Presence and bioavailability of bisphenol A in the uterus of rats and mice following single and repeated dietary administration at low doses

This research examined the distribution of low dietary doses of bisphenol A (BPA). When female rats received 50 μg/kg ¹⁴C-BPA orally, radioactivity was distributed throughout the body, with especial presence in the uterus. Pre-treatment with estradiol or the estrogen antagonist ICI 182,780 significantly reduced radioactivity in the uterus. The majority of BPA at the uterus was determined to be aglycone (receptor-active) via GC–MS. Subsequently, mice given 0.5, 5, or 50 μg/kg ¹⁴C-BPA showed more radioactivity in the uterus than in other non-metabolic tissues. When female mice received 1, 7, or 28 daily doses of 50 μg/kg ¹⁴C-BPA, then were measured 24 h after the last dose, significantly more radioactivity was detected in the uterus, liver, and kidney following repeated doses. Collectively, these data provide evidence for the in vivo interaction of BPA with estrogen receptors. They also indicate elevated presence of BPA in reproductive tissues after repeated low doses.     

Alteration in the Pharmacokinetics of Hemoglobin-Vesicles in a Rat Model of Chronic Liver Cirrhosis Is Associated with Kupffer Cell Phagocyte Activity

The hemoglobin-vesicle (HbV) is a cellular, hemoglobin-based oxygen carrier. Our previous pharmacokinetic studies demonstrated that the liver is strongly associated with the metabolism and excretion of HbV. The aim of this study was to evaluate the pharmacokinetics of HbV in a chronic cirrhosis rat (CCR) model induced by carbon tetrachloride (CCl₄) and explore whether liver functional parameters and Kupffer cell (KC) phagocyte activity are related to the pharmacokinetics of HbV. The CCRs were induced three times weekly by intraperitoneal administration of CCl₄ for 8 weeks and categorized as Child–Pugh grade B. To analyze the pharmacokinetics, the CCRs were given a single intravenous injection of ³H-HbV (1400 mg of Hb/kg). The total clearance and hepatic distribution of HbV were negatively correlated with plasma aspartate aminotransferase (AST) levels (p = 0.007). In addition, the phagocyte index was negatively correlated with plasma AST levels (p = 0.047). The excretion of lipid components in feces was also negatively correlated with plasma AST levels (p = 0.049). In conclusion, alteration in the pharmacokinetics of HbV in CCRs can be attributed to a decrease in KC phagocyte activity and the extent of damage to parenchymal cells. This represents the first demonstration of the pharmacokinetics of a liposome preparation in chronic liverimpairment.     

Investigation of PEG Crystallization in Frozen PEG–Sucrose–Water Solutions: II. Characterization of the Equilibrium Behavior During Freeze-Thawing

Our objective was to characterize, by DSC and XRD, the equilibrium thermal behavior of frozen aqueous solutions containing polyethylene glycol (PEG) and sucrose. Aqueous solutions of (i) PEG (2.5–50% w/w), (ii) sucrose (10% w/v) with different concentrations of PEG (1–20% w/v), and (iii) PEG (2% or 10% w/v) with different concentrations of sucrose (2–20% w/v), were cooled to ? 70°C at 5°C/min and heated to 25°C at 2°C/min in a DSC. Annealing was performed for 2 or 6 h at temperatures, ranging from ? 50 to ? 20°C. Experiments under similar conditions, on select compositions, were also performed in a powder X-ray diffractometer. Two endotherms, observed during heating of a frozen PEG solution (10% w/v), were attributed to PEG–ice eutectic melting and ice melting, and were confirmed by XRD. At higher PEG concentrations (> 37.5% w/w), only the endotherm attributed to the PEG–ice eutectic melting was observed. Inclusion of sucrose decreased both PEG–ice melting and ice melting temperatures. In unannealed systems with a fixed sucrose concentration (10% w/v), the PEG–ice melting event was not observed at PEG concentration < 5% w/v. Annealing for 2–6 h facilitated PEG crystallization. In unannealed systems with a fixed PEG concentration (10% w/v), an increase in the sucrose concentration increased the devitrification but decreased the PEG–ice melting temperature. The PEG–ice melting temperatures obtained by DSC and XRD were in good agreement. In ternary systems at a fixed PEG to sucrose ratio, the T_g^′ as well as the PEG–ice melting temperature were unaffected by the total solute concentration. XRD confirmed the absence of a PEG–sucrose–ice ternary eutectic. When the PEG to sucrose ratio was systematically varied, the PEG–ice and ice melting temperatures decreased with an increase in the sucrose concentration. However, at a fixed PEG to sucrose ratio, the PEG–ice melting temperature, was unaffected by the total solute concentration.     

