Development, Pharmacokinetics and Antimalarial Evaluation of Dose Flexible 3D Printlets of Dapsone for Pediatric Patients.

The focus of current studies was to fabricate dose flexible printlets of dapsone (DDS) for pediatric patients by selective laser sintering (SLS) 3D printing method, and evaluate its physicochemical, patient in-use stability, and pharmacokinetic attributes. Eight formulations were fabricated using Kollicoat® IR, Eudragit® L-100-55 and StarCap®as excipients and evaluated for hardness, disintegration, dissolution, amorphous phase by differential scanning calorimetry and X-ray powder diffraction, in-use stability at 30 oC/75% RH for a month, and pharmacokinetic study in Sprague Dawley rats. The hardness, and disintegration of the printlets varied from 2.6±1.0 (F4) to 7.7±0.9 (F3) N and 2.0±0.4 (F2) to 7.6±0.6 (F3) sec, respectively. The drug was partially present as an amorphous form in the printlets. The drug was completely (>85%) dissolved in 20 min. No change in drug form or dissolution extent was observed after storage at in use condition. Pharmacokinetic profiles of both formulations (tablets and printlets) were almost superimposable with no statistical difference in pharmacokinetic parameters (Tmax, Cmax, and AUC0-¥)between formulations (p>0.05). Values of EC50 (half maximal effective concentration) and EC90 (maximal concentration inducing 90% maximal response) were 0.50±0.15 and 1.32±0.26 mM, 0.41±0.06 and 1.11±0.21, and 0.42±0.13 and 1.36±0.19 mM for DDS, printlet and tablet formulations, respectively, and differences were statistically insignificant (p>0.05). In conclusion, tablet and printlet formulations are expected to be clinical similar, thus clinically interchangeable.

Non-compartmental and population pharmacokinetic analysis of dapsone in healthy NIGERIANS: A pilot study.

Dapsone is employed for both non-dermatological and dermatological indications but with non-existent population pharmacokinetics (popPK) data in Nigerians. This study was therefore designed to develop a popPK model in Nigerians. Non-compartmental analysis and nonlinear mixed effects modelling were utilized for data analysis. Eleven participants administered 50 mg dapsone tablet were included in the analysis. Derived pharmacokinetic parameters were: Cmax = 1.16 ± 0.32 µg/mL, Tmax = 3.77 ± 2.40 h, and t1/2z = 30.23 ± 11.76 h. PopPK model parameter estimates with inter-individual variability were Tlag = 0.40 h (10.0%, fixed); ka = 1.78 h-1 (75.9%); V/F = 89.25 L (21.6%); and Cl/F = 1.32 Lh-1 (27.7%). Sex was significantly associated with Cl/F, and body weight with V/F. Best popPK model was one-compartment with lag time, and first-order absorption and elimination. Sex and body weight significantly influenced the clearance and distribution volume of dapsone respectively.

Pharmacoproteomic analysis of topical dapsone and prednisolone interventions in the aqueous humor of anterior uveitis.

Uveitis is the inflammation of uveal tract comprising of iris, ciliary body and choroid. Blood ocular barriers maintaining the homeostasis of eye breach during uveitis, leads to high risk for sight-threatening complications. The purpose of this study was to compare the anti-inflammatory activity enabled by two diverse pharmacological agents (prednisolone and dapsone) using their effect on aqueous humor proteome. Wistar rats of either sex (150-200g) were used and randomly divided into various groups. Normal group was injected with 0.1ml normal saline (NS), endotoxin (LPS) (200 µg/0.1ml NS) was injected into endotoxin induced inflammatory groups followed by 0.1% dapsone and 1% prednisolone treatment in endotoxin induced uveitis (EIU) groups, respectively. Aqueocentesis was performed post 24 hour inflammation and samples were subjected for clinical parameter evaluation, cytokine analysis as well as global proteomic analysis using High-resolution mass spectrometer. Following which spectrum analysis, production spectra of peptides were matched against R. Norvegicus Protein Database (Uniport) using Proteome Discoverer (v2.2). Upon clinical evaluation, the anterior segment images post dapsone and prednisolone treatment have shown marked decrease in hyperaemia, miosis and iridial vessels vasodilation in rat eyes as compared to inflammation group. The result of cytokine analysis revealed 0.1% dapsone and prednisolone both significantly decreased the TNF-α levels. HRMS studies analysis expressed 140, 160, 158 and 141 proteins unique to normal, EIU, Dapsone and prednisolone group respectively. To conclude aqueous humor pharmacoproteomic revealed the anti-inflammatory activity of the dapsone comparable to the prednisolone treatment in endotoxin induced uveitis. The topical dapsone may be used as an alternative therapeutic option in treating uveitis without elevating intraocular pressure.

