Influence of processing and curing conditions on beads coated with an aqueous dispersion of cellulose acetate phthalate

The influence of fluidized-bed processing conditions, as well as curing parameters with and without humidity, on drug release from beads coated with cellulose acetate phthalate (CAP) aqueous dispersion was investigated. Theophylline beads prepared by extrusion-spheronization were coated with diethyl phthalate (DEP)-plasticized CAP dispersion (Aquacoat CPD) using a Strea-1 fluidized-bed coater. The parameters investigated were plasticizer level, outlet temperature, spray rate during coating application and fluidizing air velocities using a half-factorial design. The processing temperature during coating applications was identified as a critical factor among the variables investigated. The release rate significantly decreased when the beads were coated at 36 degrees C compared to those coated at 48 degrees C (P<0.01). Higher coating efficiencies and better coalescence of films were obtained at the lower coating temperature. Above the minimum film-formation temperature (MFFT), drug release in acid decreased as the coating temperature was decreased. Curing at 60 degrees C significantly reduced the drug release for beads coated at 32 degrees C, but had no significant effect on drug release for beads coated at temperatures above 36 degrees C. Curing at 50 degrees C in an atmosphere containing 75% RH (relative humidity), irreversibly converted poor film formation into better coalescence, and increased the mechanical toughness of films. Subsequent removal of the moisture absorbed from beads did not significantly alter the enteric profiles obtained through heat-humidity curing. The extent of coalescence via heat-humidity curing was dependent on the curing temperature, % humidity, curing time and coating temperature. The results demonstrated the importance of the selection of coating temperature for CAP-coated beads and the role of moisture on CAP film formation. Curing with humidity was found to be more effective than without.

A comparative study into the mechanisms of action of anti-tumor necrosis factor alpha, anti-CD4, and combined anti-tumor necrosis factor alpha/anti-CD4 treatment in early collagen-induced arthritis

OBJECTIVE

Anti-tumor necrosis factor alpha (anti-TNFalpha) therapy is very effective in rheumatoid arthritis (RA), whereas depleting anti-CD4 therapy is relatively ineffective. To explain the differences in efficacy between these 2 therapies, we used an animal model of RA to compare their effects on different aspects of the disease process.

METHODS

Mice with collagen-induced arthritis were treated with depleting anti-CD4 monoclonal antibodies (mAb), anti-TNFalpha mAb, or phosphate buffered saline. Another group was given a combination of anti-TNFalpha plus anti-CD4. The treatments were compared for their ability to down-regulate the expression of proinflammatory cytokines and adhesion molecules, reduce the cellularity of the joint, and inhibit Th1 activity.

RESULTS

Anti-TNFalpha significantly reduced the numbers of cells expressing TNFalpha, interleukin-1beta (IL-1beta), very late activation antigen 4 (VLA-4), vascular cell adhesion molecule 1 (VCAM-1), and numbers of CD4+ T cells and macrophages in the joint. Anti-CD4 treatment led to a small reduction in the expression of TNFalpha, IL-1beta, VLA-4, and VCAM-1, but this did not reach statistical significance. Depleting anti-CD4 was also surprisingly ineffective in eliminating CD4+ T cells from the joint. Anti-TNFalpha therapy was also more effective than anti-CD4 in reducing Thl activity, as assessed by the production of interferon-gamma in lymph node cell cultures. There was a synergistic relationship between anti-TNFalpha and anti-CD4 in the reduction of histologic score and inhibition of TNFalpha/IL-1beta expression in the joints.

CONCLUSION

The efficacy of the 3 treatments correlated with their ability to modulate the expression of inflammatory cytokines and adhesion molecules in the joint, reduce the cellularity of the joint, and inhibit Th1 activity. This kind of analysis may prove useful in the testing of novel therapies for RA.