Folate-mediated poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) nanoparticles for targeting drug delivery

A novel targeting drug delivery system (TDDS) has been developed. Such a TDDS was prepared by W₁/O/W₂ solvent extraction/evaporation method, adopting poly(3-hydroxybutyrate-co-3-hydroxyoctanoate) [P(HB-HO)] as the drug carrier, folic acid (FA) as the targeting ligand, and doxorubicin (DOX) as the model anticancer drug. The average size, drug loading capacity and encapsulation efficiency of the prepared DOX-loaded, folate-mediated P(HB-HO) nanoparticles (DOX/FA–PEG–P(HB-HO) NPs) were found to be around 240 nm, 29.6% and 83.5%. The in vitro release profile displayed that nearly 50% DOX was released in the first 5 days. The intracellular uptake tests of the nanoparticles (NPs) in vitro showed that the DOX/FA–PEG–P(HB-HO) NPs were more efficiently taken up by HeLa cells compared to non-folate-mediated P(HB-HO) NPs. In addition, DOX/FA–PEG–P(HB-HO) NPs (IC₅₀ = 0.87 μM) showed greater cytotoxicity to HeLa cells than other treated groups. In vivo anti-tumor activity of the DOX/FA–PEG–P(HB-HO) NPs showed a much better therapeutic efficacy in inhibiting tumor growth, and the final mean tumor volume was 178.91 ± 17.43 mm³, significantly smaller than normal saline control group (542.58 ± 45.19 mm³). All these results have illustrated that our techniques for the preparing of DOX/FA–PEG–P(HB-HO) NPs developed in present work are feasible and these NPs are effective in selective delivery of anticancer drug to the folate receptor-overexpressed cancer cells. The new TDDS may be a competent candidate in application in targeting treatment of cancers.     

Lipid-core nanocapsules restrained the indomethacin ethyl ester hydrolysis in the gastrointestinal lumen and wall acting as mucoadhesive reservoirs

The aim of this work was to investigate if the indomethacin ethyl ester (IndOEt) released from lipid-core nanocapsules (NC) is converted into indomethacin (IndOH) in the intestine lumen, intestine wall or after the particles reach the blood stream. NC–IndOEt had monomodal size distribution (242 nm; PDI 0.2) and zeta potential of ?11 mV. The everted rat gut sac model showed IndOEt passage of 0.16 μmol m^?2 through the serosal fluid (30 min). From 15 to 120 min, the IndOEt concentrations in the tissue increased from 6.13 to 27.47 μmol m^?2. No IndOH was formed ex vivo. A fluorescent-NC formulation was used to determine the copolymer bioadhesion (0.012 μmol m^?2). After NC–IndOEt oral administration to rats, IndOEt and IndOH were detected in the gastrointestinal tract (contents and tissues). In the tissues, the IndOEt concentrations decreased from 459 to 5 μg g^?1 after scrapping, demonstrating the NC mucoadhesion. In plasma (peripheric and portal vein), in spleen and liver, exclusively IndOH was detected. In conclusion, after oral dosing of NC–IndOEt, IndOEt is converted into IndOH in the intestinal lumen and wall before reaching the blood stream. The complexity of a living system was not predicted by the ex vivo gut sac model.     

