Pharmacokinetic Profiles of Metamizole Metabolites after Intramuscular and Intravenous Administration in Healthy Arabian Horses.

Metamizole sodium (MT) is an analgesic and antipyretic drug molecule used in humans, horses, cattle, swine, and dogs. Metamizole rapidly hydrolyzes and turns into methylamino antipyrine (MAA), an active primary metabolite of MT. The present study aims to determine the pharmacokinetic (PK) profiles of MT metabolites after intravenous (IV) and intramuscular (IM) administration into sex of Arabian horses (Equus ferus caballus) using a cross-over study design. The plasma samples were extracted by solid-phase extraction (SPE) method, and plasma concentrations of MT metabolites were analyzed by high-performance liquid chromatography (HPLC). After administrations of MT, plasma concentrations of methylamino antipyrine (MAA), amino antipyrone (AA), and acetylamino antipyrone (AAA) were determined within range of 15 min-12 h. Plasma concentrations of AA and AAA were lower than the plasma concentrations of major metabolite MAA at each sampling point. The PK parameters were statistically evaluated for MT's metabolites between male and female horses and also between IM and IV administrations of PK parameters such as Cmax , tmax , t1/2λz , AUC0-t , AUC0-∞ , λz, Cl and Vss (p < .05). The AUCIM /AUCIV ratio in female and male horses for MAA was 1.19 and 1.13, respectively. The AUCIM /AUCIV ratio for AA was lower than those found for MAA. AUCIM /AUCIV ratio was statistically significantly different between male and female horses for AA (p < .05). According to these results, some PK parameters such as Cmax, AUC, and MRT, MAA and AA concentrations have shown statistically significant differences by MT administrations.

4-Methylamino antipyrine determination in human plasma by high-performance liquid chromatography tandem mass spectrometry.

In the present study, a simple and rapid method for metamizole metabolite 4-methylamino antipyrine (MAA) determination in human plasma was developed, validated and successfully applied to a clinical trial. Chromatographic separation was achieved in HILIC mode on a YMC-Pack SIL column (100 × 2.0 mm; S-5 µm, 30 nm), with a mobile phase consisting of acetonitrile, water and formic acid. Protein precipitation of a small plasma volume using acetonitrile was selected for sample preparation. The multiple reaction monitoring transitions in the positive ionization mode were m/z 218.2 → 56.2 for MAA and m/z 221.2 → 56.2 for MAA-d3 (IS, internal standard). Concentration levels of MAA calibration standards were in the range of 0.100-20 µg/ml. Metamizole conversion into MAA in both water and organic media was investigated, and the level of the conversion in commercially available injection solutions was estimated.

Organic Anion-Transporting Polypeptide Genes Are Not Induced by the Pregnane X Receptor Activator Rifampin: Studies in Hepatocytes In Vitro and in Monkeys In Vivo.