Effects of shuanghuanglian injection on the activities of CYP1A2, 2C11, 2D1 and 3A1/2 in rats in vivo and in vitro.

Shuanghuanglian Injection (SHLI), one of the most popular herbal prescription in China, has been commonly used to treat pneumonia, tonsillitis, and other respiratory diseases caused by bacterium and virus. This study is to investigate the effects of SHLI on the activities of Cytochrome P450 (CYP) 1A2, 2C11, 2D1 and 3A1/2 in rats. Sixteen rats were randomly divided into two groups (SHLI-treated and blank control). They were administered SHLI or physiological saline for consecutive seven days. On day eight, 16 animals were administrated cocktail drugs as probe substrates of the four CYP in vivo. In addition, other four probe drugs were added, respectively, into incubation systems of rat liver microsomes (RLM) to assess the effects of SHLI on the four CYP isoforms in vitro. SHLI exhibited an inductive effect on CYP2C11 in vivo by decreasing Cmax, t1/2 and AUC0-∞ of tolbutamide, while the main pharmacokinetic parameters of caffeine, metoprolol and dapsone have no significant changes. In vitro study, SHLI showed no significant effects on the activities of CYP1A2, 2D1 and 3A1/2, but increasing the metabolism of tolbutamide in RLM. SHLI induced the activities of CYP2C11, but had no significant effects on the activities of CYP1A2, CYP2D1 and CYP3A1/2 in rats.

Safety and Pharmacokinetics of Once-Daily Dapsone Gel, 7.5% in Patients With Moderate Acne Vulgaris.

BACKGROUND: Reducing the dosing frequency of topical acne treatments to once daily may improve adherence. OBJECTIVE: Evaluate pharmacokinetics (PK), safety, and tolerability of 3 formulations of once-daily dapsone gel, 7.5% and of twice-daily dapsone gel, 5% over 28 days in patients with moderate acne vulgaris. METHODS: This phase 1, multicenter, parallel-group study randomized males and females aged 16 to 35 years to 1 of 3 dapsone gel, 7.5% formulations (DAP-11078, DAP-11079, or DAP-11080 double-blind; applied once daily) or to dapsone gel, 5% (investigator-blinded only, applied twice-daily). Blood samples were collected for PK assessments of dapsone and its metabolites, N-acetyl dapsone (NAD) and dapsone hydroxylamine (DHA), before the morning dose on days 1, 7, 14, 18, 21, 26, 27, and 28, and at several follow-up time points (days 29-32). Safety profile assessments included adverse events (AEs), physical examinations, laboratory tests, and local tolerability assessments. RESULTS: Steady-state dapsone, NAD, and DHA concentrations were reached within 7 days of the first dose in all treatment groups. Daily systemic exposures of the 3 dapsone gel, 7.5% formulations were approximately 25% to 40% lower than that for dapsone gel, 5%, and these differences were statistically significant. Among the 3 dapsone gel, 7.5% formulations, the highest daily exposure of dapsone (per the AUC) was observed with DAP-11080, with respective Cmax and AUC0-24 being approximately 28.6% and 28.7% lower relative to dapsone gel, 5%. Most AEs were mild to moderate in intensity. The safety profiles for all 3 formulations of once-daily dapsone, 7.5% gel and twice-daily dapsone gel, 5% were similar following 28 days of topical administration. All 4 dapsone formulations were well tolerated. CONCLUSIONS: This study demonstrated lower systemic exposure with all 3 once-daily dapsone gel, 7.5% formulations than with twice-daily dapsone gel, 5%. All 4 formulations were well tolerated and demonstrated similar safety profiles.

