Auranofin-induced suppression of autoimmune antibody production and inflammation in genetically autoimmune-prone mice

The gold compound auranofin and lobenzarit (CCA) were compared in regard to effects on development of an autoimmune-like disease in MRL/1 mice, which normally develop elevated levels of serum anti-DNA antibodies and rheumatoid factor as well as joint lesions similar to those seen in patients with rheumatoid arthritis. MRL/1 mice, which are genetically prone to development of autoimmune disease, were given auranofin or lobenzarit by gavage for 15 weeks, starting at 6 weeks of age. Mice were examined periodically for immunological abnormalities as well as histologic changes in articular joints. The auranofin-treated mice showed marked diminution in development of anti-DNA antibodies and serum rheumatoid factor as compared to control animals. Although higher than in the auranofin-treated animals, CCA-treated mice also had lower levels of serum autoantibodies than those seen in the control animals. Examination of limb joints for histopathologic changes indicated that the auranofin-treated animals developed only the slightest evidence of lesions as compared to control animals. CCA-treated mice also had a lessening of lesion development compared to control animals, but lesions were more developed than in auranofin-treated mice. This study indicates that auranofin is more effective than CCA in diminishing development of autoimmunity in MRL/1 mice.

5,6-Diaryl-2,3-dihydroimidazo[2,1-b]thiazoles: a new class of immunoregulatory antiinflammatory agents

A series of substituted 5,6-diaryl-2,3-dihydroimidazo[2,1-b]thiazoles were synthesized and evaluated in the rat adjuvant-induced arthritis and mouse oxazolone-induced contact sensitivity assays to determine the potential of these compounds for use as immunoregulatory antiinflammatory agents. This class of compounds was derived by combining salient structural features of the antiinflammatory agent flumizole and the immunoregulatory drug levamisole. Unlike the latter two, a number of compounds in the target series were found to possess the desired combination of activities. Exploration of structure-activity relationships in the adjuvant-induced arthritic rat assay revealed that optimal potency was exhibited by symmetrically substituted 5,6-diaryl compounds having one of the following alkyl heteroatom or halogen functions at the para position: methoxy, ethoxy, methylthio, N-ethyl-N-methylamino, fluoro, or chloro. Scrambling of these two substituent classes to yield the asymmetrically substituted 5,6-diaryl compounds resulted in potent activity only with the 5-alkyl heteroatom, 6-halo-substituted regioisomers. However in the oxazolone-induced contact sensitivity assay, no consistent relationship of variation in activity with structural change was apparent. The initial target compound 5,6-bis(4-methoxyphenyl)-2,3-dihydroimidazo[2,1-b]thiazole (1) was compared with its progenitors in additional models of inflammation and immunoregulation.

Antiinflammatory activity of 5,6-diaryl-2,3-dihydroimidazo[2,1-b]thiazoles. Isomeric 4-pyridyl and 4-substituted phenyl derivatives

Isomeric 5(6)-(4-pyridyl)- and 6(5)-(4-substituted-phenyl)-2,3-dihydroimidazo[2,1-b]thiazoles were prepared by a mixed benzoin-imidazothione route, and their structures were assigned by spectral comparison to compounds of established substitution pattern. The structural assignment was confirmed by X-ray analysis. Examination of the compounds for antiinflammatory activity by an adjuvant arthritic rat assay revealed strikingly higher potencies for one analogous series than for their isomers. This selectivity was paralleled in the ability to stimulate cell-mediated immunity, as reflected in an oxazolone-induced contact sensitivity model. A drug-receptor complex is proposed that requires at least three sites of interactions.

Biologic actions and pharmacokinetic studies of auranofin

The preclinical profiles of auranofin (Ridaura), an oral chrysotherapeutic agent, parenteral gold sodium thiomalate, gold thioglucose, and their respective ligands were compared. Auranofin was more effective than gold sodium thiomalate in suppressing inflammation and stimulating cell-mediated immunity. In contrast to gold sodium thiomalate and gold thioglucose, auranofin inhibited cellular release of lysosomal enzymes, antibody-dependent cellular cytotoxicity, production of antibodies in adjuvant arthritic rats, and antibodies involved in cytotoxicity reactions. The respective ligands were without significant biologic activity. In rats, a higher fraction of gold was associated with blood cells after auranofin administration than after gold sodium thiomalate. The absorption, distribution, metabolism, and excretion of auranofin are uniquely different from other gold compounds.

