SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Dapsone has been examined by two established animal anti-inflammatory models and found to possess anti-inflammatory activity comparable with established non-steroidal anti-inflammatory drugs. Dapsone also possess some biochemical properties common to other anti-inflammatory drugs.
Sulfonamide- and sulfone-induced hypersensitivity reactions are thought to be mediated through bioactivation of parent drug molecule(s) to their respective reactive metabolite(s). Recent studies have demonstrated that keratinocytes can bioactivate sulfonamides and sulfones. Using enzyme-linked immunosorbent assay and hapten-specific rabbit antisera developed in our laboratory, we found that incubation of either normal human epidermal keratinocytes (NHEKs) or an immortalized human keratinocyte cell line (HaCaT) with sulfamethoxazole (SMX) or dapsone (DDS) resulted in the formation of drug/metabolite protein adducts. The formation of these adducts with SMX was increased in the presence of ascorbic acid, whereas N-acetylcysteine decreased adduct formation with both SMX and DDS. Adduct formation was confirmed using confocal microscopy when NHEKs were incubated with SMX, DDS, or their respective arylhydroxylamine metabolites. Cellular distribution of adducts was compared in permeable versus nonpermeable NHEKs. Exposure to SMX, DDS, or dapsone hydroxylamine resulted in the formation of intracellular adducts, whereas SMX hydroxylamine also resulted in the presence of adducts on the cell surface. In summary, our work shows that keratinocytes can bioactivate SMX/DDS to form drug-protein adducts, which may be acquired by antigen-presenting cells upon keratinocyte cell death, evoking an immune response. In addition, keratinocytes may themselves present antigen to hapten-specific cytotoxic T lymphocytes. Furthermore, our results also suggest that different sulfonamides/sulfones may have different protein targets for in situ haptenation in keratinocytes.
Of 25 dapsone derivatives and analogs screened for activity against Mycobacterium leprae in the mouse footpad system, only 7 were active. All seven were metabolized to or contaminated with dapsone.
The in vitro activity of trimethoprim plus dapsone against oxacillin-resistant Staphylococcus aureus was comparable to that of trimethoprim plus sulfamethoxazole. Because of its different pharmacologic properties, dapsone may be a useful agent in combination with trimethoprim for the treatment of patients colonized with oxacillin-resistant S. aureus.
Twenty-four patients with newly diagnosed lepromatous leprosy were allocated randomly to three groups and treated for 56 days with 400 mg of ofloxacin daily, 800 mg of ofloxacin daily, or 400 mg of ofloxacin, 100 mg of dapsone, and 50 mg of clofazimine daily plus 300 mg of clofazimine once every 28 days. The patients in all three groups demonstrated remarkable clinical improvements, accompanied by rapid decline of the morphological index in skin smears during treatment. More than 99, > 99.99, and > 99.99% of the viable Mycobacterium leprae organisms had been killed by 14, 28, and 56 days of treatment, respectively, as measured by inoculation into the footpads of immunocompetent and nude mice of organisms recovered from skin biopsy specimens obtained before and during treatment. Mild to moderate elevations of the serum glutamic pyruvic transaminase level were observed in four patients, all after 28 days of treatment, which returned to normal after the trial had been completed. Clinical improvement, bactericidal activity, and hepatotoxicity did not differ significantly among the three groups. Ofloxacin displayed powerful bactericidal activity against M. leprae in leprosy patients and may be an important component of new multidrug regimens for the treatment of leprosy. Its optimal dosage appears to be 400 mg daily, and combination with dapsone and clofazimine does not enhance its activity.
WR99210, a dihydrofolate reductase inhibitor, has promising in vitro activity against Mycobacterium avium complex (MAC). The in vitro activities of WR99210 alone and in combination with a fixed concentration of dapsone (0.5 microgram/ml) were evaluated against 35 clinical MAC isolates by a broth dilution method. The MIC at which 50% of isolates were inhibited (MIC50) and MIC90 of WR99210 alone were 2 and 8 micrograms/ml, respectively. The MIC50 and MIC90 of WR99210 in combination with dapsone were 0.25 and 4 micrograms/ml, respectively. Overall, 75% of the MAC isolates displayed enhanced susceptibility to the combination.
