Dapsone attenuates kainic acid-induced seizures in rats

Characterization of the anticonvulsant effect of dapsone on metabolic activity assessed by [18F]FDG -PET after kainic acid-induced status epilepticus in rats

BACKGROUND

Development of effective drugs for epilepsy are needed, as nearly 30 % of epileptic patients, are resistant to current treatments. This study is aimed to characterize the anticonvulsant effect of dapsone (DDS), in the kainic acid (KA)-induced Status Epilepticus (SE) by recording the brain metabolic activity with an [¹⁸F]FDG-PET analysis.

METHODS

Wistar rats received KA (10 mg/kg, i.p., single dose) to produce sustained seizures. [¹⁸F]FDG-PET and electroencephalographic (EEG) studies were then performed. DDS or vehicle were administered 30 min before KA. [¹⁸F]FDG uptake and EEG were evaluated at baseline, 2 and 25 h after KA injection. Likewise, caspase-8, 3 hippocampal activities and Fluoro-Jade B neuronal degeneration and Hematoxylin-eosin staining were measured 25 h after KA.

RESULTS

PET data evaluated at 2 h showed hyper-uptake of [¹⁸F]FDG in the control group, which was decreased by DDS. At 25 h, hypo-uptake was observed in the control group and higher values due to DDS effect. EEG spectral power was increased 2 h after KA administration in the control group during the generalized tonic-clonic seizures, which was reversed by DDS, correlated with [¹⁸F]FDG-PET uptake changes. The values of caspases-8 activity decreased 48 and 43 % vs control group in the groups treated with DDS (12.5 y 25 mg/kg respectively), likewise; caspase-3 activity diminished by 57 and 53 %. Fewer degenerated neurons were observed due to DDS treatments.

CONCLUSIONS

This study pinpoints the anticonvulsant therapeutic potential of DDS. Given its safety and effectiveness, DDS may be a viable alternative for patients with drug-resistant epilepsy.

Dapsone, More than an Effective Neuro and Cytoprotective Drug

BACKGROUND

Dapsone (4,4'-diamino-diphenyl sulfone) is a synthetic derivative of sulfones, with the antimicrobial activity described since 1937. It is also a drug traditionally used in dermatological therapies due to its anti-inflammatory effect. In recent years its antioxidant, antiexcitotoxic, and antiapoptotic effects have been described in different ischemic damage models, traumatic damage, and models of neurodegenerative diseases, such as Parkinson's (PD) and Alzheimer's diseases (AD). Finally, dapsone has proven to be a safe and effective drug as a protector against heart, renal and pulmonary cells damage; that is why it is now employed in clinical trials with patients as a neuroprotective therapy by regulating the main mechanisms of damage that lead to cell death ObjectiveThe objective of this study is to provide a descriptive review of the evidence demonstrating the safety and therapeutic benefit of dapsone treatment, evaluated in animal studies and various human clinical trials Methods: We conducted a review of PubMed databases looking for scientific research in animals and humans, oriented to demonstrate the effect of dapsone on regulating and reducing the main mechanisms of damage that lead to cell death ConclusionThe evidence presented in this review shows that dapsone is a safe and effective neuro and cytoprotective treatment that should be considered for translational therapy.

Eutectics and Salt of Dapsone With Hydroxybenzoic Acids: Binary Phase Diagrams, Characterization and Evaluation

Poor solubility and low dissolution rate of pharmaceuticals in many cases largely limit their bioavailability and efficacy. One of the promising approaches to improve dissolution behavior is to develop new multicomponent solid forms. Herein we use this strategy to synthesize new multicomponent solids of dapsone (DAP), which belongs to BCS class IV, with a series of hydroxybenzoic acid coformers. A new salt of DAP with 2,6-dihydroxybenzoic acid (26DHBA) and 4 eutectics with other hydroxybenzoic acids were reported through comprehensive characterizations using powder X-ray diffraction DSC, and vibrational spectroscopy techniques. The salt formation was evidenced by the presence of ionic interactions detected using FT-IR and Raman spectroscopy, and the stoichiometric ratio was determined to be 1:1. Binary phase diagrams were established to determine the composition of eutectics. The cause for salt and eutectic selection was further understood by computing molecular electrostatic potential (MEP) surface where 26DHBA shows the greatest acidity. Moreover, the powder dissolution study and microenvironment pH measurement reveal that both salt and eutectics of DAP display improvements on the dissolution rate and equilibrium concentration in which the acidity of coformers plays a dominant role. Our findings provide a direction for future coformer screening of multicomponent solids with improved pharmaceutical properties.

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.

