Azathioprine in rheumatoid arthritis

The critical role of macrophages in the pathogenesis of hidradenitis suppurativa

INTRODUCTION

Hidradenitis suppurativa (HS) is a painful chronic inflammatory disease with a prevalence between 1 and 4% of general population. The pathogenesis of HS long eluded scientists, but growing evidence suggests that it is a consequence of inflammatory dysregulation.

FINDINGS

Recent studies suggest that dysregulated immune response to skin flora and overexpression of inflammatory cytokines leads to chronic skin inflammation seen in HS. Macrophages are the most numerous inflammatory cells found in HS infiltrates and release numerous pro-inflammatory cytokines such as IL-23, and IL-1β and TNF-α, exacerbating the inflammation and contributing to the pathogenesis of HS. Furthermore, in HS, there is dysregulated function of other immune players closely associated with macrophage function including: matrix metalloproteases (MMP) 2 and 9 overexpression, toll-like receptor upregulation, impaired Notch signalling, NLRP3 inflammasome upregulation, and dysregulated keratinocyte function. Lifestyle factors including obesity and smoking also contribute to macrophage dysfunction and correlate with HS incidence.

CONCLUSIONS

The overexpression of pro-inflammatory cytokines and subsequent efficacy of anti-cytokine biologic therapies highlights the importance of managing macrophage dysfunction. Future therapies should target key molecular drivers of macrophage dysfunction such as TLR2 and NLRP3 overexpression.

TPMT*26 (208F-->L), a novel mutation detected in a Chinese

AIMS

Azathioprine, mercaptopurine and thioguanine are commonly used to treat autoimmune disorders, leukaemia and solid organ transplantation. However, azathiopurine and its metabolites can also cause adverse reactions such as myelosuppression. These manifestations may be attributed to polymorphisms or mutations in the thiopurine methyltransferase (TPMT) gene that might result in low TPMT enzyme activity. Our aim was to investigate if azathioprine-related myelosuppression is associated with TPMT polymorphism, which in turn affects its enzyme activity.

METHODS

A 61-year-old Chinese man with severe atopic eczema developed moderate myelosuppression with standard doses of azathioprine. His TPMT activity was measured using radiochemical assay. Genotyping of TPMT *3C, *3A and *6 were screened using polymerase chain reaction-restriction fragment length polymorphism. Novel mutation was detected by sequencing. Family studies of his three other siblings were performed.

RESULTS

After 4 weeks of azathioprine treatment, the patient's white blood cells and absolute neutrophil count dropped by 40-45%. He was then taken off azathioprine, and blood counts returned to normal. TPMT activity test showed intermediate levels of 9.1 nmol h(-1) ml(-1) peripheral red blood cells (pRBC). Resequencing of the TPMT gene revealed a missense mutation Phe-->Leu at 208 aa position in exon 9 (ss105107120). Two of his three siblings were heterozygous for 208F-->L, which accounts for the decreased enzyme activity (brother 8.9 nmol h(-1) ml(-1) pRBC, sister 8.8 nmol h(-1) ml(-1) pRBC). The remaining sibling had wild-type allele with normal enzyme activity. Screening of 100 normal healthy Chinese subjects did not reveal any individual with this mutation.

CONCLUSION

We report a novel mutation TPMT*26 (208F-->L) associated with a decrease in TPMT enzyme activity.

Thiopurine S-methyltransferase and inosine triphosphate pyrophosphohydrolase genes in Japanese patients with inflammatory bowel disease in whom adverse drug reactions were induced by azathioprine/6-mercaptopurine treatment

BACKGROUND

The main cause of azathioprine (AZA)/6-mercaptopurine (6MP)-induced adverse reactions is a reduction in the activities of the metabolizing enzymes thiopurine S-methyltransferase (TPMT) and inosine triphosphate pyrophosphohydrolase (ITPA). Adverse reactions develop at a high frequency in Japanese patients at half the dose required for European and American patients; however, the association with TPMT and ITPA gene polymorphisms in Japanese has not been fully investigated.

METHODS

Gene mutations of TPMT and ITPA, the major AZA/6-MP -metabolizing enzymes, were investigated retrospectively in 16 Japanese patients with inflammatory bowel disease (IBD) in whom AZA/6MP treatment induced adverse reactions.

