Dapsone in rheumatoid arthritis

Dapsone and sulfones in dermatology: overview and update

In their 60-year history, dapsone and the sulfones have been used as both antibacterial and anti-inflammatory agents. Dapsone has been used successfully to treat a range of dermatologic disorders, most successfully those characterized by abnormal neutrophil and eosinophil accumulation. This article reviews and updates the chemistry, pharmacokinetics, clinical application, mechanism of action, adverse effects, and drug interactions of dapsone and the sulfones in dermatology.

Dapsone in rheumatoid arthritis

Dapsone, a synthetic sulfone with chemical similarities to sulfapyridine, has been used for a number of years to treat leprosy and dermatitis herpetiformis. Recently, a number of prospective, randomized, double-blind trials have shown their success in the management of rheumatoid arthritis, with dapsone being superior to placebo and comparable to chloroquine and hydroxychloroquine. Its mode of anti-inflammatory actions in rheumatoid arthritis is not clearly understood, but modulation of neutrophil activity or inhibition of neutrophil inflammatory product formation or release appear to play a role. The major limiting side effect is hemolytic anemia, which may be mitigated through careful patient selection, conservative drug dosing, close monitoring, and possibly, concurrent administration of antioxidants or cytochrome P450 inhibitors. Methemoglobinemia is another common finding among patients receiving dapsone therapy, but rarely does it result in prominent symptoms other than transient pallor. Less common adverse events to dapsone include the idiosyncratic reactions of leukopenia and agranulocytosis, cutaneous eruptions, peripheral neuropathy, psychosis, toxic hepatitis, cholestatic jaundice, nephrotic syndrome, renal papillary necrosis, severe hypoalbuminemia without proteinuria, an infectious mononucleosis-like syndrome, and minor neurological and gastrointestinal complaints. In this report, two patients with advanced rheumatoid arthritis, who were safely and effectively treated with dapsone after failure with other second-line agents, are described and the literature is reviewed. We suggest that dapsone is an effective second-line agent in the treatment of rheumatoid arthritis.

A double-blind comparative study of hydroxychloroquine and dapsone, alone and in combination, in rheumatoid arthritis

Eighty patients with active rheumatoid arthritis (RA) entered a double-blind randomized study of 24 weeks duration, to compare the efficacy and toxicity of hydroxychloroquine, dapsone, and a combination of both drugs in treatment of RA. Evaluation of changes in clinical, laboratory and radiologic variables was based on 63 patients completing the trial. There was no clear difference between the three therapy groups in most inflammatory variables after 24 weeks. However, only patients receiving the combination therapy improved significantly in all clinical and laboratory variables. Nine patients in the combination group and four in each single drug group discontinued during the trial, mainly because of toxicity. Four patients taking the combination therapy withdrew because of hemolytic anemia, and none in the dapsone group. These findings suggest that hydroxychloroquine in combination with dapsone is somewhat more effective and less tolerated than single drug treatments.

Adjuvant therapy of bullous pemphigoid with dapsone

Thirteen patients with recurrent severe widespread recalcitrant bullous pemphigoid (BP) were studied. These patients had been initially treated with prednisone and azathioprine, and clinically responded. However, they frequently continued to have flare-ups or activation of the disease while still on treatment with high doses of these drugs. The addition of dapsone, as an adjuvant to the treatment, helped to produce a complete clinical remission in 12 patients (92%). In addition, there was a statistically significant difference in the median dose of prednisone, before and after the institution of dapsone, and in the maintenance dose of prednisone. Patients were tapered off prednisone more easily than before and did not flare at lower doses of prednisone as previously. It is suggested that, in patients with severe, recalcitrant, recurrent disease, the addition of dapsone to the existing regime of corticosteroids and/or immunosuppressive drugs, may be beneficial. This may be especially valuable to patients in whom corticosteroids have been used for prolonged periods and in whom increasing the corticosteroid dose further may be associated with significant side-effects.

Sulphasalazine in arthritis--an old drug rediscovered

Sulphasalazine (salicyl-azo-sulphapyridine) has been in clinical use for over 40 years. Although the drug was originally introduced for the treatment of 'rheumatic polyarthritis' and ulcerative colitis, it is only in the past 10 years that its value in rheumatology has been appreciated. Controlled studies indicate that the drug is an effective remittive agent in both rheumatoid arthritis and ankylosing spondylitis. This is an area of great research interest since the drug is proving to be a useful tool for investigating the aeteology and pathogenesis of these diseases.