Study of solubility of steroids in hydrofluoroalkane propellants

The solubility of prednisone, hydrocortisone 21-acetate, hydrocortisone, dexamethasone, betamethasone 17-valerate, and danazol in hydrofluoroalkane (HFA) 134a and HFA 227 was determined at 5 degrees C and 25 degrees C. It was found that the solubility of steroid in HFA propellants was related to the melting point and the lipophilicity of the steroid. The solubility of the steroids in the binary system of HFA propellants and ethanol also was investigated in the study. Ethanol significantly increased the solubility of the steroids in HFA propellant. The magnitude of increase was related to the solubility of the corresponding steroid in ethanol alone.

Combination therapy with DMARDs and biological agents in collagen-induced arthritis

There is increasing interest in the use of combination therapy for rheumatoid arthritis and in the possibility of combining the conventional drug approach with newer biological therapies. Animal models of arthritis provide important tools for evaluating novel forms of therapy and for eludicating mechanisms of drug action. In this paper, we review the results of our own research into combination therapy in collagen-induced arthritis using biological therapies such as anti-tumor necrosis factor alpha, anti-CD4, and anti-interleukin 12 monoclonal antibodies, and small molecular weight compounds such as cyclosporin and the phosphodiesterase IV (PDE IV) inhibitor rolipram.

Application of co-grinding to formulate a model pMDI suspension

The objective of this study was to investigate the effect of co-grinding the model drug, triamcinolone acetonide (TAA), with a polymeric surfactant on the in vitro performance of a model pMDI suspension system. The physicochemical properties of TAA after co-grinding with the surfactant, Pluronic F77, were determined by laser light diffraction, helium pycnometry and equilibrium solubility measurements. TAA-surfactant interaction was investigated by differential scanning calorimetry and Fourier transform infrared spectroscopy (FTIR). The suspension characteristics of pMDI formulations prepared with co-ground TAA and surfactant were investigated by determining their in situ sedimentation, rheological profiles and vapor pressure. The performance characteristics of the pMDI formulations were determined by cascade impaction and dose delivery through-the-valve (DDV) measurements. It was found that the presence of Pluronic F77 decreased the solubility of TAA in the propellant medium. Co-grinding TAA particles with Pluronic F77 influenced the particle size distribution, sedimentation and flocculation characteristics of the pMDI suspension formulation. The addition of Pluronic F77 decreased the viscosity of the pMDI formulation. Formulating the suspension pMDI system with co-ground TAA and Pluronic F77 decreased the mass median aerodynamic diameter (MMAD) of the emitted aerosol and increased the percent respirable fraction (%RF). The co-ground TAA and Pluronic F77 pMDI suspension formulation exhibited greater physical stability which was due to the influence of the co-grinding technique on the physicochemical properties of the TAA particle surface and the propellant dispersion medium. The changes induced by co-grinding with Pluronic F77 improved the performance characteristics of a pMDI suspension formulation by stabilizing the suspension and influencing the flocculation characteristics. Co-grinding is a process which may be useful when developing new pMDI systems containing HFA propellants.

CD44 involvement in experimental collagen-induced arthritis (CIA)

CD44 is a pro-inflammatory cell surface molecule that supports cell migration and cell lodgment in target organs. Therefore, CD44 targeting with specific monoclonal antibodies (mAbs) should be useful for the inhibition of collagen-induced arthritis (CIA) as well as other autoimmune diseases that are dependent on inflammatory cells. In the present paper, we confirm and expand previous reports showing the anti-arthritogenic effect of anti-CD44 mAbs directed against constant epitopes of the CD44 receptor. We demonstrate that such anti-CD44 mAbs can induce resistance to CIA after disease onset. Even accelerated disease developed after two injections of type II collagen was markedly inhibited by IM7.8.1 anti-CD44 mAb. Although KM81 anti-CD44 mAb is a less efficient anti-arthritogenic reagent than IM7.8.1, its Fab' fragments partially inhibit CIA. This finding implies that the antibody blocks CD44 function rather than modulating CD44 cell surface expression or mediating Fc-dependent activities. Histopathological analysis revealed that the anti-CD44 mAb markedly reduces the synovial inflammatory cellular response and the consequent damage to the joint. As CD44 is an alternatively spliced multistructural molecule, similar anti-arthritogenic effects may be achieved by mAbs directed against CD44 isoforms expressed on the pathological cells in question, but not on normal cells, thus leaving the physiological functions intact.