RESULTS

The TPMT gene was found to have a wild-type sequence in all patients, but in the ITPA gene a mutation, 94C>A, was detected at a rate of 50% (8/16), with 83.3% (5/6) occurring in patients with acute bone marrow suppression and 75% (3/4) in those with agranulocytosis. The 94C>A allele frequency was 10 of 32 (0.313; 95% CI, 0.180-0.486). Adverse reactions developed earlier in patients with the 94C>A mutation. However, in half the patients, no gene polymorphism was noted.

CONCLUSIONS

It is suggested that the ITPA gene mutation is closely related to the adverse reactions of AZA/6-MP in Japanese patients, and screening for the mutant allele is useful for predicting the most serious adverse reactions, agranulocytosis and acute bone marrow suppression.

Thiopurine S-methyltransferase activity in three major Asian populations: a population-based study in Singapore

OBJECTIVE

The distribution of thiopurine methyltransferase (TPMT) activity in Asian populations has not been well documented. We studied the TPMT phenotype in three major Asian ethnic groups in Singapore, namely the Chinese (Ch), Malays (Mal) and Indians (Ind), with the aim of carrying out a comprehensive survey of the distribution of TPMT activity in Asians.

METHODS

A radiochemical assay was used to measure the enzymatic activity of TPMT in the red blood cells (RBCs) of 479 healthy adults (Ch=153, Mal=163 and Ind=163). Cut-off points for intermediate TPMT activity were validated using a receiver operating curve (ROC) analysis. PCR-based methods were used to screen for the TPMT*3C, TPMT*3A and TPMT*6 variants.

RESULTS

The histogram of the combined population cohort showed a bimodal distribution of TPMT activity, with no subject having low TPMT activity (<5 units). In total, TPMT variants were detected in 14 subjects (*1/*3C in 13 subjects; *1/*3A in one subject). We observed significant inter-ethnic differences in terms of TPMT activity (p<0.001), with the Malays showing a higher median activity than the Chinese or Indians (17.8 units vs 16.4 units). The Malays also showed a higher methylation rate--with a cut-off point for intermediate TPMT activity of 11.3 units--than the Chinese (9.9 units) or Indians (9.4 units). A high phenotype-genotype correlation of >97% was observed in all three races. We also genotyped 418 childhood leukaemias. The combined analysis of subjects participating in this and a previous study--1585 subjects--showed that 4.7% of Chinese (n=30/644), 4.4% of Malays (n=24/540) and 2.7% of Indians (n=11/401) were heterozygous at the TPMT gene locus.

CONCLUSION

This is the first comprehensive TPMT phenotype and genotype study in Asian populations, particularly in the Malays and Indians.

Azathioprine and 6-mercaptopurine pharmacogenetics and metabolite monitoring in inflammatory bowel disease

The thiopurine drugs azathioprine and 6-mercaptopurine (6-MP) are well-established in the treatment of inflammatory bowel disease (IBD). However, there is a wide inter- and intra-patient variation in the concentrations of active and toxic metabolites due to their complex metabolism and genetic polymorphisms in metabolizing enzymes. Serious drug toxicity leads to cessation of therapy in 9-25% of patients, and there is failure to achieve efficacy in approximately 15% of cases. Advances in the understanding of thiopurine drug metabolism have led to new genetic and metabolite tests to help clinicians optimize thiopurine use. Thiopurine methyltransferase (TPMT) enzyme activity can predict life-threatening myelotoxicity in the one in 300 patients who are TPMT-deficient. However, myelotoxicity can also occur in the presence of normal TPMT activity so blood count monitoring should remain standard practice. TPMT testing may also aid in dose individualization. 6-Thioguanine nucleotides (6-TGN) are thought to be the predominant active metabolites of the thiopurines. 6-thioguanine nucleotide concentration is correlated with bone marrow toxicity and may also correlate with efficacy in IBD. Measurement of 6-TGN and 6-methylmercaptopurine (6-MMP) concentration is most useful in determining why a patient is not responding to a standard dose of a thiopurine drug and may help in avoiding myelosuppression. The ratio of these metabolites can help distinguish non-compliance, under-dosing, thiopurine-resistant and thiopurine-refractory disease. Some of these investigations are entering routine clinical practice but more research is required to determine their optimal use in patients with IBD.

