Green HPLC-DAD and HPTLC Methods for Quantitative Determination of Binary Mixture of Pregabalin and Amitriptyline Used for Neuropathic Pain Management.

First analytical methods were herein developed for determination of pregabalin (PGB) and amitriptyline (AMT) as an active binary mixture used for management of neuropathic pain whether in pure forms or in human biological fluids (plasma/urine). First method is green high-performance liquid chromatography-diode array detector (HPLC-DAD) after derivatization of PGB with ninhydrin (NIN) on a reversed-phase C18 column using a mobile phase consisting of ethanol:water (97:3%, v/v) pumped isocratically at 0.8 mL/min; AMT were scanned at 215 nm, whereas PGB-NIN was scanned at 580 nm. Second method is High-performance thin-layer chromatography (HPTLC), where PGB and AMT were separated on silica gel HPTLC F254 plates, using ethanol:ethyl acetate:acetone:ammonia solution (8:2:1:0.05, by volume) as a developing system. AMT peaks were scanned at 220 nm, whereas PGB peaks were visualized by spraying 3% (w/v) ethanolic NIN solution and scanning at 550 nm. Linear calibration curves were obtained for human plasma and urine spiked with PGB and AMT over the ranges of 5-100 µg/mL and 0.2-2.5 µg/band for PGB, and 1-100 µg/mL and 0.1-2.0 µg/band for AMT for HPLC-DAD and HPTLC methods, respectively. The suggested methods were validated according to Food and Drug Administration guidelines for bioanalytical methods validation and they can be applied for routine therapeutic drug monitoring for the concerned drugs.

Effects of intravenous lidocaine, dexmedetomidine, and their combination on IL-1, IL-6 and TNF-α in patients undergoing laparoscopic hysterectomy: a prospective, randomized controlled trial.

BACKGROUND: Surgical-related inflammatory responses have negative effects on postoperative recovery. Intravenous (IV) lidocaine and dexmedetomidine inhibits the inflammatory response. We investigated whether the co-administration of lidocaine and dexmedetomidine could further alleviate inflammatory responses compared with lidocaine or dexmedetomidine alone during laparoscopic hysterectomy. METHODS: A total of 160 patients were randomly allocated into four groups following laparoscopic hysterectomy: the control group (group C) received normal saline, the lidocaine group (group L) received lidocaine (bolus infusion of 1.5 mg/kg over 10 min, 1.5 mg/kg/h continuous infusion), the dexmedetomidine group (group D) received dexmedetomidine (bolus infusion of 0.5 µg/kg over 10 min, 0.4 µg/kg/h continuous infusion), and the lidocaine plus dexmedetomidine group (group LD) received a combination of lidocaine (bolus infusion of 1.5 mg/kg over 10 min, 1.5 mg/kg/h continuous infusion) and dexmedetomidine (bolus infusion of 0.5 µg/kg over 10 min, 0.4 µg/kg/h continuous infusion). The levels of plasma interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) at different time points were the primary outcomes. Secondary outcomes included hemodynamic variables, postoperative visual analogue scale (VAS) scores, time to first flatus, and incidence of nausea and vomiting after surgery. RESULTS: The levels of plasma IL-1, IL-6, and TNF-α were lower in groups D and LD than in group C and were lowest in group LD at the end of the procedure and 2 h after the operation (P < 0.05). The VAS scores were decreased in groups D and LD compared with group C (P < 0.05). The heart rate (HR) was decreased at the end of the procedure and 2 h after the operation in groups D and LD compared to groups C and L (P < 0.001). The mean blood pressure (MBP) was lower at 2 h after the operation in groups L, D, and LD than in group C (P < 0.001). There was a lower incidence of postoperative nausea and vomiting (PONV) in group LD than in group C (P < 0.05). CONCLUSIONS: The combination of lidocaine and dexmedetomidine significantly alleviated the inflammatory responses, decreased postoperative pain, and led to fewer PONV in patients undergoing laparoscopic hysterectomy. TRIAL REGISTRATION: ClinicalTrials.gov ( NCT03276533 ), registered on August 23, 2017.

​False-positive paracetamol levels in a patient with hyperbilirubinaemia: clinical perspectives.

