Successful use of dapsone in refractory pregnancy-associated idiopathic thrombocytopenic purpura

Dapsone in dermatology and beyond

Dapsone (4,4′-diaminodiphenylsulfone) is an aniline derivative belonging to the group of synthetic sulfones. In 1937 against the background of sulfonamide era the microbial activity of dapsone has been discovered. Shortly thereafter, the use of dapsone to treat non-pathogen-caused diseases revealed alternate antiinflammatory mechanisms that initially were elucidated by inflammatory animal models. Thus, dapsone clearly has dual functions of both: antimicrobial/antiprotozoal effects and anti-inflammatory features similarly to non-steroidal anti-inflammatory drugs. The latter capabilities primarily were used in treating chronic inflammatory disorders. Dapsone has been investigated predominantly by in vitro methods aiming to get more insights into the effect of dapsone to inflammatory effector cells, cytokines, and/or mediators, such as cellular toxic oxygen metabolism, myoloperoxidase-/halogenid system, adhesion molecules, chemotaxis, membrane-associated phospholipids, prostaglandins, leukotrienes, interleukin-8, tumor necrosis factor α, lymphocyte functions, and tumor growth. Moreover, attention has been paid to mechanisms by which dapsone mediates effects in more complex settings like impact of lifespan, stroke, glioblastoma, or as anticonvulsive agent. Additionally, there are some dermatological investigations in human being using dapsone and its metabolites (e.g., leukotriene B₄-induced chemotaxis, ultraviolet-induced erythema). It could be established that dapsone metabolites by their own have anti-inflammatory properties. Pharmacology and mechanisms of action are determining factors for clinical use of dapsone chiefly in neutrophilic and/or eosinophilic dermatoses and in chronic disorders outside the field of dermatology. The steroid-sparing effect of dapsone is useful for numerous clinical entities. Future avenues of investigations will provide more information on this fascinating and essential agent.

Dapsone for primary immune thrombocytopenia in adults and children: an evidence-based review

Primary immune thrombocytopenia is a potentially life-threatening condition. Approximately two-thirds of adult patients do not have a sustained response to steroids (first-line therapy). For these patients, a number of other treatment options exist, such as rituximab, splenectomy, immunosuppressants, and thrombopoietin receptor agonists, but they are costly and have side effects. Dapsone is an inexpensive drug with a well-established safety profile. Unfortunately, this treatment option has not been explored adequately. This review is aimed at analyzing the currently available evidence for the use of dapsone as second-line or third-line therapy in primary immune thrombocytopenia.

Medical treatments for idiopathic thrombocytopenic purpura during pregnancy

BACKGROUND

Idiopathic thrombocytopenic purpura (ITP) is a common hematologic disorder caused by immune-mediated thrombocytopenia. The magnitude of the maternal-fetal risk of ITP during pregnancy is controversial. Labour management of pregnant women with ITP remains controversial. Management of ITP during pregnancy is complex because of the disparity between maternal and fetal platelet counts.

OBJECTIVES

To assess the effectiveness and safety of corticosteroids, intravenous immunoglobulin, vinca alkaloids, danazol, dapsone, and any other types of pharmacological treatments for the treatment of idiopathic thrombocytopenic purpura during pregnancy.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (February 2009), LILACS (1982 to 8 February 2009), ClinicalTrials.gov (8 February 2009), Current Controlled Trials (16 February 2009), Google Scholar (16 February 2009) and ongoing and unpublished trials cited in the reference lists of relevant articles.

SELECTION CRITERIA

Randomised controlled trials (RCTs) on any medical treatments for idiopathic thrombocytopenia purpura during pregnancy.

DATA COLLECTION AND ANALYSIS

Two review authors independently evaluated methodological quality and extracted trial data. Any disagreement was resolved by discussion or by consulting a third review author.