Old and new drugs used in rheumatoid arthritis: a historical perspective. Part 1: the older drugs

Rheumatoid arthritis is the paradigmatic immune-mediated inflammatory arthropathy and may be of comparatively recent, New World origin. Apart from the symptom-relieving nonsteroidal anti-inflammatory drugs, whose natural congeners have been in use since antiquity for musculoskeletal pain and inflammation, only a dozen drugs or drug classes--the disease-modifying antirheumatic drugs--are currently in common use in rheumatoid arthritis. Development of these drugs has been a notable achievement of the 20th century. Some were developed serendipitously (glucocorticoids, antimalarials), some were the product of faulty reasoning (gold, D-penicillamine), and others were applied for plausible reasons but whose mechanism remains unproven (sulfasalazine, methotrexate, minocycline). A minority were originally applied on the basis of actions that remain germane to the pathophysiology of rheumatoid arthritis as currently understood (azathioprine, cyclosporine, leflunomide, infliximab, etanercept). Among the latter are the more recently introduced and effective agents. The practical use of these drugs is determined by efficacy-toxicity considerations, which have also driven the recent development of the cyclooxygenase-2-selective nonsteroidal anti-inflammatory drugs.

Relationship between red cell mean corpuscular volume and 6-thioguanine nucleotides in patients treated with azathioprine

Azathioprine (AZA) is characterized by high interindividual differences in bioavailability and metabolization. The aim of the present study was to analyze, in patients treated with AZA for various immune system disorders, whether the variation in red blood cell mean corpuscular volume (deltaMCV) could be used as an indirect estimation of the level of the active immune modifier metabolite 6-thioguanine nucleotides (6-TGN). In 43 consecutive patients treated with a stable dose of AZA for at least 6 months who were not initially anemic, the erythrocyte 6-TGN levels with routine hematologic parameters were determined two to four times at 1-month intervals. In most patients MCV significantly increased after 3 months of therapy and stabilized after 6 months. The correlation between the daily dose of AZA and the 6-TGN level was mild (r = 0.51; P<.001). A weak correlation was also found between the dose of AZA and the deltaMCV after at least 6 months of therapy (r = 0.36; P<.05). The correlation between deltaMCV and 6-TGN level, however, was much better (r = 0.74; P<.001). The lack of a significant increase in MCV after 3 to 4 months of AZA therapy reflects low 6-TGN levels, sometimes a result of undertreatment. A determination of the 6-TGN level during the first months after AZA therapy is begun will allow more accurate adaptation of the effective dose. We observed that deltaMCV could be used as an indicator of 6-TGN levels after 6 months of AZA treatment. An increase in MCV of at least 6 fL is expected to reflect a 6-TGN level of about 175 pmol/8x10(8) red blood cells (probably being within a therapeutic value).

Clinical pharmacology and modification of autoimmunity and inflammation in rheumatoid disease

The increased understanding of the mechanisms which underlie rheumatoid disease has been accompanied by a more appropriate use of the limited repertoire of therapeutic agents. Conventional second-line drugs still have a role in everyday practice. The efficacy of these agents in reducing the severity of clinical signs of joint inflammation, whilst at the same time causing significant reductions in the laboratory measures of the acute phase response is undoubtedly confirmed by meta-analysis of several therapeutic trials of these agents. Whether or not these agents can influence outcome, usually assessed in terms of radiological progression, is more contentious. Furthermore, their toxicity in long term use is not inconsiderable. However, newer agents may play a more important part in therapy in the future. Such therapy can be designed to specifically interfere with the abnormalities of the immune system which characterise rheumatoid arthritis. Many of the agents reviewed have been successfully applied to animal models of arthritis but we still await large randomised controlled studies in humans to determine their clinical efficacy and toxicity. In view of the complexity of the immunological abnormalities in rheumatoid arthritis, it may be necessary to consider using a number of such agents in any particular patient. This should result in more rational therapy in rheumatoid arthritis.

