Sphingomyelin-based PEGylation Cu (DDC)2 liposomes prepared via the dual function of Cu2+ for cancer therapy: Facilitating DDC loading and exerting synergistic antitumor effects.

The old alcohol-aversion drug disulfiram (DSF) has aroused wide attention as a drug repurposing strategy in terms of cancer therapy because of the high antitumor efficacy in combination with copper ion. However, numerous defects of DSF (e.g., the short half-life and acid instability) have limited the application in cancer treatment. Cu (DDC)2, the complex of diethyldithiocarbamate (DDC, DSF metabolite) and Cu2+, have been proven as the vital active component on cancer, which have aroused the attention of researchers from DSF to Cu (DDC)2. However, the poor water solubility of Cu (DDC)2 increase more difficulties to the treatment and in-depth investigations of Cu (DDC)2. In this study, sphingomyelin (SM)-based PEGylated liposomes (SM/Chol/DSPE-mPEG2000 (55:40:5, mole%)) were produced as the carriers for Cu (DDC)2 delivery to enhance the water solubility. DDC was added to Cu-containing liposomes with a higher encapsulation efficiency of more than 90%, and it reacted with Cu2+ to synthesize Cu (DDC)2. Due to the high phase transition temperature of SM and strong intermolecular hydrogen bonds with cholesterol, SM-based liposomes would be conducive to enhancing the stability of Cu (DDC)2 and preventing drug leakage during delivery. As proven by pharmacokinetic studies, loading Cu (DDC)2 into liposomes improve bioavailability, and the area under the curve (AUC0-t) and the mean elimination half-life (t1/2) increased 1.9-time and 1.3-time to those of free Cu (DDC)2, respectively. Furthermore, the anticancer effect of Cu (DDC)2 was enhanced by the liposomal encapsulation, thus resulting in remarkable cell apoptosis in vitro and a tumor-inhibiting rate of 77.88% in vivo. Thus, it was concluded that Cu (DDC)2 liposomes could be promising in cancer treatment.

Surface Decoration via Physical Interaction of Cupric Diethyldithiocarbamate Nanocrystals and Its Impact on Biodistribution and Tumor Targeting.

The vascular wall is the first physiologic barrier that circulating nanoparticles (NPs) encounter, which also is a key biological barrier to cancer drug delivery. NPs can continually scavenge the endothelium for biomarkers of cancer, and the chance of NPs' extravasation into the tumors can be enhanced. Here, we envision P-selectin as a target for specific delivery of drug nanocrystals to tumors. The cupric diethyldithiocarbamate nanocrystals (CuET NCs) were first prepared by an antisolvent method, and then nanocrystals were coated with fucoidan via physical interaction. The fucoidan-coated CuET nanocrystals (CuET@Fuc) possess high drug loading and have the ability to interact with human umbilical vein endothelial cells expressing P-selectin, which transiently enhances the endothelial permeability and facilitates CuET@Fuc extravasation from the peritumoral vascular to achieve higher tumor accumulation of drugs than bare CuET NCs. The CuET NC shows poorer anticancer efficacy than CuET@Fuc at the same dose of CuET. Upon repeated dosing of CuET@Fuc for 2 weeks, no mortality was observed in treated melanoma-bearing mice, while the mortality in the control group and excipient-treated groups reached 23%. The growth rate of melanoma in the CuET@Fuc-treated group was significantly lower than those in other groups. Furthermore, an acute toxicity study revealed that CuET@Fuc is a safe formulation for cancer treatment.

Disulfiram Copper Nanoparticles Prepared with a Stabilized Metal Ion Ligand Complex Method for Treating Drug-Resistant Prostate Cancers.