J Drugs Dermatol. 2016;15(10):1250-1259.

Dapsone and body mass index in subjects with multibacillary leprosy.

BACKGROUND: The physiological changes in obese subjects can modify the pharmacokinetic profiles of drugs influencing the therapeutic efficacy. METHODS: In this study, the authors compare plasma dapsone trough levels of multibacillary leprosy subjects stratified by body mass index (BMI) to evaluate if obesity plays a significant role on drug levels. The relationship between drug levels and BMI was also determined. Dapsone was measured by high-performance liquid chromatography and BMI based on World Health Organization criteria. RESULTS: At steady state, the median plasma dapsone trough level was significantly lower in obesity class 2 group, when compared with other groups, but they were similar between normal weight and preobesity groups. A weak association between drug levels and BMI was observed. CONCLUSIONS: Obesity promotes a significant reduction in plasma dapsone trough levels of subjects with multibacillary leprosy with a weak association between drug levels and BMI.

Effects of Panax notoginseng saponins on the activities of CYP1A2, CYP2C9, CYP2D6 and CYP3A4 in rats in vivo.

The aim of this study was to assess the influence of the Panax notoginseng saponins (PNS) on the activities of the drug-metabolizing enzymes cytochrome P450 (CYP450) 1A2, 2 C9, 2D6 and 3A4 in rats. The activities of CYP1A2, 2 C9, 2D6 and 3A4 were measured using specific probe drugs. After pretreatment for 1 week with PNS or physiological saline (control group), probe drugs caffeine (10 mg/kg; CYP1A2 activity), tolbutamide (15 mg/kg; CYP2C9 activity), metoprolol (20 mg/kg; CYP2D6 activity) and dapsone (10 mg/kg; CYP3A4 activity) were administered to rats by intraperitoneal injection. The blood was then collected at different times for ultra performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) analysis. The data showed that PNS exhibited an induction effect on CYP1A2 by decreasing caffeine C(max) (36.3%, p < 0.01) and AUC(0-∞) (22.77%, p < 0.05) and increasing CL/F (27.03%, p < 0.05) compared with those of the control group. Western blot analysis was used to detect the effect of PNS on the protein level of CYP1A2, and the results showed that PNS could upregulate the protein expression of CYP1A2. However, no significant changes in CYP2C9, 2D6 or 3A4 activities were observed. In conclusion, the results indicate that PNS could induce CYP1A2, which may affect the disposition of medicines primarily dependent on the CYP1A2 pathway. Our work may be the basis of related herb-drug interactions in the clinic.

Localization of artesunate and its derivatives in the pregnant rat and fetus following oral administration and relationship to developmental toxicity.

BACKGROUND: The antimalarial drug artesunate affects erythroid cells leading to developmental toxicity and adult reticulocytopenia. We report on a kinetic study in rats and the tissue distribution of radioactivity following oral administration of [(3)H]-artesunate to pregnant rats using quantitative whole-body autoradiography (QWBA). METHODS: Rats were dosed orally with chlorproguanil/dapsone/artesunate (including 11.8 mg/kg artesunate) and plasma concentrations of artesunate and the active metabolite dihydroartemisinin (DHA) were determined. In the QWBA study, 6 rats received 13 mg/kg [(3)H]-artesunate on day 18 of gestation. Groups of 2 rats were euthanized at 1, 6, and 24 hours after dosing, rapidly frozen, and sectioned in a cryostat. Sagittal sections were freeze-dried and placed in contact with imaging plates. Tissue concentrations of radioactivity were quantified. RESULTS: Systemic exposure to DHA was up to 22-fold higher than the parent compound and was higher in non-pregnant females than males. In the QWBA study, high concentrations of radioactivity were seen in maternal tissues involved in absorption and excretion, the bone marrow and spleen. Fetal blood and liver levels were 3.8- to 8.8-fold higher than maternal blood levels at all timepoints. CONCLUSIONS: Excluding tissues involved in absorption and excretion, the highest concentrations of radioactivity were observed in tissues involved in hemoglobin synthesis and/or destruction in both the mother and the fetus and likely account for the maternal reticulocytopenia and embryotoxicity. Radioactivity concentrations in the fetal blood were 2.1- to 2.8-fold higher than maternal bone marrow at all timepoints and this difference could contribute to the lower dose threshold for embryotoxicity.