Induction potentials of the pregnane X receptor (PXR) activator rifampin (RIF) on transporter genes [e.g., organic anion-transporting polypeptides (OATPs)] are still in its infancy or remain controversial in the field. The present investigations characterized changes in transporter gene expression by RIF in sandwich-cultured hepatocytes from multiple donors of human and cynomolgus monkey using real-time quantitative reverse transcription polymerase chain reaction method. Three-day treatment of RIF significantly induced CYP3A4 (∼60-fold induction), but not CYP1A2 and CYP2D6 genes. SLC51B was the most highly induced uptake transporter gene (>10-fold) in both human and monkey hepatocytes. A greater induction of CYP2C9 was observed in monkey hepatocytes than that in humans. ATP-binding cassette (ABC)B1 and ABCC2 were induced slightly above 2-fold in human and monkey hepatocytes and appeared to be dose-dependent. The induction of OATP and other transporter genes was generally less than 2-fold and considered not clinically relevant. SLCO2B1 was not detectable in monkey hepatocytes. To investigate in vivo OATP induction, RIF (18 mg/kg per day) was orally dosed to cynomolgus monkeys for 7 days. Pitavastatin and antipyrine were intravenously dosed before and after RIF treatment as exogenous probes of OATP and CYP activities, respectively. Plasma coproporphyrin-I (CP-I) and coproporphyrin-III (CP-III) were measured as OATP endogenous biomarkers. Although a significant increase of antipyrine clearance (CL) was observed after RIF treatment, the plasma exposures of pitavastatin, CP-I, and CP-III remained unchanged, suggesting that OATP function was not significantly altered. The results suggested that OATP transporters were not significantly induced by PXR ligand RIF. The data are consistent with current regulatory guidances that the in vitro characterization of transporter induction during drug development is not required. SIGNIFICANCE STATEMENT: Organic anion-transporting polypeptide (OATP) genes were not induced by rifampin in sandwich-cultured human and monkey hepatocytes OATP functions measured by OATP probe pitavastatin and endogenous marker coproporphyrins were not altered in monkeys in vivo by 7-day rifampin treatment. The data suggested that OATP transporters are unlikely induced by the pregnane X receptor ligand rifampin, which are consistent with current regulatory guidances that the in vitro characterization of OATP1B induction during drug development is not required.

Changes in the Expression of Aquaporin-3 in the Gastrointestinal Tract Affect Drug Absorption.

Aquaporin-3 (AQP3) plays an important role in water transport in the gastrointestinal (GI) tract. In this study, we conducted a Caco-2 cell permeability assay to examine how changes in the expression and function of AQP3 affect the rate at which a drug is absorbed via passive transport in the GI tract. When the function of AQP3 was inhibited by mercuric chloride or phloretin, there was no change in warfarin permeability. In contrast, when the expression of AQP3 protein was decreased by prostaglandin E2 (PGE2) treatment, warfarin permeability increased to approximately twice the control level, and membrane fluidity increased by 15%. In addition, warfarin permeability increased to an extent comparable to that after PGE2 treatment when cell membrane fluidity was increased by 10% via boric acid/EDTA treatment. These findings suggest the possibility that the increased drug absorption under decreased AQP3 expression was attributable to increased membrane fluidity. The results of this study demonstrate that the rate of water transport has little effect on drug absorption. However, our findings also indicate that although AQP3 and other similar transmembrane proteins do not themselves transport drugs, changes in their expression levels can cause changes in cell membrane fluidity, thus affecting drug absorption rates.

Effects of Temperature and Humidity on the Skin Permeation of Hydrophilic and Hydrophobic Drugs.

The humidity was a well-known method to hydrate the skin; however, the published data were varied, and systemic experiments in the previous papers were few. Therefore, the in vitro permeation of excised porcine ear skin by drugs with different polarities [aminopyrine (AMP), antipyrine (ANP), methylparaben (MP), and ibuprofen (IP)] was analyzed under a constant skin surface temperature with different temperatures and humidities to reveal the effects of temperature and humidity on the skin permeation enhancement effects. Applied formulations were prepared by mixing the drug and a hydrophilic vehicle containing glycerin. The disposition-distance profiles of water and the humectant glycerin in the stratum corneum were also investigated using confocal Raman microscopy. High absolute humidity (AH) significantly contributed to the high skin penetration of the hydrophilic penetrants AMP, ANP, and MP but not the hydrophobic penetrant IP. An increase in the partition parameter and a decrease in the diffusivity parameter occurred with an increase in AH, independent of drug polarity. Moreover, we found that dew condensation induced by high AH on temperature-controlled skin surface may effectively increase water content and may provide higher glycerin distribution in the skin barrier, the stratum corneum. Increasing the amount of water and hydrophilic vehicles such as glycerin in the stratum corneum may enhance the permeation of hydrophilic penetrants AMP, ANP, and MP. These data suggested a dew condensation on the skin surface induced by high AH at a constant skin surface temperature would be important to enhance hydrophilic penetrants.

