In Situ Cocrystallization of Dapsone and Caffeine during Fluidized Bed Granulation Processing.

Different pharmaceutical manufacturing processes have been demonstrated to represent feasible platforms for the production of pharmaceutical cocrystals. However, new methods are needed for the manufacture of cocrystals on a large scale. In this work, the suitability of the use of a fluidized bed system for granulation and concomitant cocrystallization was investigated. Dapsone (DAP) and caffeine (CAF) have been shown to form a stable cocrystal by simple solvent evaporation. DAP is the active pharmaceutical ingredient (API) and CAF is the coformer. In the present study, DAP-CAF cocrystals were produced through liquid-assisted milling and the product obtained was used as a cocrystal reference. The granulation of DAP and CAF was carried out using four different experimental conditions. The solid-state properties of the constituents of the granules were characterised by differential scanning calorimetry (DSC) and x-ray powder diffraction (PXRD) analysis while the granule size distribution and morphology were investigated using laser diffraction and scanning electron microscopy (SEM), respectively. DAP-CAF cocrystal granules were successfully produced during fluidized bed granulation. The formation of cocrystals was possible only when the DAP and CAF were dissolved in the liquid phase and sprayed over the fluidized solid particles. Furthermore, the presence of polymers in solution interferes with the cocrystallization, resulting in the amorphization of the DAP and CAF. Cocrystallization via fluidized bed granulation represents a useful tool and a feasible alternative technique for the large scale manufacture of pharmaceutical cocrystals for solid dosage forms.

Development and Characterization of Dapsone Cocrystal Prepared by Scalable Production Methods.

In this study, the formation of caffeine/dapsone (CAF/DAP) cocrystals by scalable production methods, such as liquid-assisted grinding (LAG) and spray drying, was investigated in the context of the potential use of processed cocrystal powder for pulmonary delivery. A CAF/DAP cocrystal (1:1 M ratio) was successfully prepared by slow evaporation from both acetone and ethyl acetate. Acetone, ethyl acetate, and ethanol were all successfully used to prepare cocrystals by LAG and spray drying. The powders obtained were characterized by X-ray diffractometry (XRD), differential scanning calorimetry (DSC), thermogravimetry (TGA), and Fourier transform infrared spectroscopy (FTIR). Laser diffraction analysis indicated a median particle size (D50) for spray-dried powders prepared from acetone, ethanol, and ethyl acetate of 5.4 ± 0.7, 5.2 ± 0.1, and 5.1 ± 0.0 µm respectively, which are appropriate sizes for pulmonary delivery by means of a dry powder inhaler. The solubility of the CAF/DAP cocrystal in phosphate buffer pH 7.4, prepared by spray drying using acetone, was 506.5 ± 31.5 µg/mL, while pure crystalline DAP had a measured solubility of 217.1 ± 7.8 µg/mL. In vitro cytotoxicity studies using Calu-3 cells indicated that the cocrystals were not toxic at concentrations of 0.1 and of 1 mM of DAP, while an in vitro permeability study suggested caffeine may contribute to the permeation of DAP by hindering the efflux effect. The results obtained indicate that the CAF/DAP cocrystal, particularly when prepared by the spray drying method, represents a possible suitable approach for inhalation formulations with applications in pulmonary pathologies.

Ligand-Controlled Synthesis of Azoles via Ir-Catalyzed Reactions of Sulfoxonium Ylides with 2-Amino Heterocycles.

An iridium-catalyzed method was developed for the synthesis of imidazo-fused pyrrolopyrazines. The presence or absence of a nitrogenated ligand controlled the outcome of the reaction, leading to simple ß-keto amine products in the absence of added ligand and the cyclized 7- and 8-substituted-imidazo[1,2-a]pyrrolo[2,3-e]pyrazine products in the presence of ligand. This catalyst control was conserved across a variety of ylide and amine coupling partners. The substrate was shown to act as a ligand for the iridium catalyst in the absence of other ligands via NMR spectroscopy. Kinetic studies indicated that formation of the Ir-carbene was reversible and the slow step of the reaction. These mechanistic investigations suggest that the ß-keto amine products form via an intramolecular carbene N-H insertion, and the imidazopyrrolopyrazines form via an intermolecular carbene N-H insertion.

