The incidence of agranulocytosis during treatment of dermatitis herpetiformis with dapsone as reported in Sweden, 1972 through 1988

Dapsone as a Detrimental Cause of Necrotizing Fasciitis With Severe Resistant Neutropenia: A Case Report

Dapsone, which is used for treating dermatological conditions, can lead to neutropenia. Especially, resistant neutropenia makes patients vulnerable to invasive infections, indicating a medical emergency. Febrile neutropenia secondary to dapsone intake should be treated promptly before the development of sepsis, which may lead to shock and death. In addition, necrotizing fasciitis is a severe and potentially fatal soft-tissue infection that rarely develops in healthy individuals with skin lesions. In this report, we present a case of a patient with no comorbidities who presented with necrotizing fasciitis and neutropenia with a history of dapsone intake.

A retrospective cohort study of infection risk in hospitalized patients evaluated for Sweet syndrome

Sweet syndrome (SS) is divided into malignancy-associated, classical, and drug-induced subtypes. Features associated with SS, such as fevers, neutropenia, and cancer, are also high risk for serious infection. We aimed to describe hospitalized patients with a documented concern for SS on initial dermatologic evaluation, their risk of infection, and the impact of SS subtype on treatment and outcomes. We descriptively analyzed hospitalizations at The Ohio State University evaluated for SS by dermatology and performed a retrospective cohort analysis of malignancy-associated and non-malignancy-associated SS patients. Eighty-seven patient hospitalizations were evaluated for SS from 2012 to 2019. Thirty-one hospitalizations were complicated by neutropenia. Lesions in 12.9% (n = 4/31) of neutropenic hospitalizations were infected with Fusarium species (n = 2) or methicillin-resistant staphylococcus aureus (n = 2). One patient with fungal disease died within 30 days of hospitalization. Thirty-three patients were confirmed to have a final diagnosis of SS. In the confirmed SS cohort, malignancy was associated with greater overall dapsone use (p = .021), less initial (p = .046) and overall (p = .013) corticosteroid use, and fewer SS-related readmissions within one year (p = .020) and overall (p = .004). Corticosteroid treatment delay should be considered for a short period in neutropenic patients while excluding infection. Malignancy-associated SS patients were more frequently treated with dapsone and favorable outcomes were seen in cancer patients.

Dapsone for the treatment of acne vulgaris: do the risks outweigh the benefits?

Dapsone is a "4,4'-diamino diphenyl sulfone" compound and an aniline derivative from synthetic sulfones. Sulfonamides were first used in humans as antimicrobial agents to treat streptococcal infections. Dapsone derived from sulfonamides was first used in the treatment of leprosy in 1940. Today, Dapsone treatment is among the treatment options for many dermatological diseases. Acne vulgaris is a chronic inflammatory disease, which causes scar formation and changed pigmentation. Acne affects 85% of teenagers, but can occur at any age and can last into adulthood and even lifelong. Through its antimicrobial, anti-inflammatory and antioxidant effects, dapsone treatment (local or systemic) can also be used in the treatment of acne. Dapsone treatment can cause a variety of side effects that can be categorized as pharmacological, dose-related, allergic, or idiosyncratic reactions. In this review article, the risks and benefits of using dapsone treatment in acne vulgaris will be evaluated in light of the literature.

Evolving Role of Pharmacogenetic Biomarkers to Predict Drug-Induced Hematological Disorders

ABSTRACT

Drug-induced hematological disorders constitute up to 30% of all blood dyscrasias seen in the clinic. Hematologic toxicity from drugs may range from life-threatening marrow aplasia, agranulocytosis, hemolysis, thrombosis to mild leukopenia, and thrombocytopenia. Pathophysiologic mechanisms underlying these disorders vary from an extension of the pharmacological effect of the drug to idiosyncratic and immune-mediated reactions. Predicting these reactions is often difficult, and this makes clinical decision-making challenging. Evidence supporting the role of pharmacogenomics in the management of these disorders in clinical practice is rapidly evolving. Despite the Clinical Pharmacology Implementation Consortium and Pharmacogenomics Knowledge Base recommendations, few tests have been incorporated into routine practice. This review aims to provide a comprehensive summary of the various drugs which are implicated for the hematological adverse events, their underlying mechanisms, and the current evidence and practical recommendations to incorporate pharmacogenomic testing in clinical care for predicting these disorders.