Effects of ionophores on liver CYP1A and 3A in male broilers.

The effects of ionophore antibiotics on the enzyme activity, protein and mRNA expression levels of cytochrome P450 (CYP) isoenzymes were investigated in liver from male Arbor Acres (AA) broiler chicks. Monensin, salinomycin and maduramycin at the dosage of 120, 60, and 5 mg/kg were administered in feed for 14 days. CYP1A and CYP3A activities were quantitated using cocktail probe drugs and a high performance liquid chromatographic (HPLC) assay at the 15th day; the protein expressions of CYP1A and CYP3A were detected by Western blot. CYP1A4, CYP1A5 and CYP3A37 mRNA levels were detected by real-time polymerase chain reaction (real-time PCR). Monensin, salinomycin and maduramycin had no effect on caffeine metabolism, protein expression and mRNA expression, but did induce dapsone metabolism, increasing CYP3A protein expression. However, there was no change in CYP3A37 mRNA expression as compared with the control group. It is suggested that ionophore antibiotics may have an induction effect on CYP3A expression and enzyme activity and that such effect might be related to the posttranscriptional regulation of its protein expression. Consideration of the enhanced metabolism of other drugs used simultaneously with ionophores is therefore recommended.

Metabolism and interactions of antileprosy drugs.

Leprosy is a chronic infectious disease caused my Mycobacterium leprae that primarily affects peripheral nervous system and extremities and is prevalent in tropical countries. Treatment for leprosy with multidrug regimens is very effective compared to monotherapy especially in multibacillary cases. The three major antileprosy drugs currently in use are 4, 4'-diaminodiphenyl sulfone (DDS, dapsone), rifampicin, and clofazimine. During multidrug therapy, the potent antibiotic rifampicin induces the metabolism of dapsone, which results in decreased plasma half-life of dapsone and its metabolites. Furthermore, rifampicin induces its own metabolism and decreases its half-life during monotherapy. Rifampicin upregulates several hepatic microsomal drug-metabolizing enzymes, especially cytochrome P450 (CYP) family that in turn induce the metabolism of dapsone. Clofazimine lacks significant induction of any drug-metabolizing enzyme including CYP family and does not interact with dapsone metabolism. Rifampicin does not induce clofazimine metabolism during combination treatment. Administration of dapsone in the acetylated form (acedapsone) can release the drug slowly into circulation up to 75 days and could be useful for the effective treatment of paucibacillary cases along with rifampicin. This review summarizes the major aspects of antileprosy drug metabolism and drug interactions and the role of cytochrome P450 family of drug metabolizing enzymes, especially CYP3A4 during multidrug regimens for the treatment of leprosy.

Dapsone 5% gel: a review of its efficacy and safety in the treatment of acne vulgaris.

