Toxicity of 50-nm polystyrene particles co-administered to mice with acetaminophen, 5-aminosalicylic acid or tetracycline.

We investigated whether nano-sized polystyrene particles affect drug-induced toxicity. The particles, which are widely used industrially, had diameters of 50 (NPP50), 200 (NPP200) or 1000 (NPP1000) nm. The toxic chemicals tested were acetaminophen (APAP), 5-aminosalicylic acid (5-ASA), tetracycline (TC), and sodium valproate (VPA). All treatments in the absence of the nanoparticles were non-lethal and did not result in severe toxicity. However, when mice were injected with APAP, 5-ASA or TC together with polystyrene particles, synergistic, enhanced toxicity was observed in mice injected with NPP50. These synergic effects were not observed in mice co-injected with NPP200 or NPP1000. On the other hand, co-administration of VPA and NPP50, NPP200 or NPP1000 did not elevate toxicity. The results show that NPP50 differs in hepatotoxicity depending on the drug co-administered. These findings suggest that further evaluation of the interactions between polystyrene nanoparticles and drugs is a critical prerequisite to the pharmaceutical application of nanotechnology.

Engineered andrographolide nanoparticles mitigate paracetamol hepatotoxicity in mice.

PURPOSE: Paracetamol (acetaminophen, APAP) overdose is often fatal due to progressive and irreversible hepatic necrosis. The aim of this work was to design Andrographolide (AG) loaded nanoparticles to prevent similar hepatic necrosis. METHODS: Functionalized AG-loaded PLGA nanoparticles carrying different densities of heparin were prepared following a facile emulsion solvent evaporation technique. Nanoparticle morphology, loading and release kinetics were studied. Hepatic localization of the nanoparticles was investigated in both normal and APAP damaged conditions using FITC fluorescent probe. Different serum parameters and liver histopathology were further examined as indicators of hepatic condition before and after treatment. RESULT: A collection of heparin functionalized AG-loaded PLGA nanoparticles were designed. Low amount of heparin on the particle surface could rapidly localize the nanoparticles up to the liver. The new functionalized AG nanoparticles affect efficient hepatoprotection in experimental mouse APAP overdose conditions. AG nanoparticle hepatoprotection was due to the rapid regeneration of antioxidant capacity and hepatic GSH store. CONCLUSIONS: Engineered nanoparticles loaded with AG provided a fast protection in APAP induced acute liver failure.

Ammonium sulfate gradient loading of brucine into liposomes: effect of phospholipid composition on entrapment efficiency and physicochemical properties in vitro.

BACKGROUND: Brucine, the major active alkaloid constituent extracted from traditional Chinese herbal medicine Nux vomica, had been found to possess remarkable antitumor, analgesic, and anti-inflammatory activities. In this study, we attempted to encapsulate brucine into liposomes to improve its therapeutic effects. The entrapment efficiency (EE) and the stability of liposomes are two key factors associated with the therapeutic effects of liposomal drugs. We developed a novel liposome-based brucine formulation that was composed of soybean phosphatidylcholine (SPC) and hydrogenated soybean phosphatidylcholine (HSPC). METHOD: The liposomes with different phospholipid composition were characterized for their EE, vesicle size, drug release profile, and leakage in vitro. RESULTS: The molar ratio of HSPC/SPC = 1:9 was determined as the optimum ratio. Compared with conventional liposomes composed of only SPC or HSPC, EE of the brucine-loaded novel liposomes was increased markedly, especially at high drug/lipid molar ratios. The results of drug release showed that the novel liposomes were more stable than the conventional SPC liposomes in the presence of fetal calf serum. In addition, the results of the leakage experiments revealed that the novel liposomes also had better stability in phosphate buffer solution (PBS) with respect to drug retention. Although the conventional HSPC liposomes is more stable than the novel liposomes, the novel liposomes composed of 10% HSPC and 90% SPC may still have promising application potential because HSPC is much more expensive than SPC. CONCLUSION: Taken together, efficient encapsulation of brucine into the novel liposomes, their improved stability, and the price of phospholipids indicate that the novel liposomes may act as promising carriers for active alkaloids such as brucine.

Improvement of therapeutic potential N-acetylcysteine in acetaminophen hepatotoxicity by encapsulation in PEGylated nano-niosomes.

