Acetylcysteine as a cytoprotective antioxidant in patients with severe sepsis: potential new use for an old drug

Efficacy assessment of co-treated alpha-ketoglutarate and N-acetyl cysteine against the subchronic toxicity of cyanide in rats

Cyanide is an important industrial pollutant, major occupational hazard, and a potential chemical warfare agent. Its intentional or accidental exposure to humans is a big clinical problem because of its rapid mode of action. Certain plant origin foods also contain substantial amount of cyanide and cause chronic toxicity. This study explores the protective efficacy of co-treatment of alpha-ketoglutarate (AKG) and an antioxidant N-acetyl cysteine (NAC) against toxicity of subchronically exposed cyanide in rats. We explore the effect of AKG + NAC co-treatment on oxidative stress, inflammation, and histological changes induced due to long-term sublethal cyanide exposure. Cyanide induces oxidative stress by inhibiting metalloenzymes (catalase and superoxide dismutase) causing increase in lipid peroxidation (malondialdehyde) and decrease in reduced glutathione (GSH). It also increases the activity of cyclo-oxygenase enzymes causing oxidative stress-mediated inflammation in the brain. Cyanide exposure also causes degenerative changes in the brain as shown in histology. It also causes pathology in liver and kidney. AKG is known to form cyanohydrins with cyanide reducing the free cyanide levels, and its combination with NAC showed overall improvement in by reducing the oxidative stress and subsequent neuroinflammation. Their combination was also found to improve the histological outcome of vital tissues. AKG, an over-the-counter sport medicine, and the antioxidant NAC per se did not show any detrimental effects in any tested parameter. Hence, oral treatment with AKG and NAC can be beneficial for the treatment of chronic cyanide poisoning.

Recombinant Human Superoxide Dismutase and N-Acetylcysteine Addition to Exogenous Surfactant in the Treatment of Meconium Aspiration Syndrome

This study aimed to evaluate the molecular background of N-acetylcysteine (NAC) and recombinant human superoxide dismutase (rhSOD) antioxidant action when combined with exogenous surfactant in the treatment of meconium aspiration syndrome (MAS), considering redox signalling a principal part of cell response to meconium. Young New Zealand rabbits were instilled with meconium suspension (Mec) and treated by surfactant alone (Surf) or surfactant in combination with i.v. NAC (Surf + NAC) or i.t. rhSOD (Surf + SOD), and oxygen-ventilated for 5 h. Dynamic lung-thorax compliance, mean airway pressure, PaO₂/FiO₂ and ventilation efficiency index were evaluated every hour; post mortem, inflammatory and oxidative markers (advanced oxidation protein products, total antioxidant capacity, hydroxynonenal (HNE), p38 mitogen activated protein kinase, caspase 3, thromboxane, endothelin-1 and secretory phospholipase A₂) were assessed in pulmonary tissue homogenates. rhSOD addition to surfactant improved significantly, but transiently, gas exchange and reduced levels of inflammatory and oxidative molecules with higher impact; Surf + NAC had stronger effect only on HNE formation, and duration of treatment efficacy in respiratory parameters. In both antioxidants, it seems that targeting reactive oxygen species may be strong supporting factor in surfactant treatment of MAS due to redox sensitivity of many intracellular pathways triggered by meconium.

Cysteine/Glutathione Deficiency: A Significant and Treatable Corollary of Disease

Glutathione (GSH) deficiency may play a pivotal role in a variety of apparently unrelated clinical conditions and diseases. Orally administered N-acetylcysteine (NAC), which replenishes the cysteine required for GSH synthesis, has been tested in a large number of randomized placebo-controlled trials involving these diseases and conditions. This chapter focused on developing a base of evidence suggesting that NAC administration improves disease by increasing cysteine and/or GSH in a variety of diseases, thereby implying a significant role for GSH deficiency in the clinical basis of many diseases. To develop this base of evidence, we systematically selected studies which considered the hypothesis that the therapeutic efficacy for NAC is an indication that cysteine and/or GSH deficiency is a pathophysiological part of the diseases studied. In this manner we focus this chapter on explaining the biological mechanisms of NAC therapy in a wide variety of disorders and demonstrate its ubiquitous role in improving disease that involves disrupted GSH and/or cysteine metabolism.