​Serum concentrations of paracetamol are measured to investigate the cause of acute hepatitis, monitor the clearance of paracetamol from the body and to determine if supratherapeutic levels warrant treatment with N-acetylcysteine (NAC). ​A 49-year-old man treated for ischaemic colitis developed worsening renal and liver function tests. As part of the investigation of hepatorenal failure, paracetamol levels were requested, which were elevated at 14 mg/L (normal <4 mg/L) resulting in treatment with NAC. Despite treatment, levels of paracetamol remained elevated and the link between hyperbilirubinemia and false-positive paracetamol levels was identified. ​Bilirubin and its by-products have intense absorbance in the ultraviolet and visible regions of the electromagnetic spectrum, causing interference in the enzymatic colorimetric assay most commonly used to measure paracetamol concentration, resulting in false-positive paracetamol levels. Laboratories correct for this interference above a predetermined bilirubin concentration, termed the Icteric Index; however, in our case this interference occurred at a lower level of hyperbilirubinaemia than previously identified as significant. This interaction was found to be more significant at lower bilirubin levels when low or no paracetamol levels were present in the serum, resulting in a change to laboratory practice and development of a 'Sliding Scale' approach to analysis. ​Concurrent bilirubin or Icteric Index measurement is recommended for all laboratories that use the enzymatic colorimetric assay for paracetamol measurement. Lower Icteric Index or bilirubin thresholds are required when low or no paracetamol levels are present in the serum to prevent false-positive paracetamol results. We describe a new 'Sliding Scale' approach to analysis, and highlight an important interaction for clinicians to be aware of.

Hepatic Adaptation to Therapeutic Doses of Acetaminophen: An Exploratory Study in Healthy Individuals.

PURPOSE: Acetaminophen (APAP) has hepatotoxic potential when overdosed. Recent studies have reported serum alanine aminotransferase (ALT) elevations that resolve spontaneously with continued use of the drug, referred to as adaptation, in several individuals receiving therapeutic doses of APAP. However, the clinical significance of these ALT elevations remains unclear. This study was performed to investigate the incidence and characteristics of hepatic adaptation to therapeutic doses of APAP in healthy individuals. METHODS: In a randomized, single-blind, placebo-controlled study, 242 healthy Japanese individuals were enrolled. Each person received 3 g/d of APAP (n = 202) or placebo (n = 40) for 28 days. All study participants underwent analysis of genetic polymorphisms of CYP2E1 and UGT1A1; measurements of plasma APAP concentration and urine metabolites (glucuronide, sulfate, cysteine, and mercapturate); liver function monitoring, including ALT, microRNA-122, and high-mobility group box 1. Individuals with ALT levels remaining below the upper limit of normal (ULN; 40 U/L) during the study period were defined as tolerant and those with ALT elevations above the ULN as susceptible. Susceptible individuals who developed ALT elevations exceeding 2 × ULN discontinued use of the study drug for tolerability consideration. Susceptible individuals who had ALT elevations that decreased toward the ULN spontaneously with continued use of the study drug were classified as adaptation. FINDINGS: In the APAP group, 129 individuals (66%) were classified as tolerant and 65 (34%) as susceptible. Among 65 susceptible individuals, 12 (18%) discontinued use of APAP because of ALT elevations (>2 × ULN), whereas 53 (82%) completed 28-day APAP dosing. Thirty of 65 susceptible individuals (46%) had adaptation within 28 days. In the placebo group, no individuals was withdrawn from the study because of elevated ALT levels, 33 individuals (89%) were classified as tolerant, and 4 (11%) were classified as susceptible. None had clinical signs of liver injury. ALT level correlated significantly with microRNA-122 but not with high-mobility group box 1. No association was found between plasma APAP concentrations and ALT levels. Urinary excretion of APAP mercapturate was higher in susceptible than in tolerant individuals (P = 0.018, Wilcoxon or Kruskal-Wallis test). The frequency of homozygotes and compound heterozygotes for UGT1A1∗28 and UGT1A1∗6 (∗28/∗28, ∗6/∗6, and ∗6/∗28) was higher in susceptible than in tolerant individuals (13.9% vs 3.9%; P = 0.011, χ2 test). IMPLICATIONS: These findings indicate that in healthy individuals, APAP at a therapeutic dose can cause transient and self-limiting ALT elevation, reflecting subclinical hepatocellular damage, and these ALT elevations may be associated with the disposition of APAP metabolites and genetic factors. UMIN-CTR identifier: UMIN000019607.

Emulsion Droplet Crystallinity Attenuates Short-Term Satiety in Healthy Adult Males: A Randomized, Double-Blinded, Crossover, Acute Meal Study.