Paradoxical effects of adenovirus-mediated blockade of TNF activity in murine collagen-induced arthritis

Collagen-induced arthritis (CIA) is an experimental model of arthritis widely used to dissect the pathogenesis of human rheumatoid arthritis and to identify potential therapeutic targets. Among these, TNF-alpha has been recognized to play an important role. Here we investigate the feasibility and therapeutic efficacy of prolonged blockade of TNF-alpha activity through the adenovirus-mediated gene delivery of a dimeric chimeric human p55 TNFR-IgG fusion protein and compare it to protein therapy in established CIA. A single i.v. administration of the replication-deficient adenovirus yielded microgram serum levels of the chimeric fusion protein and ameliorated CIA for 10 days. Subsequently, benefit was lost and a rebound to greater inflammatory activity was observed despite the continual presence of bioactive TNFR fusion protein. A similar trend was also observed in mice injected directly with comparable amounts of a human TNFR-IgG fusion protein, whereas the administration of a control adenovirus-encoding beta-galactosidase or of a control human IgG1 protein did not significantly affect the disease course. The mechanisms of the rebound of CIA were investigated, and augmented Ab response to collagen type II and TNFR were identified as potential causes. Our results confirm the feasibility of adenovirus-mediated gene delivery of cytokine inhibitors in animal models of autoimmune diseases for investigational purposes and highlight the importance of prolonged studies. Further investigations are needed to optimize ways of exploiting the potential of adenoviral gene therapy in RA.

The midline dose distribution for a three-field radiotherapy technique

At the University of Florida, head and neck cancer often is irradiated using parallel opposed lateral fields (with inferior borders slanted superiorly) and an anterior low neck field. A common criticism is that overlap may occur at the match-line junction of the three fields, resulting in an increased risk of radiation myelitis. One setup for treatment of the oropharynx and two for the larynx were irradiated in an anthropomorphic head and neck phantom made of tissue-equivalent polyacrylamide gel with a two-dimensional thermoluminescent dosimeter array in its sagittal midplane. The results showed that no excess radiation dose was measured at the junction of the three fields. The "spinal cord dose," as percentage of dose to the central axis of the primary field, was as follows: oropharynx setup, 15% to 100%; larynx setup with midline tracheal block, 10% to 90%; larynx setup without tracheal block, 10% to 90%. In conclusion, the University of Florida three-field technique for head and neck cancer produces no measured increase in dose at field junctions.

Influence of micronization method on the performance of a suspension triamcinolone acetonide pressurized metered-dose inhaler formulation

The purpose of this study was to investigate the influence of micronization technique on performance and stability of the model drug formulated in a suspension-based pressurized metered-dose inhaler (pMDI). The model drug, triamcinolone acetonide (TAA), was subjected to ball milling or air-jet milling prior to formulation of the pMDI. The dose delivery characteristics of the emitted aerosol cloud were monitored for the ball-milled, air-jet-milled, and unmicronized TAA pMDI formulations prior to and after storage at 25 and 40 degrees C. Cascade impaction was used to determine the aerodynamic particle size distribution of the emitted dose. Both micronization techniques reduced the drug particle size distribution and the polydispersity of the drug particles to a similar extent, but the ball-milling technique reduced the crystallinity of the drug to a greater degree compared to the air-jet-milling technique. The air-jet-milled and unmicronized TAA pMDI displayed similar aerodynamic particle size distributions of the emitted aerosol and respirable fractions over the storage period. The ball-milled TAA resulted in a pMDI formulation with the smallest aerodynamically sized particles and the highest respirable fraction compared to the air-jet-milled or unmicronized TAA pMDI formulations. The micronization techniques significantly influenced the dose delivery characteristics as a result of different initial particle size distributions, amorphous contents, and surface energies.