Idiosyncratic Drug-Induced Neutropenia and Agranulocytosis in Elderly Patients

Agranulocytosis is a rare, but serious and life-threatening hematologic disorder in elderly patients. Idiosyncratic drug-induced agranulocytosis (IDIA) has been classically defined by a neutrophil count below 0.5 × 10⁹/L. The annual incidence of IDIA in Europe is about 1.6–9.2 cases per million inhabitants. Increasing age and female sex have been considered as risk factors for the development of this condition. Besides, it is well known that older people take on average more drugs than younger people. This condition is most often associated with the intake of antibacterial agents, antiplatelets, antithyroids, antipsychotics, antiepileptics and nonsteroidal anti-inflammatory drugs (NSAIDs). Initially, agranulocytosis may present without symptoms, but may quickly progress to a severe infection and sepsis. The causative drug should be immediately stopped. In febrile patients, blood cultures and where indicated, site-specific cultures should be obtained and early treatment with empirical broad-spectrum antibiotics started. Even with adequate treatment, the mortality rate is higher in elderly patients reaching up to 20%. Hematopoietic growth factors have proven to be useful as they shorten the duration of neutropenia. However, data on neutropenia and agranulocytosis in the elderly meeting the criteria of evidence-based medicine are still poor in the literature. This review analyzes the results of our experience as well as other published studies of the universal literature.

Adverse reactions in leprosy patients who underwent dapsone multidrug therapy: a retrospective study

OBJECTIVE

To investigate the occurrence and clinical characteristics of dapsone-related adverse drug reactions (ADRs) among leprosy patients who underwent multidrug therapy (MDT) from 2010 to 2013 in the western region of Nepal.

METHODS

A retrospective review was carried out in the rehabilitation center. Data were collected from the record files of the hospital.

RESULTS

From 2010 to 2013, there were 18 patients reported to have dapsone ADRs, with an occurrence rate of 0.82% in the 4-year duration. The maximum incidence of ADRs (1.043%) was in 2010 and the minimum incidence of ADRs (0.26%) was in 2013. Among two types of bacterial infections, 94.44% were of multibacillary and 5.56% were of paucibacillary type. The age range of patients with dapsone ADRs was 11-68 years. The male-to-female ratio was 1.25. The onset of dapsone ADRs after taking MDT was within a minimum of 3 weeks and a maximum of 21 weeks. There were 14 (77.77%) patients who presented with jaundice, 8 (44.44%) with exfoliative dermatitis, 5 (27.77%) with hemolytic anemia and 4 (22.22%) with fever and headache. The rare side effects (5.5%) found were agranulocytosis or toxic epidermal necrolysis. Three patients were cured; some were still on the treatment. Four patients died with dapsone ADRs.

CONCLUSION

The common dapsone ADRs present in leprosy patients were jaundice, exfoliative dermatitis and hemolytic anemia in MDT-treated patients. Patients could be cured by managing the dapsone ADRs effectively on time. Some patients may die of dapsone ADRs if clinicians fail to manage the side effects on time.

Double-blind placebo-controlled trial of dapsone in antihistamine refractory chronic idiopathic urticaria

BACKGROUND

Management of antihistamine refractory chronic idiopathic urticaria (CIU) has poorly defined therapeutic options.

OBJECTIVE

To evaluate the efficacy of dapsone (4,4'-diaminodiphenylsulfone) in antihistamine refractory CIU compared with placebo.

METHODS

Twenty-two patients with antihistamine refractory CIU were randomly assigned to 100 mg of dapsone daily or placebo for 6 weeks in a 14-week double-blind, placebo-controlled crossover trial. End points were measured from a daily diary that reflected the weekly hive score, the weekly itch score, and a visual analog scale (VAS) score. Secondary to a carryover effect, the first period results were analyzed as a parallel design that compared placebo with dapsone directly by using repeated-measures analysis.

RESULTS

After 6 weeks, the patients in the dapsone arm showed mean improvement over baseline in VAS (2.3 [95% CI, 0.6-4.1], P = .01), urticaria score (-3.5 [95% CI, -6.2 to -0.9], P = .01), and itch score (-4.8 [95% CI, -7.6 to -2.1], P = .001), whereas the placebo arm showed no improvement over baseline for VAS, urticaria, or itch scores. Dapsone showed greater improvement compared with placebo for itch (P = .047) and VAS (P = .04). Of the 22 patients, 3 showed complete resolution of hives and itch with dapsone, whereas 31% and 41% had ≥ 50% resolution of hives and itch, respectively. No serious adverse effects were observed with dapsone.

CONCLUSION

To our knowledge, this is the first double-blind, placebo controlled study of dapsone in CIU and indicates that dapsone has efficacy in patients with antihistamine refractory CIU.

[Dermatitis herpetiformis: a review]

BACKGROUND

Dermatitis herpetiformis (DH) is a rare auto-immune bullous disease characterized by its almost constant association to gluten sensitivity.

OBJECTIVE

Review of literature about epidemiology, physiopathology, clinical data and treatment of DH.