Use of short-term efficacy/toxicity tradeoffs to select second-line drugs in rheumatoid arthritis. A metaanalysis of published clinical trials

OBJECTIVE

Preferred drugs for rheumatoid arthritis (RA) should be those that have maximal efficacy with the least toxicity. We evaluated the efficacy and toxicity tradeoffs for drugs frequently used in the treatment of RA.

METHODS

We updated 2 metaanalyses of published clinical trials, by adding trials published through 1990 and trials of azathioprine (AZA). We tested 3 different definitions of efficacy, each plotted against 3 different toxicity measures, for antimalarial drugs, methotrexate (MTX), auranofin, injectable gold, D-penicillamine, sulfasalazine (SSZ), AZA, and placebo. Efficacy measures included composite efficacy (a combination of joint count, grip strength, and erythrocyte sedimentation rate), tender joint count alone, and a measure based on how many patients dropped out due to inefficacy. Toxicity measures were the proportion dropping out due to toxicity, the same dropouts with side effects weighted for severity using a modification of a published toxicity index, and the proportion with severe toxicities (defined as a score of at least 7 of 10 on the toxicity index). The latter were usually organ toxicities (e.g., cytopenias and renal involvement).

RESULTS

All 9 efficacy/toxicity tradeoff plots suggested that MTX and antimalarial drugs had the highest efficacy relative to toxicity. MTX scored among the most efficacious of the drugs and, of these, had the least toxicity. Antimalarial drugs, though showing only moderate efficacy, had the lowest toxicity rate of all the drugs. SSZ scored close to MTX but was, in general, slightly more toxic.

CONCLUSION

In the short-term context of clinical trials, antimalarial drugs and MTX have the best efficacy/toxicity tradeoffs and may, therefore, be the preferred drugs.

Azathioprine, cyclophosphamide and chlorambucil

Immunosuppressive agents serve a major role in the management of once-fatal conditions such as the systemic necrotizing vasculitides, but they are also being used in more common, chronic inflammatory disorders such as rheumatoid arthritis. The drugs are all capable of reducing cell division but they differ in their modes of action. This is in keeping with their differing rates of action, and different indications. Azathioprine is a valuable alternative to slow-acting antirheumatic drugs in older patients with rheumatoid arthritis. Cyclophosphamide has transformed the outlook of many forms of vasculitis. Chlorambucil is particularly useful in improving the prognosis for children with amyloidosis secondary to juvenile chronic arthritis. We have tried to highlight the role of these drugs in a number of rheumatic diseases. We have emphasized their clinical applications, with some laboratory evidence for their effects. The major side-effects are reviewed. Finally, we have discussed their possible mechanisms of action.

Treatment of rheumatoid arthritis

The management of the rheumatoid patient involves the considered use of pharmacologic agents as therapies to induce symptomatic relief and to reduce disease activity. Aspirin and nonsteroidal antiinflammatory drugs are used initially to lessen the degree of pain and swelling associated with the inflammatory disease process. The aggressive institution of second-line therapy, previously known as disease-modifying antiinflammatory rheumatic drugs, is advocated to modify the disease course itself. These second-line treatments include antimalarials, gold salts, methotrexate, d-penicillamine, and azathioprine. Randomized placebo controlled trials have demonstrated the efficacy of these compounds in this illness. Improvement in standard parameters of disease activity (number of painful and swollen joints, duration of morning stiffness, erythrocyte sedimentation rate) can be related to the therapeutic value of second-line agents. Whether they modify radiographic progression is under rigorous study. Newer therapies under research investigation include sulfasalazine, cyclosporin A, and combination therapy.

Immunosuppressive drugs and corticosteroids in the treatment of rheumatoid arthritis

Rheumatoid arthritis is the most common form of severe inflammatory arthropathy affecting patients at a relatively early age. Although there are a number of drugs which significantly reduce pain and swelling, few alter the development of erosions and progression of joint destruction. A significant number of patients with rheumatoid arthritis develop this progressive disability and will require treatment with corticosteroids or immunosuppressive agents. In this article the use of immunosuppressive drugs and corticosteroids in the treatment of aggressive rheumatoid arthritis is reviewed. Controlled clinical trials have shown that a number of these drugs can play a significant role in reducing pain and swelling and might possibly alter the disease course in rheumatoid arthritis. Side effects of these agents, including the potential for oncogenesis, still pose major problems in their long term use. The risks and benefits of immunosuppressive and corticosteroid drug therapy must be balanced in each patient to whom they are prescribed and reviewed at frequent intervals.