BACKGROUND: The influence of triacylglycerol (TAG) physical properties on satiety remains poorly understood. OBJECTIVES: The objective was to investigate if and how TAG digestion and absorption, modulated only by differences in TAG crystallinity, would differentially affect short-term satiety in healthy men. METHODS: We tempered 500 mL 10% palm stearin oil-in-water emulsions such that the lipid droplets were either undercooled liquid (LE) or partially crystalline solid (SE). Fifteen healthy men (mean ± SD age: 27.5 ± 5.7 y; BMI: 24.1 ± 2.5 kg/m2; fasting TAG: 0.9 ± 0.3 mmol/L) consumed each beverage at two 6-h study visits separated by ≥6 d after an overnight fast, along with 1500 mg acetaminophen suspended in water. The participants characterized the emulsion sensory properties, completed satiety visual analog scale ratings, and had serial blood samples collected for 6-h analysis of plasma peptide YY (PYY), glucagon-like peptide-1 (GLP-1), ghrelin, leptin, glucose-dependent insulinotropic polypeptide (GIP), insulin, and acetaminophen (for assessing gastric emptying). Repeated-measures ANOVAs and 2-tailed paired t tests were used to analyze the changes from baseline and incremental area under the curve (iAUC) values, respectively. RESULTS: With consumption of LE compared with SE, there was a 358% higher fullness (P = 0.015) and a 103% lower average appetite (P = 0.041) score, along with higher iAUC values for PYY (P = 0.011) and GLP-1 (P = 0.028) (103% and 66% higher, respectively), but not for ghrelin (P = 0.39), based on change from baseline values. Acetaminophen response trended toward significance (P = 0.08) and was 15% higher with LE. SE was rated as 44% thicker (P = 0.034) and 24% creamier (P = 0.05) than LE. CONCLUSIONS: The suppression of TAG digestion by the presence of partially crystalline lipid droplets blunted the appetite-suppressing effects of an oil-in-water emulsion.This trial was registered at clinicaltrials.gov as NCT03990246.

Responses of gut and pancreatic hormones, bile acids, and fibroblast growth factor-21 differ to glucose, protein, and fat ingestion after gastric bypass surgery.

Postprandial gut hormone responses change after Roux-en-Y gastric bypass (RYGB), and we investigated the impact of glucose, protein, and fat (with and without pancreas lipase inhibition) on plasma responses of gut and pancreas hormones, bile acids, and fibroblast growth factor 21 (FGF-21) after RYGB and in nonoperated control subjects. In a randomized, crossover study 10 RYGB operated and 8 healthy weight-matched control subjects were administered 4 different 4-h isocaloric (200 kcal) liquid meal tests containing >90 energy (E)% of either glucose, protein (whey protein), or fat (butter with and without orlistat). The primary outcome was glucagon-like peptide-1 (GLP-1) secretion (area under the curve above baseline). Secondary outcomes included responses of peptide YY (PYY), glucose-dependent insulinotropic polypeptide (GIP), cholecystokinin (CCK), glicentin, neurotensin, ghrelin, insulin, glucagon, bile acids, and FGF-21. In the RYGB group the responses of GLP-1, GIP, glicentin, FGF-21, and C-peptide were increased after glucose compared with the other meals. The neurotensin and bile acids responses were greater after fat, while the glucagon and CCK responses were greater after protein ingestion. Furthermore, compared with control subjects, RYGB subjects had greater responses of total PYY after glucose, glucagon after glucose and fat, glicentin after glucose and protein, and GLP-1 and neurotensin after all meals, while GIP and CCK responses were lower after fat. Ghrelin responses did not differ between meals or between groups. Orlistat reduced all hormone responses to fat ingestion, except for ghrelin in the RYGB group. In conclusion, after RYGB glucose is a more potent stimulator of most gut hormones, especially for the marked increased secretion of GLP-1 compared with fat and protein.NEW & NOTEWORTHY We investigated the impact of glucose, protein, and fat meals on intestinal and pancreatic hormones, bile acid, and fibroblast growth factor 21 (FGF-21) secretion in gastric bypass-operated patients compared with matched nonoperated individuals. The fat meal was administered with and without a pancreas lipase inhibitor. We found that the impact of the different meals on gut hormones, bile, and FGF 21 secretion differ and was different from the responses observed in nonoperated control subjects.

Dried blood microsamples: Suitable as an alternative matrix for the quantification of paracetamol-protein adducts?