Disulfiram (DSF), an alcohol-aversion drug, has been explored for cancer treatment. Copper diethyldithiocarbamate (Cu(DDC)2) complex formed by DSF and copper ions is a major active ingredient for its anticancer activity. Direct administration of Cu(DDC)2 is a promising strategy to enhance the anticancer efficacy of DSF. However, efficient drug delivery remains a significant challenge for Cu(DDC)2 and hinders its clinical use. In this study, we developed a facile stabilized metal ion ligand complex (SMILE) method to prepare Cu(DDC)2 nanoparticles (NPs). The SMILE method could prepare Cu(DDC)2 NPs with different types of stabilizers including 1,2-distearoyl- sn-glycerol-3-phosphoethanolamine-poly(ethylene glycol) (PEG) 2000, d-α-tocopherol PEG 1000 succinate, methoxy PEG 5000- b-poly(l-lactide) 5000, and other generally recognized as safe excipients approved by the US Food and Drug Administration. The optimized formulations demonstrated excellent drug-loading efficiency (close to 100%), high drug concentrations (increased drug concentration by over 200-fold compared to the traditional micelle formulation), and an optimal particle size in the sub-100 nm range. Cu(DDC)2 NPs exhibited outstanding stability in serum for 72 h and can also be stored at room temperature for at least 1 month. The anticancer effects of Cu(DDC)2 NP formulations were determined by multiple assays including 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, colony-forming assay, calcein-AM/propidium iodide staining, and others. Cu(DDC)2 NPs showed excellent activity against drug-resistant prostate cancer cells and other cancer cells with a half-maximal inhibitory concentration (IC50) of around 100 nM. Our study also demonstrated that Cu(DDC)2 NPs induced cell death in drug-resistant prostate cancer cells (DU145-TXR) through paraptosis, which is a nonapoptotic cell death. To our best knowledge, the SMILE method provides, for the first time, a simple yet efficient process for generating Cu(DDC)2 NPs with high drug concentration, excellent loading efficiency, and desirable physicochemical properties. This method could potentially address drug delivery challenges of DSF/copper-based chemotherapy and facilitate its clinical translation.

Development and optimization of an injectable formulation of copper diethyldithiocarbamate, an active anticancer agent.

Copper diethyldithiocarbamate (Cu(DDC)2) is the active anticancer agent generated when disulfiram (DSF) is provided in the presence of copper. To date, research directed toward repurposing DSF as an anticancer drug has focused on administration of DSF and copper in combination, efforts that have proven unsuccessful in clinical trials. This is likely due to the inability to form Cu(DDC)2 at relevant concentrations in regions of tumor growth. Little effort has been directed toward the development of Cu(DDC)2 because of the inherent aqueous insolubility of the complex. Here, we describe an injectable Cu(DDC)2 formulation prepared through a method that involves synthesis of Cu(DDC)2 inside the aqueous core of liposomes. Convection-enhanced delivery of a Cu(DDC)2 formulation prepared using 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC)/cholesterol liposomes into a rat model of F98 glioma engendered a 25% increase in median survival time relative to vehicle-treated animals. In a murine subcutaneous MV-4-11 model, treatment resulted in a 45% reduction in tumor burden when compared to controls. Pharmacokinetic studies indicated that the Cu(DDC)2 was rapidly eliminated after intravenous administration while the liposomes remained in circulation. To test whether liposomal lipid composition could increase Cu(DDC)2 circulation lifetime, a number of different formulations were evaluated. Studies demonstrated that liposomes composed of DSPC and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-n-(carboxy[polyethylene glycol]-2000) (95:5) enhanced Cu(DDC)2 concentrations in the circulation as reflected by a 4.2-fold increase in plasma AUC(0-∞) relative to the DSPC/cholesterol formulation. The anticancer activity of this Cu(DDC)2 formulation was subsequently evaluated in the MV-4-11 model. At its maximum tolerated dose, this formulation exhibited comparable activity to the DSPC/cholesterol formulation. This is the first report demonstrating the therapeutic effects of an injectable Cu(DDC)2 formulation in vivo.

Tendencias en la mortalidad por cáncer en México de 1980 a 2011 / Cancer mortality trends in Mexico, 1980-2011

Objetivo. Evaluar las tendencias de mortalidad por cáncer en México entre 1980 y 2011. Material y métodos. Se calcularon las tasas de mortalidad ajustadas por edad y sexo para todos los cánceres y para las 15 localizaciones más frecuentes mediante el método directo y tomando como población estándar la población mundial de 2010. Las tendencias en las tasas de mortalidad y el cambio porcentual anual para cada tipo de cáncer se estimaron a través de un modelo de regresión joinpoint. Resultados. A partir de 2004 y como consecuencia de la reducción de la mortalidad por cáncer de pulmón (-3.2% en hombres y -1.8% en mujeres), estómago (-2.1% en hombres y -2.4% en mujeres) y cérvix (-4.7%), se observó una disminución significativa (~1% anual) en la mortalidad por cáncer en general tanto en el grupo de todas las edades como en el de 35 a 64 años para ambos sexos. La mortalidad por otros cánceres como el de mama y el de ovario, en las mujeres o el de próstata, en los hombres, mostró un aumento sostenido. Conclusiones. Algunas de las reducciones en la mortalidad por cáncer pueden ser parcialmente atribuidas a la efectividad de los programas de prevención establecidos. Sin embargo, se requiere implementar registros adecuados de cáncer con base poblacional para evaluar el impacto real de estos programas, así como diseñar y evaluar intervenciones innovadoras que permitan desarrollar políticas de prevención más costo-efectivas.