METHODS

Research on Medline and Embase database without any time limit until April 2010. Because of the lack of randomized therapeutic trials in DH, retrospective series and case reports have been analyzed.

RESULTS

DH is related to auto-antibodies against epidermal transglutaminase, which belongs to the same family as tissue transglutaminase, the auto-antigen of celiac disease. Physiopathology is complex, occurring in HLA DQ2 or DQ8 predisposed patients, and implies gluten, immunological reaction in the intestinal wall then in the skin. DH and celiac disease may be encountered in the same family. DH is characterized by a very pruritic microvesicular eruption typically located on elbows, knees and buttocks. Digestive manifestations of celiac disease occur in 15% of cases. Direct immunofluorescence is necessary to confirm the diagnosis, showing granular IgA±C3 deposits in the papillary dermis. Circulating IgA and IgG antiendomysium and antitransglutaminase antibodies are detected in almost all patients at the acute phase and follow the clinical course of the disease. Gastro-intestinal endoscopy with multiple duodenal biopsies shows partial or complete villous atrophy in two thirds of cases, intraepithelial lymphocyte infiltrate in the other cases. Other auto-immune diseases may be associated in 10-20% of cases. The main long-term risk is the occurrence of T or B nodal or intestinal tract lymphoma in 2% of cases (relative risk close to 6 in several studies, but not admitted by all authors), especially if adherence to gluten-free diet is not strict. Treatment is based on dapsone, which is quickly efficient on cutaneous manifestations, but not on the digestive involvement and on strict and definitive gluten-free diet, which cures villous atrophy and reduces the risk of lymphoma.

CONCLUSION

DH is associated to a gluten enteropathy and its physiopathology is better known. Even if the risk of secondary lymphoma seems little, most of the authors recommend a definitive gluten-free diet.

The management of mucous membrane pemphigoid and pemphigus

Mucous membrane pemphigoid and pemphigus vulgaris are autoimmune blistering disorders in which many similar drugs and therapeutic strategies are utilized. In general, localized disease can be treated with topical agents. In contrast, patients with more severe and progressive disease usually require a combination of systemic corticosteroids and immunosuppressive medications. Oral corticosteroids, adjuvant immunosuppressive agents, antibiotics such as dapsone and immunomodulatory procedures like intravenous immunoglobulin are the main therapeutic agents used in treating these two disorders. Much of the morbidity and mortality associated with these disorders are related to the sites involved and to the drugs used for therapy. Treatment should be individualized based on severity, extent, and rate of progression of disease, comorbidities, and age of the patient. Serum levels of specific autoantibodies and indirect immunofluorescence titers, in certain cases, can be used to monitor response to therapy.

Efficacy of dapsone in the treatment of pemphigus and pemphigoid: analysis of current data

Dapsone is a chemotherapeutic agent primarily used in treating leprosy, Pneumocystis jiroveci (previously carinii) pneumonia, and malaria. It is also used as an adjuvant in the treatment of pemphigus and pemphigoid. To assess the role of dapsone in the treatment of pemphigus and pemphigoid, a retrospective review of reports in the English-language literature was conducted. Information on the number of patients treated, their average age, prior therapies, indications for use, protocol (dose and interval) used, concomitant therapies, reported adverse effects, and clinical outcomes were analyzed. There were 35 case reports/series published describing the use of dapsone in a total of 427 patients. Data on 55 pemphigus patients were obtained from several case reports and some case series and one randomized controlled trial. Of these, 32 patients with pemphigus vulgaris and 14 patients with pemphigus foliaceus responded to dapsone. Data from 13 case series, each including at least five patients, accounted for 372 patients with pemphigoid. The overall response rates to dapsone, when given either alone or in combination with corticosteroids or immunosuppressive agents, were 84% in mucous membrane pemphigoid, and 81% in bullous pemphigoid. Hemolysis was the most common adverse effect observed. Dapsone is a promising and useful agent in patients with autoimmune mucocutaneous blistering diseases, especially in mucous membrane pemphigoid. It can be used as a corticosteroid-sparing agent. Therefore, its combined use with oral corticosteroids may be useful in pemphigus vulgaris and bullous pemphigoid. Adverse effects of dapsone are dose dependent and usually reversible. Hemolysis and concomitant anemia secondary to hemolysis are expected in most patients. In the opinion of the authors, dapsone is underutilized in the treatment of autoimmune mucocutaneous blistering diseases.

Idiosyncratic drug-induced agranulocytosis: possible mechanisms and management

The incidence of drug-induced neutropenia has not changed in the western hemisphere over the last 30 years. Yet, the drug panorama has changed considerably. This implies that host factors may play an intriguing role for this idiosyncratic reaction. The knowledge as to mechanisms for the reaction has advanced with emerging understanding of neutropoiesis and immune regulation. Nonetheless, it is still remarkably difficult to pinpoint why and how a drug causes this unexpected, severe adverse event in a patient. Patient characteristics, e.g. genetics, appear to be keys for better understanding, predictions and prevention. Am. J. Hematol. 2009. (c) 2009 Wiley-Liss, Inc.