Paracetamol (acetaminophen, APAP) is the most frequently used analgesic drug worldwide. However, patients in several specific populations can have an increased exposure to toxic APAP metabolites. Therefore, APAP-protein adducts have been proposed as an alternative marker for the assessment of APAP intoxications and as an effective tool to study and steer APAP treatment in patients with an increased risk of APAP-induced liver damage. These adducts have been determined in plasma or serum as a matrix. Blood microsampling allows the determination of a variety of analytes, including protein adducts, in a drop of blood, facilitating convenient follow-up of patients in a home-sampling context, as well as repeated sampling of pediatric patients. We therefore evaluated the use of blood-based volumetric microsamples for the quantification of APAP-protein adducts. Quantitative methods for the determination of APAP-protein adducts in dried blood and dried plasma volumetric absorptive microsamples were developed and validated. Also a preliminary evaluation of pediatric patient dried blood microsamples was conducted. Method validation encompassed the evaluation of selectivity, carry over, calibration model, accuracy and precision, matrix effect, recovery and the effect of the hematocrit on the recovery, dilution integrity, and stability. All pre-set acceptance criteria were met, except for stability. Spiking of blank blood with APAP revealed a concentration-dependent ex vivo formation of APAP-protein adducts, resulting in a response for the measurand APAP-Cys, with an apparent role for the red blood cell fraction. Analysis of authentic samples, following intake of APAP at therapeutic dosing, revealed much higher APAP-Cys concentrations in dried blood vs. dried plasma samples, making interpretation of the results in the context of published intervals difficult. In addition, in contrast to what was observed during method validation, the data obtained for the patient samples showed a high and unacceptable variation. We conclude that, for a combination of reasons, dried blood is not a suitable matrix for the quantification of APAP-protein adducts via the measurement of the APAP-Cys digestion product. The collection of plasma or serum, either in the form of a liquid sample or a dried microsample for this purpose is advised.

Adducts Post Acetaminophen Overdose Treated with a 12-Hour vs 20-Hour Acetylcysteine Infusion.

INTRODUCTION: Acetaminophen protein adducts in the circulation are a specific biomarker of acetaminophen oxidation, and may be a more sensitive measure of impending hepatic injury following overdose than alanine transaminase (ALT). We performed an exploratory analytical substudy of adducts during a clinical trial (NACSTOP) of abbreviated (12-hour) versus control (20-hour) acetylcysteine to identify any signal of diminished antidotal effectiveness with shortened therapy. METHODS: We measured adducts at 0, 12, and 20 hours from a convenience sample of subjects enrolled in the cluster-controlled NACSTOP trial evaluating a 12-hour ("abbreviated"; 200 mg/kg over 4 hours, 50 mg/kg over 8 hours) vs 20-hour acetylcysteine regimen ("control"; 200 mg/kg over 4 hours, 100 mg/kg over 16 hours). Adducts were assayed using high-performance liquid chromatography/mass spectrometry. RESULTS: Median ALT 20 hours after the initiation of acetylcysteine was 12 U/L (IQR 8,14) in the abbreviated 12-hour regimen group (N = 8), compared with the control group 16 U/L (IQR 11,21; N = 21) (p = 0.46). Adduct concentrations were similarly low in both groups: abbreviated [(0.005 µmol/L, IQR (0,0.14)] and control [(0.005 µmol/L, IQR (0,0.05)] (p = 0.61). CONCLUSIONS: There were minimal to no acetaminophen protein adducts detected. These findings further support discontinuing acetylcysteine when acetaminophen concentrations are low and liver function tests normal after 12 hours of treatment.

[Improved and harmonised laboratory analysis of paracetamol provides safer assessment of poisoning cases]. / Bättre labbanalys av paracetamol ger säkrare bedömning av förgiftningsfall - Bestämning av koncentrationen är grunden för rätt behandling.

Toxicological analysis is an important part of the acute treatment of various intoxications. Rapid laboratory responses are important for the patient to be assessed and treated correctly, and also to exclude poisoning and thus avoid unjustified and costly overtreatment. In Sweden, paracetamol (acetaminophen) is one of the most common pharmaceuticals in drug poisoning. Paracetamol overdose can cause severe liver damage unless treated early with the antidote acetylcysteine. A nation-wide initiative for improved laboratory measurement of paracetamol in plasma/serum samples has resulted in a marked reduction in the inter-laboratory coefficient of variation to generally below 10%. The introduction of a harmonized national reporting range for plasma/serum paracetamol covering at least 50-5 000 µmol/l was also recommended. This initiative will hopefully contribute to better healthcare from both a patient and health resource perspective in cases of paracetamol poisoning.

Acetaminophen Protein Adducts in Hospitalized Children Receiving Multiple Doses of Acetaminophen.