Systemic exposure to parabens: Pharmacokinetics,tissue distribution,excretion balance and plasma metabolites of [14C]-methyl-, propyl- and butylparaben in rats after oral,topical or subcutaneous administration

Parabens (PB) are preservatives used in food, drugs and personal care products preventing microbial and fungal contamination. We investigated ADME profiles of [¹⁴C]-methyl-, propyl- or butylparaben (MP, PP, BP) following single oral, dermal or subcutaneous (BP) doses at 100 mg/kg to Sprague–Dawley rats. Plasma C_max and AUC values after oral or subcutaneous doses were 4- to 10-fold higher relative to respective values after dermal administration. t_max ranged from 0.5, 2 or 8 h after oral, subcutaneous or dermal administration, respectively. MP produced higher blood C_max and AUC levels relative to those after PP or BP. Following oral or subcutaneous administration, urinary excretion was predominant (>70%, mainly during the first 24 h), less than 4% were eliminated in the feces, 2% were retained in the tissues and carcasses. Following dermal application, >50% of the dose was unabsorbed, 14–27% or <2% were respectively excreted in the urine or feces, respectively. Overall, parabens were well absorbed after oral and subcutaneous, and partially absorbed after dermal administration. All administration routes produced a single peak in the plasma, corresponding to that of para-hydroxybenzoic acid (PHBA) suggesting that PB produce no significant systemic exposure of mammalian organisms after oral, topical or subcutaneous administration.     

The pharmacokinetics and hypoglycaemic effect of sunitinib in the diabetic rabbits

BackgroundDiabetes is one of the most common metabolic diseases in the world, which may influence changes in the pharmacokinetics and pharmacodynamics of drugs. Sunitinib is a tyrosine kinase inhibitor (TKI) broadly used for treatment of numerous cancers, which exhibits the side hypoglycaemic effect. The aim of the study was a comparison of concentrations and pharmacokinetics of sunitinib after a single administration in rabbits with hyperglycaemia and normoglycaemia (control group). Additionally, the effect of sunitinib on glucose levels was investigated.MethodsThe research was carried out on a control group (n = 6) and a group of rabbits with diabetes (n = 6). The rabbits were treated with sunitinib in the oral dose of 25 mg. Plasma concentrations of sunitinib and its metabolite (SU12662) were measured with validated HPLC method with UV detection.ResultsThe comparison of the sunitinib C_max and AUC_0–∞ in the diabetic group with the control group gave the ratios of 1.63 [90% confidence interval (CI) [1.59; 1.66] and 2.03 [1.97; 2.09], respectively. Statistically significant differences between the analyzed groups were revealed for C_max (p = 0.006), AUC_0–∞ (p = 0.0088), and AUC_kel (p = 0.009). The maximum glycaemia drop of 14.4–69.6% and 15.4–33.5% was observed in the diabetic animals and in the control group, respectively. The glycaemia values returned to the initial values in 24 h after the administration of the drug.ConclusionsThe research proved the significant influence of diabetes on the pharmacokinetics of sunitinib and it confirmed the hypoglycaemic effect of the TKI in diabetic rabbits and in normoglycaemia.     

Methyl-γ-butyrobetaine decreases levels of acylcarnitines and attenuates the development of atherosclerosis

ObjectiveThe elevation of the levels of l-carnitine and its fatty acid esters, acylcarnitines, in tissue or plasma has been linked to the development of atherosclerosis. Recently, a potent inhibitor of l-carnitine biosynthesis and transport, methyl-γ-butyrobetaine (methyl-GBB), was discovered. In this study, we evaluated the effects of γ-butyrobetaine (GBB), l-carnitine and methyl-GBB administration on the progression of atherosclerosis.MethodsApolipoprotein E knockout (apoE^−/−) mice were treated with methyl-GBB, l-carnitine or GBB for 4 months. Following the treatment, the amount of atherosclerotic lesions, the number of immune cells in atherosclerotic lesions and the plasma lipid profile were analysed. The l-carnitine and acylcarnitine levels were determined in the aortic tissues of CD-1 outbred mice 2 weeks after treatment with methyl-GBB at the dose of 10 mg/kg.ResultsTreatment with methyl-GBB decreased the acylcarnitine and l-carnitine levels in the aortic tissues by seventeen- and ten-fold, respectively. Methyl-GBB treatment at a dose of 10 mg/kg reduced the size of atherosclerotic plaques by 36%. Neither l-carnitine nor GBB treatment affected the development of atherosclerosis.ConclusionsMethyl-GBB administration significantly attenuated the development of atherosclerosis in apoE^−/−mice. Our results demonstrate that decreasing the acylcarnitine pools can attenuate the development of atherosclerosis.     