The optimum management of arthropathies

The aims in management of an arthropathy are to relieve symptoms, preserve function, and control the disease process. Drugs are an important, although not the only, part of any therapeutic regimen enabling us to achieve these aims. Although each individual requires a unique strategy, there is a logical progression from first-line agents to second-line agents. Third-line agents and experimental methods are reserved for aggressive or life-threatening disease. The choice of agent in each group is personal preference, but many agents have high adverse effect profiles, and close monitoring is essential.

Azathioprine hypersensitivity manifesting as acute focal hepatocellular necrosis

Images

Azathioprine in giant cell arteritis/polymyalgia rheumatica: a double-blind study

The ability of azathioprine to reduce the maintenance prednisolone requirement of 31 patients with polymyalgia rheumatica (PMR) or giant cell arteritis (GCA), or both, was tested in a double-blind placebo controlled study over one year. Clinical and laboratory assessments were made at four-weekly intervals over a period of 52 weeks. A statistically significant difference (p less than 0.05) in mean prednisolone dose was noted between the two groups at the end of 52 weeks, there being a fall in steroid requirement in the azathioprine treated group.

Azathioprine in 50 rheumatoid arthritic patients intolerant or unresponsive to gold or penicillamine

This is a retrospective review of 50 rheumatoid patients who had experienced side effects with gold and/or penicillamine and who were treated with azathioprine in routine clinical practice. The mean duration of the disease at commencement of azathioprine was 9.4 years; despite attempts to maintain the dose at 2.5 mg/kg.d because of minor side effects the average daily dose was 1.68 mg/kg.d. By one year, 11 (22%) had discontinued the drug due to side effects; 6 (12%) had not improved in any respect, 20 (40%) had a reduction in the total number of active joints with maintenance of function and in 13 (26%) the total number of active joints had been reduced by more than a half. During year 2 a further 4 discontinued therapy for adverse reactions. No further formal analysis has been performed though 31 patients were still on the drug with a mean duration of therapy for a period of 5 years. Ten of these had less than half their originally affected joints still active; this condition was usually associated with a fall in ESR and rise in haemoglobin but this was not invariable.

Mechanisms of action and clinical applications of cytotoxic drugs in rheumatic disorders

Failure to suppress disease activity in certain rheumatic disorders such as systemic lupus, polyarteritis nodosa, or Wegener's granulomatosis may significantly heighten the probability of a fatal outcome. In other rheumatic disorders (for example, rheumatoid or psoriatic arthritis) the disease left unchecked may indeed be severely crippling but rarely is it fatal. Thus the decision on whether to add a cytotoxic drug often evolves into a benefit-to-risk analysis, a decision in which the patient must also be intimately involved. There are two few well-controlled studies of the use of cytotoxic agents to make dogmatic statements regarding their use in the treatment of rheumatic disorders. Nevertheless, a review of the literature, some of which has been cited above, does permit one to make some reasoned judgments in choosing a drug for a particular disease (Table 2).

Azathioprine versus D-penicillamine in rheumatoid arthritis patients who have been treated unsuccessfully with gold

Two hundred six patients were entered into a prospective controlled, double-blind, multicenter trial comparing azathioprine (AZA) 1.25-1.5 mg/kg/day with D-penicillamine (DP) 10-12 mg/kg/day. One hundred thirty-four patients completed 24 weeks of therapy. Improvement in nearly all efficacy variables was seen in both groups. Patients taking DP demonstrated a greater rise in hemoglobin concentration and greater fall in erythrocyte sedimentation rate than patients receiving AZA; these were the only efficacy variables with a significant difference between the treatment groups. Fewer withdrawals for adverse reactions occurred among the patients receiving AZA, but the difference was not significant. Patients receiving AZA were withdrawn from the drug mainly for abnormal liver function test results, nausea and gastrointestinal upset, and leukopenia. The main reasons for withdrawal of patients receiving DP were nausea, rash and pruritus, thrombocytopenia, dysgeusia, and proteinuria.