Superoxide radical production by human leukocytes exposed to immune complexes: inhibitory action of gold compounds

Superoxide radicals produced by phagocytic cells are considered to be important mediators in the rheumatoid inflammation. The effect of the gold compounds auranofin (AF) and gold sodium thiomalate (GST) on superoxide production by human leukocytes was investigated in two models of immunologic injury: immune-complex phagocytosis and frustrated phagocytosis. In both systems, AF (0.5-1.0 micrograms Au/ml) showed a potent inhibitory activity on superoxide generation, quantitated by ferricytochrome c and NBT reduction. GST showed only modest inhibition at higher concentrations (100 microM). The thiol protecting agent dithiothreitol, 1 mM, completely blocks the inhibitory effect of AF. The inhibition of the oxy radical generation by AF may play an important role in the control of rheumatoid inflammation; it is suggested that this action might be mediated through sulfhydryl-AF interaction at the cellular membrane level.

Distribution of gold in rat blood after intravenous administration of auranofin, gold sodium thiomalate and aurothioglucose to rats

Serum, blood and cell-associated gold were determined at various time periods after intravenous administration of 1 mg Au/kg of auranofin (AF), gold sodium thiomalate (GSTM) and aurothioglucose (GTG). AF gold exhibited an early phase of decay with high levels of cell-association; whereas, after 72 h cell-associated gold was not detectable. In contrast, GSTM and GTG serum gold values were generally higher than blood values since cell-associated gold rarely occurred. These observations suggest that, in contrast to GSTM and GTG, intravenous administration of AF results in a dynamic equilibrium of gold between the cellular and serum compartments of blood.

The pharmacological profile of auranofin, an orally active gold compound

Auranofin (AF; ' Ridaura '), an oral chrysotherapeutic agent, parenteral gold sodium thiomalate (GST) and gold thioglucose (GTG) were evaluated in order to compare their preclinical profiles. AF was found to be more effective than GST and GTG in suppressing inflammation and stimulating cell-mediated immunity. In contrast to GST, AF inhibited cellular release of lysosomal enzymes, antibody-dependent cellular cytotoxicity, production of antibodies in adjuvant arthritic rats, and antibodies involved in cytotoxicity reactions. In pharmacokinetic studies, plasma gold in rats following AF administration, exhibited greater cell association than after GST administration. In conclusion, the pharmacological profile of AF is markedly different from those of GST and GTG and this suggests potential for improvements in chrysotherapy.

Comparative pharmacology and biological effects of different gold compounds

Auranofin's (AF) physical, chemical, pharmacological, and pharmacokinetic properties differ from those of gold sodium thiomalate (GSTM). AF is lipid soluble, monomeric, nonconductive and is not a potent sulfhydryl reagent. In further contrast to GSTM, AF gold is orally absorbed, exhibits protracted blood levels, is bound to cellular elements of the blood, excreted mainly in the feces, and exhibits less tissue retention. AF is more effective in acute inflammatory models and is a potent inhibitor of lysosomal enzyme release, antibody-dependent cellular cytotoxicity, and superoxide production. AF can suppress antibodies produced in adjuvant arthritic rats and those involved in cytotoxicity reactions; whereas, GSTM is ineffective or immunoenhancing. AF is more effective in stimulating abnormalized cell-mediated immunity. In conclusion, AF is a unique oral chrysotherapeutic agent which can affect cellular and immunopathological events involved in the perpetuation of inflammation and tissue damage.

Pharmacokinetics of auranofin in animals

Gold from orally administered auranofin (AF) was absorbed 17-23% in rats and 15-38% in dogs. Gold was highly bound to blood cells and plasma proteins. Gold terminal half life was 1.2-1.8 days in rat blood and plasma (measured for 7 days post dose) and 19.5 days in the dog (measured for 42 days). Excretion of gold (rat and dog) was via feces (84 and 81%) urine (10 and 16%) and bile (3% of dose). Rat tissue levels of gold were highest in the kidney. Evidence indicated that AF was rapidly degraded to triethylphosphine oxide with the remaining molecular fragments postulated to be a protein-gold complex and acetylthioglucose.