Sulfone therapy in the treatment of leukocytoclastic vasculitis. Report of three cases

Dapsone therapy for leukocytoclastic (necrotizing) vasculitis has been little used, except for the variant forms of erythema elevatum diutinum and urticarial vasculitis. We report three patients with the common (palpable purpura) form of the disease, limited to the skin, and successfully treated with moderate doses of dapsone (100-150 mg daily). Although the natural course of leukocytoclastic vasculitis is highly unpredictable, the prompt disappearance of new lesion formation after initiation of treatment and the rapid recurrence of lesions after therapy is discontinued (both often within 4 to 8 days after the critical dose level is reached) reflect drug efficacy. We believe that dapsone deserves wider evaluation as a therapeutic agent for chronic or recurrent cases of the common form of leukocytoclastic vasculitis.

Pharmacological studies of antigen-induced arthritis in BALB/c mice. II. The effects of second-line antirheumatic drugs and cytotoxic agents on the histopathological changes

The effects of treatment with second-line antirheumatic drugs and cytotoxic agents on the severity of experimental monoarticular arthritis in BALB/c mice have been investigated. The arthritis was assessed histologically in terms of synovitis and erosions of cartilage and bone. Azathioprine (20 mg/kg) and sulphasalazine (10-30 mg/kg oral; 30-100 mg/kg i.p.) produced significant suppression of synovitis and erosions when administered daily for 4 weeks commencing 2 weeks after induction of the arthritis. Dapsone (1-10 mg/kg) and to a lesser extent methotrexate (2 mg/kg) produced some suppression of erosive disease when administered daily for 4 weeks commencing 2 weeks after induction of the arthritis but this failed to reach statistical significance. Chloroquine, D-penicillamine and sodium aurothiomalate all failed to have any effect on the disease with any of the treatment schedules used. Auranofin had no effect on the disease when treatment commenced 2 weeks after intra-articular injection but produced variable suppression at high doses when administered from the day of intra-articular injection.

Acantholysis producedin vitro with pemphigus serum: Hydrocortisone inhibits acantholysis, while dapsone and 6-mercaptopurine do not inhibit acantholysis

Many studies have shown that human skin in organ cultures containing pemphigus antibody undergoes acantholysis, the histologic hallmark of pemphigus vulgaris. This in vitro organ culture system provides a good model to determine if drugs used to treat pemphigus inhibit the effect of pemphigus antibody after it is produced. In this study we determined if hydrocortisone, dapsone, and 6-mercaptopurine (6-MP) could inhibit acantholysis observed in human skin organ cultures containing high constant levels of pemphigus plasma. In six experiments we demonstrated that hydrocortisone (10(-3) and 5 X 10(-4) M) present at the start of organ culture inhibited acantholysis induced by pemphigus sera. Thus, this study raises the possibility that the large doses of steroids used to treat acute pemphigus could act directly on the skin, inhibiting acantholysis in the presence of high titers of pemphigus antibody. Other effective immunosuppressive drugs, such as dapsone and 6-MP, probably do not act directly on the skin.

Report on chloroquine and dapsone in the treatment of rheumatoid arthritis: a 6-month comparative study

A controlled study compared 6 months' treatment of 60 patients with rheumatoid arthritis (RA). Half were randomly allocated to treatment with chloroquine 250 mg daily, the other half dapsone 100 mg daily (50 mg/day for the first 7 days) following a one-month run-in assessment period. All patients had active or progressing disease. Both treatment groups showed significant improvement in morning stiffness, number of painful joints, pain scores, Ritchie index, and proximal interphalangeal joint size, and the chloroquine group alone in grip strength. Laboratory tests showed significant decreases in erythrocyte sedimentation rate, C-reactive protein, and total serum protein levels, with significant increase in serum albumin in the dapsone group, where there was a significant mean drop in haemoglobin (less than 1 g/dl) and a rise in serum bilirubin, associated with its haemolytic effect. X-ray erosion scores were not significantly affected. The clinical and laboratory responses became evident by the time of the 2-month assessment. Criteria for clinical and laboratory improvement were defined, according to which there were 21/26 improvers in the chloroquine group and 12/29 in the dapsone group. It is concluded that although both are effective preparations, chloroquine showed a significantly higher improvement rate and was certainly better tolerated. It is the preferred treatment for patients with active or progressive disease not controlled by nonsteroidal anti-inflammatory drugs, with dapsone as an alternative for patients who fail to respond to or cannot tolerate chloroquine.