MAIN RESULTS

This review included one RCT in which 38 women (41 pregnancies) were randomised, with only 26 women (28 pregnancies) being analysed.This RCT comparing the effect of betamethasone (1.5 mg/day) with no medication found no statistically significant difference in neonatal thrombocytopenia (risk ratio (RR) 1.12, 95% confidence interval (CI) 0.62 to 2.05) and neonatal bleeding (RR 1.00, 95% CI 0.24 to 4.13). Review authors conducted an intention-to-treat analysis which showed similar findings: RR 1.18, 95% CI 0.57 to 2.45 and RR 1.05, 95% CI 0.24 to 4.61, respectively. Maternal death, perinatal mortality, postpartum haemorrhage and neonatal intracranial haemorrhage were not studied by this RCT.

AUTHORS' CONCLUSIONS

Current evidence indicates that compared to no medication, betamethasone did not reduce the risk of neonatal thrombocytopenia and neonatal bleeding in ITP during pregnancy. There is insufficient evidence to support the use of betamethasone for treating ITP. This Cohrane review does not provide evidence about other medical treatments for ITP during pregnancy. This systematic review also identifies the need for well-designed, adequately powered randomised clinical trials for this medical condition during pregnancy. Unless randomised clinical trials provide evidence of a treatment effect and the trade off between potential benefits and harms are established, policy-makers, clinicians, and academics should not use betamethasone for ITP in pregnant women. Any future trials on medical treatments for treating ITP during pregnancy should test a variety of important maternal, neonatal or both outcome measures, including maternal death, perinatal mortality, postpartum haemorrhage and neonatal intracranial haemorrhage.

Dapsone Therapy for Malaria During Pregnancy

The need to consider using dapsone in pregnant women for its antimalarial activity is becoming greater in areas where Plasmodium falciparum resistance to chloroquine and pyrimethamine-sulfadoxine is rapidly increasing. Dapsone in combination with other antimalarials might provide a valuable alternative for both treatment and prophylaxis. This review assesses the clinical pharmacology of dapsone and its adverse drug reactions in relation to haemolysis, glucose-6-phosphate dehydrogenase (G6PD) deficiency, blood dyscrasias and methaemoglobinaemia. Studies are summarised reporting its use in leprosy, dermatological and other conditions, and malaria, in relation to maternal and infant outcomes. A total of 924 pregnancies were identified during which dapsone therapy was taken. Only limited data are available and this precludes a meaningful quantitative benefit-risk analysis. Mild degrees of haemolysis consistently occur with continued therapy, although adverse effects may be less likely with intermittent treatment, as most reported adverse effects have occurred with long-term use of dapsone. There are a number of gaps in knowledge where more data are needed. These include no data on pharmacokinetics in pregnancy and whether these are altered with co-administration of chlorproguanil. Potential complications in women with severe anaemia are unknown and there is no information on haemolytic effects in women or the fetus with G6PD deficiency. The use of dapsone in HIV-infected women in malarious areas could carry increased risks because of the immunosuppressive actions of the drug. Trials of dapsone therapy in pregnancy should be considered in malarious areas where there is good reason for its deployment. Controlled trials have provided data on maternal tolerance, and dapsone in combination with other antimalarial drugs can offer clear benefit in terms of improved birthweight. The use of dapsone combinations should be considered when no good alternative is available and the threat of malaria is the greater risk.

Dapsone therapy for children with immune thrombocytopenic purpura

Dapsone has been shown to be effective in treating adults with immune thrombocytopenic purpura (ITP). This retrospective review describes the authors' experience using dapsone in children with refractory, symptomatic ITP. Seven children were treated with dapsone. Dapsone was discontinued in two patients because of methemoglobinemia. In the remaining five patients, three achieved platelet counts of more than 100 x 10(3)/microL. Discontinuation resulted in a rapid decline in platelet counts in all three patients. Two of the three responded to a second round of treatment. Additional study of dapsone in children is warranted. Children receiving dapsone should be monitored for methemoglobinemia.

Platelet disorders in pregnancy

Before the advent of automated cell counters, thrombocytopenia was looked for and identified after a clinical question. With automation, thrombocytopenia in pregnancy was commonly found, and with its commonality its clinical meaning went out of focus. For the majority of women, thrombocytopenia is benign and, as a marker of fetal thrombocytopenia, the value of maternal thrombocytopenia is almost non-existent.