Azathioprine and cyclophosphamide as slow-acting drugs for rheumatoid arthritis

Therapy with azathioprine and cyclophosphamide is described as reducing disease activity in rheumatoid arthritis. The well recognized untoward effects are tractable save for the definite augmentation of carcinogenesis, a measurable risk that is regarded as acceptable in treating rheumatoid arthritis with azathioprine and rheumatoid arteritis with cyclophosphamide.

Does drug therapy slow radiographic deterioration in rheumatoid arthritis?

Many clinicians believe that slow-acting therapeutic agents, such as fold, penicillamine, the antimalarials, and cytotoxic drugs, can retard joint destruction in rheumatoid arthritis. We reviewed 60 published studies employing these drugs to evaluate critically the evidence that drug therapy can slow the radiographic progression of disease. Seventeen studies were found that included radiographic assessment of both treated and control groups; they were analyzed using methodologic criteria known to be important in affecting the results of drug trials. In addition to numerous qualitative methodologic deficiencies, many studies showed inadequacies in sample size and duration of treatment, and the drug dosage used varied from one study to another. We found evidence suggesting that both gold and cyclophosphamide can retard radiographic progression of joint destruction. At present, there are too few technically adequate studies to permit even provisional conclusions concerning other agents.

Sustained improvement of intractable rheumatoid arthritis after total lymphoid irradiation

Total lymphoid irradiation (TLI) was administered to 11 patients who had intractable rheumatoid arthritis that was unresponsive to conventional medical therapy, including aspirin, multiple nonsteroidal antiinflammatory drugs, gold salts, and D-penicillamine. Total lymphoid irradiation was given as an alternative to cytotoxic drugs such as azathioprine and cyclophosphamide. After radiotherapy, 9 of the 11 patients showed a marked improvement in clinical disease activity as measured by morning stiffness, joint tenderness, joint swelling, and overall functional abilities. The mean improvement of disease activity in all patients ranged from 40-70 percent and has persisted throughout a 13-28 month followup period. This improvement permitted the mean daily steroid dose to be reduced by 54%. Complications included severe fatigue and other constitutional symptoms during radiotherapy, development of Felty's syndrome in 1 patient, and an exacerbation of rheumatoid lung disease in another. After therapy, all patients exhibited a profound T lymphocytopenia, and a reversal in their T suppressor/cytotoxic cell to helper cell ratio. The proliferative responses of peripheral blood mononuclear cells to phytohemagglutinin, concanavalin A, and allogeneic leukocytes (mixed leukocyte reaction) were markedly reduced, as was in vitro immunoglobulin synthesis after stimulation with pokeweed mitogen. Alterations in T cell numbers and function persisted during the entire followup period, except that the mixed leukocyte reaction showed a tendency to return to normal values.

Low dose oral methotrexate in rheumatoid arthritis: an uncontrolled trial and review of the literature

New therapeutic alternatives are needed for patients with progressive RA unresponsive to gold or D-penicillamine. Azathioprine and cyclophosphamide can be effective but have been linked with the development of lymphoreticular malignancies. In an effort to exploit a less toxic agent, we have been impressed by the results and minimal toxicity of low dose oral MTX. Extensive application of this regimen in psoriasis and psoriatic arthritis indicates that low dose MTX does not have an unusual risk for developing cancer. In addition, prior experience with other rheumatic disorders and preliminary studies on the mechanism of action suggest a potential value in RA. We present our initial retrospective results in 28 patients with refractory RA given low dose oral MTX over the past 2.5 yr. An apparent positive response was noted in 19 of these patients (67%) and is similar to the experience of other clinicians. At the same time, the toxicity has been low and, with one exception, amenable to dose modification. Methotrexate in various regimens is being increasingly employed in refractory RA. Issues concerning the pharmacology and potential toxicity are, therefore, important. These topics are reviewed with emphasis on low dose therapy and hepatotoxicity. Despite the encouraging preliminary results it is unclear whether MTX can prevent erosions or improve long-term function and quality of life in RA. There are still no controlled perspective studies comparing MTX to placebo or other immunosuppressive agents in RA. Although short-term toxicity is low, long-term toxicity, especially hepatic, is uncertain. As a result, a controlled, long-term prospective study is necessary.