The harmful effect of prolonged high-dose methylprednisolone in acute lung injury

Although many literatures have shown that prolonged high-dose administration of corticosteroids is hazardous and not indicated to therapy acute lung injury (ALI), there is little information on the harmful effect of prolonged high-dose corticosteroids in acute lung injury. In this study, we aimed to investigate the effect of prolonged high-dose methylprednisolone (MPL) on ALI and improve knowledge regarding the appropriate use of corticosteroids in ALI. The different doses of MPL (3, 30, 180 mg·kg^? 1) were given via tail vein injection 1 h after the first time LPS administration and were daily administrated for 14 days. Lung tissues and lavage samples were isolated for biochemical determinations and histological measurements at 12 h, 7 days and 14 days after LPS administration. Single administration of 180 mg·kg^? 1 MPL decreased the lung injury score, wet-to-dry ratio, the total cell numbers and level of procollagen type III in BALF at 12 h after LPS challenge. However, prolonged therapy with 180 mg·kg ^? 1 MPL for 7 days and 14 days decreased the number of AMs in BALF and increased the above-mentioned indexes. These results suggested that the prolonged high-dose MPL has harmful effects to treat LPS-induced ALI in rats.     

Triple-component nanocomposite films prepared using a casting method: Its potential in drug delivery

The purpose of this study was to fabricate a triple-component nanocomposite system consisting of chitosan, polyethylene glycol (PEG), and drug for assessing the application of chitosan–PEG nanocomposites in drug delivery and also to assess the effect of different molecular weights of PEG on nanocomposite characteristics. The casting/solvent evaporation method was used to prepare chitosan–PEG nanocomposite films incorporating piroxicam-β-cyclodextrin. In order to characterize the morphology and structure of nanocomposites, X-ray diffraction technique, scanning electron microscopy, thermogravimetric analysis, and Fourier transmission infrared spectroscopy were used. Drug content uniformity test, swelling studies, water content, erosion studies, dissolution studies, and anti-inflammatory activity were also performed. The permeation studies across rat skin were also performed on nanocomposite films using Franz diffusion cell. The release behavior of films was found to be sensitive to pH and ionic strength of release medium. The maximum swelling ratio and water content was found in HCl buffer pH 1.2 as compared to acetate buffer of pH 4.5 and phosphate buffer pH 7.4. The release rate constants obtained from kinetic modeling and flux values of ex vivo permeation studies showed that release of piroxicam-β-cyclodextrin increased with an increase in concentration of PEG. The formulation F10 containing 75% concentration of PEG showed the highest swelling ratio (3.42 ± 0.02) in HCl buffer pH 1.2, water content (47.89 ± 1.53%) in HCl buffer pH 1.2, maximum cumulative drug permeation through rat skin (2405.15 ± 10.97 μg/cm²) in phosphate buffer pH 7.4, and in vitro drug release (35.51 ± 0.26%) in sequential pH change mediums, and showed a significantly (p < 0.0001) higher anti-inflammatory effect (0.4 cm). It can be concluded from the results that film composition had a particular impact on drug release properties. The different molecular weights of PEG have a strong influence on swelling, drug release, and permeation rate. The developed films can act as successful drug delivery approach for localized drug delivery through the skin.     

Antioxidant biomarker survey ensuing long-term selenium withdrawal in Acipenser baeri fed Se-cysteine diets

Two selenium withdrawal periods, 30 and 90 days, were considered for sturgeon fed 90 days three Se-cysteine diets (1.25, 5, 20 mg kg⁻¹). Subsequently Acipenser baeri was fed the previous control diet (0.32 mg Se kg⁻¹) for 90 days. Levels of superoxide dismutase, catalase, glutathione peroxidases, glutathione reductase, glyoxalase-II and malondialdehyde were determined in liver and kidney. Chemical analyses were carried out for the same tissues and for muscle. A reduction of Se levels in all tissues was recorded and the metalloid concentration decreased more quickly in liver than in kidney and muscle. At the end of the withdrawal Se concentration in muscle remained high in specimens previously fed 20 mg Se kg⁻¹ diet, and disturbance of key antioxidant enzymes was recorded in liver and kidney. Moreover, alterations in glutathione peroxidases, and glyoxalase-II activities persisted even after 90 withdrawal days and were indicative of oxidative stress induced by Se-cysteine concentrations.     