Prediction of sustained fetal toxicity induced by ketoprofen based on PK/PD analysis using human placental perfusion and rat toxicity data.

AIM: We encountered a case of fetal toxicity due to ductus arteriosus (DA) constriction in a 36-week pregnant woman who had applied multiple ketoprofen patches. The aim of the present study was to present the case and develop a model to predict quantitatively the fetal toxicity risk of transdermal administration of ketoprofen. METHODS: Human placenta perfusion studies were conducted to estimate transplacental pharmacokinetic (PK) parameters. Using a developed model and these parameters, human fetal plasma concentration profiles of ketoprofen administered to mothers were simulated. Using pregnant rats, DA constriction and fetal plasma drug concentration after ketoprofen administration were measured, fitted to an Emax model, and extrapolated to humans. RESULTS: Transplacental transfer value at the steady state of ketoprofen was 4.82%, which was approximately half that of antipyrine (passive marker). The model and PK parameters predicted almost equivalent mother and fetus drug concentrations at steady state after transdermal ketoprofen administration in humans. Maximum DA constriction and maximum plasma concentration of ketoprofen after administration to rat dams were observed at different times: 4 h and 1 h, respectively. The model accurately described the delay in DA constriction with respect to the fetal ketoprofen concentration profile. The model with effect compartment and the obtained parameters predicted that use of multiple ketoprofen patches could potentially cause severe DA constriction in the human fetus, and that fetal toxicity might persist after ketoprofen discontinuation by the mother, as observed in our case. CONCLUSION: The present approach successfully described the sustained fetal toxicity after discontinuing the transdermal administration of ketoprofen.

Application of Osmotic Pumps for Sustained Release of 1-Aminobenzotriazole and Inhibition of Cytochrome P450 Enzymes in Mice: Model Comparison with the Hepatic P450 Reductase Null Mouse.

The effectiveness of controlled release 1-aminobenzotriazole (ABT) administration to inhibit cytochrome P450 (P450) enzymes has been evaluated in mice. To maximize the duration of P450 inhibition in vivo, ABT was administered via an osmotic pump. The degree of P450 inhibition was compared with that achieved with a single bolus dose of ABT. Two-hour prior subcutaneous treatment of mice with ABT (50 mg/kg) inhibited antipyrine clearance by 88%. A less pronounced inhibitory effect (29% reduction in clearance) was observed when ABT was administered 24-hours before antipyrine administration, indicating partial restoration of P450 activity during this longer pretreatment time. The duration of ABT in mice was very short (mean residence time = 1.7 hours) after subcutaneous bolus administration. When the inhibitor was delivered by an osmotic pump, maximum blood concentrations of the inhibitor were observed 24 hours after device implantation and were maintained at steady state for 6 days. Inhibition of P450 activity, as measured by antipyrine clearance, was confirmed at 24 hours and 120 hours after pump implantation, highlighting the utility of this method as a longer-term model for P450 inhibition in mice. The magnitude of P450 inhibition in ABT-treated mice was compared with that in hepatic P450 reductase null mice and both models were comparable. In vivo ABT administration by an osmotic pump offers an effective approach for longer-term P450 inhibition in mice and avoids the necessity for multiple dosing of the inhibitor.

In vivo use of the CYP inhibitor 1-aminobenzotriazole to increase long-term exposure in mice.