AIMS: N-Acetylcysteine (NAC) is an effective antidote for the treatment of acetaminophen (APAP) poisoning; however, due to its low stability and bioavailability, repeated dosing of NAC is needed. This study investigated the therapeutic efficacy of NAC by niosomal carriers. MATERIALS AND METHODS: Niosomes were synthesized using surface active agents film hydration method and their physicochemical properties were characterized. In the in vivo study, in addition to control group, male rats were divided in different groups and challenged with an oral dose of APAP (2000 mg/kg); 4 h later, rats were administered normal saline, empty niosome (NIO), NAC (25 mg/kg) and NAC-loaded niosome (NAC-NIO) respectively, and sacrificed 48 h post-APAP overdose. KEY FINDINGS: The particle size and zeta potential of NAC-NIO were 242.3 ± 18.5 nm and -23.9 ± 1.6 mV. The loading and encapsulation efficiency of niosomes were 1.22% ± 0.02% and 26.76% ± 6.02%. APAP administration leads to hepatic damage as evidenced by increases in serum hepatic enzyme levels and tissue levels of nitric oxide and lipid peroxidation as well as decreases in hepatic levels of reduced glutathione, catalase, superoxide dismutase, and glutathione peroxidase. Treatment of rats with NIO-NAC was remarkably more effective than NAC in improving biochemical changes such as serum hepatic aminotransferases. These findings were correlated well to the histopathological experiments. SIGNIFICANCE: Our results suggest that NAC when delivered as a niosomal structure, is potentially more effective than NAC standard, in improving APAP-induced hepatotoxicity.

Effects of fructose-induced hypertriglyceridemia on hepatorenal toxicity of acetaminophen in rats. II. Role of enhancement of fructose metabolism and overproduction of triglyceride in the liver and kidney on hepatorenal toxicity of acetaminophen.

Fructose-induced hypertriglyceridemic rats are resistant to hepatoxicity and susceptible to nephrotoxicity of acetaminophen (APAP) as compared with normal ones. The present studied were designed to evaluate how fructose-treatment affects the developmental mode of hepatorenal toxicity of APAP. First, following fructose-pretreatment for various durations (1 day, 1 week or 3 weeks), 1-day-fructose-pretreatment induced hypertriglyceridemia and enhancement of APAP-nephrectoxicity simultaneously. However, it took at least 3 weeks for fructose-pretreatment to reduce APAP-hepatotoxicity. Second, following fructose, sucrose or glucose-pretreatment for 3 weeks, fructose-pretreated rats showed marked hypertriglyceridemia and modification of APAP-hepatorenal toxicity. Sucrose-pretreated rats showed less effects than fructose-pretreated rats. Glucose-pretreated rats showed no changes in plasma triglyceride and APAP-hepatorenal toxicity. Third, rats with hypertriglyceridemia induced by olive oil or Triton WR-1339 which did not produce enhanced metabolism and triglyceride-overproduction in the liver and kidney showed no modification of APAP-hepatorenal toxicity. Pretreatment of glycerol which was metabolized in liver and kidney and induced an overproduction of triglyceride resulted in an enhancement of APAP-nephrotoxicity. These results indicate that an enhancement of fructose metabolism and an overproduction of triglyceride in liver and kidney are responsible for the modification of APAP-hepatorenal toxicity in fructose-induced hypertriglyceridemic rats.

[Toxicity of drugs on nasal mucocilia and the method of its evaluation].

Effect of solutions or suspensions of eight drugs including analgin, paracetamol, propafenone hydrochloride, propranolol hydrochloride, ephedrine hydrochloride, gentamycin sulfate, sodium deoxycholate and hydrocortisone on ciliary movement were evaluated with in vitro or in situ toad palate model and scanning electron microscope. In vitro toad palate model: 0.2 ml of test drug solution or suspension was applied to a piece of freshly dissected upper palate of toad. The mucocilia were examined with an optical microscope and the lasting time of ciliary movement was recorded after drug application. The upper palate was rinsed with physiological saline when the ciliary movement stopped. The lasting time of ciliary movement after rinsing was then recorded again. In situ palate model: 0.5 ml of test drug solution or suspension was applied to the upper palate of toad for 30 min, and rinsed with physiological saline. The palate was dissected out and the operation was carried out in a similar manner. The results showed that the in situ toad palate model is a satisfactory method for studying the ciliotoxicity of drugs. The in vitro toad palate model is unsuitable for suspension and gel. The results of the eight drugs revealed that ciliary movement is frequently affected by many drugs and, therefore, care must be taken in developing any nasal dosage form to ensure its least ciliotoxicity.