Dapson in heterocyclic chemistry, part V: synthesis, molecular docking and anticancer activity of some novel sulfonylbiscompounds carrying biologically active dihydropyridine, dihydroisoquinoline, 1,3-dithiolan, 1,3-dithian, acrylamide, pyrazole, pyrazolopyrimidine and benzochromenemoieties.

N,N'-(4,4'-Sulfonylbis(4,1-phenylene))bis(2-cyanoacetamid) 2 was utilized as a key intermediate for the synthesis of novel dihydropyridines 3, 4, 8, dihydroisoquinolines 5-7, dithiolan 10, dithian 11, acrylamide 12, benzochromenes 17 and 18 and chromenopyridones 19 and 20. Compound 2 was the starting material in the synthesis of the acrylamide derivative 14, the pyrazole derivative 15 and the pyrazolopyrimidine derivative 16. All the synthesized compounds were evaluated for their in vitro anticancer activity against human breast cancer cell line (MCF7). Compound 19 showed the best cytotoxic activity with IC(50) value 19.36 µM. In addition, molecular docking study of the synthesized compounds on the active sites of farnesyltransferase and arginine methyltransferase was performed in order to give a suggestion about the mechanism of action of their cytotoxic activity.

Acyl derivatives of p-aminosulfonamides and dapsone as new inhibitors of the arginine methyltransferase hPRMT1.

Arginine methylation is an epigenetic modification that receives increasing interest as it plays an important role in several diseases. This is especially true for hormone-dependent cancer, seeing that histone methylation by arginine methyltransferase I (PRMT1) is involved in the activation of sexual hormone receptors. Therefore, PRMT inhibitors are potential drugs and interesting tools for cell biology. A dapsone derivative called allantodapsone previously identified by our group served as a lead structure for inhibitor synthesis. Acylated derivatives of p-aminobenzenesulfonamides and the antilepra drug dapsone were identified as new inhibitors of PRMT1 by in vitro testing. The bis-chloroacetyl amide of dapsone selectively inhibited human PRMT1 in the low micromolar region and was selective for PRMT1 as compared to the arginine methyltransferase CARM1 and the lysine methyltransferase Set7/9. It showed anticancer activity on MCF7a and LNCaP cells and blocked androgen dependent transcription specifically in a reporter gene system. Likewise, a transcriptional block was also demonstrated in LNCaP cells using quantitative RT-PCR on the mRNA of androgen dependent genes.

Computer-aided synthesis of dapsone-phytochemical conjugates against dapsone-resistant Mycobacterium leprae.

Leprosy continues to be the belligerent public health hazard for the causation of high disability and eventual morbidity cases with stable prevalence rates, even with treatment by the on-going multidrug therapy (MDT). Today, dapsone (DDS) resistance has led to fear of leprosy in more unfortunate people of certain developing countries. Herein, DDS was chemically conjugated with five phytochemicals independently as dapsone-phytochemical conjugates (DPCs) based on azo-coupling reaction. Possible biological activities were verified with computational chemistry and quantum mechanics by molecular dynamics simulation program before chemical synthesis and spectral characterizations viz., proton-HNMR, FTIR, UV and LC-MS. The in vivo antileprosy activity was monitored using the 'mouse-foot-pad propagation method', with WHO recommended concentration 0.01% mg/kg each DPC for 12 weeks, and the host-toxicity testing of the active DPC4 was seen in cultured-human-lymphocytes in vitro. One-log bacilli cells in DDS-resistant infected mice footpads decreased by the DPC4, and no bacilli were found in the DDS-sensitive mice hind pads. Additionally, the in vitro host toxicity study also confirmed that the DCP4 up to 5,000 mg/L level was safety for oral administration, since a minor number of dead cells were found in red color under a fluorescent microscope. Several advanced bioinformatics tools could help locate the potential chemical entity, thereby reducing the time and resources required for in vitro and in vitro tests. DPC4 could be used in place of DDS in MDT, evidenced from in vivo antileprosy activity and in vitro host toxicity study.