Antioxidant, anticonvulsive and neuroprotective effects of dapsone and phenobarbital against kainic acid-induced damage in rats

Excitotoxicity due to glutamate receptors (GluRs) overactivation is a leading mechanism of oxidative damage and neuronal death in various diseases. We have shown that dapsone (DDS) was able to reduce both neurotoxicity and seizures associated to the administration of kainic acid (KA), an agonist acting on AMPA/KA receptors (GluK1-GluK5). Recently, it has been shown that phenobarbital (PB) is also able to reduce epileptic activity evoked by that receptor. In the present study, we tested the antioxidative, anticonvulsive and neuroprotective effects of DDS and PB administered alone or in combination upon KA toxicity to rats. Results showed that KA increased lipid peroxidation and diminished reduced glutathione (GSH), 24 h after KA administration and both drugs in combination or individually inhibited these events. Likewise, KA promotes mortality and this event was antagonized by effect of both treatments. Additionally, the behavioral evaluation showed that DDS and PB administered alone or in combination decreased the number of limbic seizures and reduced the percentage of animals showing tonic-clonic seizures versus the control group, which was administered only with KA. Finally, our study demonstrated that all of the treatments prevented the neuronal death of the pyramidal cell layer of hippocampal CA-3. In conclusion, the treatment with DDS and PB administrated alone or in combination exerted antioxidant, anticonvulsive and neuroprotective effects against the neurotoxicity induced by KA in rats, but their effects were not additive. Thus, it may be good options of treatment in diseases such as epilepsy and status epilepicus, administered separately.

Safety and tolerability of dapsone for the treatment of patients with drug-resistant, partial-onset seizures: an open-label trial

Dapsone has shown anti-convulsive properties in animal models of epilepsy. In the present study, we tested the safety and tolerability of dapsone as adjunctive therapy in adult patients with drug-resistant partial-onset seizures. Twenty-two adult patients with drug-resistant partial-onset seizures were included. After a 3-month baseline period, patients received dapsone 100 mg per day, for a 3-month evaluation period. Plasma concentrations of anti-epileptic drugs (AEDs) did not significantly change during the study. No alteration of mean clinical laboratory values was observed. The reported adverse events were: mild methemoglobinemia (50%), headache (31.8%), paleness (27.3%) and somnolence (4.5%).Sixteen of 22 patients reduced their seizure frequency in more than 50% as a result of dapsone treatment. Three subjects remained seizure-free during the entire dapsone treatment period. This open-label study of adjunctive dapsone therapy at 100 mg/day suggests that dapsone is safe, and well-tolerated in adults with drug-resistant partial-onset seizures.

Delayed administration of dapsone protects from tissue damage and improves recovery after spinal cord injury

After spinal cord injury (SCI), a complex cascade of pathophysiological processes increases the primary damage. The inflammatory response plays a key role in this pathology. Recent evidence suggests that myeloperoxidase (MPO), an enzyme produced and released by neutrophils, is of special importance in spreading tissue damage. Dapsone (4,4'-diaminodiphenylsulfone) is an irreversible inhibitor of MPO. Recently, we demonstrated, in a model of brain ischemia/reperfusion, that dapsone has antioxidant, antiinflammatory, and antiapoptotic effects. The effects of dapsone on MPO activity, lipid peroxidation (LP) processes, motor function recovery, and the amount of spared tissue were evaluated in a rat model of SCI. MPO activity had increased 24.5-fold 24 hr after SCI vs. the sham group, and it had diminished by 38% and 19% in the groups treated with dapsone at 3 and 5 hr after SCI, respectively. SCI increased LP by 45%, and this increase was blocked by dapsone. In rats treated with dapsone, a significant motor function recovery (Basso-Beattie-Bresnahan score, BBB) was observed beginning during the first week of evaluation and continuing until the end of the study. Spontaneous recovery 8 weeks after SCI was 9.2 ± 1.12, whereas, in the dapsone-treated groups, it reached 13.6 ± 1.04 and 12.9 ± 1.17. Spared tissue increased by 42% and 33% in the dapsone-treated groups (3 and 5 hr after SCI, respectively) vs. SCI without treatment. Dapsone significantly prevented mortality. The results show that inhibition of MPO by dapsone significantly protected the spinal cord from tissue damage and enhanced motor recovery after SCI.