Dapsone, a synthetic sulfone that has been available for over 60 years, has been used to treat a myriad of cutaneous disorders. Prior to the general acceptance of isotretinoin, oral dapsone had been reported to be effective in the treatment of nodulocystic acne. However, the potential for systemic toxicity prevented its widespread adoption in the treatment of acne. For many years scientists explored the possibility of developing a topical formulation of dapsone for the treatment of acne in the hope of minimizing the adverse hematologic effects of oral dapsone. Such a formulation had been unavailable until recently. Dapsone 5% gel (Aczone) was recently developed to treat acne vulgaris. This topical formulation was approved in the US based on two randomized, vehicle-controlled studies. A 12-month, open-label study was also conducted to assess the safety and efficacy of topical dapsone over the long term. Finally, two open-label phase I pharmacokinetic studies were conducted to evaluate the systemic absorption of topical dapsone compared with oral dapsone. This article reports the results of these studies, which show a reduction in acne lesion count comparable to those observed in clinical trials of other approved topical acne therapies. With regard to safety, the studies demonstrated that the concentrations of dapsone and N-acetyl dapsone remain low and do not accumulate over time once steady state is reached. Of the total of 50 patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency in all the studies, only two experienced a drop in hemoglobin levels, and those shifts in values were consistent with fluctuations observed for other study participants. A recent study evaluating the risk of hemolysis in patients with G6PD deficiency found topical dapsone 5% gel to be safe to use in this patient population. Based on the observations noted in the above-mentioned studies, we conclude that topical dapsone 5% gel is safe and effective in the treatment of acne vulgaris.

Pharmacokinetics of chlorproguanil, dapsone, artesunate and their major metabolites in patients during treatment of acute uncomplicated Plasmodium falciparum malaria.

OBJECTIVE: Chlorproguanil (CPG)-dapsone (DDS)-artesunate was in development for the treatment of uncomplicated Plasmodium falciparum malaria. The pharmacokinetics of CPG, DDS, artesunate and their metabolites chlorcycloguanil (CCG), monoacetyl dapsone (MADDS) and dihydroartemisinin (DHA) were investigated in patients with P. falciparum given CPG-DDS alone or plus artesunate. METHODS: Adult patients from Malawi and The Gambia taking part in a phase II clinical trial were randomised to receive a 3-day treatment of CPG-DDS alone (2/2.5 mg/kg/day) or plus 1, 2 or 4 mg/kg/day artesunate. Blood samples for pharmacokinetic analysis were collected up to 24 h post-first dose. RESULTS: The pharmacokinetic analysis included 115 patients. For CPG, there was no significant effect of artesunate on C(max) or AUC(0-24), except the 90% confidence interval (CI) for AUC(0-24) for the 4 mg/kg artesunate dose was slightly below that for the standard bioequivalence range (90% CI 0.78, 1.11); this was not considered clinically relevant. Artesunate increased the CCG AUC(0-24) by 6-17% and C(max) by 0-16%. Artesunate had no significant effect on the rate or extent of absorption of DDS. For MADDS, artesunate increased the AUC(0-24) by 13-47% and C(max) by 8-45%. For 1, 2 and 4 mg/kg artesunate dosing, artesunate AUC(0-infinity) was 64.6, 151 and 400 ng.h/ml and C(max) 48.9, 106 and 224 ng/ml respectively; DHA AUC(0-infinity) was 538, 1,445 and 3,837 ng.h/ml and C(max) 228, 581 and 1,414 ng/ml respectively. Using a power model, the point estimates of slope were greater than 1 for artesunate AUC(0-t) by 16% and C(max) by 5% and for DHA by 39 and 21% respectively. CONCLUSION: Artesunate did not significantly affect CPG or DDS pharmacokinetics. For CCG and MADDS, small to moderate increases in exposure with artesunate dosing were observed. There was a greater than proportional increase in artesunate and DHA exposure with increasing artesunate dose. These effects are not considered to be clinically relevant. It should be noted that the CPG-DDS-artesunate programme has now been stopped following unacceptable haematological toxicity in patients with glucose-6-phosphate dehydrogenase deficiency during a phase III trial. In addition, the CPG-DDS combination has been withdrawn from clinical use.

Metabolic, pharmacokinetic, and toxicological issues surrounding dapsone.