Objective. To evaluate trends in cancer mortality in Mexico between 1980-2011. Material and methods. Through direct method and using World Population 2010 as standard population, mortality rates for all cancers and the 15 most frequent locations, adjusted for age and sex were calculated. Trends in mortality rates and annual percentage change for each type of cancer were estimated by joinpoint regression model. Results. As a result of the reduction in mortality from lung cancer (-3.2% -1.8% in men and in women), stomach (-2.1% -2.4% in men and in women) and cervix (-4.7%); since 2004 a significant (~1% per year) decline was observed in cancer mortality in general, in all ages, and in the group of 35-64 years of both sexes. Other cancers such as breast and ovarian cancer in women; as well as for prostate cancer in men, showed a steady increase. Conclusions. Some of the reductions in cancer mortality may be partially attributed to the effectiveness of prevention programs. However, adequate records of population-based cancer are needed to assess the real impact of these programs; as well as designing and evaluating innovative interventions to develop more cost-effective prevention policies.

In vitro cell culture model for anti-cataract drug penetration studies.

Immortalized human corneal epithelial cells (HCECs) and human lens epithelial cells (HLECs) were cultured in vitro. Cells were observed under a phase-contrast microscope and the integrity of cell monolayers was assayed by transepithelial electrical resistance (TEER) determination. The permeability of disulfiram (DSF) through a HCECs monolayer was compared with that of DSF through an excised rabbit cornea. The permeability coefficients of DSF through a HCECs monolayer and excised rabbit cornea were 29.5 +/- 4.8 x 10(-6) cm/s and 34.7 +/- 5.2 x 10(-6) cm/s, respectively. Diethyldithiocarbamate (DDC) had high permeability through HLECs monolayer with a permeability coefficient of 44.6 +/- 7.1 x 10(-6) cm/s. The cytotoxicity of DDC against HLECs was investigated using the trypan blue exclusion test. For a DDC concentration of 5 mmol/l, more than 85% cells were viable. DH3a1 mRNA was expressed in cultured HLECs. The expression of aldehyde dehydrogenase 3a1 (ALDH3a1), which may be be responsible for DSF-DDC conversion, was detected using RT-PCR and agarose gels electrophoresis. These results demonstrate that the permeability of DSF can be detected and intra-ocular drug action may be predicted using the cultured HCEC and HLEC monolayers as model.

Combined pulmonary toxicity of cadmium chloride and sodium diethyldithiocarbamate.

The pulmonary toxicity of sodium diethyldithiocarbamate and cadmium chloride, each separately and in combination, was compared in Sprague-Dawley rats after single intratracheal instillation in sequential experiments by chemical, immunological and morphological methods. With combined exposure, the cadmium content of the lungs increased permanently relative to that of the lungs of just cadmium-treated animals. Immunoglobulin levels of the whole blood did not change, whereas in bronchoalveolar lavage the IgA and IgG levels increased significantly. Morphological changes were characteristic of the effects of cadmium but were more extensive and more serious than in the case of cadmium administration alone: by the end of the first month, interstitial fibrosis, emphysema and injury of membranes of type I pneumocytes developed and hypertrophy and loss of microvilli in type II pneumocytes were detectable. These results showed that although dithiocarbamates as chelating agents are suitable for the removal of cadmium from organisms, they alter the redistribution of cadmium within the organism, thereby increasing the cadmium content in the lungs, and structural changes are more serious than observed upon cadmium exposure alone.

Identification of the human P-450 enzymes responsible for the sulfoxidation and thiono-oxidation of diethyldithiocarbamate methyl ester: role of P-450 enzymes in disulfiram bioactivation.