Progression of radiological changes in rheumatoid arthritis

A prospective study over one year of patients who had active rheumatoid arthritis discovered 64 who had received treatment for an adequate time with second-line drugs. In these patients there was evidence of continuing joint destruction as shown by radiological progression. During the year there were highly significant correlations between improvements in clinical and laboratory measurements, but neither group of tests was related to the degree of radiological change. However, in the second 6 months of treatment there was evidence that radiological progression was reduced. In a second prospective study of 88 patients with rheumatoid arthritis given prolonged, intensive therapy with second-line drugs and followed up for 10 years two-thirds showed radiological progression. However, the number of joints damaged per year fell significantly during the study period. There was a divergence between deterioration in radiological features and improvements in the ESR and functional capacity, though patients with a persistently low ESR had less radiological progression. These studies provide evidence that treatment may be associated with a reduced rate of radiological progression but suggest that changes in radiological progression and clinical and laboratory measurements may result from different mechanisms.

Comparison between penicillamine and sulphasalazine in rheumatoid arthritis: Leeds-Birmingham trial

Sulphasalazine was first formulated by Svartz in the early 1940s, specifically for use as a remission inducing drug in rheumatoid arthritis. After the publication of an unfavourable trial, however, the drug was restricted to patients with ulcerative colitis. In the late 1970s sulphasalazine was re-examined in rheumatoid arthritis and favourable results reported in "open" trials. A double blind controlled trial was therefore conducted comparing enteric coated sulphasalazine and D-penicillamine in patients with active rheumatoid arthritis. A total of 63 patients were recruited in two centres; 31 were treated with sulphasalazine and 32 received penicillamine. After 16 weeks' treatment both drugs had produced significant improvements in clinical score, pain score measured on a visual analogue scale, grip strength, Ritchie articular index, erythrocyte sedimentation rate, and serum C reactive protein concentration. Nausea was the major side effect in the sulphasalazine treated group. No potentially dangerous effects of sulphasalazine were encountered in contrast with those seen in the penicillamine group. The results suggest that sulphasalazine is an effective and safe drug capable of producing remissions in active rheumatoid arthritis. They also lend confidence to the use of preliminary "open" trials as a means of screening for remission inducing drugs in rheumatoid arthritis.

A comparison between clinical and laboratory tests in rheumatoid arthritis

Five clinical measurements (clinical score, articular index, visual analogue pain score, visual analogue function score, grip strength) were compared with two laboratory tests (the erythrocyte sedimentation rate and serum C-reactive protein concentration) in 68 patients with rheumatoid arthritis (RA). Patients treated with nonsteroid anti-inflammatory drugs showed clinical deterioration when treatment was interrupted, followed by improvement on resumption; there was no change in the laboratory tests. Patients treated with remission-inducing drugs (RIDs) had improved clinical measurements and also reduced erythrocyte sedimentation rate and serum C-reactive protein levels. Treatment with RID's led to similar trends in both clinical and laboratory tests, but correlation coefficients between the tests at intervals rarely attained statistical significance. The different response times for each test and probably also errors inherent in clinical measurements introduced sufficient variability to account for the discrepancy. Of the clinical tests, 'clinical score' appeared the most satisfactory.

Therapeutic progress--review VI. Treatment of rheumatoid arthritis

Anti-rheumatic drugs used in rheumatoid arthritis fall into two distinct groups: non-steroidal anti-inflammatory and second-line drugs. Non-steroidal anti-inflammatory drugs give early symptomatic improvement and reduce the degree of acute inflammatory synovitis. Second-line drugs such as gold or D penicillamine exert an anti-inflammatory effect only after two to three months and act by suppressing disease activity: these reduce the ESR and other acute phase responses. However, the evidence that any of these drugs halt the progression of radiological changes or can be used as long-term agents to control the disease over a period of years is weak. The current use of anti-rheumatic drugs follows a general pattern with non-steroidal anti-inflammatory drugs used alone in patients with mild disease, whereas patients with severe disease also receive second-line drugs. As yet the long-term effect of this policy is not known. Cytotoxic drugs should be restricted to patients with severe disease who either fail to respond to conventional second-line drugs or have active extra-articular disease, particularly those with vasculitis.

Double-blind trial of dapsone against placebo in the treatment of rheumatoid arthritis

Dapsone given over 14 weeks in a dose of 50 mg a day for 1 week and thereafter 100 mg a day was found to have a beneficial effect in rheumatoid arthritis when compared with placebo administration to a matched group of patients. Significant improvement in 5 out of 7 clinical measurements and in erythrocyte sedimentation rate, viscosity, C-reactive protein was found in those patients taking dapsone. There was significant improvement compared to the placebo group in 2 out of the 7 clinical measurements and again in all 3 acute-phase reactants. The drug was quite well tolerated over the 14-week duration of the trial. The tendency to cause haemolysis will be its main limiting factor as a practical alternative to other suppressive agents currently in use.