Effect of N-acetylcysteine supplementation on intracellular glutathione, urine isoprostanes, clinical score, and survival in hospitalized ill dogs

BACKGROUND

Antioxidant depletion and lipid peroxidation have been correlated with disease severity and associated with poor outcomes.

HYPOTHESIS/OBJECTIVES

Supplementing dogs with N-acetylcysteine (NAC) during the first 48 hours of hospitalization will increase cysteine, normalize glutathione concentrations, and decrease the degree of lipid peroxidation associated with illness.

ANIMALS

Sixty systemically ill hospitalized client-owned dogs and 14 healthy control dogs.

METHODS

Randomized investigator-blinded, placebo-controlled prospective study. Dogs were randomized to treatment with NAC (n = 30) versus placebo (n = 30). Antioxidants, urine 8-isoprostane/creatinine (IP/Cr), and clinical score were determined before and after treatment with NAC. Glutathione, cysteine, and vitamin E concentrations were quantified using high-performance liquid chromatography. Atomic absorption spectroscopy and enzyme-linked immunosorbent assays were used to quantify selenium and isoprostane concentrations, respectively.

RESULTS

Ill dogs had significantly lower vitamin E concentrations (27 versus 55 μg/mL; P = .0005) as well as elevated IP/Cr ratios (872 versus 399 pg/mg; P = .0007) versus healthy dogs. NAC supplementation significantly increased plasma cysteine (8.67 versus 15.1 μM; P < .0001) while maintaining glutathione concentrations. Dogs in the placebo group experienced a statistically significant decrease in glutathione concentrations (1.49 versus 1.44 mM; P = .0463). Illness severity and survival were unchanged after short duration NAC supplementation.

CONCLUSIONS

Ill dogs experience systemic oxidative stress. Supplementation with NAC during the first 48 hours of hospitalization stabilized erythrocyte glutathione concentrations. The clinical impact of this supplementation and glutathione concentration stabilization was undetermined.

N-acetylcysteine for sepsis and systemic inflammatory response in adults

BACKGROUND

Death is common in systemic inflammatory response syndrome (SIRS) or sepsis-induced multisystem organ failure and it has been thought that antioxidants such as N-acetylcysteine could be beneficial.

OBJECTIVES

We assessed the clinical effectiveness of intravenous N-acetylcysteine for the treatment of patients with SIRS or sepsis.

SEARCH METHODS

We searched the following databases: Cochrane Central Register of Clinical Trials (CENTRAL) (The Cochrane Library 2011, Issue 12); MEDLINE (January 1950 to January 2012); EMBASE (January 1980 to January 2012); CINAHL (1982 to January 2012); the NHS Trusts Clinical Trials Register and Current Controlled Trials (www.controlled-trials.com); LILACS; KoreaMED; MEDCARIB; INDMED; PANTELEIMON; Ingenta; ISI Web of Knowledge and the National Trials Register to identify all relevant randomized controlled trials available for review.

SELECTION CRITERIA

We included only randomized controlled trials (RCTs) in the meta-analysis.

DATA COLLECTION AND ANALYSIS

We independently performed study selection, quality assessment and data extraction. We estimated risk ratios (RR) for dichotomous outcomes. We measured statistical heterogeneity using the I(2) statistic.

MAIN RESULTS

We included 41 fully published studies (2768 patients). Mortality was similar in the N-acetylcysteine group and the placebo group (RR 1.06, 95% CI 0.79 to 1.42; I(2) = 0%). Neither did N-acetylcysteine show any significant effect on length of stay, duration of mechanical ventilation or incidence of new organ failure. Early application of N-acetylcysteine to prevent the development of an oxidato-inflammatory response did not affect the outcome, nor did late application that is after 24 hours of developing symptoms. Late application was associated with cardiovascular instability.

AUTHORS' CONCLUSIONS

Overall, this meta-analysis puts doubt on the safety and utility of intravenous N-acetylcysteine as an adjuvant therapy in SIRS and sepsis. At best, N-acetylcysteine is ineffective in reducing mortality and complications in this patient population. At worst, it can be harmful, especially when administered later than 24 hours after the onset of symptoms, by causing cardiovascular depression. Unless future RCTs provide evidence of treatment effect, clinicians should not routinely use intravenous N-acetylcysteine in SIRS or sepsis and academics should not promote its use.