Mechanisms of action of auranofin: effects on humoral immune response

Auranofin (AF) and gold sodium thiomalate (GSTM) were evaluated in antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent antibody responses. AF decreased the ability of immune sera to participate in ADCC, whereas GSTM did not. Immune serum from AF-treated rats also exhibited a decreased antibody-dependent complement lysis (ADCL) reactivity. In contrast, immune sera from GSTM-treated rats enhanced ADCL. AF also suppressed '7S' hemagglutinin antibody response to sheep red blood cells in adjuvant arthritic rats, whereas neither GSTM nor gold sodium thioglucose significantly suppressed hemagglutinin antibody titers at doses which produced antiinflammatory activity.

Augmentation of concanavalin A-induced immunosuppression by indomethacin

These studies show that, in BALB/C mice, when antibody synthesis against sheep red blood cells is suppressed by concanavalin A, treatment with indomethacin (4-8 mg/kg per os) will augment this suppression. Two other nonsteroidal anti-inflammatory drugs, flufenamic acid and meclofenamic acid (50 mg/kg), also have this effect, whereas phenylbutazone was inactive at this dose. The augmentation of concanavalin A-induced immunosuppression by indomethacin could not be demonstrated on the response to the T-independent antigen polyvinypyrrolidone. In contrast to indomethacin, which inhibits cyclooxygenase, neither nordihydroguaiaretic acid, an inhibitor of the lipoxygenase pathway, nor eicosa-5,8,11,14-tetraynoic acid, an inhibitor of both the cyclooxygenase and the lipoxygenase pathways, had this augmenting effect. Therefore, we do not have strong evidence that the absence of a prostaglandin is responsible for the effect of indomethacin. However, inhibition of the pathway leading to prostaglandin synthesis causes an increase in arachidonic acid metabolism via the lipoxygenase pathway. A product of this pathway, such as a leukotriene, may have immunosuppressive effects in this model. Evidence for the enhancement of a suppressor cell population is provided by an in vitro coculture assay. Cells treated with concanavalin A and indomethacin had more suppressive activity than cells treated with concanavalin A or indomethacin alone.

Effect of selected immunoregulatory agents on low-grade contact sensitivity

The effect of selected compounds with known immunoregulatory activity was examined in a 45-h sensitization period oxazolone contact-sensitivity reaction. Oxazolone sensitivity was induced by applying 0.1 ml of 5% oxazolone in absolute ethanol to the shaved abdomen of C57Bl/6 mice on day 0. Challenge with oxazolone followed 45 h later and was accomplished by painting a 5% solution of oxazolone in absolute ethanol on the left hindpaw. The response at 24 h was determined plethysmographically. Histamine (0.062-1.0 mg/kg, subcutaneously, twice a day), concanavalin A (0.31-5.0 mg/kg intravenously), penicillamine (6.25-25 mg/kg, subcutaneously), chloroquine (6.25-25 mg/kg, subcutaneously), and thymosin fraction 5 (0.125-1.25 mg/kg subcutaneously) all stimulated the oxazolone reaction when administered on day 0. These data suggest that the low-grade oxazolone response may be a useful assay to detect immunostimulatory activity.

Studies of the effect of auranofin, a new antiarthritic agent, on platelet aggregation

Auranofin (AF), at a concentration of 10 micrograms/ml, was found to be a potent inhibitor of ADP-, epinephrine-, or collagen-induced platelet aggregation utilizing platelet-rich plasma obtained from human blood. In contrast, aurothioglucose was less effective than AF in inhibiting epinephrine- or collagen- induced platelet aggregation. The inhibitory effect of AF was more evident on the second phase of aggregation. The inhibitory effect of AF was more evident on the second phase of aggregation and was a function of drug preincubation time. Compared to platelet-rich plasma, washed platelets were superior for detecting the inhibitory action of AF (greater than or equal to 0.1 microgram/ml) on ADP-induced platelet aggregation. This potent inhibitory action of AF on ADP-induced platelet aggregation was antagonized by dithioerythriol, a potent reducing agent. These results suggest that AF can inhibit both platelet release and aggregation mechanisms which may be relevant to its antiarthritic activity. Further studies are required to elucidate the cellular mechanism by which AF inhibits platelet aggregation.