INTRODUCTION: In their 70-year history, dapsone and other sulfones have been used as both antibacterial and anti-inflammatory agents. Dapsone has been the main active principle in the multidrug regimen recommended by the World Health Organization for the treatment of leprosy. In addition, dapsone has been successfully used to treat a wide range of dermatological and systemic disorders, mostly characterized by neutrophilic and eosinophilic accumulation and infiltration. Areas covered: The PubMed database was searched using combinations of the following keywords: dapsone, sulfones, pharmacodynamics, pharmacology, adverse events, pharmacokinetics, drug interaction, dermatologic uses, and antimicrobial uses. This article reviews and updates the chemistry, pharmacokinetics, mechanism of action, adverse effects, drug interactions, and clinical application of sulfones. Expert opinion: Dapsone exhibits clinical efficacy in several cutaneous and systemic conditions and is now generally accepted as the therapy of choice for leprosy and for rare dermatosis, as dermatitis herpetiformis. Careful patient selection and close monitoring during treatment are mandatory to provide safe and effective use of dapsone. Familiarity with sulfones and dapsone is crucial because of this agent retains its niche in the clinician's therapeutic armamentarium.

In vivo phenotyping of cytochrome 450 isoforms involved in the metabolism of anti-HIV and anti-tubercular drugs in human using cocktail approach: An LC-MS/MS analysis.

PURPOSE: In vivo phenotyping of CYP isoforms involved in the metabolism of anti-HIV and antitubercular drugs is important to determine therapeutic dose levels in HIV/AIDS-TB coinfections. In this study, we used a cocktail of bupropion, losartan and dapsone for in vivo phenotyping of CYP2B6, CYP2C9 and N-acetyltransferase-2 (NAT2) in plasma. CYP2B6 is the main catalyst of anti-HIV efavirenz, while NAT2 is involved in antitubercular drug isoniazid metabolism. CYP2C9 has a significant association with antitubercular drug-induced reactions. The activity level of these isoforms has a significant bearing on therapeutic dose in rapid and poor metabolizers. METHODS: Briefly, a cocktail of probe drugs was administered to human volunteers and the drugs and metabolites were determined by an inhouse LC-MS/MS method in 250 µl plasma. The mobile phase and drug/metabolite extraction methods were optimized before analysis. Retention time, Cmax and tmax were calculated from the same sample and the values were used for phenotyping the isoforms. RESULTS: Retention time of drugs and metabolites was calculated. The method was sensitive (4.5-8.2 %CV) and no interfering peak was observed in any batch. %Accuracy of the calibrator and QC was 85-115%. %CV of storage stability testing was within FDA approved limits. Cmax and tmax were comparable to the values reported for individual drugs. CONCLUSIONS: This study advocates the use of a cocktail of bupropion, losartan and dapsone for in vivo phenotyping of CYP2B6, CYP2C9 and NAT2, which is important in determining therapeutic dose levels of anti-HIV and anti-TB drugs in HIV/AIDS-TB coinfections.

Evaluation of protective effects of Chi-Zhi-Huang decoction on Phase I drug metabolism of liver injured rats by cocktail probe drugs.

AIM OF THE STUDY: Chi-Zhi-Huang decoction (PGR) is one of the traditional Chinese medicine (TCM) preparations with unique effect on withdrawing jaundice and has been used to treat icteric patients in China for many years. In this research, we aim at to evaluate the potential activity of PGR in restoring hepatic drug metabolism in a damaged liver. MATERIALS AND METHODS: A cocktail approach with caffeine (10mg/kg), dapsone (10mg/kg) and chlorzoxazone (20mg/kg) respectively as probe drug of cytochrome P450 (CYP) isoform of CYP 1A2, 3A4 and 2E1 was used to evaluate its possible effects on Phase I oxidative metabolism. Pretreated with three dosages of PGR water extract (0.75, 1.5 and 3g/kg, po) for 5 days, male Wistar rats (220-240 g) were intoxicated by phenylisothiocyanate (PITC, 100mg/kg, po) 24h before probes intravenous injection. The pharmacokinetics of the probes in the blood was determined simultaneously by HPLC, and their non-compartmental parameters were used to evaluate the metabolic difference among the groups. Moreover, the levels of liver enzymes (ALT, AST, ALP) and bilirubins were also measured for insight of liver function. RESULTS: The findings in this study suggest that PGR induces CYP 3A4, does not have much effect on CYP 2E1, and inhibits CYP 1A2 at high dosage. CONCLUSION: The current pharmacokinetic approach allowed the protective effects of PGR on oxidative drug metabolism in damaged liver to be systemically examined and will certainly help in the explanation of synergistic effect of the composites formula.