Effect of alpha-ketoglutarate and N-acetyl cysteine on cyanide-induced oxidative stress mediated cell death in PC12 cells

Cyanide is a mitochondrial poison, which is ubiquitously present in the environment. Cyanide-induced oxidative stress is known to play a key role in mediating the neurotoxicity and cell death in rat pheochromocytoma (PC12) cells. PC12 cells are widely used as a model for neurotoxicity assays in vitro. In the present study, we investigated the protective effects of alpha-ketoglutarate (A-KG), a potential cyanide antidote, and N-acetyl cysteine (NAC), an antioxidant against toxicity of cyanide in PC12 cells. Cells were treated with various concentrations (0.625—1.25 mM) of potassium cyanide (KCN) for 4 hours, in the presence or absence of simultaneous treatment of A-KG (0.5 mM) and NAC (0.25 mM). Cyanide caused marked decrease in the levels of cellular antioxidants like superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR). Lipid peroxidation indicated by elevated levels of malondialdehyde (MDA) was found to be accompanied by decreased levels of reduced glutathione (GSH) and total antioxidant status (TAS) of the cells. Cyanide-treated cells showed notable increase in caspase-3 activity and induction of apoptotic type of cell death after 24 hours. A-KG and NAC alone were very effective in restoring the levels of GSH and TAS, but together they significantly resolved the effects of cyanide on antioxidant enzymes, MDA levels, and caspase-3 activity. The present study reveals that combination of A-KG and NAC has critical role in abbrogating the oxidative stress-mediated toxicity of cyanide in PC12 cells. The results suggest potential role of A-KG and NAC in cyanide antagonism.

The role of nutrients in modulating disease

The role of nutrition in the management of diseases has often centred on correcting apparent nutrient deficiencies or meeting estimated nutritional requirements of patients. Nutrition has traditionally been considered a supportive measure akin to fluid therapy and rarely it has been considered a primary means of ameliorating diseases. Recently, however, further understanding of the underlying mechanisms of various disease processes and how certain nutrients possess pharmacological properties have fuelled an interest in exploring how nutritional therapies themselves could modify the behaviour of various conditions. Nutrients such as omega-3 fatty acids, antioxidants and certain amino acids such as arginine and glutamine have all been demonstrated to have at least the potential to modulate diseases. Developments in the area of critical care nutrition have been particularly exciting as nutritional therapies utilising a combination of approaches have been shown to positively impact outcome beyond simply proving substrate for synthesis and energy. Application of certain nutrients for the modulation of diseases in veterinary patients is still in early stages, but apparent successes have already been demonstrated, and future studies are warranted to establish optimal approaches. This review describes the rationale of many of these approaches and discusses findings both in human beings and in animals, which may guide future therapy.

Stability of acetylcysteine solution repackaged in oral syringes and associated cost savings

PURPOSE

The physical and chemical stability of repackaged acetylcysteine 600 mg/3 mL solution in oral syringes stored under refrigeration or at room temperature was studied for six months; a cost analysis was also conducted.

METHODS

Acetylcysteine 20% solution for inhalation was repackaged undiluted as 600 mg/3 mL in capped oral syringes and stored either under refrigeration or at room temperature exposed to fluorescent light. Four samples for each storage condition were analyzed in duplicate on day zero, weekly for the first month, and then every two weeks during months 2-6. Physical stability was assessed, and the chemical stability of acetylcysteine was evaluated by high-performance liquid chromatography.

RESULTS

Acetylcysteine solution in syringes was physically stable during the entire six-month study period. When stored at room temperature, acetylcysteine retained 99% of the original concentration at three months and 95% at six months after preparation of the syringes. Loss of acetylcysteine was <2% at six months when stored under refrigeration. Packaging acetylcysteine in batches of 100 syringes instead of preparing individual syringes reduced wastage to zero syringes, saving an estimated $247 in drug costs. The estimated pharmacy time savings was 30 hours ($702).