B6C3F1 mice that had been thymectomized at 8 to 12 weeks of age, subjected to 950 R of whole-body X irradiation, and transfused with syngeneic bone marrow were challenged in a footpad with Mycobacterium leprae or M. marinum, or intravenously or intraperitioneally with Listeria monocytogenes. Also, mice inoculated with M. leprae in a hind footpad were administered dapsone in the mouse chow. The thymectomized-irradiated (T + R) mice did not survive as well as non-thymectomized mice when housed in the vivarium with no special precautions, but survived sufficiently well to permit the completion of some long-term experiments. M. leprae multiplied to a higher "ceiling" and survived longer in the T + R mice than in the non-thymectomized controls. But a ceiling to multiplication of M. leprae was imposed, and finally the organisms were killed. The histopathological appearance of the footpad tissues, studied by electron microscopy, was consistent with the measurements of bacterial numbers and viability. Swelling of the footpad after local inoculation with M. marinum was greater in T + R mice than in non-thymectomized controls. Similarly, the number of L. monocytogenes following intravenous challenge was greater in the spleens of T + R than of non-thymectomized mice, and the survival of the T + R mice was impaired after intraperitoneal challenge with L.monocytogenes, compared to the survival of non-thymectomized mice. None of these differences was striking, suggesting that these T + R mice had retained or regained some immune competence. The effects of dapsone treatment of T + R mice inoculated with M. leprae were much the same as those of treatment of non-thymectomized mice. Because these T + R mice were not greatly immunosuppressed, they would not have provided a model of human lepromatous leprosy suitable for chemotherapeutic studies.
Dapsone given over 14 weeks in a dose of 50 mg a day for 1 week and thereafter 100 mg a day was found to have a beneficial effect in rheumatoid arthritis when compared with placebo administration to a matched group of patients. Significant improvement in 5 out of 7 clinical measurements and in erythrocyte sedimentation rate, viscosity, C-reactive protein was found in those patients taking dapsone. There was significant improvement compared to the placebo group in 2 out of the 7 clinical measurements and again in all 3 acute-phase reactants. The drug was quite well tolerated over the 14-week duration of the trial. The tendency to cause haemolysis will be its main limiting factor as a practical alternative to other suppressive agents currently in use.
Oral dapsone was used to treat five patients who presented in the acute inflammatory phase of ocular pemphigoid. The diagnosis was made clinically by identifying cicatricial changes which were in some cases difficult to find. In all cases it was the inflammatory rather than the cicatricial features which responded to treatment. An initial dose of 100 mg/day was effective without toxicity. When 150 mg/day was used patients experienced side effects. A clinical response was obtained after 1-4 weeks and could be maintained on a dose of between 50 mg on alternate days and 100 mg/day. Therapy was withdrawn during remissions which lasted up to 32 weeks but all cases required continuing therapy which has remained effective. Immunopathological examination was carried out on two occasions in all cases and although positive on at least one occasion the results did not correlate with disease activity or treatment. The inflammatory phase of ocular pemphigoid should be added to the list of diseases responsive to dapsone.
The relative risks of non-specific upper respiratory tract infections were studied in two well matched groups of military recruits to see whether dapsone-pyrimethamine (Maloprim) given as antimalarial prophylaxis was associated with immunosuppression. Mean risks of upper respiratory tract infection were 64% higher in the study group than in the controls, the largest monthly differences being recorded in the months of harder training. These findings were unlikely to have been due solely to harder training in the study group, as concurrently measured sprains (arguably more likely to have been affected) were increased by only 19%. A more likely explanation was some degree of immunosuppression, physical stress possibly having a synergistic effect. These findings suggest that travellers taking dapsone-pyrimethamine as antimalarial prophylaxis may be rendered more susceptible to commoner infections, especially when engaged in increased physical activity.
Concentrations of dapsone (DDS) and its metabolite, monoacetyl dapsone (MADDS) were measured in plasma and saliva samples collected concurrently from volunteers receiving a 50-mg oral dose of DDS. A liquid chromatographic technique was employed to separate the compounds from each other and from endogenous materials. Fluorescence detection provided limited sensitivities to 0.1 ng/ml of sample. Saliva levels of DDS were consistently 15-20% of the plasma levels of DDS during the study period, which ranged from 4 to 48 h. Decay rates for DDS from saliva and plasma were nearly identical. In 4-hour samples of plasma subjected to equilibrium dialysis, we found amounts of DDS in the dialysates nearly identical to levels found in saliva collected at that time. Saliva levels of MADDS ranged from 0.8 to 2.6% of their plasma levels at all times. Decay rates of MADDS from the two fluids were nearly identical and saliva levels of MADDS in 4-hour samples were nearly identical to levels found in paired plasma dialysates. Nevertheless, levels of MADDS were so low that a reliable definition of the subjects' acetylator phenotype from levels of MADDS in saliva only was impossible.