Diethyldithiocarbamate methyl ester (DDTC-Me) is a precursorto the formation of S-methyl-N,N-diethylthiolcarbamate sulfoxide, the active metabolite proposed to be responsible for the alcohol deterrent effects of disulfiram. The present study investigated the role of human cytochrome P-450 (CYP) enzymes in sulfoxidation and thiono-oxidation of DDTC-Me, intermediary steps in the activation of disulfiram. Several approaches were used in an attempt to delineate the particular P-450 enzyme(s) involved in the sulfoxidation and thiono-oxidation of DDTC-Me. These approaches included the use of cDNA-expressed human P-450 enzymes, correlation analysis with sample-to-sample variation in human P-450 enzymes in a bank of human liver microsomes, and chemical and antibody inhibition studies. Multiple human P-450 enzymes (CYP3A4, CYP1A2, CYP2A6, and CYP2D6) catalyzed the sulfoxidation of DDTC-Me, as determined with cDNA-expressed enzymes. Several lines of evidence suggest that the sulfoxidation of DDTC-Me by human liver microsomes is primarily catalyzed by CYP3A4/5, including (1) a high correlation between DDTC-Me sulfoxidation and testosterone 6beta-hydroxylation; (2) increased DDTC-Me sulfoxidation in the presence of alpha-naphthoflavone, an activator of CYP3A enzymes; (3) inhibition of this reaction by inhibitors of CYP3A4/5 enzymes, such as troleandomycin and ketoconazole; and (4) inhibition of DDTC-Me sulfoxidation by antibodies against CYP3A enzymes. On the other hand, several lines of evidence suggested that the thiono-oxidation of DDTC-Me by human liver microsomes is catalyzed in part by CYP1A2, CYP2B6, CYP2E1, and CYP3A4/5, including (1) these human P450 enzymes among others have the capacity to catalyze this reaction, as determined with cDNA-expressed enzymes; (2) a high correlation between DDTC-Me thiono-oxidation and testosterone 6beta-hydroxylation, weak inhibition by ketoconazole, troleandomycin, and anti-CYP3A antibodies suggested a minor role for CYP3A4; (3) a high correlation with immunoreactive CYP2B6 suggested involvement of this enzyme; (4) weak inhibition of DDTC-Me thiono-oxidation by furafylline and anti-CYP1A antibody suggested involvement of CYP1A2; and (5) inhibition of DDTC-Me thiono-oxidation by DDTC and anti-CYP2E antibodies suggested a role for CYP2E1. Collectively, these data suggested CYP3A4/5 enzymes are the major contributors to the sulfoxidation of DDTC-Me by human liver microsomes, and CYP1A2, CYP2B6, CYP2E1, and CYP3A4/5 contribute toward DDTC-Me thiono-oxidation by human liver microsomes. This study, in conjunction with others (Madan et al., Drug Metab. Dispos. 23:1153-1162, 1995), may help explain the variability in disulfiram's effectiveness as an alcohol deterrent.

Induction of apoptosis by thiuramdisulfides, the reactive metabolites of dithiocarbamates, through coordinative modulation of NFkappaB, c-fos/c-jun, and p53 proteins.

Prolinedithiocarbamate (PDTC) and diethyldithiocarbamate (DDTC) are cancer chemopreventive agents and can be biotransformed to prolinethiuramdisulfide (PTDS) and tetraethylthiuramdisulfide (disulfiram; DTDS), respectively. We found that the reactive metabolites PTDS and DTDS induced apoptosis after G1/S arrest. Phosphorylation of cyclin E, inhibition of cyclin-dependent kinase 2 activity, and degradation of cyclin E were found in human hepatoma Hep G2 cells during apoptosis. Moreover, PTDS and DTDS decreased the level of bcl-2 but increased the level of p53. In contrast, PDTC, DDTC, and ammonium dithiocarbamate (ADTC) did not induce apoptosis; rather they led to the induction of p53 and p21 followed by G1/S arrest. PDTC, DDTC, and ADTC also arrested cells in G1 phase. We then examined the effects of PTDS and DTDS on the signal transduction mechanisms leading to apoptosis. Although the transcription factors NFkappaB and AP-1 cooperatively decreased their DNA-binding activities to kappaB and 12-O-tetradecanoylphorbol-13-acetate-responsive elements, respectively, and p53 increased DNA-binding activity in the early stage but decreased it in the latter stage after treatment with PTDS, when the human Hep G2 cells were undergoing apoptosis. In summary, our results indicated that (i) PTDS and DTDS induced apoptosis and G1/S arrest mediated by p53, whereas PDTC, DDTC, and ADTC induced p53-dependent p21 expression leading to G1/S arrest; (ii) PDTC, DDTC, and ADTC induced p21/KIP1/CIP1 expression in a p53-dependent pathway leading to G1/S arrest; and (iii) NFkappaB, AP-1, and bcl-2 were downregulated during PTDS- and DTDS-induced apoptosis. These results suggested that PTDS and DTDS induced p53-dependent apoptosis, whereas PDTC, DDTC, and ADTC induced G1/S arrest. Apoptosis is regulated by the modulation of intracellular effectors such as NFkappaB, AP-1, and bcl-2 and activation of p53 in early stages.

