Acetaminophen intoxication and length of treatment: how long is long enough?

The granulopoietic cytokine granulocyte colony-stimulating factor (G-CSF) induces pain: analgesia by rutin

Rutin is a glycone form of the flavonol quercetin and it reduces inflammatory pain in animal models. Therapy with granulocyte colony-stimulating factor (G-CSF) is known by the pain caused as its main side effect. The effect of rutin and its mechanisms of action were evaluated in a model of hyperalgesia induced by G-CSF in mice. The mechanical hyperalgesia induced by G-CSF was reduced by treatment with rutin in a dose-dependent manner. Treatment with both rutin + morphine or rutin + indomethacin, at doses that are ineffectual per se, significantly reduced the pain caused by G-CSF. The nitric oxide (NO)-cyclic guanosine monophosphate (cGMP)-protein kinase G (PKG)-ATP-sensitive potassium channel (K_ATP) signaling pathway activation is one of the analgesic mechanisms of rutin. Rutin also reduced the pro-hyperalgesic and increased anti-hyperalgesic cytokine production induced by G-CSF. Furthermore, rutin inhibited the activation of the nuclear factor kappa-light-chain enhancer of activated B cells (NFκB), which might explain the inhibition of the cytokine production. Treatment with rutin upregulated the decreased mRNA expression of the nuclear factor (erythroid-derived 2)-like 2 (Nrf2) combined with enhancement of the mRNA expression of the Nrf2 downstream target heme oxygenase (HO-1). Intraperitoneal (i.p.) treatment with rutin did not alter the mobilization of neutrophils induced by G-CSF. The analgesia by rutin can be explained by: NO-cGMP-PKG-K_ATP channel signaling activation, inhibition of NFκB and triggering the Nrf2/HO-1 pathway. The present study demonstrates rutin as a promising pharmacological approach to treat the pain induced by G-CSF without impairing its primary therapeutic benefit of mobilizing hematopoietic progenitor cells into the blood.

The clinical management of acetaminophen poisoning in a community hospital system: factors associated with hospital length of stay

Acetaminophen (APAP) overdose is the most common pharmaceutical poisoning. The objective of this study was to examine the management of patients admitted for treatment of APAP overdose. Factors impacting hospital length of stay (LOS) were of particular interest. This was a retrospective cohort study of patients admitted to Kaiser Permanente Northern California hospitals for APAP overdose from July 2003 through December 2007. Medical records were abstracted for patient demographic data, key factors of overdose, California Poison Control System (CPCS) contact, data regarding hospital course, transfer for liver transplantation, and death. Four hundred thirty-five patients were included. The mean hospital LOS was 66.5 h (95% CI 62.1, 71.0). Four patients (0.9%) died. Eight patients (1.8%) were transferred for liver transplantation, but all of these patients later recovered without transplant. Of 289 cases eligible for placement on the Rumack-Matthew nomogram (acute ingestion with known time of ingestion <24 h and normal liver enzymes), 161 (55.7%) had APAP levels above the "200" line and 77 (26.6%) fell below the "150" line. CPCS was contacted in 295 cases (67.8%). Mean LOS in cases with CPCS consultation was 61.9 h (95% CI 57.2, 66.5 h) versus 76.3 h (95% CI 66.6, 86.0 h) in those without. LOS in cases treated with IV NAC was 67.1 h (95% CI 57.7, 76.5 h) versus 66.4 h (95% CI 61.2, 71.5 h) in cases treated with oral NAC. Many patients admitted for APAP overdose had serum APAP levels below the minimum toxicity level. Use of IV NAC did not impact hospital LOS. CPCS consultation appeared to decrease mean hospital LOS.

Reversing the Myths Obstructing the Determination of Optimal Age- and Disease-Based Drug Dosing in Pediatrics

The need for critical, well-designed comprehensive clinical pharmacology research in pediatrics that encompasses the age continuum, from the most premature infant through adolescence, may be more important today than ever. New drug regimens often require greater adherence to specific dose guidelines to maximize efficacy and minimize toxic potential. The climate that allowed the propagation of the “therapeutic orphan” concept is now mostly of historical perspective. Nevertheless, the negative impact of this concept continues to linger due to continued propagation of many, now outdated myths surrounding the effective study of optimal drug dosing in pediatrics. Advances in clinical medicine combined with the advances in study design, sampling, and analysis has dramatically improved the paradigm for clinical pharmacology research in infants and children. Capitalizing upon and thoughtfully using these many advances while dispelling these myths will result in greater research focused on optimal drug therapy in pediatric practice.