Influence of formulation technique for hydroxypropyl-beta-cyclodextrin on the stability of aspirin in HFA 134a

The objective of this study was to determine the influence of the formulation technique for 2-hydroxypropyl-beta-cyclodextrin (HP beta CD) on the stability of aspirin in a suspension-based pressurized metered-dose inhaler (pMDI) formulation containing a hydrofluoroalkane (HFA) propellant. HP beta CD was formulated in a pMDI as a lyophilized inclusion complex or a physical mixture with aspirin. A pMDI formulation containing aspirin alone was used as the control. The chemical stability of aspirin in each pMDI formulation was determined over 6-months storage at 5, 25 and 40 degrees C. The quantity of water taken up into the pMDI canister was determined by Karl Fisher titration after storage for 6 months. Differential scanning calorimetry (DSC) was used to confirm the formation of a complex between HP beta CD and aspirin. Aspirin in the lyophilized inclusion complex exhibited the most significant degree of degradation during the 6-months storage, while aspirin alone in the pMDI demonstrated a moderate degree of degradation. Aspirin formulated in the physical mixture displayed the least degree of degradation. The water uptake study showed that water ingress occurred to the greatest extent for formulations containing aspirin and HP beta CD physical mixture, and to the least extent for formulations containing aspirin alone. Finally, the DSC study indicated that an inclusion complex was formed in situ in the pMDI formulations containing the HP beta CD and aspirin physical mixture. In conclusion, HP beta CD may be used to enhance the stability of a chemically labile drug, but the drug stability may be affected by the method of preparation of the formulation.

Amelioration of collagen-induced arthritis and suppression of interferon-gamma, interleukin-12, and tumor necrosis factor alpha production by interferon-beta gene therapy

OBJECTIVE

To investigate the therapeutic effects and possible mechanisms of action of constitutive expression of interferon-beta (IFNbeta) by syngeneic fibroblasts from DBA/1 mice in the collagen-induced arthritis (CIA) model.

METHODS

Immortalized embryonic DBA/1 fibroblasts were infected with a retrovirus expressing murine IFNbeta. IFNbeta-expressing fibroblasts were then implanted intraperitoneally into mice immunized with bovine type II collagen. The effect of IFNbeta on paw swelling, anticollagen antibody levels, IgG1/IgG2a isotype profiles, arthritis score, histologic joint damage, and cytokine secretion from lymph node cells and from bone marrow-derived macrophages was assessed.

RESULTS

A single injection of IFNbeta-secreting fibroblasts was sufficient to prevent arthritis or to ameliorate existing disease. Thus, IFNbeta reduced the clinical score and paw swelling irrespective of whether the injection was administered before or after disease onset in treated mice, compared with that in the untreated control group (P < 0.05). Histologic findings in the IFNbeta-treated mice were markedly less severe than in the control group (P < 0.001). This effect was accompanied by a decrease in total anticollagen IgG levels, a decrease in anticollagen IgG2a, and an increase in IgG1. In vitro, supernatants from these engineered fibroblasts inhibited collagen-induced interferon-gamma secretion from lymph node cells, and reduced the levels of tumor necrosis factor alpha and interleukin-12 produced by lipopolysaccharide/IFNgamma-treated bone marrow-derived macrophages. This effect was specific, since it was reversed with anti-IFNbeta polyclonal antibodies.

CONCLUSION

These results indicate that IFNbeta, which is currently used as a treatment for relapsing, remitting multiple sclerosis, is a potent immunomodulatory and antiinflammatory cytokine in CIA and should be considered for the treatment of rheumatoid arthritis.