Previous reports have questioned the safety of multiple doses of acetaminophen administered to ill children. Acetaminophen protein adducts (adducts) are a biomarker of acetaminophen-induced liver injury and reflect the oxidative metabolism of acetaminophen, a known mechanism in acetaminophen toxicity. In this prospective observational study, we analyzed adduct concentrations in 1034 blood samples obtained from 181 hospitalized children (1 to 18 years inclusive) who received 2 or more doses of acetaminophen. Linear regression analysis showed that serum adduct concentrations increased as a function of the cumulative acetaminophen dose, which could be attributed, in part, to a long half-life of adducts (2.17 ± 1.04 days [mean ± standard deviation]) in children. However, few patients (2%) were found to have adduct concentrations higher than 1.0 nmol/mL, a previously identified toxicity cut point for the diagnosis of acetaminophen-induced liver injury in patients with alanine aminotransferase values exceeding 1000 IU/L. A small cohort of patients with suspected infection was noted to show higher adduct concentrations. In addition, adduct concentrations showed a stronger correlation with cumulative acetaminophen doses in adolescents compared with children (R2 = 0.41 vs 0.26). No other covariates (body weight, body mass index z score, sex, race, or surgery) remarkably correlated with adduct elevation. In summary, low levels of adducts can be detected in hospitalized children receiving multiple doses of acetaminophen, and adduct levels correlate with cumulative acetaminophen dose.

Retrospective evaluation of repeated supratherapeutic ingestion (RSTI) of paracetamol †.

Background: Repeated supratherapeutic ingestion (RSTI) of paracetamol can result in acute liver injury. Management guidelines vary worldwide and in Australia, acetylcysteine treatment is recommended in patients with a paracetamol concentration ≥20 mg/L and/or alanine transaminase (ALT) ≥50 U/L. Objectives: To investigate patients with RSTI of paracetamol and determine whether admission ALT <50 U/L rules out those who develop hepatotoxicity (ALT >1000 U/L). Method: Retrospective review of paracetamol RSTI presentations to two toxicology services over a four-year period. Patients were included if they ingested >4 g per 24 h of paracetamol for a period >8 h, regardless of intent. Data collected included demographics, ingestion history, pathology results, treatments and outcomes. Results: 266 patients were identified with median ingested dose of 9 g per 24 h (IQR: 6-12 g) over a median of 2 days (IQR: 1-5 days). On presentation, paracetamol was detected in 192 (72%), with median concentration of 14 mg/L (IQR: 7-27 mg/L). Median ALT on admission in those developing hepatotoxicity was significantly higher, 1182 U/L (IQR: 598-4251 U/L), compared to 30 U/L (IQR: 18-59 U/L; p < .0001) in those who did not. All 17 who developed hepatotoxicity had an ALT ≥50 U/L on presentation. Five patients presenting with an ALT <50 U/L developed a peak ALT between 50 and 1000 U/L, of which three had a paracetamol concentration <20 mg/L. 139 (52%) received acetylcysteine, of which 64 received an abbreviated course (<20 h), with a median length of infusion of 11 h (IQR: 7-14 h). 127 (48%) patients were not treated with acetylcysteine, none of these patients returned to hospital. Conclusions: Our results confirm that those developing hepatotoxicity from RSTI of paracetamol have an elevated ALT on presentation. Presenting ALT <50 U/L appears to be a safe threshold not to administer acetylcysteine, provided the paracetamol concentration is low.

What is the most appropriate dose of N-acetylcysteine after massive acetaminophen overdose?

While the traditional intravenous N-acetylcysteine (NAC) dosing regimen works well for the vast majority of acetaminophen overdoses, there may be cases of massive overdose where additional NAC may be necessary. Recent evidence suggests that patients with acetaminophen concentrations above the "300-line" develop hepatotoxicity at a higher rate than those below the 300-line, suggesting that an increase of dose may be beneficial at this cut-off. Additional clinical data suggest a further increase in doses at the 450-line and 600-lines. I propose a strategy for step-wise increases in NAC dosing in response to high acetaminophen concentrations at the 300-, 450-, and 600-lines after acute massive acetaminophen overdoses.

An improved ultra-high-performance liquid chromatography-tandem mass spectrometric method for the quantitation of dexmedetomidine in small volume of pediatric plasma.