Identifying adults at risk of paracetamol toxicity in the acute dental setting: development of a clinical algorithm.

Paracetamol is widely used and effective for the management of dental pain in the UK. Acute dental pain is a recognised precipitant of unintentional paracetamol overdose and in a small but significant number of cases this results in hepatotoxicity. Patients' understanding of the risks of excess paracetamol ingestion remains poor and risk of over-medication before presentation is increased due to a variety of factors including dental anxiety and fragmented provision of dental emergency services. Early recognition of overdose is crucial to preventing significant hepatotoxicity and death. Dentists have a role to play in recognising unintentional overdose cases and directing patients timeously to appropriate medical care. Guidelines on the treatment of paracetamol toxicity are readily available but our data suggests some dental settings may present a weak link in the care pathway and overdose may not be readily recognised. We have developed an algorithm and training package targeted at dentists in the acute dental setting with the aim of improving recognition of paracetamol toxicity in adults and directing onward referral appropriately. This paper also revises the key pharmacokinetics and pharmacodynamics of paracetamol and is intended to raise awareness of issues of toxicity for dentists.

Design and optimization of self-nanoemulsifying delivery system to enhance quercetin hepatoprotective activity in paracetamol-induced hepatotoxicity.

The present study aimed to develop optimized quercetin (QT)-loaded self-nanoemulsifying drug delivery system (SNEDDS) that offers protective effect against liver damage. Solubility study of QT in different oils, surfactants, and cosurfactants was performed. Ternary phase mixtures of the selected components were constructed to select a suitable range for each component. Experimental mixture design was utilized to optimize SNEDDSs that possess smaller globule size with enhanced emulsification and dissolution rates. QT SNEDDS was compared with QT suspension control and silymarin. In vivo evaluation and histopatholgical study of the selected QT SNEDDSs were achieved after administration of paracetamol over dosage to albino rats. Two optimized formulations were selected; one based on Sefsol and the other based on linoleic acid as an oily phase, Tween(®) 80 and polyethylene glycol 400 as surfactant and cosurfactant, respectively. Both Sefsol and linoleic-acid-optimized SNEDDS formulation showed no symptoms associated with toxicity and offered protective effect against paracetamol-induced hepatotoxicity by scavenging free radicals, attenuating lipid peroxidation, and enhancing the activity of antioxidants. The histopatholgical observations revealed that the inflammatory infiltrations induced by paracetamol were significantly ameliorated.

The therapeutic applications of and risks associated with acetaminophen use: a review and update.

BACKGROUND: In response to the April 2010 U.S. Food and Drug Administration's (FDA's) revision of warning labeling for over-the-counter (OTC) acetaminophen, or N-acetyl-p-aminophenol (APAP), products, the authors reviewed APAP's potential for liver toxicity. TYPES OF STUDIES REVIEWED: The authors reviewed the literature in which investigators examined data related to the epidemiology of APAP-related liver toxicity, studies in which the investigators evaluated the risk factors for its occurrence and case reports. They included articles that were used by the FDA as the basis for establishing the new labeling requirements. RESULTS: Findings from the literature in which investigators have examined the relationship between APAP and liver toxicity indicate several key risk factors. Foremost are the extensive use of one or more APAP-containing compounds (particularly combinations with opioid agents) and the small margin of safety between the therapeutic and toxic doses. Both of these factors lead to unintentional or intentional drug overdose. Concurrent use of alcohol may contribute to hepatotoxicity, but it may be related to behavior rather than biochemical mechanisms involved in liver damage. CONCLUSIONS: The widespread use of APAP has contributed to a substantial increase in the number of cases of acute liver toxicity in the United States. Since APAP is a component of many prescription and OTC medications, unintentional overdose can occur. CLINICAL IMPLICATIONS: APAP has numerous applications in dentistry, but if it is used conjointly for other conditions, the risk of the patient's experiencing an overdose increases. In the context of recent FDA concerns about the increased incidence of APAP-related liver toxicity, the authors provide recommendations for safe prescribing practices for APAP. Practitioners should caution patients to follow recommended dosage instructions and avoid taking multiple APAP-containing products.