Innovative use of dapsone

After synthesis of dapsone (4,4' diaminodiphenylsulfone) in 1908, the compound was known exclusively in chemistry. Following the epoch-making discovery of the antimicrobial potential for sulfonamides emerged, the sulfone class was included in the medical armamentarium. The therapeutic role of sulfones related to both pathogen-caused diseases and chronic inflammatory dermatoses has led to extensive use in dermatology. At present dapsone is the only sulfone congener available for clinical practice. The sulfone is used in rifampin-based multiple-drug regiments to treat multibacillary and paucibacillary leprosy and to treat Pneumocystis jiroveci pneumonia and prevent toxoplasmosis in individuals with AIDS. In dermatology, dapsone is the preferred drug for treating dermatitis herpetiformis (Duhring's disease) and is useful in the management of a broad range of chronic inflammatory entities, especially autoimmune bullous disorders. With proper administration and monitoring, the sulfone should be considered a useful and safe agent.

Neuroprotective effect of dapsone in an occlusive model of focal ischemia in rats

Dapsone (4,4'-diaminodiphenylsulfone) is employed in the chemotherapy against leprosy. Dapsone also prevents neuronal damage induced by glutamate agonists. As glutamate excitotoxicity is implicated in the damage after ischemia, we tested the ability of dapsone to prevent ischemic injury in a model of permanent middle cerebral artery (MCA) occlusion in rats. Either dapsone (9.375 or 12.5 mg/kg doses) or vehicle were i.p. administered 30 min after occlusion. Rats from the control group showed a permanent neurological deficit after occlusion, while dapsone-treated groups improved significantly. Dapsone-treated animals showed a reduction of 93% (9.375 mg/kg dose) and 92% (12.5 mg/kg dose) in the infarction volume as compared to control values.

Anticonvulsant activity of dapsone analogs. Electrophysiologic evaluation

BACKGROUND

In a previous study we reported that 4,4'diaminodiphenylsulfone (dapsone) has anticonvulsant activity using kainic acid (KA) model. This work shows the behavioral and electrophysiologic changes caused by systemic application of several dapsone derivatives. These derivatives include disodium salt of 4,4'-diaminodifenylsulfone N,N'-diformaldehyde sulfoxylate (I), 4,4'-diaminodiphenylsulfone N,N'-didextrose sulfonate (II), sodium dibisulfite 4,4'-biscinamilidenamindiphenyl sulfone (III), and N,N'-dimethyl-4,4'-dimethylphenylsulfone (IV), which were synthesized and purified in our laboratory.

METHODS

A KA model was used to provoke limbic seizures. Limbic seizures were provoked by injection, KA, and electrophysiologic recorder at the following concentrations: 6.25 and 12.50 mg/kg of III and 6.25 and 12.50 mg/kg of IV.

RESULTS

Compounds III and IV caused decrease of postdischarges; we found percentage of protection of 55.60 and 70.78%, respectively. This showed possible anticonvulsant activity of these compounds (III and IV), while I and II showed no significant changes. We also studied whether there was a dose-dependence relationship, and different doses of compound IV were evaluated (25.00, 12.50, 6.25, 3.12, and 1.62 mg/kg). We found that greatest anticonvulsant effect occurred using doses of 3.12 and 6.25 mg/kg (two of the three lowest doses).

CONCLUSIONS

We concluded that IV at doses of 3.25 and 6.25 mg/kg has anticonvulsant effect because it diminished duration of the first limbic seizure induced by KA; latency of first limbic seizure crisis was also increased. Both facts demonstrated possible therapeutic application of compound IV as anticonvulsant.

Dapsone prevents morphological lesions and lipid peroxidation induced by quinolinic acid in rat corpus striatum

Increasing doses of dapsone were tested on rats administered intrastriatally with quinolinic acid in order to evaluate a possible protective action of this drug on the striatal lesions produced after the excessive activation of N-methyl-D-aspartate receptors. Morphological lesions were evaluated 7 days after the intrastriatal injection of quinolinate (240 nmol/microl) by light microscopy, and the ratio of neuronal damage per field was also estimated as a quantitative index of the striatal toxicity. Quinolinate alone produced extensive necrosis and loss of striatal neurons. No protective effects on the striatal tissue from quinolinate-treated rats were observed at lower doses of dapsone (6.25 and 9.375 mg/kg). However, at higher doses (12.5 and 25 mg/kg), dapsone prevented significantly the striatum from quinolinate toxicity. Dapsone alone had no effect on the striatal tissue from control rats. A single dose of dapsone (12.5 mg/kg) was tested also on the index of lipid peroxidation 2 h after the striatal injection of quinolinate, resulting in a significant protection (78% vs. QUIN). Findings of this study, in accordance with our previous reports, demonstrate the ability of dapsone to prevent the neuronal damage associated with the excitatory action of quinolinate via overactivation of NMDA receptors, and provide evidences to support the hypothesis that this drug is acting against the pattern of toxicity elicited by agonists of glutamate receptors.