Dexmedetomidine (Dex), a highly selective α2 -adrenergic agonist, is used primarily for the sedation and anxiolysis of adults and children in the intensive care setting. A sensitive and selective assay for Dex in pediatric plasma was developed by employing ultra-high-performance liquid chromatography-tandem mass spectrometry with d4-Dex as an internal standard. Dex was extracted from 0.1 mL of plasma by micro-elution solid-phase extraction. Separation was achieved with a Waters XBridge C18 column with a flow rate of 0.3 mL/min using a mobile phase comprising 5 mm ammonium acetate buffer with 0.03% formic acid in water and methanol-acetonitrile (50:50, v/v). The intra-day precision (coefficient of variation) and accuracy for quality control samples ranged from 1.32 to 8.91% and from 92.8 to 108%, respectively. The inter-day precision and accuracy ranged from 2.13 to 8.45% and from 97.0 to 104%, respectively. The analytical method showed excellent sensitivity using a small sample volume (0.1 mL) with a lower limit of quantitation of 5 pg/mL. This method is robust and has been successfully employed in a pharmacokinetic study of Dex in neonates and infants postoperative from cardiac surgery.

Paracetamol metabolite concentrations following low risk overdose treated with an abbreviated 12-h versus 20-h acetylcysteine infusion.

CONTEXT: To compare degree of liver injury and paracetamol metabolite concentrations after treatment with standard of care (20-h) vs. abbreviated (12-h) acetylcysteine regimens used in paracetamol overdose (NACSTOP trial). METHODS: Timed blood samples from a cohort of subjects enrolled in the cluster-controlled NACSTOP trial evaluating a 12-h acetylcysteine regimen (200 mg/kg over 4 h, 50 mg/kg over 8 h) were assayed for paracetamol metabolites as a pilot study, using liquid chromatography/mass spectrometry. Control group subjects received a 20-h course of acetylcysteine (200 mg/kg over 4 h, 100 mg/kg over 16 h). The intervention group received a 12-h acetylcysteine regimen (stopped after at least 12 h of treatment). Positive control groups not in the trial with acute liver injury (ALI) or hepatotoxicity were also studied. RESULTS: One hundred and forty-one blood samples were collected from 40 patients receiving acetylcysteine after paracetamol overdose. Median ALT after 20 h of acetylcysteine was 12 U/L (IQR 8.14) in the abbreviated regimen group, compared to the control group 16 U/L (IQR 11.21) (p = .46). There was no significant difference in median metabolite concentrations on presentation and after 20 h of acetylcysteine between these two groups (p > .05). Presentation median sum CYP-metabolite/total metabolite percentages were 2.5 and 3.0 in the abbreviated and control NACSTOP groups, respectively. CONCLUSIONS: An abbreviated 12-h acetylcysteine regimen for paracetamol overdose used in the NACSTOP trial had similar circulating metabolite concentrations compared to a 20-h regimen in selected subjects with low risk of hepatotoxicity. This suggests that further acetylcysteine may not be needed in the abbreviated group at time of cessation.

Acetaminophen pharmacokinetics in severely obese adolescents and young adults.

BACKGROUND: Intravenous acetaminophen is commonly administered as an adjunctive to opioids during major surgical procedures, but neither the correct pharmacokinetic size descriptor nor the dose is certain in severely obese adolescents undergoing bariatric surgery. METHODS: Adolescents, 14-20 years of age, with a body mass index (BMI) ≥95th percentile for age and sex or BMI ≥40 kg·m-2 , presenting for laparoscopic or robotic assisted or vertical sleeve gastrectomy were administered intravenous acetaminophen (1000 mg) following completion of the surgical procedure. Venous blood was drawn for acetaminophen assay at eight time points, starting 15 minutes after completion of the infusion and up to 12 hours afterward. Time-concentration data profiles were analyzed using nonlinear mixed effects models. Parameter estimates were scaled to a 70-kg person using allometry. Normal fat mass was used to assess the impact of obesity on pharmacokinetic parameters. RESULTS: The study cohort comprised 11 female patients, age 17 SD 2 years with a weight of 125 SD 19 kg and a mean BMI of 46 SD 5 kg·m-2 . The plasma acetaminophen serum concentration was 17 (SD 4) µg·mL-1 at 10-20 minutes after completion of the infusion and 5 (SD 6) µg·mL-1 at 80-100 minutes. A two-compartment model, used to investigate pharmacokinetics, estimated clearance 10.6 (CV 72%) L·h·70 kg-1 , intercompartment clearance 37.3 (CV 63%) L·h·70 kg-1 , central volume of distribution 20.4 (CV 46%) L·70 kg-1 , and peripheral volume of distribution 16.8 (CV 42%) L·70 kg-1 . Clearance was best described using total body weight. Normal fat mass with a parameter that accounts for fat mass contribution (Ffat) of 0.88 best described volumes. CONCLUSION: Current recommendations of acetaminophen to a maximum dose of 1000 mg resulted in serum concentrations below detection limits in all patients within 2 hours after administration. Dose is better predicted using total body mass with allometric scaling.