1-Aminobenzotriazole (ABT) is a well-known in vivo nonspecific inhibitor of cytochrome P450 (CYP) enzymes. An effective dosing regimen of ABT for a multiple-administration study is needed to conduct pharmacological studies for proof-of-concept, although it has been established for single-administration study, to characterize the pharmacokinetics of drug candidates. This study demonstrated a suitable dosing vehicle of ABT for continuous administration and increased exposure to antipyrine, which is a nonspecific probe of CYP, using ABT for a long period in mice. The dosing vehicle of ABT was 0.5% (w/v) hydroxypropyl methylcellulose and 0.5% (v/v) Tween 80 in N,N-dimethylacetamide/20% hydroxypropyl-ß-cyclodextrin aqueous solution (2:8, v/v) based on the duration of apparent solubility. After implantation of an ALZET osmotic pump with ABT, the plasma concentrations of ABT were maintained at more than 4.1 µg/ml over 336 h. Compared with the vehicle group, the CLtot of antipyrine with ABT decreased to approximately one-fourth, and the BA of antipyrine with ABT increased up to 3-fold. In addition, the enhancement of exposure of antipyrine by ABT was maintained over the 336 h. The body weight, food consumption and hematological parameters of mice did not change with ABT administration for 16 days. These findings demonstrated that pretreatment of ABT can increase long-term exposure using continuous administration with the ALZET osmotic pump in mice with no overt toxicity. It is concluded that the in vivo use of 1-aminobenzotriazole can be applied to pharmacological studies for proof-of-concept, thus contributing to the selection of drug candidates at an early drug discovery stage. Copyright © 2016 John Wiley & Sons, Ltd.

POST-ANESTHETIC REHABILITATION PERIODS AND ANESTHESIA DOSAGE FOR LAPAROSCOPIC CHOLECYSTECTOMY: RELATIONSHIP TO THE TOTAL OXIDATIVE CAPACITY OF LIVER.

Analysis of the results of pharmacological phenotyping using antipyrine test prior to providing anesthesia for laparoscopic cholecystectomy showed that trimeperidine (promedol) dosing with allowance for the total oxidative capacity of liver and the patient mass allows the periods of post-anesthetic rehabilitation to be controlled. Clear algorithm of trimeperidine dosing based on established indices of the total oxidative capacity of liver and is yet nor developed because of restricted sampling set. The obtained results show expediency of using and studying antipyrine test as a simple, cheap, and informative method of individual anesthesia dosing for increasing the adequacy of general anesthesia.

Age-related pharmacokinetic changes of acetaminophen, antipyrine, diazepam, diphenhydramine, and ofloxacin in male cynomolgus monkeys and beagle dogs.

1. The pharmacokinetics of acetaminophen (marker of gastric emptying), antipyrine (marker of hepatic metabolic activity and total body water), diazepam (lipophilic and highly distributed), diphenhydramine (hepatic blood flow-limited and alpha-1 acid glycoprotein bound) and ofloxacin (renally eliminated) were evaluated in cynomolgus monkeys (3-18 years old) and beagle dogs (2-11 years old) as models in elderly persons. 2. Gastric pH fluctuated with aging in monkeys and dogs. The concentration of alpha-1 acid glycoprotein appeared to be increased by aging. There were no age-related differences in the absorption rates of the drugs under the conditions used in the study. Total body fat increased and water decreased in monkeys, but these parameters did not change in dogs. 3. Hepatic blood flow decreased in both species, but a significant decrease of hepatic clearance was only seen in monkeys. Renal clearance decreased significantly with age in monkeys and showed a tendency to decrease in dogs. 4. Age-related alterations of physiological parameters in monkeys are in agreement with clinical observations in humans, except for the lack of a change in the plasma albumin concentration. Therefore, this study suggests that monkey might be a suitable animal model for prediction of age-related changes in pharmacokinetics in humans.

LC-MS/MS methods for the determination of edaravone and/or taurine in rat plasma and its application to a pharmacokinetic study.