Stimulation of contact sensitivity to oxazolone by disodium cromoglycate

The subcutaneous administration of 0.01-10 mg/kg of the antiallergic agent disodium cromoglycate on day 0 30 min prior to sensitization of C57Bl/6 male mice with 5% 2-phenyl-4-ethoxy-methylene oxazolone proved to cause a significant stimulation of the low-grade volume response as measured plethysmographically in 24 h after challenge. The investigation of the mechanism favors the conclusion that histamine release is involved in the action of disodium cromoglycate as judged by the ability of the antihistaminics chlorpheniramine and metiamide to inhibit the disodium cromoglycate action and by the inhibitory effect of polymyxin B induced depletion of histamine.

Effect of auranofin dose regimen change upon cell-associated gold in rheumatoid arthritic patients

We examined whether changes in auranofin dose regimen in rheumatoid arthritis (RA) patients affect cell-associated and/or serum gold levels. In 7 RA patients, a reduction in daily dosage of auranofin from 3 mg bid to 3 mg qd was correlated with a marked reduction (81%-95%) in cell-associated gold, whereas a return to the 3 mg bid dose level resulted in a reinstatement of cell-associated gold. These changes in cell-associated gold were not reflected in alterations of serum gold levels. This apparent lack of change in serum gold level as opposed to cell-associated gold suggests that this phenomenon warrants further investigation.

Pharmacokinetics of gold following administration of auranofin (SK+FD-39162) and myochrysine to rats

Auranofin orally administered to rats resulted in delayed and protracted peak blood and serum gold levels occurring 24 to 48 h post administration. During this period, the gold concentration in blood was higher than in serum indicating that a major portion of gold was associated with the cellular components. During 1st order elimination (greater than 48 h), the blood/serum gold ratio decreased which suggested dissociation of cellular gold. Biliary cannulation experiments demonstrated that the protracted gold levels (24 to 48 h) could not be due to hepatic recirculation. In contrast to auranofin, gold sodium thiomalate produced blood gold levels which peaked within 3 h, rapidly declined and were consistently lower than serum gold levels.

Effect of auranofin on antibody-dependent cellular cytotoxicity (ADCC) mediated by rat peripheral blood polymorphonuclear leukocytes and mononuclear cells

Auranofin and other clinically used gold compounds were evaluated in vitro for effects on antibody-dependent cellular cytotoxicity (ADCC) of L929 fibroblast target cells mediated by adjuvant rat peripheral blood PMNs or mononuclear cells. Auranofin (10 microM) was found to be a potent inhibitor of PMNADCC. In contrast, gold sodium thiomalate (10-100 microM), gold thioglucose (10-1000 microM), and nongold substructures of auranofin (10 microM) were not inhibitory.. In continuous culture, gold sodium thiomalate and relatively low concentrations of auranofin (smaller than or equal to microM) significantly enhanced PMNADCC. Results of pretreatment studies indicate that auranofin's inhibitory activity of PMNADCC is caused by a noncytotoxic effect on PMN function which is not associated with alteration of PMN-target cell contact. In contrast to its inhibitory activity on PMNADCC, auranofin pretreatment of mononuclear cells resulted in enhanced target cell destruction which appeared to correlate with increased mononuclear cell-target cell contact.

Studies of the intestinal metabolism of oral gold

In order to understand some of the unique toxic/therapeutic properties of the orally administered gold containing compound auranofin, the intestinal metabolism of gold was studied in 4 normal subjects. A triple lumen intestinal perfusion apparatus was used to measure intestinal flux using a non-absorbable radiolabelled marker dilution technique. Over a short (50 cm) segment of proximal small bowel, substantial disappearance of gold was observed; the findings, however, were most consistent with a loose, reversible adsorption onto the enteric cell surface rather than true trans-mucosal absorption. There was no evidence for an entero-hepatic recirculation of gold in these subjects or in 4 additional patients with rheumatoid arthritis studied in a similar manner.