Long-term azathioprine in rheumatoid arthritis: a double-blind study

Several studies have demonstrated the beneficial effect of azathioprine in rheumatoid arthritis. But fears have been expressed about the possible mutagenic and teratogenic effects of prolonged use. If the drug could be withdrawn once remission is achieved, and this remission be then maintained with other agents, the possible complications of long-term therapy might be avoided. A double-blind controlled study was carried out over 8 months in 32 patients receiving long-term azathioprine therapy for rheumatoid arthritis. Substitution of placebo for active drug resulted in clinical deterioration.

Azathioprine in rheumatoid arthritis: double-blind study of full versus half doses versus placebo

To test whether azathioprine in effective in rheumatoid arthritis in doses smaller than those normally used the drug was tested at 2 dosage levels, 2.5 and 1.25 mg/kg/day (2.5 AZ and 1.25 AZ), against placebo under double-blind conditions over 24 weeks. Dropouts were 7 out of 15 in the 2.5 AZ group, 4 out of 14 in the 1.25 AZ group, and 2 out of 13 in the placebo group. Some significant improvement occurred in all 3 groups, including those on placebo. However, the 2.5 AZ group fared significantly better than the placebo group, while the 1.25 AZ group results tended to fall between the other 2 groups. We conclude that, in order to obtain the reported effectiveness of azathioprine in rheumatoid arthritis, it is necessary to start treatment with 2.5 mg/kg/day. Halving this dosage reduces the effectiveness of the drug.

Antirheumatic drugs: clinical pharmacology and therapeutic use

With the exception of the treatment of gout and bacterial infections of joints, therapy in the rheumatic diseases remains inadequate. Although many patients gain symptomatic improvement on the drugs currently available, their impact on the underlying disease process remains uncertain. Hope for future therapeutic development is highest in rheumatoid arthritis with the second-line agents (e.g. gold, penicillamine), as unravelling their mechanism of action may lead to the design of more effective and less toxic medications. The cytotoxic agents appear to hold some promise in the therapy of vasculitis, but problems with their use have by no means been solved. In the major problem area of osteoarthritis, important gains are being made in the field of joint replacement, and the use of non-steroidal anti-inflammatory drugs in the interim has made symptoms more tolerable. Obviously much remains to be done in research in the area of antirheumatic drugs.

Cause of death in patients with rheumatoid arthritis with particular reference to azathioprine

Three hundred and eleven patients with classical or definite rheumatoid arthritis were observed over an 11-year period. This group is of particular interest since 214 patients were given cytotoxic therapy, 203 were treated with azathioprine (52 of these also received chlorambucil or cyclophosphamide), and 11 were treated with cyclophosphamide or chlorambucil alone. Forty-six patients died. This is an excess mortality compared with the expected rate for the general population matched with respect to age and sex. The death rate was higher than expected in the age group 45-64 years but lower in those aged 75 years or over. There were more deaths from neoplasia and ischaemic heart disease in the younger age group. One patient died of lymphosarcoma; treatment had been with corticosteroids, gold, and chloroquine. No other tumours of the reticuloendothelial system were recorded, and no patient developed leukaemia.

Remission-inducing drugs in rheumatoid arthritis

The administration of certain drugs to patients with established rheumatoid arthritis frequently results in improvement that is slow to appear but persists for long periods, even after the drug is discontinued. The three main drugs with this effect, whose efficacy and toxicity are reviewed in this paper, are gold salts, D-penicillamine and chloroquine. The cytotoxic agents used to treat rheumatoid arthritis, which likely have nonspecific anti-inflammatory actions and have serious long-term side effects, are also briefly reviewed. A new drug, levamisole, is currently being tested in patients with rheumatoid arthritis. It is suggested that the time for considering the introduction of a remission-inducing drug in patients with progressive rheumatoid arthritis is after an adequate trial of therapy with salicylates or other nonsteroidal anti-inflammatory agents, or both, and before the oral administration of steroids. It is difficult, however, on the basis of rigorous clinical comparisons, to recommend which of the three main remission-inducing drugs should be tried first, although gold salts have been used the most. Patients who have improved with 6 months of chrysotherapy may continue treatment for at least 3 years, during which time the frequency of mucocutaneous and renal toxic effects will steadily decrease. Some aspects of the medical economics of therapy with remission-inducing drugs for rheumatoid arthritis are discussed.