Studies on the toxicity of analogues of dapsone in-vitro using rat, human and heterologously expressed metabolizing systems.

Three metabolizing systems (rat, heterologously expressed CYP3A4 and human liver) were used to evaluate 12 analogues of dapsone (4,4'diaminodiphenylsulphone) in-vitro. Methaemoglobin formation in a two-compartment and cytotoxicity in a single-compartment model were studied using human erythrocytes and neutrophils, respectively, as target cells. In the two-compartment system using rat microsomes as a generating system and methaemoglobin as an endpoint, the least potent methaemoglobin formers tested were the 2-methyl-4-propylamino (AXDD14), 2-hydroxy-4-4'amino (ABDD5) derivatives and a sulphone/trimethoprim derivative (K-130). Dapsone itself, a 2-methoxy-4-ethylamino (W10) and a 2-hydroxyl-4-ethylamino compound (ABDD39) were the most toxic. In the single-compartment cytotoxicity test using rat microsomes, AXDD14 was again among the least toxic, as was a 2-methyl 4-cyclopentyl derivative (AXDD17) and surprisingly ABDD39. The most cytotoxic compounds again included dapsone itself as well as two 2-trifluoromethyl derivatives. The only significant methaemoglobin formation and cytotoxicity shown with the heterologously expressed human CYP 3A4 was with AXDD14, which was extensively activated. Interestingly, metabolism of dapsone was low using the expressed CYP 3A4. In the two-compartment system using human liver microsomes, AXDD14, K-130 and ABDD5 were oxidized to a significantly lesser extent compared with dapsone and these preliminary findings indicate that future development of these compounds may be worthwhile.

Chemical drug delivery systems: I. Preparation and evaluation of prodrugs of dapsone.

Several prodrugs of dapsone have been prepared and evaluated in vivo for the release of parent drug. The prodrug: 4,4'-dibutyrylaminodiphenyl sulfone gave blood levels above 0.5 micrograms/ml of DDS for about 34 days in rabbits injected intragluteally. The results have been compared with DDS and DADDS.

[Synthesis of promin in Japan and global elimination of Hansen's disease].

Prof. Morizo Ishidate synthesized "Promin" for the treatment of leprosy/Hansen's disease which had been considered "incurable" until the discovery of antileprosy effect of that drug by Dr. Faget of U.S.A. in 1941. Prof. Ishidate was the first to synthesize the drug in Japan in 1946 based on a brief news item on a Swiss journal smuggled in during the War. For this achievement, he is known as "father of chemotherapy for leprosy in Japan." Prof. Ishidate also contributed to the global fight against leprosy as the Chairman of the Board of Directors of Sasakawa Memorial Health Foundation, which he helped to establish in May 1974, with a full financial backing of Mr. Ryoichi Sasakawa, President of Japan Shipbuilding Industry Foundation. Prof. Ishidate, with his scientific knowledge as well as christianity based humanitarian concern, advised Mr. Sasakawa how to spend JSIF money wisely for eliminating leprosy and nearly US$200 million was channeled through WHO and SMHF. The successful outcome of global multidrug therapy (MDT) programme in the '80s resulted in the adoptation of resolution by the World Health Assembly, "Elimination of Leprosy, as a public health problem" by the Year 2000. The synthesis of "Promin" in Japan and promoting the global implementation of MDT, both achievement can be attributed to Prof. Ishidate.

Studies on 2,3,N,N'-substituted 4,4'-diaminodiphenylsulfones as potential antimalarial agents.

A series of new 4,4'-diaminodiphenylsulfones substituted at 2 and 3 position and also at primary amino group of the phenyl rings have been synthesized and evaluated for their antimalarial activity against Plasmodium berghei infection in mice. Some of these compounds were active and showed complete inhibition of parasitaemia which included 7a1-7a4, 7b3, 7b4 and 16a at 1 mg/kg i.p. for 4 days and 16a, at 0.3 mg/kg for 4 days. Some compounds tested for their synthetase inhibitory action in cell-free system isolated from P. berghei (7b1, 7b2 and 8b2) were found to be more active than diaminodiphenylsulphone. The difference in order of activity between these in vivo and in vitro tests may be due to differences in their pharmacokinetic properties.