Dithiocarbamate toxicity toward thymocytes involves their copper-catalyzed conversion to thiuram disulfides, which oxidize glutathione in a redox cycle without the release of reactive oxygen species.

We have reported previously that diethyldithio-carbamate (DDC) and pyrrolidine dithiocarbamate (PDTC) induce apoptosis in rat thymocytes. Apoptosis was shown to be dependent upon the transport of external Cu ions into the cells and was accompanied by the oxidation of intracellular glutathione, indicating the inducement of pro-oxidative conditions (C. S. I. Nobel, M. Kimland, B. Lind, S. Orrenius, and A. F. G. Slater, J. Biol. Chem. 270, 26202-26208, 1995). In the present investigation we have examined the chemical reactions underlying these effects. Evidence is presented to suggest that dithiocarbamates undergo oxidation by CuII ions, resulting in formation of the corresponding thiuram disulfides, which are then reduced by glutathione, thereby generating the parent dithiocarbamate and oxidized glutathione (glutathione disulfide). Although DDC and PDTC were found to partially stabilize CuI ions, limited redox cycling of the metal ion was evident. Redox cycling did not, however, result in the release of reactive oxygen species, which are believed to be scavenged in situ by the dithiocarbamate. DDC and PDTC were, in fact, shown to prevent copper-dependent hydroxyl radical formation and DNA fragmentation in model reaction systems. The thiuram disulfide disulfiram (DSF) was found to induce glutathione oxidation, DNA fragmentation, and cell killing more potently than its parent dithiocarbamate, DDC. Of particular importance was the finding that, compared with DDC, the actions of DSF were less prone to inhibition by the removal of external copper ions with a chelating agent. This observation is consistent with our proposed mechanism of dithiocarbamate toxicity, which involves their copper-catalyzed conversion to cytotoxic thiuram disulfides.

In vivo spin trapping of nitric oxide generated in the small intestine, liver, and kidney during the development of endotoxemia: a time-course study.

Spin trapping of nitric oxide (NO.) in vivo in liver, small intestine, kidney, and plasma of intact rats was accomplished using diethyldithiocarbamate (DETC) administered intraperitoneally. DETC combines with Fe2+ to form (DETC)2-Fe and is an excellent trapping agent for nitric oxide. DETC distribution and uptake by the organs of interest was determined and the formation of the active trapping agent (DETC)2-Fe was assayed in the various organs and plasma. The capacity of this spin trap to capture NO. in vivo was demonstrated by administering sodium nitroprusside to the animals. The trapping procedure was then used to assess the course of NO. generation during a 6 h period in animals that had been treated with endotoxin. The rate of NO. generation/gram tissue was determined during the last 15 min of each time period. The results indicate that induction of nitric oxide generation begins earliest in the small intestine, then in the liver, and still later in the kidney and plasma. Nitric oxide production was most intense in the liver and was still increasing at the end of the experiment. Control animals receiving the spin trapping agent showed only little or no evidence of nitric oxide production except for the small intestine. The results show that induction of NO. generation caused by endotoxin begins at different times in different organs.

Assay of ditiocarb sodium and its methyl ester in mouse plasma by column-switching HPLC.

AIM: To establish a column-switching high pressure liquid chromatograpy (CSHPLC) with direct injection for determination of ditiocarb sodium (DTC) and its methyl ester (DTC-Me) in mouse plasma. METHODS: After automated online pretreating column enrichment and clear-up, DTC-Me was flushed and chromatographed on an ordinary reversed-phase analytical column, and monitored by UV at lambda absorption = 276 nm. DTC was methylated before determination. RESULTS: No potential interfering peaks were identified. The calibration curves of both analytes were linear within the range of 0.1-150 mg.L-1. The correlation coefficients of DTC and DTC-Me were 0.9998 and 0.9995, respectively. The detection limit was 25 micrograms.L-1 and the coefficient of variation in the assay was within 7% for both compounds. The average recoveries were in the range of 95.28 -100.06%. A typical application was presented for mouse after i.v. DTC 50 mg.kg-1. CONCLUSION: The rapid CSHPLC method with direct injection can be used for the study of pharmacokinetics of DTC and DTC-Me.

S-methyl-N,N-diethylthiocarbamate sulfoxide and S-methyl-N,N-diethylthiocarbamate sulfone, two candidates for the active metabolite of disulfiram.