Drug-related blood dyscrasias in a Swedish reporting system, 1985-1994

Drug-related blood dyscrasias as reported in Sweden during a 10-yr period have been analysed in relation to sales and prescription data. The number of cases reported were as follows: agranulocytosis 390, thrombocytopenia 391, pancytopenia 50 and aplastic anaemia 36. The annual incidence rates per 10(6) inhabitants were: agranulocytosis 4.8, thrombocytopenia 5.6, pancytopenia 1.1 and aplastic anaemia 0.5. Incidences in the elderly were higher for all dyscrasias except aplastic anaemia. The most commonly reported drugs for all dyscrasias were sulphonamides and diuretics, but when related to sales data the risk of agranulocytosis was high for clozapine, dapsone, mianserin and sulphasalazine, while the risk did not seem to be increased for furosemide. For thrombocytopenia, furosemide, co-trimoxazole and the measles, mumps and rubella vaccine were most commonly reported. The risk for pancytopenia and aplastic anaemia was increased for acetazolamide and co-trimoxazole. As spontaneous reporting systems are primarily set up for signalling purposes, such data must always be interpreted with utmost care.

In Vivo Metabolism and Final Disposition of a Novel Nonsteroidal Androgen in Rats and Dogs

Compound S-4 (S-3-(4-acetylamino-phenoxy)-2-hydroxy-2-methyl-N-(4-nitro-3-trifluoromethyl-phenyl)-propionamide) is a novel nonsteroidal androgen agonist that mimics many of the beneficial pharmacologic effects of testosterone with lesser effects on the prostate. S-4 demonstrated high androgen receptor binding affinity as well as anabolic specificity during in vivo pharmacologic studies in rats, identifying it as the first member of a new class of selective androgen receptor modulators. The purpose of these studies was to determine the pharmacokinetics and metabolism of S-4 in dogs. S-4 showed linear pharmacokinetics after both intravenous (i.v.) and oral (p.o.) administrations at pharmacologically relevant doses, with a mean clearance of 4.6 ml/min/kg and a mean half-life of about 200 min. It is interesting that dose-dependent oral bioavailability was seen. However, at pharmacologically relevant doses, the oral bioavailability of S-4 was 91%. Species differences were observed in S-4 metabolism; the major metabolic pathway for S-4 in dogs was deacetylation of the B-ring acetamide group and reduction of the A-ring nitro group, whereas the major metabolic pathway for S-4 in rats was hydrolysis on the amide bond and reduction of the A-ring nitro group. In addition, oxidative metabolites and phase II metabolites were identified in both rats and dogs. These studies demonstrate that S-4 maintains its promising pharmacokinetic properties in dogs (i.e., high oral bioavailability and linear kinetics) and is largely eliminated via hepatic metabolism by both phase I and phase II enzymes.

Pharmacokinetics and metabolism of a selective androgen receptor modulator in rats: implication of molecular properties and intensive metabolic profile to investigate ideal pharmacokinetic characteristics of a propanamide in preclinical study

S-1 [3-(4-fluorophenoxy)-2-hydroxy-2-methyl-N-[4-nitro-3-(trifluoromethyl)phenyl]-propanamide] is one member of a series of potent selective androgen receptor modulators (SARMs) that are being explored and developed for androgen-dependent diseases. Recent studies showed that S-1 holds great promise as a novel therapeutic agent for benign hyperplasia [W. Gao, J. D. Kearbey, V. A. Nair, K. Chung, A. F. Parlow, D. D. Miller, and J. T. Dalton (2004) Endocrinology 145:5420-5428]. We examined the pharmacokinetics and metabolism of S-1 in rats as a component of our preclinical development of this compound and continued interest in structure-activation relationships for SARM action. Forty male Sprague-Dawley rats were randomly assigned to treatment groups and received either an i.v. or a p.o. dose of S-1 at a dose level of 0.1, 1, 10, or 30 mg/kg. S-1 demonstrated a low clearance (range, 3.6-5.2 ml/min/kg), a moderate volume of distribution (range, 1460-1560 ml/kg), and a terminal half-life ranging from 3.6 to 5.2 h after i.v. doses. The oral bioavailability of S-1 ranged from 55% to 60%. Forty phase I and phase II metabolites of S-1 were identified in the urine and feces of male Sprague-Dawley rats dosed at 50 mg/kg via the i.v. route. The two major urinary metabolites of S-1 were a carboxylic acid and a sulfate-conjugate of 4-nitro-3-trifluoromethylphenylamine. Phase I metabolites arising from A-ring nitro reduction to an aromatic amine and B-ring hydroxylation were also identified in the urinary and fecal samples of rats. Furthermore, a variety of phase II metabolites through sulfation, glucuronidation, and methylation were also found. These studies demonstrate that S-1 is rapidly absorbed, slowly cleared, moderately distributed, and extensively metabolized in rats.