Clinical cases in acute intoxication

Over 2.5 million accidental and intentional drug-related poisonings are reported annually in the United States. Early diagnosis and management of patients who present with acute intoxication can significantly reduce both morbidity and mortality. The initial evaluation of patients with suspected or proven intoxications should focus on hemodynamic stability, mental status, and respiratory function. However, early recognition of toxic ingestion is paramount to implementing life-saving treatments. Important historical clues are often found in a social history that considers intravenous drug use, alcohol use, and any access or exposure to illicit substances. A patient's medication list should also be scrutinized for psychoactive or sedative medications, such as tricyclic antidepressants or opioids. In this article we present case-based discussions of the specific diagnosis and management of 5 commonly occurring acute intoxication syndromes.

Characterization of a gastrointestinal tract microscale cell culture analog used to predict drug toxicity

The lining of the gastrointestinal (GI) tract is the largest surface exposed to the external environment in the human body. One of the main functions of the small intestine is absorption, and intestinal absorption is a route used by essential nutrients, chemicals, and pharmaceuticals to enter the systemic circulation. Understanding the effects of digestion on a drug or chemical, how compounds interact with and are absorbed through the small intestinal epithelium, and how these compounds affect the rest of the body is critical for toxicological evaluation. Our goal is to create physiologically realistic in vitro models of the human GI tract that provide rapid, inexpensive, and accurate predictions of the body's response to orally delivered drugs and chemicals. Our group has developed an in vitro microscale cell culture analog (microCCA) of the GI tract that includes digestion, a mucus layer, and physiologically realistic cell populations. The GI tract microCCA, coupled with a multi-chamber silicon microCCA representing the systemic circulation, is described and challenged with acetaminophen. Proof of concept experiments showed that acetaminophen passes through and is metabolized by the in vitro intestinal epithelium and is further metabolized by liver cells, resulting in liver cell toxicity in a dose-dependent manner. The microCCA response is also consistent with in vivo measurements in mice. The system should be broadly useful for studies on orally delivered drugs or ingestion of chemicals with potential toxicity.

Acetaminophen hepatotoxicity

Acetaminophen is a commonly used antipyretic and analgesic agent. It is safe when taken at therapeutic doses; however, overdose can lead to serious and even fatal hepatotoxicity. The initial metabolic and biochemical events leading to toxicity have been well described, but the precise mechanism of cell injury and death is unknown. Prompt recognition of overdose, aggressive management, and administration of N-acetylcysteine can minimize hepatotoxicity and prevent liver failure and death. Liver transplantation can be lifesaving for those who develop acute liver failure.

N-acetylcysteine treatment protects against VEGF-receptor blockade-related emphysema

Administration of the VEGF receptor blocker SU5416 to rats causes alveolar septal cell apoptosis and emphysema; both can be prevented by a superoxide dismutase mimetic. Here we show that SU5416 induces the expression of heme oxygenase-1 in the lung tissue and that administration of antioxidant N-acetyl-l-cysteine protects alveolar septal cells against apoptosis, as demonstrated by caspase-3 lung immunohistochemistry, and against emphysema.

Metabolic insights into the hepatoprotective role of N-acetylcysteine in mouse liver

The hepatoprotective mechanisms of N-acetylcysteine (NAC) in non-acetaminophen-induced liver injury have not been studied in detail. We investigated the possibility that NAC could affect key pathways of hepatocellular metabolism with or without changes in glutathione (GSH) synthesis. Hepatocellular metabolites and high-energy phosphates were quantified from mouse liver extracts by 1H- and 31P-NMR (nuclear magnetic resonance) spectroscopy. 13C-NMR-isotopomer analysis was used to measure [U-13C]glucose metabolism through pyruvate dehydrogenase (PDH) and pyruvate carboxylase (PC). NAC (150-1,200 mg/kg) increased liver concentrations of GSH from 8.60 +/- 0.48 to a maximum of 12.95 +/- 1.03 micromol/g ww, whereas hypotaurine (HTau) concentrations increased from 0.05 +/- 0.02 to 9.95 +/- 1.12 micromol/g ww. The limited capacity of NAC to increase GSH synthesis was attributed to impaired glucose metabolism through PC. However, 300 mg/kg NAC significantly increased the fractional 13C-enrichment in Glu (from 2.08% +/- 0.26% to 4.00% +/- 0.44%) synthesized through PDH, a key enzyme for mitochondrial energy metabolism. This effect could be uncoupled from GSH synthesis and was associated with the prevention of liver injury induced by tert-butylhydroperoxide and 3-nitropropionic acid. In conclusion, NAC (1) has a limited capacity to elevate GSH synthesis; (2) increases HTau formation linearly; and (3) improves mitochondrial tricarboxylic acid (TCA) cycle metabolism by stimulation of carbon flux through PDH. This latter effect is independent of the capacity of NAC to replete GSH stores. These metabolic actions, among other yet unknown effects, are critical for NAC's therapeutic value and should be taken into account when deciding on a wider use of NAC.