CONCLUSION

Acetylcysteine 20% solution repackaged as 600 mg/3 mL in oral syringes is both physically and chemically stable under refrigeration or at room temperature under normal fluorescent lighting for six months. The total loss of acetylcysteine was approximately 5% at room temperature under fluorescent lighting and <2% under refrigeration. Repackaging the solution in syringes in bulk rather than in single doses demonstrated a measurable cost saving.

A novel antioxidant N-acetylcysteine amide prevents gp120- and Tat-induced oxidative stress in brain endothelial cells

Free radical production and, consequently, oxidative stress play an important role in the pathogenesis of AIDS and cause damage to lipids, proteins, and DNA. In our previous study, the HIV-1 envelope glycoprotein (gp120) and transregulatory protein (Tat) of HIV-1 have been found to induce oxidative stress in an immortalized endothelial cell line from rat brain capillaries, RBE4 (in vitro model of the blood-brain barrier). Here, we have determined the effects of a novel antioxidant, N-acetylcysteine amide (NACA), on gp120- and Tat-induced oxidative stress. Various oxidative stress parameters, including reduced glutathione (GSH), oxidized glutathione (GSSG), catalase (CAT) activity, and glutathione reductase (GR) activity, as well as malondialdehyde (MDA) levels, were used as measures of oxidative stress. NACA significantly increased the levels of intracellular GSH, CAT, and GR and decreased the levels of MDA in RBE4 cells, showing that oxidatively challenged cells were protected. Gp120- and Tat-induced increases in intracellular reactive oxygen species (ROS) were observed by using the 2',7'-DCF assay; the ROS scavenger, NACA, blocked ROS generation. A well-known apoptosis indicator, caspase-3 activity, was measured and was also found to have been returned to its control levels by NACA. Treatment of RBE4 cells with gp120 and Tat caused an increase in toxicity, as measured by lactate dehydrogenase (LDH) and tetrazolium reduction (MTS) assays. HIV-1 protein-induced toxicity in these cells was blocked by treatment with NACA. These studies show that NACA reverses gp120- and Tat-induced oxidative stress in immortalized endothelial cells.

Metabolic, antioxidant, nutraceutical, probiotic, and herbal therapies relating to the management of hepatobiliary disorders

Many nutraceuticals, conditionally essential nutrients, and botanical extracts have been proposed as useful in the management of liver disease. The most studied of these are addressed in terms of proposed mechanisms of action, benefits, hazards, and safe dosing recommendations allowed by current information. While this is an area of soft science, it is important to keep an open and tolerant mind, considering that many major treatment discoveries were in fact serendipitous accidents.

Comparison of different anti-inflammatory agents in suppressing the monocyte response to orthopedic particles

Three different anti-inflammatory agents--diclofenac, dexamethasone, and N-acetylcysteine--were compared to evaluate their effectiveness in suppressing monocyte-macrophage cell culture activation and mediator release (tumor necrosis factor-alpha [TNF-alpha] and interleukin-1beta [IL-1beta]) in response to polymethylmethacrylate particulate debris. N-acetylcysteine and diclofenac were most effective in suppressing TNF-alpha and IL-1beta expression by the monocyte-macrophages. Dexamethasone reduced TNF-alpha expression but was not as effective suppressing IL-1beta expression. N-acetylcysteine and dexamethasone had no effect on cell viability whereas diclofenac at the highest concentrations decreased cell viabilities. N-acetylcysteine and diclofenac, but less so dexamethasone, are effective in suppressing wear debris-related cell activation and mediator release and thus potentially represent therapeutic or preventive modalities for periprosthetic osteolysis.

Vascular endothelial growth factor (VEGF) and melanoma. N-acetylcysteine downregulates VEGF production in vitro