Pharmacokinetics of dapsone gel, 5% for the treatment of acne vulgaris.

BACKGROUND: Oral dapsone has been available for over 60 years and has been used to treat severe acne vulgaris; however, the oral formulation is known to cause dose-dependent haematological reactions and is currently indicated only for diseases such as dermatitis herpetiformis and Hansen's disease. A gel formulation of dapsone was recently developed to treat acne vulgaris. As dapsone is administered topically, it was expected that systemic absorption would be considerably lower than that observed with oral dapsone therapy, thereby avoiding any adverse haematological effects. OBJECTIVE: To report the pharmacokinetic profile of topically applied dapsone gel, 5% in the treatment of acne vulgaris. STUDY PARTICIPANTS AND METHODS: Three prospective, open-label studies enrolled a total of 548 subjects with acne vulgaris: two phase I pharmacokinetic studies (crossover and drug interaction) and one phase III long-term safety study. In the crossover study (n = 18), topical dapsone gel applied twice daily for a total of 14 days to 22.5% of the body surface area was compared with a single dose of oral dapsone 100mg (the typical clinical dose). In the drug-interaction study (n = 24), oral trimethoprim/sulfamethoxazole monotherapy, topical dapsone gel monotherapy and the two in combination were used twice daily for 7, 21 and 7 days, respectively. In the long-term safety study (n = 506), topical dapsone gel was applied twice daily to acne-affected areas for up to 12 months. Blood samples were drawn at various timepoints in each study to assess drug and metabolite concentrations. Systemic concentrations of dapsone, N-acetyl dapsone, dapsone hydroxylamine, trimethoprim and sulfamethoxazole were determined, according to the study design. RESULTS: In the crossover study, the mean area under the plasma concentration-time curve (AUC) from 0 to 24 hours for dapsone was 417.5 ng x h/mL after 2 weeks of dapsone gel therapy (n = 10), compared with an AUC from time zero to infinity of 52,641 ng x h/mL after a single dose of oral dapsone; this represents a 126-fold lower systemic exposure for dapsone gel at typical therapeutic doses. In the drug-interaction study, the AUC from 0 to 12 hours for dapsone was 221.52 ng x h/mL after 3 weeks of dapsone gel monotherapy compared with 320.3 ng x h/mL after 1 week of coadministration with trimethoprim/sulfamethoxazole. In the long-term safety study, the mean plasma dapsone concentrations ranged from 7.5 to 11 ng/mL over 12 months. Overall, total systemic exposures to dapsone and its metabolites were approximately 100-fold less for dapsone gel than for oral dapsone, even in the presence of trimethoprim/sulfamethoxazole. There were no reports of any haematological adverse events. CONCLUSIONS: Topical application of dapsone gel in various settings ranging from 2 weeks to 12 months resulted in systemic exposures to dapsone and its metabolites that were approximately 100-fold less than those after oral dapsone at a therapeutic dose level. The concentrations of dapsone and its metabolites reached steady state and did not increase during prolonged treatment.

Supervised Machine-Learning Reveals That Old and Obese People Achieve Low Dapsone Concentrations.