Prevention of acetaminophen-induced liver injury by alginate.

INTRODUCTION: Acetaminophen (APAP) intoxication is a major cause of acute liver failure. Alginate, an anionic polysaccharide, was previously shown as a macroporous scaffold, to reduce liver inflammation and sustain hepatic synthetic function, when implanted on liver remnant after extended partial hepatectomy. In the recent study we wanted to examine in a model of APAP intoxication the potential of a specially formulated alginate solution to prevent APAP toxicity. METHODS: Three alginate solutions from low (30-50 kDa, VLVG), medium (100 kDa, LVG54) and high (150 kDa, LVG150) molecular weights were examined. Mice were orally administered with the alginate solution before, with and after APAP administration and were compared to control mice which received vehicle only. All mice were euthanized 24 h after APAP administration. Liver enzyme, blood APAP, IL-6 and liver histology including Ki-67 proliferation, IgG necrosis and nitrotyrosine staining were studied. RESULTS: VLVG- treated mice presented low ALT levels while 20-40 fold increase was demonstrated in control mice. The effect of LVG solutions was marginal. Accordingly, liver histology was normal with no hepatocytes proliferation in the VLVG group while massive centrilobular necrosis, increased nitrotyrosine staining and high proliferation appeared in livers of control mice. APAP blood levels were comparable in the two groups. Treatment with VLVG was associated with prevention of increase of IL-6 serum levels. CONCLUSION: VLVG, a novel alginate solution, alleviated the liver toxicity and inhibited oncotic necrosis and related immune-mediated damage. VLVG may serve as a novel hepato-protector and prevent drug induced liver injury.

Analgesic effectiveness, pharmacokinetics, and safety of a paracetamol/ibuprofen fixed-dose combination in children undergoing adenotonsillectomy: A randomized, single-blind, parallel group trial.

BACKGROUND: Pain following tonsillectomy is often poorly managed in the home setting. Multimodal analgesia with acetaminophen (paracetamol) and nonsteroidal anti-inflammatory drugs offers superior analgesia over monotherapy but may be difficult for caregivers to manage. A fixed-dose combination oral suspension product containing paracetamol and ibuprofen has been developed to facilitate pediatric dosing. AIMS: The aims of this study are to determine the analgesic effectiveness, pharmacokinetics, and safety of the fixed-dose combination at two doses in the pediatric population. METHODS: In this prospective, multicenter, randomized, single-blind, parallel group trial, 251 children aged 2-12 years undergoing day-stay (adeno)tonsillectomy were randomized to two dose groups of the fixed-dose combination. A doubled loading dose was given preoperatively, followed by treatment for up to 11 days (Higher dose: paracetamol 15 mg/kg + ibuprofen 4.5 mg/kg, Lower dose: paracetamol 12 mg/kg + ibuprofen 3.6 mg/kg). Blood samples were collected for pharmacokinetic analysis for up to 6 hours after the loading dose. The analgesic effectiveness was examined on the first day after surgery using both Parents Postoperative Pain Measurement and modified Wong-Baker Faces pain scales. Rescue medication consumption was recorded throughout the study. RESULTS: Differences in maximum plasma concentration (Cmax ) and total exposure (AUC0→t ) between the treatment groups for both analytes were consistent with a 25% increase in dose; there was no difference in time to peak concentration (Tmax ). On the first postoperative day, there was no difference in pain scores or rescue medication use between treatment groups (approximately 30% in both groups). The combination was well tolerated by both groups. The most common adverse events were vomiting and nausea. The incidence of postoperative bleeding was 4.4%. CONCLUSION: The shallow dose-response relationship and good tolerability of the fixed-dose combination over an extended study period supports the utility of both doses of the fixed-dose combination in the home setting.

The concomitant use of lapatinib and paracetamol - the risk of interaction.