Vascular endothelial growth factor (VEGF), the most potent angiogenic factor identified to date, is associated with growth and metastasis of solid tumours, including melanoma. It has been shown in vitro that melanoma cells produce raised concentrations of VEGF. We examined the VEGF concentrations in plasma of 20 patients with primary melanoma, local recurrence and metastatic melanoma. We also studied the inhibiting effect of one antioxidant, N-acetylcysteine, on VEGF production in three human melanoma cell lines. We found elevated levels of VEGF (median 205 pg ml; 95 percent confidence interval, 80-414) in metastatic melanoma, with respect to primary and locally recurrent melanoma (75 pg/ml; 95 percent confidence interval, 35-130). The health control patients had levels of 25 pg/ml (95 percent confidence interval, 10-35). Human melanoma cell lines secreted VEGF in basal conditions (550-963 +/- 125 pg/ml) and N-acetylcysteine (0.5-20 mM) significantly decreased the VEGF production in a dose-dependent manner. VEGF concentrations were found to be raised in patients with primary melanoma, local recurrence, and above all, metastatic melanoma (P=0.008). N-acetylcysteine inhibits VEGF production in three human melanoma cell lines. This antioxidant might have therapeutic applications in metastatic melanoma in combination with other cytotoxic drugs.

Antioxidants attenuate nuclear factor-kappa B activation and tumor necrosis factor-alpha production in alcoholic hepatitis patient monocytes and rat Kupffer cells, in vitro

There is increased tumor necrosis factor-alpha (TNF) activity in alcoholic hepatitis (AH).

OBJECTIVES

To examine the effects of antioxidants and glutathione enhancing agents on NF-kappaB activation and TNF production in Kupffer cells and monocytes.

DESIGN AND METHODS

Isolated rat Kupffer cells and peripheral blood monocytes from AH patients were treated in vitro. NF-kappaB activation was assessed by electrophoretic mobility shift assay and TNF was measured in cell culture supernatants.

RESULTS

Monocytes from AH patients had greater TNF production compared to normal volunteers. Pretreatment with antioxidants or gluathione enhancing agents inhibited TNF production and NF-kappaB activation in both monocytes from normal and AH patients as well as in rat Kupffer cells.

CONCLUSIONS

There may be a therapeutic role for antioxidants or glutathione enhancing agents in disease states with increased TNF activity such as AH.

Prenatal vitamin E treatment improves lung growth in fetal rats with congenital diaphragmatic hernia

PURPOSE

Congenital diaphragmatic hernia (CDH) is associated with pulmonary hypoplasia. To discover factors that would accelerate fetal lung growth, the authors developed models of hypoplasia, found that antioxidants improved lung growth in vitro, and then proceeded to in vivo studies.

METHODS

Timed-pregnant rats were fed nitrofen (100 mg) on gestational day 9.5 (term, 22), and fetal lungs were harvested at day 13.5 and placed in organ culture in serum-free media with (n = 10) or without (n = 9) additional vitamin E (0.134 IU/mL). Camera lucida tracings were made daily on live, unstained lungs for 4 days, scanned, digitized, and analyzed for multiple growth parameters. Similar nitrofen-exposed rats were fed an optimized total dose of 150 IU vitamin E (n = 19) or olive oil (n = 13) from days 16.5 to 20.5, and fetal lungs were harvested at day 21.5, weighed and fixed for histology, or homogenized and biochemically analyzed.

RESULTS

Vitamin E accelerated hypoplastic fetal lung growth in vitro as measured by area, perimeter, lung bud count, perimeter over square root area, and fractal dimension. In vivo vitamin E significantly increased lung weights, total DNA, and protein contents.

CONCLUSIONS

Vitamin E accelerates hypoplastic fetal rat lung growth and complexity in vitro, and prenatal vitamin E treatment in vivo improves pulmonary hypoplasia in fetal rats with CDH.

Effects of bucillamine and N-acetyl-L-cysteine on cytokine production and collagen-induced arthritis (CIA)

We investigated the effects of bucillamine and N-acetyl-L-cysteine (NAC) on cytokine production and CIA. Bucillamine and NAC inhibited NF-kappaB activation and tumour necrosis factor-alpha (TNF-alpha) mRNA expression in human monocytic leukaemia cell line THP-1, and cytokine production from monocyte cell lines at concentrations >10-3 M. They also inhibited cytokine production and CIA in mice at a dose of 500 mg/kg. These results suggest that NF-kappaB inhibitors such as bucillamine and NAC may inhibit cytokine-related diseases, including arthritis.