Three liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods were respectively developed and validated for the simultaneous or independent determination of taurine and edaravone in rat plasma using 3-methyl-1-p-tolyl-5-pyrazolone and sulfanilic acid as the internal standards (IS). Chromatographic separations were achieved on an Agilent Zorbax SB-Aq (100 × 2.1 mm, 3.5 µm) column. Gradient 0.03% formic acid-methanol, isocratic 0.1% formic acid-methanol (90:10) and 0.02% formic acid-methanol (40:60) were respectively selected as the mobile phase for the simultaneous determination of two analytes, taurine or edaravone alone. The MS acquisition was performed in multiple reaction monitoring mode with a positive and negative electrospray ionization source. The mass transitions monitored were m/z [M + H](+) 175.1 → 133.0 and [M + H](+) 189.2 → 147.0 for edaravone and its IS, m/z [M - H](-) 124.1 → 80.0 and [M - H](-) 172.0 → 80.0 for taurine and its IS, respectively. The validated methods were successfully applied to study the pharmacokinetic interaction of taurine and edaravone in rats after independent intravenous administration and co-administration with a single dose. Our collective results showed that there were no significant alterations on the main pharmacokinetic parameters (area under concentration-time curve, mean residence time, half-life and clearance) of taurine and edaravone, implying that the proposed combination therapy was pharmacologically feasible.

Safety, tolerability and pharmacokinetics of MCI-186 in patients with acute ischemic stroke: new formulation and dosing regimen.

BACKGROUND AND PURPOSE: MCI-186 (edaravone) is a free radical scavenger approved in Japan since 2001 for the treatment of patients with acute ischemic stroke within 24 h from the onset of symptoms. It was recommended by the Japanese Guidelines for the Management of Stroke 2004. Our aim was to investigate the safety, tolerability and pharmacokinetics of a new formulation and dose regimen (intravenous bolus plus infusion) of MCI-186 suitable for the treatment of acute ischemic stroke in Europe because the Japanese treatment protocol includes twice-a-day intravenous infusion of MCI-186 for a maximum of 14 days. Such a treatment protocol is not very practical in Europe, where hospital stay is much shorter in acute hospitals. METHODS: In a double-blind, placebo-controlled randomized clinical trial we studied two dosing regimens, each in a cohort of 18 patients. Patients were randomized in a 2:1 ratio in both cohorts to receive MCI-186 or placebo. Review of safety and plasma concentration data from the first cohort (loading dose 0.08 mg/kg + 0.2 mg/kg/h infusion) preceded the second cohort (loading dose 0.16 mg/kg + 0.4 mg/kg/h infusion). Safety parameters included adverse events, severe adverse events, physical examinations, local reactions at infusion site, ECG, clinical chemistry and hematology, modified Total Neuropathy Score and CT scans. RESULTS: Mean age and National Institutes of Health Stroke Scale (NIHSS) score on admission of patients in cohorts 1 and 2 and the placebo group were 64, 63, and 69 years and 5, 5, and 6, respectively. The number of treatment emergent adverse events that occurred was 109, most of which were transient, mild or moderate. Both doses of the new formulation and dosing regimen were well tolerated. After the initiation of the infusion, plasma concentrations of MCI-186 reached or exceeded prespecified target levels within 24 h in both MCI-186 cohorts, which were in the putative therapeutic range in humans. Geometric mean values of MCI-186 plasma concentration at the end of the infusion in cohorts 1 and 2 were 391 and 1,595 ng/ml, respectively. CONCLUSIONS: The primary objective of the present study, safety and tolerability of the new formulation and dosing regimen, was achieved. The new formula and both dosing regimens were well tolerated and achieved intended plasma concentrations suitable for larger safety studies before pivotal trials.

Transepithelial transport of a natural cholinesterase inhibitor, huperzine A, along the gastrointestinal tract: the role of ionization on absorption mechanism.