Rat primary hepatocytes show enhanced performance and sensitivity to acetaminophen during three-dimensional culture on a polystyrene scaffold designed for routine use.

The in vitro evaluation of hepatotoxicity is an essential stage in the research and development of new pharmaceuticals as the liver is one of the most commonly impacted organs during preclinical toxicity studies. Fresh primary hepatocytes in monolayer culture are the most commonly used in vitro model of the liver but often exhibit limited viability and/or reduction or loss of important liver-specific functions. These limitations could potentially be overcome using three-dimensional (3D) culture systems, but their experimental nature and limited use in liver toxicity screening and drug metabolism has impaired their uptake into commercial screening programs. In this study we use a commercially available polystyrene scaffold developed for routine 3D cell culture to maintain primary rat hepatocytes for use in metabolism and toxicity studies over 72 h. We show that primary hepatocytes retain their natural cuboidal morphology with significantly higher viability (>74%) than cells grown in monolayer culture (maximum of 57%). Hepatocytes in the 3D scaffolds exhibit differential expression of genes associated with phase I, II, and III drug metabolism under basal conditions compared with monolayer culture and can be induced to stably express significantly higher levels of the cytochrome-P450 enzymes 1A2, 2B1, and 3A2 over 48 h. In toxicity studies the hepatocytes in the 3D scaffolds also show increased sensitivity to the model toxicant acetaminophen. These improvements over monolayer culture and the availability of this new easy to use 3D scaffold system could facilitate the uptake of 3D technologies into routine drug screening programs.

Life-history consequences for Daphnia pulex exposed to pharmaceutical carbamazepine.

The effects of the antiepileptic, analgesic drug carbamazepine on the growth, morphology, and life-history characteristics of Daphnia pulex were examined at nominal concentrations of 0, 0.1, 1, 10, 100, and 200 microg L(-1). At 1 microg carbamazepine L(-1), Daphnia matured and reproduced slightly earlier than did controls, and at a given body length females produced more offspring than did controls or those receiving other treatments. In combination with a relatively high juvenile somatic growth rate and highest total number of progeny produced per female, carbamazepine at 1 microg L(-1) seemed to exert a stimulatory effect. The rates of population growth of the 100 and 200 microg L(-1) treatment groups was 9% and 32% lower, respectively, than the rates of growth of the controls and the Daphnia receiving treatments of up to 10 microg carbamazepine L(-1). At the highest dose, retardation of juvenile somatic growth resulted in delayed maturity and consequently in a lower rate of population growth. Adult somatic growth, spine length, reproductive output, and size of newborns were similar among treatments. Male offspring were only produced in the third broods, with broods that were 8% and 28% male at 1 and 10 microg L(-1), respectively. Neck teeth were never observed in Daphnia. Chronic adverse effects of carbamazepine on nontarget Daphnia were detected at 200 microg carbamazepine L(-1), but stimulatory effects might occur at environmentally realistic concentrations. However, additional studies of chronic toxicity investigating various combinations of pharmaceuticals and various environmental stresses, such as food condition, temperature, and kairomones, are needed to fully explore potential long-term adverse effects and to assess the environmental risk of common pharmaceuticals.

Role of macrophages in acetaminophen (paracetamol)-induced hepatotoxicity.

Research into the pathogenesis of acetaminophen (paracetamol)-induced hepatotoxicity has concentrated on the generation of toxic metabolites by the hepatocytes. It has, however, recently been shown that human macrophages cultured with acetaminophen secrete increased quantities of tumour necrosis factor (TNF). This study examines whether macrophages have a direct role in acetaminophen toxicity, using a mouse model in which it is possible to eliminate more that 99 per cent of hepatic macrophages by previously injecting liposomes containing dichloromethylene disphosphonate (DMDP). Acetaminophen-induced liver damage was assessed biochemically and histologically. It was shown that the liver damage occurring 0.5, 1, and 2 h after an intraperitoneal injection of acetaminophen was significantly less in mice previously injected with liposomes containing DMDP than in previously untreated mice, or mice previously injected with empty liposomes. By 4 h there was no difference between the groups. We conclude that macrophages play an early and probably a direct role in mediating the liver damage due to acetaminophen. This is consistent with the role that macrophages have been shown to play in the pathogenesis of alcohol-induced liver damage.