Oral chrysotherapy in rheumatoid arthritis: minimum effective dose

We studied the dose-response to a new oral gold compound in 28 patients with definite rheumatoid arthritis, divided in 4 groups of 7 patients, each treated with different doses of auranofin for 3 months. Clinical and laboratory parameters were recorded weekly, and blood gold levels (BGL) measured by atomic absorption spectroscopy. Six and 9 mg daily doses of auranofin were most effective based on clinical and laboratory results. Correlation studies between BGL and percent decrease of humoral measurements, within the 3 months were statistically were statistically significant. Mean BGL, associated with clinical improvement, reached 0.73 microgram/ml, and was accompanied by a 17.6% decrease from initial value of IgG, 17.1% of alpha 2-globulin, 48.9% of RF titer and 25.9% of ESR.

Distribution in normal and inflammatory tissue of a new semisynthetic cephalosporin, SK&F 75073

SK&F 75073 is a new cephalosporin with broad spectrum antibacterial activity. SK&F 75073-14C and cefazolin-35S were administered separately to groups of rats as a single intramuscular dose of 20 mg/kg. Tissues with highest drug levels 15 minutes following dose were as follows: (SK&F 75073/cefazolin levels), kidney - 86/70 microgram/g, liver - 33/22 microgram/g, lung - 29/17 microgram/g, heart - 23/10 microgram/g, adrenal - 13/7 microgram/g. Plasma levels at peak were 134 microgram SK&F 75073/ml (half-life, 1.9 hours) and 72 microgram cefazolin/ml (half-life, 0.75 hours). Dose excreted in 24 hours was: SK&F 75073, urine 66% and feces 27%; cefazolin, urine 96% and feces 2%. Both antibiotics were also administered, at 20 mg/kg, to rats with the carrageenan-induced inflammatory pouches. Exudate from these pouches contained from 2 to 10 times more SK&F 75073 than cefazolin. Radioassay and bioassay of these substances in the exudate gave similar results. Serum protein binding ranged from 96 approximately 98% for SK&F 75073 and 34 approximately 69% for cefazolin. Data indicated that highly protein bound SK&F 75073 enters tissues and tissue fluid to a greater extent than the lesser bound but therapeutically proven antibiotic agent cefazolin.

Immunopharmacology of gold sodium thiomalate and auranofin (SK&F D-39162): effects on cell-mediated immunity

The effects of gold sodium thiomalate (GST) and auranofin (SK&F D-39162) on cell-mediated immunity were investigated using oxazolone-induced contact sensitivity and delayed hypersensitivity to sheep red blood cells. C57Bl mice were sensitized to oxazolone on day 0 and challenged either 45 or 72 h later. The resulting paw edema was read plethysmographically 24 h after challenge. GST and auranofin both were capable of stimulating oxazollone-induced contact sensitivity which was compromised by using a shortened sensitization period (45 h). Auranofin but not GST stimulated the response to oxazolone in immunosuppressed mice, but neither agent significantly altered the uncompromised response in normal mice. The stimulatory effect of auranofin and GST on cell-mediated immunity was corroborated using SRBC to induce delayed hypersensitivity. Comparison of blood Au levels revealed that gold in the form of auranofin was approximately 4x more effective in stimulating cell-mediated immunity than was gold in the form of GST. These results were suggested to be due to the possible stimulation by gold of T effector as well as T suppressor lymphocytes, thus explaining the condition dependency of the immunoregulation.

Restoration of methotrexate-suppressed oxazolone-induced contact sensitivity with levamisole

The effect of levamisole upon cell-mediated immunity was investigated using the oxazolone-induced contact sensitivity response in immunosuppressed and nonimmunosuppressed C57Bl male mice. Mice were sensitized to oxazolone on day 0, and where appropriate, methotrexate (1 mg/kg, p.o.) was administered on days 1 and 2. On day 3, levamisole (5--50 mg/kg, p.o., base) was administered. One hour later, the animals were challenged with oxazolone on the left hindpaw. Twenty-four hours after challenge, the resulting edema was read plethysmographically. Levamisole, in the absence of immunosuppression, had no significant effect upon the oxazolone response whereas, in the face of immunosuppression, restoration of oxazolone responsiveness was observed. These results were suggested to be due to (1) the ability of levamisole to stimulate opposing suppressor and effector components of the oxazolone response coupled with (2) an apparent alteration of suppressor influence by methotrexate allowing levamisole to enhance an unencumbered effector cell population.