During recent years there has been increasing interest in the Lycopodium alkaloid huperzine A as a potential therapeutic agent for neurodegenerative diseases. This study aimed to characterize huperzine A's permeability across the enterocyte barrier along the gastrointestinal tract with an emphasis on the effect of ionization on the drug absorption. Intestinal permeability of huperzine A was evaluated by in vitro Caco-2 and parallel artificial membrane permeation assay models and by the ex vivo Ussing chamber model. The permeability rate was strongly dependent on the degree of ionization and increased with elevation of the donor medium pH in all studied models. The transport of the unionized fraction was similar to the permeability of the markers for passive transcellular diffusion. Addition of the paracellular permeability modulator palmitoylcarnitine in the Caco-2 model led to significant enhancement in the permeability of the ionized huperzine A fraction. No evidence of active transport of huperzine A was detected in this study. The Ussing chamber model experiments showed similar drug permeability along the entire rat intestine. In conclusion, huperzine A permeates the intestinal border mainly by passive transcellular diffusion whereas some fraction, dependent on the degree of huperzine A ionization, is absorbed by the paracellular route. Huperzine A's permeability characteristics pave the way to the development of its oral extended release dosage form. The specific population of the potential users of huperzine A and the high potency of this molecule support the rationale for such a delivery.

Glucuronidation of edaravone by human liver and kidney microsomes: biphasic kinetics and identification of UGT1A9 as the major UDP-glucuronosyltransferase isoform.

Edaravone was launched in Japan in 2001 and was the first neuroprotectant developed for the treatment of acute cerebral infarction. Edaravone is mainly eliminated as glucuronide conjugate in human urine (approximately 70%), but the mechanism involved in the elimination pathway remains unidentified. We investigated the glucuronidation of edaravone in human liver microsomes (HLM) and human kidney microsomes (HKM) and identified the major hepatic and renal UDP-glucuronosyltransferases (UGTs) involved. As we observed, edaravone glucuronidation in HLM and HKM exhibited biphasic kinetics. The intrinsic clearance of glucuronidation at high-affinity phase (CL(int1)) and low-affinity phase (CL(int2)) were 8.4 ± 3.3 and 1.3 ± 0.2 µl · min(-1) · mg(-1), respectively, for HLM and were 45.3 ± 8.2 and 1.8 ± 0.1 µl · min(-1) · mg(-1), respectively, for HKM. However, in microsomal incubations contained with 2% bovine serum albumin, CL(int1) and CL(int2) were 16.4 ± 1.2 and 3.7 ± 0.3 µl · min(-1) · mg(-1), respectively, for HLM and were 78.5 ± 3.9 and 3.6 ± 0.5 µl · min(-1) · mg(-1), respectively, for HKM. Screening with 12 recombinant UGTs indicated that eight UGTs (UGT1A1, UGT1A6, UGT1A7, UGT1A8, UGT1A9, UGT1A10, UGT2B7, and UGT2B17) produced a significant amount of glucuronide metabolite. Thus, six UGTs (UGT1A1, UGT1A6, UGT1A7, UGT1A9, UGT2B7, and UGT2B17) expressed in human liver or kidney were selected for kinetic studies. Among them, UGT1A9 exhibited the highest activity (CL(int1) = 42.4 ± 9.5 µl · min(-1) · mg(-1)), followed by UGT2B17 (CL(int) = 3.3 ± 0.4 µl · min(-1) · mg(-1)) and UGT1A7 (CL(int) = 1.7 ± 0.2 µl · min(-1) · mg(-1)). Inhibition study found that inhibitor of UGT1A9 (propofol) attenuated edaravone glucuronidation in HLM and HKM. In addition, edaravone glucuronidation in a panel of seven HLM was significantly correlated (r = 0.9340, p = 0.0021) with propofol glucuronidation. Results indicated that UGT1A9 was the main UGT isoform involved in edaravone glucuronidation in HLM and HKM.

Prediction and evaluation of fetal toxicity induced by NSAIDs using transplacental kinetic parameters obtained from human placental perfusion studies.