Formulation of a protein with propellant HFA 134a for aerosol delivery

The purpose of this study was to investigate the formulation and delivery of a protein in a pressurized metered-dose inhaler (pMDI) containing HFA 134a as the propellant for aerosol delivery. Ethanol and surfactants, including polyoxyethylene 10 oleyl ether (Brij 97), polyoxyethylene 20 oleyl ether (Brij 98), polyoxyethylene sorbitan monooleate (Tween 80) and Aerosol OT (AOT), were investigated as formulation adjuvants to improve the dose delivery characteristics of the model protein (bovine serum albumin) containing pMDI formulations. The aqueous solution of a surfactant and protein was lyophilized to obtain a solid carrier system of the protein. Readily dispersible suspensions were obtained by suspending this solid carrier system in HFA 134a with ethanol as a dispersing aid. The formulations containing Tween 80 resulted in the highest respirable fraction. This study suggested a potential formulation containing a lyophilized complex of surfactant and protein readily dispersible in HFA 134a for delivering a therapeutic protein to the respiratory tract by inhalation.

Influence of temperature on the emitted dose of an oral metered dose inhaler

The performance of metered dose inhalers is critical for the efficient delivery of drugs to the intended site of deposition in the respiratory tract. The temperature at which metered dose inhaler products are used by patients may influence the physicochemical characteristics of the emitted dose. Product performance characteristics of a metered dose inhaler containing beclomethasone dipropionate and oleic acid in a blend of chlorofluorocarbon propellants, Freon-11 and Freon-12, were determined by cascade impaction analysis and dose delivery through the valve after the metering chamber was loaded and actuated at 4 degrees C, 23 degrees C, and 40 degrees C. The dose delivered from the valve was not affected by the temperature at which the metering chamber was loaded and actuated. The mass median aerodynamic particle size of the emitted aerosol decreased and the percentage respirable fraction increased as the temperature was increased. The geometric standard deviation of the particle size distribution was not significantly affected by the temperature at which the metering chamber was loaded and actuated. The temperature at which a metered dose inhaler is used by a patient may influence the amount of drug that is potentially respirable; therefore, the dose expected to be delivered and the corresponding therapeutic effect may also be affected.

Characterization of an inclusion complex of cholesterol and hydroxypropyl-beta-cyclodextrin

Interactions between endogenous cholesterol and cyclodextrins have been investigated by several researchers, and they found altered skin penetration of some drugs, membrane disruption, and extraction of cholesterol from the large lipoprotein particles or animal fat. In the present study, an inclusion complex composed of cholesterol and hydroxypropyl-beta-cyclodextrin (HPbetaCD) prepared by lyophilization was investigated and characterized in order to confirm these interactions. Five grams of cholesterol were dispersed in 50 ml of 73.2 mM HPbetaCD aqueous solution, mixed for 2 days, and the filtrate lyophilized. A phase solubility study was performed by mixing an excess amount of cholesterol with an aqueous solution containing increasing amounts of HPbetaCD. The amount of cholesterol in solution after mixing for 2 days at 25 degrees C was determined by HPLC. The inclusion complex was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry, and differential scanning calorimetry (DSC). An Ap-type Higuchi phase solubility diagram, DSC, FTIR, and X-ray diffraction demonstrated the formation of an inclusion complex. DSC thermograms indicated that the endothermic peaks of cholesterol and physical mixture of cholesterol with HPbetaCD due to the fusion of drug crystals, were absent in DSC thermograms obtained on the freeze dried inclusion complex. FTIR spectra indicated that some of the absorption peaks in the lyophilized inclusion complex were different from that of the physical mixture of cholesterol and HPbetaCD. X-ray diffraction patterns showed that the pure cholesterol and a physical mixture of cholesterol and HPbetaCD exhibited crystalline characteristics whereas the lyophilized inclusion complex and HPbetaCD displayed amorphous characteristics. The results indicated that the formation of a cholesterol/HPbetaCD inclusion complex is more water soluble than cholesterol alone.

Therapeutic actions of cyclosporine and anti-tumor necrosis factor alpha in collagen-induced arthritis and the effect of combination therapy

OBJECTIVE

To define the mechanisms of action of 2 novel drugs, cyclosporine and anti-tumor necrosis factor alpha (TNFalpha), in collagen-induced arthritis and to determine the effect of combination therapy.