The mechanism of action of disulfiram involves inhibition of hepatic aldehyde dehydrogenase (ALDH). Although disulfiram inhibits ALDH in vitro, it is believed that the drug is too short-lived in vivo to inhibit the enzyme directly. The ultimate inhibitor is thought to be a metabolite of disulfiram. In this study, we examined the effects of S-methyl-N,N-diethylthiocarbamate (MeDTC) sulfoxide and S-methyl-N,N-diethylthiocarbamate sulfone (confirmed and proposed metabolites of disulfiram, respectively) on rat liver mitochondrial low K(m) ALDH. MeDTC sulfoxide and MeDTC sulfone, in 10-min incubations with detergent-solubilized mitochondria, inhibited ALDH activity with an IC50 (mean +/- SD) of 0.93 +/- 0.04 and 0.53 +/- 0.11 microM, respectively, compared with 7.4 +/- 1.0 microM for the parent drug disulfiram. Inhibition by MeDTC sulfone and MeDTC sulfoxide, both at 0.6 microM, was time-dependent, following apparent pseudo-first-order kinetics with a t1/2 of inactivation of 3.5 and 8.8 min, respectively. Dilution of ALDH inhibited by either sulfoxide or sulfone did not restore activity, an indication of irreversible inhibition. Addition of glutathione (50 to 1000 microM) to ALDH before the inhibitors did not alter the inhibition by MeDTC sulfoxide. In contrast, the inhibition by MeDTC sulfone was decreased > 10-fold (IC50 = 6.3 microM) by 50 microM of glutathione and almost completely abolished by 500 microM of glutathione. The cofactor NAD, in a concentration-dependent manner, protected ALDH from inhibition by MeDTC sulfoxide and MeDTC sulfone. In incubations with intact mitochondria, the potency of the two compounds was reversed (IC50 of 9.2 +/- 3.6 and 0.95 +/- 0.30 microM for the MeDTC sulfone and sulfoxide, respectively). Our results suggest that MeDTC sulfone is highly reactive with normal cellular constituents (e.g., glutathione), which may protect ALDH from inhibition, unless this inhibitor is formed very near the target enzyme. In contrast, MeDTC sulfoxide is a better candidate for the ultimate active metabolite of disulfiram, because it is more likely to be sufficiently stable to diffuse from a distant site of formation, such as the endoplasmic reticulum, penetrate the mitochondria, and react with ALDH located in the mitochondrial matrix.

In vivo detection of mouse liver nitric oxide generation by spin trapping electron paramagnetic resonance spectroscopy.

Nitric oxide, a paramagnetic molecule synthesized in biological systems, plays an important role in many pathophysiological processes. In vivo electron paramagnetic resonance spectroscopy/imaging could be a useful tool to study, in situ and in real time, nitric oxide generation. In this study the intracellular production of nitric oxide in tissues of living septic-shock mouse was detected by the spin trapping technique in combination with electron paramagnetic resonance spectroscopy. A lipophilic spin trap agent was used and nitric oxide formation was determined by the intensity of its iron-mononitrosyl complex. Among all examined tissues at 20 degrees C, the highest signal intensity of the trapped nitric oxide was found in the liver homogenates (n = 5). The amount of complex found in the kidneys was about 40% of that found in the liver. In the brain and lung, around 10% was found. This study reports, for the first time, the in vivo detection of nitric oxide generation in the upper abdomen of septic-shock mice (n = 3). Within 1 h after the trap injection, the signal was stable, indicating that the formation had reached a steady state.

Comparative effects of diethyldithiocarbamate and N-benzyl-D-glucamine dithiocarbamate on cis-diamminedichloroplatinum-induced toxicity in kidney and gastrointestinal tract in rats.

Sodium diethyldithiocarbamate (DDTC) and sodium N-benzyl-D-glucamine dithiocarbamate (BGD) were compared for their protective effects against cis-diamminedichloroplatinum (DDP)-induced toxicity in kidney and gastrointestinal tract in rats. Rats were injected i.p. with the dithiocarbamates (2.0 mmol kg-1) immediately or 1 h after i.v. injection of DDP (20 mumol kg1). Treatment with BGD immediately or at 1 h after DDP injection effectively prevented the nephrotoxicity of DDP, but administration of DDTC immediately or 1 h after DDP afforded little protection. N-Benzyl-D-glucamine dithiocarbamte significantly reversed the reduction in maltase, sucrase and aminopeptidase activities of jejunal mucosa of rats treated with DDP, whereas treatment with DDTC concurrent with DDP could not reverse the reduction in disaccharidase activity following DDP injection. The platinum concentrations in liver and kidney were significantly decreased by treatment with BGD and DDTC. The treatment with DDTC at 1 h after DDP was more effective on the reduction of platinum concentrations in these tissues than that immediately after DDP. There was no difference between the renal and hepatic concentrations of platinum in two time intervals of BGD. The pharmacokinetic studies indicated that DDTC is more rapidly metabolized than BGD, resulting in larger total clearance and elimination rate constant values. These results reveal that the administration of BGD immediately and at 1 h after DDP can protect against the renal and gastrointestinal toxicities caused by DDP, whereas DDTC afforded little protection, and that the time interval between administration of DDP and DDTC greatly influences its protective effect on DDP-induced toxicity, indicating that the chelation therapy of BGD for DDP is superior to that of DDTC.

