of TNF-alpha and IL-1 due to activation of immunocompetent cells characterises the pathophysiology of RA. This has lead to the emergence of TNF-alpha inhibitors such as etanercept and infliximab in its management. Periodontal disease has a microbial aetiology. But it is similar to RA, in its cyclical pattern of destruction associated with high levels of pro-inflammatory cytokines, which can persist after removal of the antigenic stimulus. Non steroidal anti-inflammatory agents (NSAIDs) have been used as an adjunct to mechanical removal of bacterial antigen, in the management of periodontal disease. The non-reproductive functions of steroid hormones include effects on immunocompetent cells, fibroblasts and osteoblasts, which affect the initiation and progression of inflammatory diseases. Hormone replacement therapy could be another facet in a multifaceted treatment approach in these patients, where indicated.     

Effects of TNF inhibitor on innate inflammatory and Th17 cytokines in stimulated whole blood from rheumatoid arthritis patients

Background

Recent studies point to important roles for IL-17 and Th17 cells in sustaining chronic inflammation and articular destruction in rheumatoid arthritis (RA). We investigated the effects of TNF inhibitor on innate inflammatory and Th17 cytokines production by ex vivo lipopolysaccharide (LPS)-stimulated whole blood in patients with RA and the associations of cytokine levels in whole blood cultures with autoantibodies and markers of disease activity.

Materials and methods

Whole blood cultures from 18 healthy volunteers and 19 RA patients on etanercept therapy were stimulated with LPS and the production of IL-6, TNF-??, IL-23, IL-17A and IL-21 was measured by ELISA.

Results

After stimulation with LPS, the interleukin (IL)-17A (p?=?0.020) and IL-21 (p?=?0.0001) secretions were significantly higher in patients with RA than in controls, while the TNF-?? (p?=?0.002) was significantly lower at baseline. Etanercept significantly decreased IL-21 production (p?=?0.007), while IL-6 production (p?=?0.005) significantly increased after 6?months of therapy. IL-21 significantly correlated with RF (r?=?0.917, p?<?0.01) and antimutated citrullinated vimentin antibodies (r?=?0.770, p?<?0.01) at baseline. Logistic regression analysis revealed that baseline IL-21 levels (p?=?0.004) were significant predictors of DAS28-ESR at 6?months follow-up.

Discussion

Stimulation with LPS increased production of Th17 cytokines in whole blood cultures in patients with RA. Etanercept therapy decreased IL-21 secretion, while the capacity of whole blood cells to produce IL-6 increased. IL-21 production is strongly associated with the levels of autoantibodies. Our findings suggest that IL-21 production in LPS-stimulated whole blood cultures may be predictive of clinical response to etanercept treatment in patients with RA.     

IgM-rheumatoid factor and responses to second-line drugs in rheumatoid arthritis.

We have examined the relationship between IgM-rheumatoid factor (RF) and responses to second-line drugs in patients with rheumatoid arthritis (RA). Patients with active RA who were beginning treatment with gold, methotrexate or both were studied. Clinical responses were assessed with ESR, joint count, grip strength and activities of daily living questionnaire scores. Production of IgM-RF by peripheral blood mononuclear cells in vitro and plasma levels of IgM-RF were measured by ELISA. Overall, 31 of 44 patients completing more than 6 months treatment improved including 10 treated with gold, 12 with MTX and 9 with both. Production of IgM-RF by peripheral blood mononuclear cells was decreased by 59% in patients who improved on treatment, but increased 2-fold in the unimproved group. Plasma levels of IgM-RF were decreased from 121 to 66 micrograms/ml in the improved group after 6 months of treatment, with similar decreases seen for each of the three treatments. In contrast, plasma IgM-RF levels in the unimproved group did not decrease until 1 year of treatment was completed. Nine patients converted to seronegativity, and all but one of these were in the improved group. The results suggest that IgM-RF is correlated with responses to second-line drug in RA patients.     

糖皮质激素对类风湿关节炎治疗作用的讨论

糖皮质激素加入临床治疗行列中是20世纪临床医学最具突破意义的事件之一.     

右布洛芬片与布洛芬片治疗类风湿关节炎比较

目的:评估右布洛芬治疗类风湿关节炎的疗效和安全性。方法: 81例类风湿关节炎病人随机分为试验组和对照组,试验组给予右布洛芬 0. 4 ~0. 6g,po,bid,对照组给予布洛芬 0. 4 ~0. 6g,po,bid,疗程 4wk。结果:试验组总改善率为 ( 52±s17) %,总有效率为 80 %,对照组总改善率为(38±13) %,总有效率为 58 % (P<0. 01,P<0. 05);不良反应发生率试验组为 11 %,对照组为 14 % (P>0. 05)。结论:右布洛芬疗效优于布洛芬,不良反应未增加,用药安全。     

通痹汤与氨甲喋呤联合治疗类风湿性关节炎疗效观察

目的 观察通痹汤与氨甲喋呤联合治疗类风湿关节炎疗效。方法 治疗组采用中药通痹汤与氨甲喋呤联合治疗类风湿性关节炎（ＲＡ）７９例，以风湿液与氨甲喋呤联合治疗的４０例ＲＡ作对照。其中治疗组１８例，对照组９例。结果与结论 两组疗效均比文献所报告的单用氨甲喋呤疗效为佳。而通痹汤更具较强的抗炎镇痛及免疫调节作用，可使关节肿痛症状迅速消失，关节功能明显改善，晨僵时间消失或缩短，并随着关节炎症的减轻，使血液中ＩｇＧ，ＩｇＭ，ＩｇＡ恢复正常，血沉下降曲线平稳，类风湿因子（ＲＦ）阴转率达６７．５７％。用药后撤停激素快，无反跳现象，副作用少。骨质修复作用明显，具有改善病情作用。其疗效明显优于对照组。     

内抑素抗血管生成及抗类风湿性关节炎治疗

血管生成是类风湿性关节炎(RA)早期滑膜病理改变特征之一,也是产生和维持RA血管翳的主要因素。内抑素可特异性抑制新生血管内皮细胞增殖、迁移、诱导其凋亡而发挥抗血管生成作用,应用内抑素抑制滑膜新生血管生成可成为治疗RA的一种全新方法。内抑素还可通过抑制成纤维样滑膜细胞增殖,促进其凋亡发挥抗RA效应。