The role of macrophage secretory products in chronic inflammatory processes

Mononuclear phagocytes participate in various stages of chronic inflammatory responses and associated diseases. Such participation is mediated by (a) direct interaction with pericellular interstitial tissue components as well as with other cell types present at sites of inflammation and (b) by secretion of soluble mediators. Several of these mediators are synthesized and secreted in increased amounts after macrophages interact with inflammatory stimuli. In this paper we pay particular attention to neutral proteinases and prostaglandins. It is shown that these 2 classes of mediators are released in significant amounts under different conditions. Prostaglandins are synthesized most readily by resident populations of mouse peritoneal macrophages responding to various model inflammatory stimuli. Mouse peritoneal macrophage populations elicited in vivo by inflammatory stimuli are less responsive in this respect. In contrast neutral proteinase secretion does not occur in resident cell populations but is observed on a continuous basis in elicited populations. Such secretion can be increased further by addition of phagocytic stimuli and initiated in resident populations by model inflammatory stimuli such as phorbol myritate acetate. Other secretory products of macrophages with possible relevance to inflammation are discussed briefly. Finally some of the effects of antiinflammatory glucocorticoids, cyclooxygenase inhibitors and dapsone on the secretory activity of macrophages are briefly summarized.

Rheumatoid arthritis: effects of a new agent (ICI 55 897) on serum acute phase proteins and the erythrocyte sedimentation rate

Thirty-four patients with rheumatoid arthritis (RA) were treated with a new agent (ICI 55 897) in addition to basic therapy with nonsteroid anti-inflammatory drugs. Five patients had the drug for less than 28 days; the remaining 29 were observed for periods up to a year. At 140 days, when all but 2 patients were in the study, there had been statistically significant improvement in clinical score, serum C-reactive protein, erythrocyte sedimentation rate, and plasma fibrinogen. Thereafter results continued to improve but were biased because some patients had stopped taking the drug. The final conclusion was that 17 patients had improved with 1 late relapse, and 15 had not responded. Adverse effects were trivial except in 2 instances: one patient had a transient unexplained rise in blood urea, another had a haematemesis. Neither effect could be attributed with certainty to the drug. ICI 55 897 has no intrinsic analgesic or anti-inflammatory properties. We suggest the findings of this study indicate that this agent, with low toxicity and the ability to lower acute-phase protein levels, may be an alternative to gold or penicillamine in the treatment of RA.

Comparative effects of drugs on four paw oedema models in the rat

The development of novel anti-inflammatory drugs (AID) has been claimed to be dependent on the discovery of models of inflammation that differ from those currently used for drug screening, e.g. carrageenen paw oedema and u.v. erythema. We have thus evaluated the effect of a variety of drugs in a number of novel models of inflammation in the rat produced in the hind paw. We have utilized kaolin, zymosan, anti-rat IgG (anti-IgG) and the Reversed Passive Arthus (RPA) reaction to produce these oedema models. We found that the non-steroidal AID's, e.g. aspirin, flufenamic acid, indomethacin, naproxen, and phenylbutazone, were active in all four tests. Of the nine novel AID examined, levamisole and tetramisole demonstrated considerable activity in all four tests and dapsone was especially active in the anti-IgG and RPA tests. In contrast, the anti-rheumatic d-penicillamine was inactive in all four models. Each of the ten compounds tested which has been claimed to influence complement function, was active in the RPA but not in the kaolin model. These results are discussed in the context of the aetiology of each oedema and the suspected mode of action of the various drugs.

The anti-inflammatory profile of dapsone in animal models of inflammation

Dapsone has been shown to possess anti-inflammatory activity in a variety of animal models. It possesses oral anti-oedema activity especially pronounced in novel models of acute inflammation, viz. anti-IgG and reversed passive Arthus oedemas. However, it is not very active in the guinea pig u.v. erythema model. It is effective in chronic models such as adjuvant arthritis and the cotton pellet granuloma although multiple administration may also produce cyanosis. Antipyretic and analgesic effects for dapsone have been demonstrated and are similar to those produced by phenylbutazone. It inhibits zymosan-induced beta-glucuronidase release from cultured macrophages and also the activity of this enzyme. Dapsone does not appear to be ulcerogenic in the rat.

Salazopyrin in rheumatoid arthritis

After a 12-week preliminary period of observation 32 patients with consistently active rheumatoid arthritis (RA) were treated for up to 22 weeks with salazopyrin. Seven patients could not tolerate the drug. The remaining 25 patients had a marked improvement in subjective clinical state and significant falls in serum C-reactive protein and the erythrocyte sedimentation rate 6 weeks after treatment began. The improvement was maintained after 22 weeks. The results strongly suggest that further trials with this drug in RA are needed.