Dapson-induzierte Agranulozytose

A 34-year-old female patient with a three year history of generalized granuloma annulare was treated systemically with dapsone (DADPS). Six weeks after the onset of treatment, the patient developed an extensive tonsillitis of the base of the tongue with fever and malaise. Routine laboratory work showed a leukocytopenia with agranulocytosis. Further investigation revealed a marked decrease of the enzyme activity of N-acetyltransferase 2, which plays an important role in dapsone metabolism. Treatment included the cessation of dapsone, antibiotic coverage, and G-CSF leading to the rapid improvement of symptoms and normalization of leukocyte counts. Dapsone-induced angina agranulocytotica is a rare event and is interpreted as an idiosyncratic reaction. Depending on genetic polymorphisms of various enzymes, dapsone can be metabolized to immunologically or toxicologically relevant intermediates. Because of the risk of severe hematologic reactions, dapsone should only be employed for solid indications and with appropriate monitoring.

Disulone

For 60 years, dapsone has been used as a both antibacterial and anti-inflammatory agent. Dapsone (4,4'-diaminodiphenylsulfone, DDS) continues to be used successfully to treat a wide range of dermatologic disorders, notably those characterized by abnormal neutrophil and eosinophil polynuclear accumulation. A considerable number of other inflammatory as well as bullous dermatoses, of which dermatitis herpetiformis is the best known, have been shown to respond in varying degrees to dapsone, although the indication for the molecule has not been demonstrated in of them all. This article reviews current knowledge on the pharmacokinetics, mechanism of action and side effects of dapsone in dermatology. Despite the lack of controlled studies, the aim of this study is to specify and classify the pathological states in which disulone could be indicated.

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.

Recognition and management of the cutaneous manifestations of celiac disease: a guide for dermatologists

In celiac disease, the ingestion of gluten-containing cereals, such as wheat, rye, and barley, results in small-bowel mucosal inflammation and villous atrophy with crypt hyperplasia. The prevalence of the condition may be as high as 1% in the adult population. The disease can also embrace various extraintestinal manifestations, of which dermatitis herpetiformis is the best known. Earlier, dermatitis herpetiformis was considered a skin disease occurring often concomitantly with celiac disease. At present, a body of evidence shows that dermatitis herpetiformis is a cutaneous manifestation of celiac disease, and affects approximately 25% of patients with celiac disease. Both conditions can appear in the same family and are closely linked to HLA class II locus in chromosome 6; 90% of patients have HLA DQ2 and, almost all the remainder, HLA DQ8. All patients with dermatitis herpetiformis have at least some-degree of mucosal inflammation or lesion consistent with celiac disease. The etiology of celiac disease in not fully understood, but tissue transglutaminase seems to be the predominant autoantigen both in the intestine and the skin. Serum antibodies against tissue transglutaminase can be used in the serologic screening and follow-up of dietary compliance of patients with celiac disease. Gluten-free diet is essential in the treatment of both conditions, and oral dapsone is usually needed in newly detected dermatitis herpetiformis in order to alleviate symptoms. Oral mucosal lesions, alopecia areata, and vitiligo probably occur more frequently in patients with dermatitis herpetiformis than in the general population. By contrast, the reported association of celiac disease with psoriasis seems to be coincidental.

Case-population studies in pharmacoepidemiology

The case-population approach aims at providing a risk estimate by comparing the incidence of the disease of interest among those exposed to the drug under study with the incidence among the non-exposed. For that purpose, the cases with the disease of interest have to be ascertained independently of the exposure status. Their rate and pattern of exposure have to be ascertained by interview with a structured questionnaire. Information on the patterns and the prevalence of drug consumption is needed in order to estimate the rate of exposure, and drug consumption statistics can be used to this end. In this paper, we review the main characteristics of studies using this approach or a similar one, and studies where series of cases exposed to the drug of interest were compared with drug consumption statistics. We looked at selected basic methodological requirements. Most of the studies reviewed suffer from incomplete case ascertainment, inaccurate definition of the disease of interest, incomplete information on exposures and other risk factors, and/or limited control of potential confounding, among other limitations. All the reviewed studies had several limitations regarding the estimation of the population at risk. The methods used in case-population studies should be clearly described, particularly with respect to the identification of the cases (numerator) and the estimation of the consumption prevalence (denominator). Case-population studies can give approximate risk estimates, but the method should be validated by comparing its results with those of case-control studies.