The human species is becoming increasingly obese. Dapsone, which is extensively used across the globe for dermatological disorders, arachnid bites, and for treatment of several bacterial, fungal, and parasitic diseases, could be affected by obesity. We performed a clinical experiment, using optimal design, in volunteers weighing 44-150 kg, to identify the effect of obesity on dapsone pharmacokinetic parameters based on maximum-likelihood solution via the expectation-maximization algorithm. Artificial intelligence-based multivariate adaptive regression splines were used for covariate selection, and identified weight and/or age as predictors of absorption, systemic clearance, and volume of distribution. These relationships occurred only between certain patient weight and age ranges, delimited by multiple hinges and regions of discontinuity, not identified by standard pharmacometric approaches. Older and obese people have lower drug concentrations after standard dosing, but with complex patterns. Given that efficacy is concentration-dependent, optimal dapsone doses need to be personalized for obese patients.

Extracorporeal treatments in a dapsone overdose: a case report.

INTRODUCTION: Intentional dapsone intoxication can be life-threatening. There is limited data on the clinical effect of extracorporeal treatments (ECTRs) on dapsone elimination. We describe a case of severe dapsone toxicity treated with different ECTRs. CASE DETAILS: A 23-year-old woman was admitted 2.5 h after ingesting 2.2 g of dapsone. She developed methemoglobinemia (39.9%) and showed signs of toxicity (hemodynamic instability and altered mental status) despite multiple-activated charcoal, methylene blue, vasopressors and endotracheal intubation. Continuous venovenous hemofiltration (CVVH) was then initiated for 5 h, followed by intermittent hemodialysis with hemoperfusion (IHD-HP) for 4 h, and CVVH for another 48 h. The platelet count decreased to 32 × 109/L 3 h after IHD-HP. The elimination half-life of dapsone was 2.0 h during IHD-HP, and 14.2 h during CVVH. Mean dapsone clearance with IHD was 62 mL/min versus 22 mL/min with CVVH. IHD removed 95.3 mg, and CVVH removed 67.8 mg over 3.8 h. No rebound occurred following ECTR cessation. The toxicokinetics of dapsone metabolites were also accelerated during ECTR. The patient was extubated after 3.5 days and discharged without sequelae after 7 days. DISCUSSION: Dapsone clearance was enhanced by ECTR, especially by IHD-HP. However, HP was associated with severe asymptomatic thrombocytopenia.

Design and statistical modeling of mannose-decorated dapsone-containing nanoparticles as a strategy of targeting intestinal M-cells.

The aim of the present work was to develop and optimize surface-functionalized solid lipid nanoparticles (SLNs) for improvement of the therapeutic index of dapsone (DAP), with the application of a design of experiments. The formulation was designed to target intestinal microfold (M-cells) as a strategy to increase internalization of the drug by the infected macrophages. DAP-loaded SLNs and mannosylated SLNs (M-SLNs) were successfully developed by hot ultrasonication method employing a three-level, three-factor Box-Behnken design, after the preformulation study was carried out with different lipids. All the formulations were systematically characterized regarding their diameter, polydispersity index (PDI), zeta potential (ZP), entrapment efficiency, and loading capacity. They were also subjected to morphological studies using transmission electron microscopy, in vitro release study, infrared analysis (Fourier transform infrared spectroscopy), calorimetry studies (differential scanning calorimetry), and stability studies. The diameter of SLNs, SLN-DAP, M-SLNs, and M-SLN-DAP was approximately 300 nm and the obtained PDI was <0.2, confirming uniform populations. Entrapment efficiency and loading capacity were approximately 50% and 12%, respectively. Transmission electron microscopy showed spherical shape and nonaggregated nanoparticles. Fourier transform infrared spectroscopy was used to confirm the success of mannose coating process though Schiff's base formation. The variation of the ZP between uncoated (approximately -30 mV) and mannosylated formulations (approximately +60 mV) also confirmed the successful coating process. A decrease in the enthalpy and broadening of the lipid melting peaks of the differential scanning calorimetry thermograms are consistent with the nanostructure of the SLNs. Moreover, the drug release was pH-sensitive, with a faster drug release at acidic pH than at neutral pH. Storage stability for the formulations for at least 8 weeks is expected, since they maintain the original characteristics of diameter, PDI, and ZP. These results pose a strong argument that the developed formulations can be explored as a promising carrier for treating leprosy with an innovative approach to target DAP directly to M-cells.