Anti-interleukin-8 monoclonal antibody reduces free radical production and improves hemodynamics and survival rate in endotoxic shock in rabbits

BACKGROUND

Although high levels of interleukin-8 (IL-8) have been found in patients with sepsis and a monoclonal antibody (MoAb) against IL-8 has been successfully used in some animal models of inflammation, no specific therapeutic agent against IL-8 has been tested for the treatment of sepsis. We studied the effects of a MoAb against IL-8 in the treatment of endotoxic shock with a prospective randomized rabbit endotoxic shock model.

METHODS

Twenty New Zealand white rabbits were anesthetized and divided into four groups: normal, anti-IL-8, control-Ab, and lipopolysaccharide (LPS). Anti-IL-8 and control-Ab groups received a MoAb (immunoglobulin G, 3 mg/kg) 5 minutes before the LPS injection. All groups, except the normal group, received a continuous 20-minute infusion of LPS (500 micrograms/kg). The normal group received NaCl (0.9%) rather than LPS.

RESULTS

The 7-day survival rates were 100% for normal group, 80% for anti-IL-8 group, 40% for control-Ab group, and 0% for LPS group. Compared with the LPS group, anti-IL-8 rabbits had a smaller decrease in mean arterial blood pressure (p < 0.05) and increased urinary volume (p < 0.05). Anti-IL-8 rabbits had lower plasmatic levels of IL-1 beta, less free radical production (p < 0.05), and a higher survival rate (p < 0.01).

CONCLUSIONS

IL-8 plays a significant role in endotoxic shock, and IL-8 blockage results in attenuation of the hypotensive and tachypneic effects of LPS, reduced free radical production, and an increased survival rate after lethal endotoxic shock.

Pharmacotherapy of sepsis

During the past few years, many promising new agents for the treatment of sepsis have been studied to varying degrees in vitro as well as in vivo in animals and humans. Although there is a relative plethora of animal data, full-scale clinical trials of size sufficient to yield clear answers are rare. Many of the agents appear to hold promise based on preliminary data in animals or from small human studies, and some are undergoing multicenter clinical investigation. At present, however, none of the agents discussed clearly has shown survival benefit when administered to patients with sepsis. Certainly, none can be recommended as standard therapy, and others such as glucocorticoids should be avoided. Nevertheless, the pharmacotherapy of sepsis remains an area of intense research, and ongoing clinical trials as well as continuing basic research into the pathophysiologic mechanisms of sepsis yet may yield a well-studied drug that offers survival benefit to patients with sepsis.

N-acetylcysteine: pharmacological considerations and experimental and clinical applications

The diversity of application of the thiol drug NAC in both the experimental setting, as a tool for the study of the mechanisms and consequences of oxidative stress, and the clinical setting, as a therapeutic agent, clearly reflects the central role played by the redox chemistries of the group XVI elements, oxygen and sulfur, in biology. As our understanding of such redox processes increases, particularly their roles in specific pathophysiological processes, new avenues will open for the use of NAC in the clinical setting. As a drug, NAC represents perhaps the ideal xenobiotic, capable of directly entering endogenous biochemical processes as a result of its own metabolism. Thus, it is hoped that the experience gained with this unique agent will help in future efforts to design antioxidants and chemoprotective principles which are able to more accurately utilize endogenous biochemical processes for cell- or tissue-specific therapy.

Glutathione in health and disease: pharmacotherapeutic issues

OBJECTIVE

To review the current research and importance of glutathione (GSH) therapy in health and disease and to provide a basic overview of the widespread use and interest in this compound.

DATA IDENTIFICATION

Articles were obtained via a MEDLINE search of the term glutathione in conjunction with specific disease states mentioned, and via extensive review of references found in articles identified by computer search.

STUDY SELECTION

Emphasis was placed on the most recent research, human research, and in discussing multiple disease states.

DATA EXTRACTION

The literature was reviewed for methodology, quality, and practical aspects of interest to clinical pharmacists.

DATA SYNTHESIS

GSH is a tripeptide of extreme importance as a catalyst, reductant, and reactant. It continues to be investigated in diverse areas such as acute respiratory distress syndrome, toxicology, AIDS, aging, oncology, and liver disease. Despite the widespread clinical interest in GSH, we were not able to identify an in-depth review of this compound in the pharmacy literature.

CONCLUSIONS

The list of potential indications for modulation of GSH is extensive and broad. This review introduces clinicians to what GSH is, its basic chemistry, and some areas of active research.