METHODS

Type II collagen-immunized DBA/1 mice with established arthritis were treated with cyclosporine alone, anti-TNFalpha alone, cyclosporine plus anti-TNFalpha, or saline.

RESULTS

Cyclosporine was found to ameliorate arthritis, suppress interferon-gamma (IFNgamma) production by CD4+ T cells, and reduce TNFalpha expression in arthritic joints. However, cyclosporine did not directly inhibit TNFalpha production by macrophages, indicating that the decrease in TNFalpha expression observed in vivo was probably an indirect consequence of the reduction in type 1 T helper cell activity. Anti-TNFalpha also reduced IFNgamma production by T cells, indicating that TNFalpha is involved in the cellular immune response to collagen. Combined treatment with cyclosporine plus anti-TNFalpha had an additive therapeutic effect.

CONCLUSION

Although cyclosporine and anti-TNFalpha target different points in the inflammatory pathway, there is an overlap in the consequences of their actions in vivo.

Influence of propellant composition on drug delivery from a pressurized metered-dose inhaler

Hydrofluoroalkanes (HFAs) are used to replace chlorofluorocarbons (CFCs) as non-ozone-depleting propellants for pressurized metered-dose inhalers (pMDIs). HFA 134a and HFA 227 are used in combination to precisely manipulate the density and vapor pressure of pMDI formulations. The influence of propellant composition on the dose delivery characteristics of a suspension-based pMDI formulation was investigated. The results showed that as the density of the propellant blends approached the density of the suspended drug particles, the formulation became more physically stable and exhibited the most consistent dose delivery and greatest respirable fraction. The mass median aerodynamic diameter of the aerosolized particles contained in the emitted dose also was decreased by using propellant blends with higher vapor pressures. The performance of a suspension-based pMDI formulation was optimized by varying the propellant composition using HFA 134a and HFA 227.

Suppression of TNF-alpha expression, inhibition of Th1 activity, and amelioration of collagen-induced arthritis by rolipram

Rolipram is a type IV phosphodiesterase inhibitor that suppresses inflammation and TNF-alpha production. As anti-TNF-alpha therapy is effective in rheumatoid arthritis, we investigated the effect of rolipram on collagen-induced arthritis (CIA), a murine model of rheumatoid arthritis. Rolipram was administered after the onset of clinical arthritis at doses of 0.5, 3, 5, or 10 mg/kg twice daily, with a dose-dependent therapeutic effect on clinical severity and joint erosion. Immunohistochemical analysis of joints of rolipram-treated mice revealed 67% reduction in TNF-alpha-expressing cells compared with control arthritic mice. In vitro studies using bone marrow-derived macrophages confirmed that rolipram directly suppressed TNF-alpha and IL-12 production following stimulation with IFN-gamma and LPS. The effect of rolipram on T cell activity was studied by measuring Th1/Th2 cytokine production by collagen-stimulated draining lymph node cells from arthritic mice treated in vivo with rolipram. Rolipram reduced IFN-gamma production and increased IL-10, indicating that rolipram down-regulated the ongoing Th1 response to type II collagen. Finally, the effect on CIA of combination therapy was studied using rolipram plus either anti-TNF-alpha or anti-CD4 mAbs. Rolipram plus anti-TNF-alpha was not therapeutically additive, whereas rolipram plus anti-CD4 mAb was clearly additive. This result indicates that the therapeutic effects of rolipram overlap with TNF-alpha blockade, but are complementary to anti-CD4 treatment. It is therefore proposed that a major mechanism of action of rolipram in CIA is suppression of TNF-alpha activity. These findings suggest that type IV phosphodiesterase inhibitors may be effective in pathologic conditions, such as RA, with overexpression of TNF-alpha.