Condition-dependent immunoregulatory control of contact sensitivity by levamisole

The immunostimulatory activity of levamisole [1-(-),2,3,5,6-tetrahydro-6-phenylimidazo(2,1-beta)-thiazole] was investigated using oxazolone-induced contact sensitivity in C57Bl mice. Oxazolone sensitivity was induced by applying 0.1 ml of 3 or 5% oxazolone in ethanol to the shaved abdomen (day 0). Challenge with oxazolone followed on day 2 (45 h) or day 3, and was accomplished by painting a 1--5% solution of oxazolone in ethanol to the left hind paw. The response at 24 h was determined plethysmographically. Levamisole (50 mg/kg, p.o., days 0--3 or day 0 only) failed to stimulate consistently the oxazolone response in a 3-day (minimal) sensitization period regimen. Use of a subliminal (45 h) sensitization, by contrast, revealed a consistent immunostimulatory effect of levamisole (12.5--100 mg/kg, p.o., day 0 only). It is speculated that the observed difference in levamisole effectiveness is attributable to (1) the ability of levamisole to stimulate both effector and suppressor mechanisms, and (2) the apparent absence of significant suppressor influence at 2-day postsensitization, leaving only the effector mechanism to be stimulated by levamisole.

Inhibition of lysosomal enzyme release from rat leukocytes by auranofin. A new chrysotherapeutic agent

Auranofin (SK&F D-39162), a new antiarthritic gold compound reported to be orally effective in animal (adjuvant rat) and human (rheumatoid) arthritic conditions, is a potent in vitro inhibitor of the release of lysosomal enzymes from phagocytizing rat leukocytes. Auranofin, at micromolar concentrations (1-10 microM), produced a dose-dependent reduction in extracellular levels of lysosomal enzyme markers (beta-glucuronidase and lysozyme) which are selectively released from rat leukocytes during phagocytosis of zymosan particles. The reduction in extracellular levels of lysosomal enzymes appears to be caused by inhibition of their selective cellular release, since effective concentrations of auranofin did not produce leukocyte cytotoxicity or inhibition of cell-free lysosomal enzyme activity. Morphologic and biochemical evidence indicated that auranofin also interferes with phagocytosis of zymosan particles. The potent in vitro activity of auranofin appears to result from its unique gold complex, since neither structurally related nongold compounds nor clinically used gold compounds (gold sodium thiomalate and gold thioglucose) were potent inhibitors of lysosomal enzyme release. The results of this investigation suggest that the antiarthritic activity of auranofin may be caused at least in part, by inhibition of lysosomal enzyme release and/or cellular processing of antigens.

Effect of auranofin, a new antiarthritic agent, on immune complex-induced release of lysosomal enzymes from human leukocytes

Auranofin, an oral chrysotherapeutic agent effective in the treatment of rheumatoid arthritis (RA), was found to be a potent, noncytotoxic inhibitor of IgG-RF immune complex-induced lysosomal enzyme release (LER) from human leukocytes. At a concentration of 1 microg Au/ml (5 microM), auranofin produced a marked reduction in beta-glucuronidase (100%), acid phosphatase (88%), and lysozyme (72%) release. In contrast, gold sodium thiosulfate (GST, an injectable gold compound) had no inhibitory activity on LER at equivalent gold concentrations (i.e., 1 microg Au/ml) and only modest activity (less than 36% inhibition) at concentrations as high as 40 microg Au/ml. The 50% inhibitory dose (LD50) of auranofin on LER was calculated to be 3-4 microM (0.6-0.8 microg Au/ml). Blood gold levels in auranofin-treated RA patients were found to be within the range required for in vitro inhibition of LER, and correlated with decreases in IgG, RF titers, and IgG-RF immune-complex formation in vitro. These results suggest that the therapeutic action of auranofin may be caused, at least in part, by inhibition of LER and/or decreases in immune-complex formation.