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.

Cicatricial pemphigoid

Cicatricial pemphigoid (CP) is a heterogeneous group of rare, chronic, subepithelial blistering disorders of the mucous membranes and, occasionally, the skin, which can have serious and rarely fatal consequences. The most common clinical features are desquamative gingivitis, oral erosions, and conjunctival fibrosis. Skin lesions occur less frequently and may present as widespread vesicles and bullae, as in bullous pemphigoid (BP). In some patients, the scarring can be a source of significant morbidity because it can result in odynophagia, strictures of the upper aerodigestive tract, or corneal opacities leading to eventual blindness. This article is a comprehensive review and discusses clinical, pathologic, and pathophysiologic aspects of this group of disorders collectively known as CP. (J Am Acad Dermatol 2000;43:571-91.)

LEARNING OBJECTIVE

At the conclusion of this learning activity, participants should be familiar with the clinical spectrum of CP, the histopathologic and immunopathologic characteristics, the differential diagnosis, the treatment, and the natural history of the disease. Furthermore, this learning activity should facilitate early diagnosis of CP and should promote the idea that the involvement of other specialists, including ophthalmologists, otolaryngologists, gastroenterologists, and oral medicine specialists, as appropriate, will aid in providing these patients with the highest quality of care.

Reactions and interactions of some commonly used systemic drugs in dermatology

This article deals with the main interactions and adverse effects of some drugs that are used daily by dermatologists. It includes tetracyclines and Minocycline in the treatment of acne; antimalarials and discoid lupus; dapsone; thalidomine; oral retinoids; methotrexate and cyclosporine. Several of these drugs are discussed.

Dapsone toxicity: some current perspectives

1. Dapsone is a potent anti-inflammatory and anti-parasitic compound, which is metabolised by cytochrome P-450 to hydroxylamines, which in turn cause methaemoglobinaemia and haemolysis. However, during the process of methaemoglobin formation, erythrocytes are capable of detoxifying the hydroxylamine to the parent drug, which may either reach the tissues to exert a therapeutic effect or return to the liver and be re-oxidised in a form of systemic cycling. This glutathione-dependent effect, combined with the un-ionised state of the drug at physiological pH, may contribute to its efficacy. 2. Paradoxically, other aspects of the glutathione-dependent cycling of the hydroxylamine metabolite may contribute to the major adverse reaction of the drug, agranulocytosis. Erythrocytes exposed to the metabolite and repeatedly washed may still release the hydroxylamine in sufficient concentration to kill mononuclear leucocytes in vitro. Thus, erythrocytes may be a conduit for the hydroxylamine to reach the bone marrow to covalently bind to granulocyte precursors, which may trigger an immune response in certain individuals and may lead to the potentially fatal eradication of granulocytes from the circulation. 3. Attempts to increase patient tolerance to dapsone have been most successful using a metabolic inhibitor to reduce hepatic oxidation of the drug to the hydroxylamine. Methaemoglobin formation in the presence of cimetidine was maintained at 30% below control levels for almost 3 mo, and patients' reported side effects such as headache and lethargy were significantly reduced. 4. As clinical application of new and safer dapsone analogues is years away, the use of cimetidine provides an immediate route to increasing patient compliance during dapsone therapy, especially in those maintained on dapsone dosages in excess of 200 mg/day.

Minimizing cicatricial pemphigoid orodynia with minocycline

Cicatricial pemphigoid is a rare autoimmune blistering disease of the elderly. It predominantly affects the mucosae, causing pain and scarring. the target antigen is within the lamina lucida of the basement membrane zone. Potential complications of systemic steroid and other immunosuppressive therapy have prompted trials of other means of treatment. We describe a series of seven patients treated with minocycline, six of whom derived sustained alleviation of orodynia. Four patients developed hyperpigmentation, and two complained of gastrointestinal discomfort which necessitated cessation of minocycline. Complete steroid withdrawal was achieved in two cases. Neither the disease progression nor the response to treatment was influenced by the immunoglobulin isotype or titre. The role of minocycline as a useful adjunct to therapy is discussed.

Dapsone-induced aplastic anemia in a woman with bullous systemic lupus erythematosus

Aplastic anemia developed in a black woman who was receiving dapsone therapy for bullous systemic lupus erythematosus. Aplastic anemia is an uncommon adverse hematologic effect in patients treated with dapsone, the pathogenesis of which remains unknown. To our knowledge, dapsone-induced aplastic anemia has been previously reported in only four patients; the characteristics of their cases are described herein. Conservative monitoring of hematologic variables may alert clinicians to the early stages of this rare drug reaction.