Suppression of TNF-alpha expression, inhibition of Th1 activity, and amelioration of collagen-induced arthritis by rolipram

Rolipram is a type IV phosphodiesterase inhibitor that suppresses inflammation and TNF-alpha production. As anti-TNF-alpha therapy is effective in rheumatoid arthritis, we investigated the effect of rolipram on collagen-induced arthritis (CIA), a murine model of rheumatoid arthritis. Rolipram was administered after the onset of clinical arthritis at doses of 0.5, 3, 5, or 10 mg/kg twice daily, with a dose-dependent therapeutic effect on clinical severity and joint erosion. Immunohistochemical analysis of joints of rolipram-treated mice revealed 67% reduction in TNF-alpha-expressing cells compared with control arthritic mice. In vitro studies using bone marrow-derived macrophages confirmed that rolipram directly suppressed TNF-alpha and IL-12 production following stimulation with IFN-gamma and LPS. The effect of rolipram on T cell activity was studied by measuring Th1/Th2 cytokine production by collagen-stimulated draining lymph node cells from arthritic mice treated in vivo with rolipram. Rolipram reduced IFN-gamma production and increased IL-10, indicating that rolipram down-regulated the ongoing Th1 response to type II collagen. Finally, the effect on CIA of combination therapy was studied using rolipram plus either anti-TNF-alpha or anti-CD4 mAbs. Rolipram plus anti-TNF-alpha was not therapeutically additive, whereas rolipram plus anti-CD4 mAb was clearly additive. This result indicates that the therapeutic effects of rolipram overlap with TNF-alpha blockade, but are complementary to anti-CD4 treatment. It is therefore proposed that a major mechanism of action of rolipram in CIA is suppression of TNF-alpha activity. These findings suggest that type IV phosphodiesterase inhibitors may be effective in pathologic conditions, such as RA, with overexpression of TNF-alpha.

Suppression of collagen-induced arthritis by continuous administration of IL-4

The onset of collagen-induced arthritis in DBA/1 mice is accompanied by a predominantly Th1 response, characterized by production of the proinflammatory cytokines IFN-gamma and TNF-alpha, and a predominance of IgG2a anti-collagen Abs. This study has primarily addressed the effects of continuous administration of exogenous IL-4, a Th2 cytokine, on collagen-induced arthritis in terms of time of onset, clinical symptoms, and histologic changes compared with those in untreated controls. The contributions of Th1 and Th2 cell responses were studied by examining anti-CII IgG subclasses, serum IgE levels, and cytokine production by synovial membrane and lymph node cell cultures. Continuous exposure to IL-4 for 28 days significantly delayed the onset of arthritis from 19 to 37 days and suppressed clinical symptoms. Arthritis occurred approximately 13 to 24 days after treatment ceased. Thereafter, the severity and duration of clinical symptoms were similar to those in control animals, although both joint damage and inflammation at the histologic and cellular levels were less severe than those in untreated controls. During IL-4 treatment, anti-collagen Ab levels were reduced (most significantly those of the IgG2a subclass), histology scores were lower, and the most striking effect was a 1000-fold decrease in TNF-alpha secretion by synovial cells. No significant differences in IgE levels were found between controls and IL-4-treated mice. These data suggest that the anti-inflammatory properties of IL-4 are mediated in part by down-regulation of Th1 responses rather than up-regulation of Th2 responses.