Characteristics of clodronate-induced apoptosis in osteoclasts and macrophages.

Bisphosphonates (BPs), such as clodronate and pamidronate, are inhibitors of bone resorption and are used on a widespread basis in the treatment of hyper-resorptive bone diseases. At the cellular level, BPs inhibit osteoclasts, but the precise molecular mechanisms are unclear. BPs have also been shown to affect the survival of macrophages, cells ontogenetically related to osteoclasts. We show that both clodronate and pamidronate induce apoptosis in isolated osteoclasts. Clodronate, when administered in liposomes, also induced apoptosis in rat peritoneal macrophages in vitro and in liver macrophages of mice in vivo but not in murine macrophage-like RAW-264 cells. The subcellular localization and staining intensity of Bcl-2, an anti-apoptotic protein known to protect several cell types against drug-induced apoptosis, were similar in RAW-264 and peritoneal macrophage cells, as revealed by immunofluorescence. The clodronate-induced apoptotic pathway was further characterized in isolated osteoclasts cultured on glass coverslips through the use of clodronate-containing liposomes and several inhibitors of the apoptotic cascade. None of the agents tested could totally prevent clodronate-induced osteoclast death. Partial protection was, however, obtained by the addition of staurosporine or homocysteine. The results suggest that primarily cytoplasmic, protein kinase C-activated mechanisms are involved in the execution of clodronate-induced apoptosis of osteoclasts.

Displacement of platelets from blood to spleen following intravenous injection of liposomes encapsulating dichloromethylene bisphosphonate.

Liposomes encapsulating dichloromethylene bisphosphonate (Cl2MBP-liposomes) have been shown to cause selective depletion of phagocytic macrophages. We have shown that intravenous injection of Cl2MBP-liposomes into mice induces an almost complete depletion of F4/80-positive cells (mature macrophages) in the liver and in the splenic red pulp, but not in the lung. Platelets in the mouse contain a large amount of 5-hydroxytryptamine (5HT; serotonin) and so, by measuring 5HT, it is possible to assess the translocation of platelets to tissues. The injection of Cl2MBP-liposomes was found to induce a prolonged and marked increase in 5HT that occurred selectively in the spleen. On the other hand, 5HT in the blood decreased by as much as 50%. These changes in 5HT corresponded well with each other in terms of both time course and dose-response relationship. To judge from measurements made at the peak of the response, the 5HT increase in the spleen corresponded to about 80% of the 5HT lost from the blood. Electron microscopic analysis revealed a great accumulation of platelets in the splenic cords. We have shown that aggregation and degranulation of platelets in the lung is involved in rapid anaphylactoid shock induced within 10 min of intravenous injection into mice of a lipopolysaccharide [Shibazaki, M., Nakamura, M., Endo, Y., 1996. Biphasic, organ-specific, and strain-specific accumulation of platelets induced in mice by a lipopolysaccharide from Escherichia coli and its possible involvement in shock. Infect. Immun. 64, 5290-5294; Endo, Y., Shibazaki, M., Nakamura, M., Takada, H., 1997. Contrasting effects of lipopolysaccharides (endotoxins) from oral black-pigmented bacteria and Enterobacteriaceae on platelets, a major source of serotonin, and on histamine-forming enzyme in mice. J. Infect. Dis. 175, 1404-1412]. In the present study, it was found that such shock was almost completely prevented in those mice in which platelets were displaced from the blood by Cl2MBP-liposomes. These results suggest that in the spleen the depletion of phagocytic macrophages may impair the function or structure of this organ. This may lead to the entry of platelets into the spleen in such large numbers as to reduce their level in the blood and result in their prolonged accumulation in the spleen. The Cl2MBP-liposome may be an excellent tool for the in vivo investigation of the role of platelets, as well as that of macrophages.