Preparation of estradiol chitosan nanoparticles for improving nasal absorption and brain targeting

The estradiol(E₂)-loaded chitosan nanoparticles (CS-NPs) were prepared by ionic gelation of chitosan with tripolyphosphate anions (TPP). The CS-NPs had a mean size of (269.3 ± 31.6) nm, a zeta potential of +25.4 mV, and loading capacity of E₂ CS-NPs suspension was 1.9 mg ml⁻¹, entrapment efficiency was 64.7% on average. Subsequently, this paper investigated the levels of E₂ in blood and the cerebrospinal fluid (CSF) in rats following intranasal administration of E₂ CS-NPs. E₂-loaded CS-NPs were administered to male Wister rats either intranasally or intravenously at the dose of 0.48 mg kg⁻¹. The plasma levels achieved following intranasal administration (32.7 ± 10.1 ng ml⁻¹; t_max 28 ± 4.5 min) were significantly lower than those after intravenous administration (151.4 ± 28.2 ng ml⁻¹), while CSF concentrations achieved after intranasal administration (76.4 ± 14.0 ng ml⁻¹; t_max 28 ± 17.9 min) were significantly higher than those after intravenous administration (29.5 ± 7.4 ng ml⁻¹ t_max 60 min). The drug targeting index (DTI) of nasal route was 3.2, percent of drug targeting (DTP%) was 68.4%. These results showed that the E₂ must be directly transported from the nasal cavity into the CSF in rats. Finally, compared with E₂ inclusion complex, CS-NPs improved significantly E₂ being transported into central nervous system (CNS).     

Clinical Pharmacokinetics of Paclitaxel Liposome with a New Route of Administration in Human Based on the Analysis with Ultra Performance Liquid Chromatography

We investigated the clinical pharmacokinetics of paclitaxel liposome with a new route of administration, which was intrapleural infusion, in nine advanced nonsmall-cell lung cancer (NSCLC) patients with malignant pleural effusions after a single administration. Paclitaxel concentrations were measured in pleural fluid and plasma using a simple and rapid ultra performance liquid chromatography (UPLC) method following intra-and inter-day validations. In subjects, AUC_0–96h values in pleural fluid and plasma were 17831 ± 6439 μgh/mL and 778 ± 328 μgh/mL, respectively, and T_max values were initial time and 6.67 h after administration and the corresponding C_max values were 558 ± 44 μg/mL and 12.89 ± 6.86 μg/mL, respectively. The T_{1/2 IP}, CL_IP and Vd_IP values in pleural fluid were 76 ± 48 h, 0.005 ± 0.002 L/hm² and 0.53 ± 0.23 L/m², respectively. The T_1/2,_pla, CL_pla, and Vd_pla values in plasma were 68.34 ± 56.74 h, 0.184 ± 0.080 L/hm², and 17.53 ± 16.57 L/m², respectively. However, some paclitaxel concentrations from several patients in plasma could not be detected at some designed time-points. Our results might offer new opportunities to design and determine individually appropriate therapeutic dosage regimens based on a pharmacokinetic profile.     

Triclosan elevates estradiol levels in serum and tissues of cycling and peri-implantation female mice

Triclosan, an antimicrobial agent added to personal care products, can modulate estrogenic actions. We investigated whether triclosan affects concentrations of exogenous and endogenous estradiol. Female mice were given injections of triclosan followed by 1 μCi tritium-labeled estradiol. Mice given daily 2-mg triclosan doses (57.9 mg/kg/dose) showed significantly elevated radioactivity in tissues and serum compared to controls. A single dose of 1 or 2 mg triclosan increased radioactivity in the uterus in both cycling and peri-implantation females. We also measured natural urinary estradiol at 2–12 h following triclosan injection. Unconjugated estradiol was significantly elevated for several hours following 1 or 2 mg of triclosan. These data are consistent with evidence that triclosan inhibits sulfonation of estrogens by interacting with sulfotransferases, preventing metabolism of these steroids into biologically inactive forms. Elevation of estrogen concentrations by triclosan is potentially relevant to anti-reproductive and carcinogenic actions of excessive estrogen activity.     