Auranofin. New oral gold compound for treatment of rheumatoid arthritis

Eight patients with rheumatoid arthritis were treated with SK & F D-39162 (auranofin), a new oral gold compound which was effective in suppressing adjuvant-induced arthritis in rats. Clinical and humoral parameters were studied during a 3-month period of drug administration followed by a 3-month period under placebo. The drug was absorbed, well tolerated, and its action was manifested by a drop in the mean IgG blood levels in the third week of treatment accompanied by clinical improvement after 5 weeks of oral gold intake. Together with IgG changes, an increase of the albumin ratio was observed, as well as a decrease of alpha2-globulin and rheumatoid factor titres. From a total number of 60 swollen joints found initially in the 8 patients only 17 were swollen at week 12 and 9 at week 15. Although the number of patients treated was too small to allow definite conclusions, a follow-up study under placebo of clinical and laboratory changes in the same patients during another 3-month period showed that IgG serum levels rapidly reverted preceding a flare up of disease activity after withdrawal of the drug. This confirmed a direct role in cause-effect relation played by the new oral gold compound.

Antiarthritic properties and unique pharmacologic profile of a potential chrysotherapeutic agent: S K & F D-30162

SK&F D-39162, a potential chrysotherapeutic agent, on oral administration was effective in suppressing the development of inflammatory lesions and 7S anti-sheep red blood cell antibody formation in adjuvant arthritic rats. Oral absorption of SK&F D-39162 was indicated by the presence of serum gold levels. In contrast to orally administered SK&F D-39162, gold sodium thiomalate administered intramuscularly at equivalent gold doses, appeared to be less effective in suppressing the primary and secondary lesions of adjuvant arthritis, produced relatively higher levels of gold in both serum and kidneys and produced marked toxicity. Other pharmacologic properties of SK&F D-39162 distinguishing it from gold sodium thiomalate which may have clinical significance include potent inhibitory activity on antibody-forming cells, immediate hypersensitivity reactions and extracellular release of lysosomal enzymes. In further contrast to gold sodium thiomalate, SK&F D-39162 is not a potent inhibitor of sulfhydryl group reactivity. In pharmacokinetic studies, the daily oral administration of SK&F D-39162 to normal rats produced greater stability of blood gold levels and less kidney gold accumulation than parenterally administered gold sodium thiomalate.

Synthesis and biological evaluation of tetrakis(acetylsalicylato)-mu-dicopper(II)

The synthesis of a copper-aspirin chelate, previously reported to be a more active anti-inflammatory agent than aspirin itself, is given. Reaction of potassium acetylsalicylate with cupric sulfate gave a stable copper complex, which analysis and molecular weight determination showed to be a 4:2 chelate structure. Oil-water partition measurements showed the complex to be 10-fold more oil soluble than aspirin. Biological evaluation in rats showed the copper complex of aspirin to be approximately equal to aspirin in reducing carrageenan-induced inflammation, but it was 1.7 times more active than aspirin in reducing the primary lesion of adjuvant arthritis. Whereas aspirin produced a 50% or greater incidence of GI erosions at doses of 100-300 mg/kg in rats, the copper complex caused no erosions in doses up to 1200 mg/kg.

Inhibition of prostaglandin synthetase and carrageenan-induced edema by tricyclic analogs of flufenamic acid

A group of tricyclic analogs of flufenamic acid were tested for their ability to inhibit both the biosynthesis of prostaglandin and carrageenan-induced inflammation of the rat paw. All had activity greater than phenylbutazone as inhibitors of prostaglandin synthetase, with SK&F 22908 being as active as flufenamic acid. The anti-inflammatory activities of these compounds correlated only to a minor degree with the inhibition of prostaglandin biosynthesis. The data support the position that within this series of compounds inhibition of prostaglandin synthetase and non-steroidal antiinflammatory activity, as well as ulcerogenic liability, may be an expression of different mechanisms.