Individualized drug utilization statistics. Analysing a population's drug use from the perspective of individual users

The Danish retail pharmacies' drug subsidy system is completely computerized. The data are person-identifiable, making it possible to chart the population's drug use from the perspective of individual users. We decided to explore the potential of this data source and to analyse heavy drug users specifically. The analysis encompassed all 890,352 prescriptions presented by citizens of Odense in 1991. There was a total sales volume of 32 million defined daily doses consumed by 113,468 adult drug users, corresponding to 65.1% of the adult population. We found 2388 heavy drug users, defined by an annual purchase of more than 2000 defined daily doses. Heavy drug users accounted for 1.4% of the adult population and 22.9% of drug sales. They were remarkably well characterized by their main therapeutic class, which constituted a median of 47% of their drug use. A median of 97% of each heavy user's drugs were issued by one main prescriber. We conclude that heavy drug use can generally be ascribed to severe disease rather than to irresponsible prescribing. For the most important drug classes, we present various epidemiological measures of drug use, including 1-year prevalence, incidence, duration of therapy and some measures of skewness in utilization. If analysed regularly these measures can disclose subtle trends in clinical drug use that would not be evident from the wholesale figures.

Reduction of dapsone hydroxylamine to dapsone during methaemoglobin formation in human erythrocytes in vitro. IV: Implications for the development of agranulocytosis

We have studied the efflux of dapsone hydroxylamine from normal and diabetic erythrocytes by the use of a two-compartment (1 and 2) in vitro dialysis system, in order to model the in vivo blood supply to the bone marrow. When both types of erythrocytes were dialysed against mononuclear leucocytes, the hydroxylamine crossed the membrane and caused significantly greater white cell death compared with dialysis of leucocytes against untreated erythrocytes. However, in the case of both normal and diabetic cells, the presence of the glutathione depletor diethyl maleate (DEM) caused a marked reduction in movement of hydroxylamine from compartment 1 to 2. Diethyl dithiocarbamate (DDC), a methaemoglobin accelerant, caused a marked reduction in movement of hydroxylamine from erythrocytes (diabetic and normal) in compartment 1 to 2 which led to a significant reduction in white cell death compared with the absence of DDC (18.3 +/- 5.5 vs 34.8 +/- 8.1%, P < 0.05). Dapsone recovery from compartment 1 rose significantly in the presence of DDC compared with control in both erythrocyte types. In contrast, recovery of dapsone from normal erythrocytes incubated in compartment 1 was significantly reduced by the presence of DEM compared with control, although there was no difference between control and DEM-treated diabetic cells. Dapsone analysis in compartment 2 revealed a significant increase in dapsone recovery in both diabetic (11.3 +/- 1.1%) and normal (11.9 +/- 1.1%) erythrocytes in the presence of DDC compared with diabetic (3.3 +/- 0.4%) and normal control (4.8 +/- 2.0%, P < 0.001). The presence of DEM in compartment 1 caused a significant fall in dapsone recovery in compartment 2 (3.7 +/- 0.26) compared with control (4.7 +/- 0.36%, P < 0.05). Hence, dapsone hydroxylamine is capable of leeching out of normal and diabetic erythrocytes, traversing a semipermeable membrane and causing toxicity to human mononucleocyte cells in vitro. This process may be one of the first stages in immune-mediated agranulocytosis.

Sulfasalazine associated agranulocytosis in Sweden 1972-1989. Clinical features, and estimation of its incidence

During the 18 year period 1972-1989 a total of 62 cases of agranulocytosis associated with the use of sulphasalazine were reported to the Swedish Adverse Drug Reactions Advisory Committee (SADRAC). The median age of the patients was 52 y and median duration of sulphasalazine treatment was 43 days. The fatality rate was 6.5%, and among patients who recovered the median recovery time was 10 days. Twelve patients were treated concomitantly with other drugs generally suspected to induce agranulocytosis. From sales and prescription data the average incidence of agranulocytosis during sulphasalazine therapy was estimated to be 1/1750 patient years of exposure. From an ongoing Prescription Monitoring Project in a Swedish county it was possible to calculate the proportion of patients receiving sulphasalazine for different periods of time. The incidence of agranulocytosis during the first 30 days was estimated to be 1/2400 patients, while it was 1/700 between Days 31-90 and 1/11200 during Days 91-365. The risk of developing agranulocytosis during sulphasalazine treatment is considerable during the first three months of treatment, and the traditional way of expressing the risk (1/1750 patient years) underestimates the risk for the individual patient.