AIM: The use of nonsteroidal anti-inflammatory drugs (NSAIDs) in full-term pregnant women leads to fetal or neonatal toxicity, such as constriction of the ductus arteriosus (DA) and persistent pulmonary hypertension in the newborn. The aim of this study was to predict quantitatively the fetal toxicity of three NSAIDs (antipyrine, salicylic acid and diclofenac) using the transplacental pharmacokinetic parameters obtained from our previous placental perfusion studies. METHODS: Human fetal plasma concentration profile after oral administration of each NSAID to the mother was estimated using the transplacental pharmacokinetic parameters and pharmacokinetic parameters in adult women. The fetal plasma concentration-response relationship for the three NSAIDs was estimated by pharmacokinetic/pharmacodynamic analysis of the results of previous studies investigating the effects of NSAIDs on the ratio of inner diameter of the DA to that of the pulmonary artery (DA/PA) in rats and the plasma concentration profiles of NSAIDs in pregnant rats. RESULTS: The risk of constriction of the DA was well predicted by the model. Mean DA/PA ratio after oral administration of diclofenac to the mother was estimated to be 39.0%, whereas both of the corresponding values after oral administration of antipyrine and salicylic acid were estimated to be 5.9%. These results suggest that the fetal risk of diclofenac is higher than those of salicylic acid and antipyrine. CONCLUSIONS: This study presents a novel approach to predict quantitatively the fetal risk of NSAIDs administered to the mother. Human placental perfusion study and pharmacokinetic/pharmacodynamic analysis may provide basic data for predicting human fetal toxicity of drugs.

Hepatocellular necrosis, fibrosis and microsomal activity determine the hepatic pharmacokinetics of basic drugs in right-heart-failure-induced liver damage.

PURPOSE: To explore how liver damage arising from cardio-hepatic syndromes in RHF affect the hepatic pharmacokinetics of basic drugs. METHODS: The hepatic pharmacokinetics of five selected basic drugs with different physicochemical properties were studied in IPRL from control rats and rats with RHF. Hepatic pharmacokinetic modelling was performed with a two-phase physiologically-based organ pharmacokinetic model with the vascular space and dispersion evaluated with the MID technique. The liver damage arising from RHF was assessed by changes in liver biochemistry and histopathology. The expression of various CYP isoforms was evaluated by real-time RT-PCR analysis. RESULTS: Four of the five basic drugs had a significantly lower E in RHF rat livers compared to the control rat livers. Hepatic pharmacokinetic analysis showed that both the CL int and PS were significantly decreased in the RHF rat livers. Stepwise regression analysis showed that the alterations in the pharmacokinetic parameters (E, CL int and PS) can be correlated to the observed histopathological changes (NI, CYP concentration and FI) as well as to the lipophilicity of the basic drugs (logP app). CONCLUSIONS: Serious hepatocellular necrosis and fibrosis induced by RHF affects both hepatic microsomal activity and hepatocyte wall permeability, leading to significant impairment in the hepatic pharmacokinetics of basic drugs.

Synthesis physicochemical profile and PAMPA study of new NO-donor edaravone co-drugs.

A new class of co-drugs were synthesised by joining antioxidant edaravone with a vasodilating substructure containing NO-donor nitrooxy functions, and characterised for their stability in different media, lipophilicity and permeability profile. The products display good stability in water/co-solvent at different pH. Conversely, they are rapidly metabolised into edaravone and NO-donor moieties when incubated in human serum or rat-liver homogenates. In the latter conditions time dependent production of nitrite/nitrate (NO(x)) occurs. The compounds display wide-ranging lipophilicity. PAMPA studies predict good gastrointestinal absorption for a number of these compounds. The title products are potentially useful for treating ROS-related conditions accompanied by decreased NO availability.

Gender differences in pharmacokinetics of antipyrine in a simulated weightlessness rat model.