Comparative studies on the pharmacokinetics of hydrophilic prolinedithiocarbamate, sarcosinedithiocarbamate and the less hydrophilic diethyldithiocarbamate.

The pharmacokinetics of the antitoxic and anticarcinogenic compounds diethyldithiocarbamate, prolinedithiocarbamate and sarcosinedithiocarbamate were compared in rats. The bioavailability, the distribution in the organism, the oxidation to thiuramdisulfides, the cleavage to CS2 and the excretion in urine and bile were investigated. The results showed different behaviour of the three compounds. The more toxic diethyldithiocarbamate had a short in vivo half-life, was oxidized to tetraethylthiuramdisulfide in blood, and was metabolized to high yields of CS2 in 24 h. In contrast, prolinedithiocarbamate was more stable in vivo, was found predominantly in the urinary tract and was excreted in urine. The differences could not be explained by the presence of the carboxy group in the latter dithiocarbamate, since sarcosinedithiocarbamate, which also contains a carboxy group, behaved like diethyldithiocarbamate.

A dose-ranging pharmacokinetics study of sodium diethyldithiocarbamate in normal healthy volunteers.

Sodium diethyldithiocarbamate (DDTC) is an investigational modulator of the toxicity produced by cisplatin. The pharmacokinetics of DDTC were evaluated after administration of 200 mg/m2/hr (n = 8) and 400 mg/m2/hr (n = 7) DDTC as 4-hour intravenous infusions to normal male healthy volunteers. Diethyldithiocarbamate concentration at steady-state (Cpss) increased disproportionally from 27.0 +/- 7.6 microM for the low dose to 74.8 +/- 19.3 microM for the high dose, whereas total body clearance decreased from 23.83 +/- 8.23 mL/min/kg for the low dose to 15.48 +/- 2.72 mL/min/kg for the high dose (P < 0.05). However, the volume of distribution in the terminal phase remained unchanged. Diethyldithiocarbamate terminal elimination half-life (t1/2 beta) increased from 3.74 +/- 1.10 minutes for the low dose to 6.08 +/- 1.07 minutes for the high dose (P < 0.005). The data were then fitted using a one-compartment open model with zero-order infusion and Michaelis-Menten elimination kinetics. The Km for DDTC was estimated to be 124.3 +/- 19.9 microM, whereas the Vm was estimated to be 3.67 +/- 1.15 mumol/min/kg. However, DDTC t1/2 beta was independent of DDTC concentrations, suggesting that the nonlinearity in DDTC kinetics does not exactly follow Michaelis-Menten elimination kinetics. Thus, DDTC pharmacokinetics are dose dependent and may not be concentration dependent. Clinically, DDTC Cpss will increase nonlinearly with an increase in dose.

Sugar-linked dithiocarbamates as modulators of metabolic and genotoxic properties of N-nitroso compounds.

A series of putative anticarcinogenic and antimutagenic compounds was synthesized on the basis of tetraethylthiuram disulfide (disulfiram) and its metabolite, diethyldithiocarbamate (DDTC). Diallyldithiocarbamate was synthesized in order to combine the anticarcinogenic properties of diallyl sulfide, a known inhibitor of chemical carcinogenesis from Allium species, and those of DDTC. Several sugar-linked dithiocarbamates (SDTCs) were prepared using glucose, cellobiose, and lactose as glycosyl donors and DDTC and diallyldithiocarbamate as acceptors. All the S--glycoside bonds of SDTCs were very stable under physiological conditions in vitro. At low nitrosamine concentrations, glucose-DDTC inhibited microsomal nitrosamine dealkylases in vitro. In vivo these enzymes were also inhibited 4 h after i.p. administration of glucose-DDTC or lactose-DDTC to rats (1.7 mmol/kg); after 24 h, the values had returned to control levels. Glucose-DDTC induced the activity of glutathione-related enzymes. Concomitant treatment of rats with glucose-DDTC and N-nitrosodiethylamine (NDEA) led to a depression of the oxidative metabolism of [14C]NDEA to 14CO2 but increased the elimination of unchanged [14C]NDEA in the urine. Furthermore, glucose-DDTC totally inhibited the formation of DNA single-strand breaks induced by NDEA. All these effects may contribute to possible antimutagenic and anticarcinogenic actions of the dithiocarbamates investigated.