The use of cimetidine to reduce dapsone-dependent methaemoglobinaemia in dermatitis herpetiformis patients

1. We have attempted to reduce dapsone-dependent methaemoglobinaemia formation in six dermatitis herpetiformis patients stabilised on dapsone by the co-administration of cimetidine. 2. In comparison with control, i.e. dapsone alone, methaemoglobinaemia due to dapsone fell by 27.3 +/- 6.7% and 26.6 +/- 5.6% the first and second weeks after commencement of cimetidine administration. The normally cyanotic appearance of the patient on the highest dose of dapsone (350 mg day-1), underwent marked improvement. 3. There was a significant increase in the trough plasma concentration of dapsone (2.8 +/- 0.8 x 10(-5)% dose ml-1) at day 21 in the presence of cimetidine compared with control (day 7, 1.9 +/- 0.6 x 10(-5)% dose ml-1, P less than 0.01). During the period of the study, dapsone-mediated control of the dermatitis herpetiformis in all six patients was unchanged. 4. Trough plasma concentrations of monoacetyl dapsone were significantly increased (P less than 0.05) at day 21 (1.9 +/- 1.0 x 10(-5)% dose ml-1) compared with day 7 (1.6 +/- 0.9 x 10(-5)% dose ml-1:control). 5. Over a 12 h period, 20.6 +/- 8.9% (day 0) of a dose of dapsone was detectable in urine as dapsone hydroxylamine. Significantly less dapsone hydroxylamine was recovered from urine at day 14 (15.0 +/- 8.4) in the presence of cimetidine, compared with day 0 (control: P less than 0.05). 6. The co-administration of cimetidine may be of value in increasing patient tolerance to dapsone, a widely used, effective, but comparatively toxic drug.

Monitoring for adverse effects from systemic drugs used in dermatology

Systemic drugs with an associated element of risk are essential in managing many important dermatoses. This review identifies eight major drugs or drug groups used in dermatology that require systematic monitoring for adverse effects. The complete monitoring process is emphasized, including significant patient involvement in reporting key signs or symptoms that allow early diagnosis of many of these adverse effects. The concepts of "risk-risk" assessment and "critical toxicities" are defined, emphasizing their important role in maximizing drug benefits and safety. Drug-related risk factors, disease-specific risk factors, and patient characteristics or habits that increase the risks from systemic drugs are identified. Basic principles of monitoring for adverse effects, specific clinical features of the most important adverse effects, along with detailed monitoring guidelines for methotrexate, retinoids, dapsone, corticosteroids, and cyclosporine are presented.

The role of leukocyte-generated reactive metabolites in the pathogenesis of idiosyncratic drug reactions

Evidence strongly suggests that many adverse drug reactions, including idiosyncratic drug reactions, involve reactive metabolites. Furthermore, certain functional groups, which are readily oxidized to reactive metabolites, are associated with a high incidence of adverse reactions. Most drugs can probably form reactive metabolites, but a simple comparison of covalent binding in vitro is unlikely to provide an accurate indication of the relative risk of a drug causing an idiosyncratic reaction because it does not provide an indication of how efficiently the metabolite is detoxified in vivo. In addition, the incidence and nature of adverse reactions associated with a given drug is probably determined in large measure by the location of reactive metabolite formation, as well as the chemical reactivity of the reactive metabolite. Such factors will determine which macromolecules the metabolites will bind to, and it is known that covalent binding to some proteins, such as those in the leukocyte membrane, is much more likely to lead to an immune-mediated reaction or other type of toxicity. Some reactive metabolites, such as acyl glucuronides, circulate freely and could lead to adverse reactions in almost any organ; however, most reactive metabolites have a short biological half-life, and although small amounts may escape the organ where they are formed, these metabolites are unlikely to reach sufficient concentrations to cause toxicity in other organs. Many idiosyncratic drug reactions involve leukocytes, especially agranulocytosis and drug-induced lupus. We and others have demonstrated that drugs can be metabolized by activated neutrophils and monocytes to reactive metabolites. The major reaction appears to be reaction with leukocyte-generated hypochlorous acid. Hypochlorous acid is quite reactive, and therefore it is likely that many other drugs will be found that are metabolized by activated leukocytes. Some neutrophil precursors contain myeloperoxidase and the NADPH oxidase system, and it is likely that these cells can also oxidize drugs. Therefore, although there is no direct evidence, it is reasonable to speculate that reactive metabolites generated by activated leukocytes, or neutrophil precursors in the bone marrow, could be responsible for drug-induced agranulocytosis and aplastic anemia. This could involve direct toxicity or an immune-mediated reaction. These mechanisms are not mutually exclusive, and it may be that both mechanisms contribute to the toxicity, even in the same patient. In the case of drug-induced lupus, a prevalent hypothesis for lupus involves modification of class II MHC antigens.(ABSTRACT TRUNCATED AT 400 WORDS)