BACKGROUND: Gender differences in gastrointestinal physiology and hepatic metabolizing enzyme systems may potentially modify drug absorption and disposition during spaceflight. This study evaluated the effect of simulated weightlessness on gender-related pharmacokinetic differences of intravenously administered antipyrine, a marker compound for hepatic oxidative metabolism, using the tail-suspended (TS) rat model for microgravity. METHODS: TS rats were suspended at a 45 degrees angle from the cage floor for 3 d prior to and for 8 h after antipyrine administrations. Control and TS jugular vein-cannulated male and female Sprague-Dawley rats received a 20 mg x kg(-1) intravenous dose of antipyrine. Serial blood samples (0.25 ml) were collected from each rat at 14 predetermined times. Plasma drug concentrations were measured by a HPLC method. Plasma antipyrine concentration-time data were analyzed using noncompartmental pharmacokinetic methods. Statistical comparisons were made using the nonparametric Mann-Whitney U-test. RESULTS: In male rats, simulated weightlessness appreciably and significantly reduced the mean total body clearance of antipyrine by 44.7% and increased the mean residence time of antipyrine by 58.3%, but had no significant effect on the apparent volume of distribution of the drug. In striking contrast to that observed in male rats, simulated weightlessness had no significant effect on the disposition kinetics of antipyrine in female rats. CONCLUSION: Significant gender difference exists in microgravity-induced changes in drug disposition, where simulated weightlessness apparently has more of an effect in male versus female rats in terms of hepatic enzymatic functions.

[Dynamics of antipirin test at patients with alcoholic liver disease on the background of metadoksin drug receiving].

AIM: To study the effect of the drug metadoxin on drug-metabolizing liver function in patients with liver lesions alcoholic etiology (ALD). MATERIALS AND METHODS: 36 patients with ALD, of which 16 patients were diagnosed with hepatitis, while 20 - with the liver cirrhosis. All the patients underwent biochemical blood analysis and the study of drug-metabolizing liver function according to the pharmacokinetics of antipyrine in saliva before and after treatment with metadoxin. Metadoxin was administered at a dose of 500 mg once a day for 28 days. Concentrations of antipyrine in saliva samples were determined by HPLC. RESULTS. It was shown that of 36 patients examined in the 28-patients with ALD (group 2) there was a significant decrease in activity of liver enzymes according to the test with antipyrine (T1/2 = 28.7 +/- 3.4, CL = 17,9 +/- 5.2; p < 0,01 vs normal), whereas in 8 patients (group 1) was noted the typical for alcohol inductive influence on the activity of liver monooxygenases (T1/2 = 7.8 +/- 1.5, CL = 39.1 +/- 6.8; p < 0,05 vs normal). As a result of the 28-day therapy with metadoxin was a normalization of the pharmacokinetic parameters of AP in Gr. 1 (12.6 +/- 1.8; p < 0.05; NS vs normal) and a significant improvement of it in patients of Gr. 2 (17.9 +/- 5.2, vs N, p <0.05). Biochemical markers of ALD (AST/ALT, GGT, ALP) also demonstrated a positive dynamics in patients of both study groups. Correlation analysis of changes in CL and GGT (r1) and changes in AST/ALT and T1/2 (r2) showed a fairly high degree of correlation between these parameters (r1 = 0.58, r2 = 0.65). CONCLUSION: The results showed marked improvement of drug-metabolizing liver function according to the test with antipyrine in patients with ALD after treatment with metadoxin.

Transfer of bisphenol A across the human placenta.

OBJECTIVE: The objective of the investigation was to study placental transfer and conjugation of bisphenol A (BPA) across the human placenta. STUDY DESIGN: Human placentae obtained from healthy term singleton pregnancies were utilized in a dual recirculating model of ex vivo placental perfusion. Seven placentae were perfused with BPA (10 ng/mL) added to the maternal perfusate for 180 minutes. Antipyrine and fluorescein isothiocyanate dextran were used as positive and negative controls, respectively, to validate integrity of the circuits. Concentrations of BPA and its conjugates were determined by liquid chromatography-mass spectrometry. RESULTS: The transfer percentage for antipyrine and BPA were 25.5 +/- 1.13% and 27.0 +/- 1.88%, respectively, and the transfer index for BPA was 1.1 +/- 0.09 after 180 minutes of perfusion. Only 3.2 +/- 1.6% of BPA in the fetal compartment was in the conjugated form. CONCLUSION: Bisphenol A at low environmentally relevant levels can transfer across the human placenta, mainly in active unconjugated form.