Diethyldithiocarbamate methyl ester sulfoxide, an inhibitor of rat liver mitochondrial low Km aldehyde dehydrogenase and putative metabolite of disulfiram.

S-methyl N,N-diethylthiolcarbamate sulfoxide (DETC-MeSO) is a potent inhibitor of rat liver mitochondrial low Km aldehyde dehydrogenase (ALDH2) both in vivo and in vitro, and has been proposed to be the metabolite responsible for ALDH2 inhibition by disulfiram. Diethyldithiocarbamate methyl ester (DDTC-Me), a key intermediate in the metabolism of disulfiram, has been shown to be bioactivated by microsomal monooxygenases to diethyldithiocarbamate methyl ester sulfoxide (DDTC-Me sulfoxide). Studies were conducted to determine if DDTC-Me sulfoxide was also an active metabolite of disulfiram and inhibitor of ALDH2. DDTC-Me sulfoxide inhibited ALDH2 in vitro with an IC50 of 10 microM, and in vivo with an ID50 of 31 mg/kg (170 mumol/kg). Maximal ALDH2 inhibition in vivo was observed 8 hr after the administration of 45.2 mg/kg DDTC-Me sulfoxide, with ALDH2 activity returning to control levels after 48 hr. Although DDTC-Me sulfoxide inhibited ALDH2 in vivo, DDTC-Me sulfoxide was not detected in plasma from rats treated with either disulfiram (75 mg/kg), DDTC-Me (122.25 mg/kg), or DDTC-Me sulfoxide (45.2 mg/kg). However, DDTC-Me and S-methyl N,N-diethylthiolcarbamate (DETC-Me) were detected in plasma from rats treated with DDTC-Me sulfoxide. In rats treated with DDTC-Me sulfoxide and challenged with ethanol, a small increase of approximately microM in blood acetaldhyde and an inconsistent drop in blood pressure was observed. In conclusion, DDTC-Me sulfoxide inhibited ALDH2 in vitro and in vivo, was less potent than DETC- MeSO, and was not detected after disulfiram administration.

In vivo pharmacodynamic studies of the disulfiram metabolite S-methyl N,N-diethylthiolcarbamate sulfoxide: inhibition of liver aldehyde dehydrogenase.

S-methyl N,N-diethylthiolcarbamate sulfoxide (DETC-MeSO) is proposed to be the metabolite of disulfiram responsible for the in vivo inhibition of liver low Km aldehyde dehydrogenase (ALDH) in the rat. Studies were conducted in male Sprague-Dawley rats and also in vitro using both rat liver mitochondrial and purified bovine mitochondrial low Km ALDH to investigate further the pharmacodynamic and pharmacokinetic characteristics of DETC-MeSO. Administration of DETC-MeSO to rats produced a rapid and maximal inhibition of liver mitochondrial low Km ALDH within 2 hr, which was still inhibited 30% after 168 hr. After DETC-MeSO treatment, the maximum plasma concentration of DETC-MeSO was reached within 0.5 hr, with DETC-MeSO being undetectable 2 hr after DETC-MeSO dosing. Although a trace amount of DETC-Me was detected in the plasma 0.5 hr after DETC-MeSO administration to rats, this disappeared within 1 hr. When rats were treated with disulfiram, the maximal plasma concentration of DETC-MeSO was found within 2 hr, with only a very small quantity of DETC-MeSO still detectable after 8 hr. Rats also were given the disulfiram metabolites diethyldithiocarbamate (DDTC), diethyldithiocarbamate-methyl ester (DDTC-Me), and S-methyl N,N-diethylthiolcarbamate (DETC-Me), and plasma analyzed for DETC-MeSO 2 hr after the administration of these metabolites. DETC-MeSO was detected in plasma, further illustrating that DETC-MeSO can be found in plasma after the administration of either disulfiram, or the subsequent in vivo metabolites DDTC, DDTC-Me, or DETC-Me.(ABSTRACT TRUNCATED AT 250 WORDS)