Activation of CYP2C9-mediated metabolism by a series of dapsone analogs: kinetics and structural requirements.

Cytochrome P450 2C9-mediated metabolism has been shown to be activated in the presence of the effector dapsone. However, it has yet to be established what effector structural features are necessary to activate CYP2C9 activity. To address this question, kinetic studies were conducted with nine analogs of dapsone containing various functional properties (three sulfone compounds, three carbonyl compounds, and three sulfonamide compounds), to examine the functional groups important for enzyme activation by the effector (dapsone). Results show that phenylsulfone (dapsone without the para-amino groups) activates flurbiprofen 4'-hydroxylation comparable to dapsone but inhibits naproxen demethylation. Meanwhile, p-tolylsulfone had little effect on flurbiprofen metabolism, but activated naproxen demethylation, albeit only at high concentrations. These substrate-dependent differences in effect suggest that naproxen has a different binding orientation compared with flurbiprofen. Perhaps most interesting is that replacement of only one amino group from dapsone with a nitro group (4-(4-nitrophenylsulfonyl)-aniline) resulted in substantial inhibition of flurbiprofen 4'-hydroxylation, suggesting that electronic effects may influence activation of this substrate. Other analogs either had minor or no effect on CYP2C9-mediated metabolism. Overall, it is apparent from these studies that a sulfone group in direct association with two benzene rings with para-electron-donating groups represents the most efficient activator of CYP2C9. However, the effects of these analogs appear to be concentration- and substrate-dependent, further complicating the prediction of these types of in vitro interactions.

New antifolate 4,4'-diaminodiphenyl sulfone substituted 2,4-diamino-5-benzylpyrimidines. Proof of their dual mode of action and autosynergism.

New 4,4'-diaminodiphenylsulfone substituted 2,4-diamino-5-benzylpyrimidines were synthesized. These compounds are highly active inhibitors of both bacterial dihydrofolate reductase (DHFR) and dihydropteroic acid synthase (SYN). The simultaneous inhibition of both enzymes leads to autosynergism in whole cells in the same way as known for combinations of sulfonamides with trimethoprim. The inhibitory activity is demonstrated in cell-free systems of DHFR and SYN derived from various species (M. lufu, E. coli, C. albicans) and in whole cell systems of the mycobacterial strain M. lufu. The compounds are rare examples for the combination of two mechanisms of action in one molecule.

Preparation and biological activity of new substituted antimalarial diaminodiphenylsulfones.

Starting from 4,4'-diamino-diphenylsulfone (DDS) as a lead structure, new 2-substituted analogues as well as new 2-substituted 4-alkylamino-4'-amino diphenylsulfones have been designed and synthetized in different ways. This has led to compounds the inhibitory activity of which against 7,8-dihydropteroic acid synthase of plasmodia and mycobacteria is clearly superior to that of sulfadoxine and in most cases to that of DDS. Of special interest is 4'-amino-4-n-propylamino-2-methyl-diphenylsulfone. Together with inhibitors of 7,8-dihydrofolate reductase in vitro and in vivo it possesses a marked synergistic inhibitory activity against plasmodia. In contrast to DDS in doses up to 200 mg/kg p.o. (cat) no methemoglobin formation is observed. The compound has been selected for further studies.

Acometimento hepático na síndrome sulfona dapsona-induzida durante tratamento de hanseníase / Hepatic involvement in sulfone dapsone-induced syndrome during treatment of leprosy

A hanseníase é uma doença endêmica no Brasil e constitui grave problema de saúde pública. Em números absolutos, o Brasil é o segundo país que mais registra novos casos da doença por ano no mundo. O tratamento da hanseníase compreende: quimioterapia específica, supressão dos surtos reacionais, prevenção de incapacidades físicas, reabilitação física e psicossocial. A síndrome sulfona é uma condição multissistêmica potencialmente grave que pode ocorrer durante o tratamento de algumas dermatoses, entre elas a hanseníase. Relatamos um caso de síndrome de hipersensibilidade à dapsona (SHD) em um paciente masculino, de 32 anos, ocorrida durante o tratamento de hanseníase multibacilar...