Prolonged thoracic-duct drainage in rheumatoid arthritis and systemic lupus erythematosus

Images

Azathioprine treatment of adjuvant arthritis

Administration of azathioprine in the diet to Lewis rats reduced the lethality of this drug relative to various regimens by gavage. This mode of administration made it possible to administer effective doses with reduced toxicity. Azathioprine blocked the early development of adjuvant arthritis and decreased the joint scores of animals with established adjuvant disease. A combination of azathioprine and prednisolone produced an additive reduction of both developing and established joint scores. A 10 day pulse regimen of prednisolone resulted in a strong, rapid decrease in established joint scores. This decrease was sustained by continuous administration of azathioprine. In all cases removing azathioprine and/or prednisolone from the diet of animals with established adjuvant arthritis resulted in recurrence of disease. The results of these studies support the validity of the adjuvant model for prediction of anti-arthritic activity.

Cancer and teratogenesis: infrequent occurrence after medical use of immunosuppressive drugs

This study examines long term "medical" immunosuppression with azathioprine or cyclophosphamide for immunopathic disease in relation to cancer and foetal malformation. The experience represent an aggregate of 241 years of treatment and 508 patient-years of follow-up in 133 non-transplant patients. For azathioprine the mean duration of treatment was 1-9 years and the mean duration of observation was 3-8 years, and for cyclophosphamide, the mean durations of treatment and observation were 0-7 and 4-6 years. A sample of 70 patients was shown by in vivo tests to have significantly suppressed cell-mediated immunity. In the period of review there were observed two cancers, both squamous cell carcinomas of skin, two benign neoplasms and six keratoses; after the period of review, three further cancers were recorded, one being in a subject with a known previous cancer. Nine pregnancies with azathioprine yielded no foetal malformations.

Azathioprine in early rheumatoid arthritis. Comparison with gold and chloroquine

This study compares the effect of azathioprine with those of gold and chloroquine in early (Class II) rheumatoid arthritis (RA). Thirty-three similar patients with classic or definite RA of less than 5 years duration were randomly entered, 11 into each drug group. Assessment of standard clinical and laboratory measures at 12 and 24 weeks showed significant improvement in all three groups. In general, all three drugs were effective antirheumatic agents with low toxicity. However, because of serious potential toxicity, azathioprine could not be recommended over gold and chloroquine in early RA therapy.

Rheumatoid arthritis treated with chlorambucil: a five-year follow-up

The results of a five-year study of chlorambucil in patients suffering from rheumatoid arthritis are presented. The effect of treatment was to allow a reduction in corticosteroid dosage and a sustained remission of disease activity in patients. Three patients of the series of 22 developed neoplastic disease, and the signficance of this is discussed.

Controlled trial of cyclophosphamide in rheumatoid arthritis

Twenty-four patients with severe progressive rheumatoid arthritis were randomly assigned to cyclophosphamide or placebo in a double-blind crossover trial. Eleven patients who completed 9 months on cyclophosphamide (average dose: 1.8 mg/kg/day) demonstrated significant decrease in painful joints, swollen joints, and morning stiffness and increase in grip strength when compared to 11 patients on placebo. After crossover, significant improvement was observed in patients switched to cyclophosphamide, and deterioration within 2 months was observed in most patients changed from drug to placebo. Serum immunoglobulins and rheumatoid factor titers decreased with cyclophosphamide but antibody response to Vi antigen was unaffected. Primary delayed immune response to 2,4-dinitrochlorobenzene was markedly depressed. Adverse effects were troublesome--hemorrhagic cystitis affected 4 patients and amenorrhea occurred in 3. Despite striking beneficial effect, cyclophosphamide should be prescribed cautiously and only in severe resistant cases of rheumatoid arthritis.