Lapatinib is a tyrosine kinase inhibitor used for the treatment of breast cancer. Paracetamol is an analgesic commonly applied to patients with mild or moderate pain and fever. Cancer patients are polymedicated, which involves high risk of drug interactions during therapy. The aim of the study was to assess the interaction between lapatinib and paracetamol in rats. The rats were divided into three groups of eight animals in each. One group received lapatinib + paracetamol (IL + PA), another group received lapatinib (IIL), whereas the last group received paracetamol (IIIPA). A single dose of lapatinib (100 mg/kg b.w.) and paracetamol (100 mg/kg b.w.) was administered orally. Plasma concentrations of lapatinib, paracetamol and its metabolites - glucuronide and sulphate, were measured with the validated HPLC-MS/MS method and HPLC-UV method, respectively. The pharmacokinetic parameters of both drugs were calculated using non-compartmental methods. The co-administration of lapatinib and paracetamol increased the area under the plasma concentration-time curve (AUC) and the maximum concentration (Cmax) of lapatinib by 239.6% (p = 0.0030) and 184% (p = 0.0011), respectively. Lapatinib decreased the paracetamol AUC0-∞ by 48.8% and Cmax by 55.7%. In the IL + PA group the Cmax of paracetamol glucuronide was reduced, whereas the Cmax of paracetamol sulphate was higher than in the IIIPA group. Paracetamol significantly affected the enhanced plasma exposure of lapatinib. Additionally, lapatinib reduced the concentrations of paracetamol. The co-administration of lapatinib decreased the paracetamol glucuronidation but increased the sulphation. The findings of this study may be of clinical relevance to patients requiring analgesic therapy.

Anaphylactoid Reactions to Intravenous N-Acetylcysteine during Treatment for Acetaminophen Poisoning.

BACKGROUND: Anaphylactoid reactions to intravenous (IV) N-acetylcysteine (NAC) are well-recognized adverse events during treatment for acetaminophen (APAP) poisoning. Uncertainty exists regarding their incidence, severity, risk factors, and management. We sought to determine the incidence, risk factors, and treatment of anaphylactoid reactions to IV NAC in a large, national cohort of patients admitted to hospital for acetaminophen overdose. METHODS: This retrospective medical record review included all patients initiated on the 21-h IV NAC protocol for acetaminophen poisoning in 34 Canadian hospitals between February 1980 and November 2005. The primary outcome was any anaphylactoid reaction, defined as cutaneous (urticaria, pruritus, angioedema) or systemic (hypotension, respiratory symptoms). We examined the incidence, severity and timing of these reactions, and their association with patient and overdose characteristics using multivariable analysis. RESULTS: An anaphylactoid reaction was documented in 528 (8.2%) of 6455 treatment courses, of which 398 (75.4%) were cutaneous. Five hundred four (95.4%) reactions occurred during the first 5 h. Of 403 patients administered any medication for these reactions, 371 (92%) received an antihistamine. Being female (adjusted OR 1.24 [95%CI 1.08, 1.42]) and having taken a single, acute overdose (1.24 [95%CI 1.10, 1.39]) were each associated with more severe reactions, whereas higher serum APAP concentrations were associated with fewer reactions (0.79 [95%CI 0.68, 0.92]). CONCLUSION: Anaphylactoid reactions to the 21-h IV NAC protocol were uncommon and involved primarily cutaneous symptoms. While the protective effects of higher APAP concentrations are of interest in understanding the pathophysiology, none of the associations identified are strong enough to substantially alter the threshold for NAC initiation.

Paracetamol clinical dosing routine leads to paracetamol underexposure in an adult severely ill sub-Saharan African hospital population: a drug concentration measurement study.

BACKGROUND: Hospitals in sub-Saharan Africa (SSA) continue to receive high numbers of severely ill (HIV-infected) patients with physical pain that may suffer from hepatic and renal dysfunction. Paracetamol is widely used for pain relief in this setting but it is unknown whether therapeutic drug concentrations are attained. The aim of this study was to assess the occurrence of therapeutic, sub-therapeutic and toxic paracetamol concentrations in SSA adult hospital population. METHODS: In a cross-sectional study, plasma paracetamol concentrations were measured in patients with an oral prescription in a referral hospital in Mozambique. From August to November 2015, a maximum of four blood samples were drawn on different time points for paracetamol concentration measurement and biochemical analysis. Study endpoints were the percentage of participants with therapeutic (≥ 10 and ≤ 20 mg/L), sub-therapeutic (< 10 mg/L) and toxic (> 75 mg/L) concentrations. RESULTS: Seventy-six patients with a median age of 37 years, a body mass index of 18.2, a haemoglobin concentration of 10.3 g/dL and an albumin of 29 g/L yielded 225 samples. 13.4% of participants had one or more therapeutic paracetamol concentrations. 86.6% had a sub-therapeutic concentration at all time points and 70.2% had two or more concentrations below the lower limit of quantification. No potentially toxic concentrations were found. CONCLUSIONS: Routine oral dosing practices in a SSA hospital resulted in substantial underexposure to paracetamol. Palliation is likely to be sub-standard and oral palliative drug pharmacokinetics and dispensing procedures in this setting need further investigation.