A case of dapsone-induced severe haemolytic anaemia and agranulocytosis is described. A possible common pathogenic mechanism for the simultaneous occurrence of these side effects of dapsone therapy in a patient with normal glucose-6-phosphate-dehydrogenase activity is proposed.
With the purpose of obtaining pro-drugs of dapsone and sulfadimethoxine, those chemotherapeutic agents were attached through covalent bonding to starch polymeric dialdehyde (Sumstar-190). The antimalarial activity of the two resulting compounds - the dapsone saccharidic polymer (PS6) and the sulfadimethoxine saccharidic polymer (PS7) - in mice experimentally inoculated with Plasmodium berghei was significantly increased with this molecular modification. Mice infected with malaria and kept without treatment together with others which received different doses of PS6 and PS7 were also partially or totally cured, possibly due to the ingestion of excrements containing the parent chemotherapeutic agents.
The multiple-dose kinetics of a daily dose of proguanil (200 mg) coadministered with dapsone (10 mg) was investigated in 6 healthy adult male volunteers. The kinetics of dapsone (DDS), monoacetyldapsone (MADDS), proguanil (PROG) and its active metabolite cycloguanil (CYCLO) were derived from plasma drug concentrations after the last maintenance dose. The following kinetic parameters (mean values) were estimated for DDS and PROG, respectively: maximum concentration (Cmax) = 285 and 151 ng/ml, minimum concentration (Cmin) = 125 and 31 ng/ml, elimination half-life (t1/2) = 23.3 and 18.3 h, plasma clearance (Cl) = 0.032 and 1.27 l/h/kg and apparent volume of distribution (Vss) = 1.05 and 33.32 l/kg. The Cmax, Cmin and t1/2 of CYCLO were 56 ng/ml, 17 ng/ml and 15.0 h, respectively. The antimalarial activity of the proguanil/dapsone combination was assessed in vitro by measuring the inhibition of re-invasion of two Plasmodium falciparum isolates grown in the presence of volunteers' sera. Both FC-27 [chloroquine (CQ)- and pyrimethamine (PYR)-sensitive] and K1 (CQ- and PYR-resistant) isolates were completely inhibited by the drug combination at steady-state concentrations. These findings suggest that the drug regimen may be effective against drug-resistant falciparum malaria.
Dapsone 100 mg daily led to a rapid and complete clearing of extensive vasculitic urticarial lesions in a female patient with systemic lupus erythematosus. Complement determinations revealed an intensive activation of the classical pathway before dapsone therapy. Normalization of CH50, C1 and C2 occurred during the treatment, whereas C3 and C4 remained lowered.
Hypocomplementemic urticarial vasculitis (HUV) is often misdiagnosed. The response to drug therapy may be unsatisfactory, and immunosuppressive therapy may be associated with significant side effects. A 35-year-old patient whose condition was resistant to cyclophosphamide, corticosteroids, pentoxyphylline, cyproheptadine, sulindac, and colchicine was maintained in remission with dapsone, which may be the drug of choice for HUV. Emphysema has been reported to complicate HUV, but this is the first account of vasculitis-related emphysema with no confounding history of tobacco smoke exposure. The relationship of proteolytic injury to the pulmonary and other manifestations is considered, as is the possible role for dapsone in reducing it.
The authors present a case of methaemoglobinaemia of acute onset, with an unusually protracted course. The long persistence of this disorder led to a search for the cause which was eventually traced to medication with dapsone. The latter was found to be inappropriately being taken by the patient instead of an antispasmodic that had been prescribed for a spinal condition; this was because the tablets had been incorrectly labelled and dispensed in a pharmacy. The patient took increasing doses of the presumed 'antispasmodic' tablets as they seemed to lack clinical effect, thus further exacerbating the toxic consequences. Moreover, the patient brought his wrongly labelled tablets into hospital and was allowed to use them there, contrary to normal hospital policy. As treatment for the methaemoglobinaemia both bolus and continuous infusions of methylene blue were used, which probably contributed to the severe haemolysis which followed. Furthermore, the development of a rare side effect of dapsone toxicity, namely that of a sensorimotor neuropathy, is reported.
Dapsone produces a potentially reversible toxic neuropathy, with its primary effect on the soma and axons of motor neurons as opposed to myelin. There is very little evidence to suggest involvement of sensory axons in most cases; if present, it would appear minimal. A "dying back" of motor axons is postulated to produce the clinical features of primarily distal weakness and wasting. Recovery appears to occur via axon regeneration and peripheral sprouting. The sporadic occurrence of this neuropathy may be due to slow acetylation of dapsone in some patients.