Suppression of collagen-induced arthritis by continuous administration of IL-4

The onset of collagen-induced arthritis in DBA/1 mice is accompanied by a predominantly Th1 response, characterized by production of the proinflammatory cytokines IFN-gamma and TNF-alpha, and a predominance of IgG2a anti-collagen Abs. This study has primarily addressed the effects of continuous administration of exogenous IL-4, a Th2 cytokine, on collagen-induced arthritis in terms of time of onset, clinical symptoms, and histologic changes compared with those in untreated controls. The contributions of Th1 and Th2 cell responses were studied by examining anti-CII IgG subclasses, serum IgE levels, and cytokine production by synovial membrane and lymph node cell cultures. Continuous exposure to IL-4 for 28 days significantly delayed the onset of arthritis from 19 to 37 days and suppressed clinical symptoms. Arthritis occurred approximately 13 to 24 days after treatment ceased. Thereafter, the severity and duration of clinical symptoms were similar to those in control animals, although both joint damage and inflammation at the histologic and cellular levels were less severe than those in untreated controls. During IL-4 treatment, anti-collagen Ab levels were reduced (most significantly those of the IgG2a subclass), histology scores were lower, and the most striking effect was a 1000-fold decrease in TNF-alpha secretion by synovial cells. No significant differences in IgE levels were found between controls and IL-4-treated mice. These data suggest that the anti-inflammatory properties of IL-4 are mediated in part by down-regulation of Th1 responses rather than up-regulation of Th2 responses.

Determination of diazolidinyl urea in a topical cream by high-performance liquid chromatography

A high-performance liquid chromatographic method for the determination of diazolidinyl urea (DU) in a cream formulation is described. The aqueous phase of the emulsion was separated by centrifugation, removed, filtered, diluted and applied onto the HPLC system. DU was detected by ultraviolet absorption at a wavelength of 214 nm. The calibration curve was linear over the range of 79-553 micrograms/ml, and identical when determined on consecutive days. The relative standard deviation for repeat determinations was less than 0.5%. Recoveries were 97.74-101.72%. This analytical method is useful for quantitation of DU in cream formulations.

Influence of metering chamber volume and water level on the emitted dose of a suspension-based pMDI containing propellant 134a

PURPOSE

To determine the influence of metering chamber volume of a valve and water content of an aerosol formulation containing propellant 134a on dose delivery through the valve (DDV) and aerodynamic particle size distribution of the emitted dose.

METHODS

The drug was admixed with ethanol, sonicated, and metered into cans. Valois DF10 RC valves were crimped onto the cans and propellant 134a was gassed through the valve. The DDV was determined using a dosage sampling tube. Aerodynamic particle size distributions were determined by cascade impaction. The water content was determined by Karl Fisher titration.

RESULTS

The DDV increased linearly and the aerodynamic particle size distribution was not influenced as the metering chamber volume of the valve was increased. More drug was emitted from the valve from the initial actuations of the can than from the end. Valves with larger metering chamber volumes demonstrated less variability in DDV than those with smaller metering chamber volumes for the initial actuations. The DDV determined for actuations at the end of the can decreased as water was added extemporaneously. The mass median aerodynamic diameter (MMAD) increased as the water level was increased in the formulation. The geometric standard deviation (GSD) and percent respirable fraction (RF) were not influenced by metering chamber volume or water content.

CONCLUSIONS

The valve chosen for the development of pressurized metered dose inhaler (pMDI) formulations with propellant HFA 134a must be investigated to determine the uniformity of drug delivery. The presence of water influences the characteristics of the emitted dose.

TNF blockade in rheumatoid arthritis: implications for therapy and pathogenesis

The role of the immune response in rheumatoid arthritis (RA) is a subject of debate, although it is widely believed to be a T-cell-driven disease. Progress is being hindered by lack of convincing evidence of a defined specific antigen initiating or perpetuating the response. Clinical trials using monoclonal antibodies directed against T-cell surface molecules such as CD4. CD5, and CD7 have thus far not provided evidence of efficacy. The negative data may reflect inadequate dosing or could suggest that indiscriminate depletion of T cells is insufficient by itself as a therapeutic strategy. Blocking proinflammatory cytokines (e.g. TNF alpha, IL-1) or augmenting anti-inflammatory cytokines (e.g. IL-10) offers an alternative approach to therapy. Clinical trials using monoclonal anti-TNF alpha have been particularly successful in controlling inflammation and markedly reducing acute phase proteins and cellular ingress. However, because disease invariably relapses, repeated therapy is necessary. Preliminary experience suggests that this is possible. Anti-TNF therapy for RA has defined a molecular target and new approach for treating immuno-inflammatory disorders.