Surface functionalization of doxorubicin-loaded liposomes with octa-arginine for enhanced anticancer activity

Doxorubicin-loaded PEGylated liposomes (commercially available as DOXIL® or Lipodox®) were surface functionalized with a cell-penetrating peptide, octa-arginine (R8). For this purpose, R8-peptide was conjugated to the polyethylene glycol–dioleoyl phosphatidylethanolamine (PEG–DOPE) amphiphilic co-polymer. The resultant R8–PEG–PE conjugate was introduced into the lipid bilayer of liposomes at 2 mol% of total lipid amount via spontaneous micelle-transfer technique. The liposomal modification did not alter the particle size distribution, as measured by Particle Size Analyzer and transmission electron microscopy (TEM). However, surface-associated cationic peptide increased zeta potential of the modified liposomes. R8-functionalized liposomes (R8-Dox-L) markedly increased the intracellular and intratumoral delivery of doxorubicin as measured by flow cytometry and visualizing by confocal laser scanning microscopy (CLSM) compared to unmodified Doxorubicin-loaded PEGylated liposomes (Dox-L). R8-Dox-L delivered loaded Doxorubicin to the nucleus, being released from the endosomes at higher efficiency compared to unmodified liposomes, which had marked entrapment in the endosomes at tested time point of 1 h. The significantly higher accumulation of loaded drug to its site of action for R8-Dox-L resulted in improved cytotoxic activity in vitro (cell viability of 58.5 ± 7% for R8-Dox-L compared to 90.6 ± 2% for Dox-L at Dox dose of 50 μg/mL for 4 h followed by 24 h incubation) and enhanced suppression of tumor growth (348 ± 53 mm³ for R8-Dox-L, compared to 504 ± 54 mm³ for Dox-L treatment) in vivo compared to Dox-L. R8-modification has the potential for broadening the therapeutic window of pegylated liposomal doxorubicin treatment, which could lead to lower non-specific toxicity.     

Assessment of the mutagenic effect of 1,1-dimethyl hydrazine

The mutagenic effect of the rocket fuel 1,1-dimethyl hydrazine has been studied experimentally and compared to the well-recognized mutagene N-nitroso dimethylamine. The manifestation of the effect for both compounds was disclosed through a significant increase in the chromosome aberration frequency in the bone marrow cells of intoxicated rats. The levels of chromosome aberrations induced by 1,1-dimetyl hydrazine were studied following both single (1 h) and repeated doses (daily for 10 consecutive days) by inhalation (205–1028 mg/m³) and gavage (5.4–26.8 mg/kg) administration, respectively. For comparison N-nitroso dimethylamine were administered by inhalation (2 h/daily for 10 consecutive days) and by gavage in concentrations of 2.4–48 mg/m³ and 1–30 mg/kg, respectively. A clear dependence of concentration as well of time was disclosed. The BenchMark Dose approach was employed to derive guideline doses for the two compounds, the implications towards human health being discussed.     

Solid Lipid Microparticles for the Stability Enhancement of a Dopamine Prodrug

The oral or peripheral administration of dopamine for the treatment of Parkinson’s disease is hampered by its extensive metabolism and inability to cross the blood-brain barrier. Consequently, the enhancement of dopamine stability in physiologic environments and its brain targeting appear useful in formulation development. We propose the preparation and characterization of solid lipid microparticles based on tristearin as a sustained delivery system for dopamine. The microparticles were produced by conventional hot emulsion techniques. The synthesis of a new valeroyl ester of dopamine (3,4-O-divaleroyl-dopamine, DVD) was necessary to obtain its encapsulation in the microparticles. DVD appeared totally hydrolyzed to dopamine in human plasma within 40 s. The amount of encapsulated DVD in microparticles was 2.67 ± 1.2%. The mean diameter of particles was 14.2 ± 4.8 mm. The DVD release from microparticles was characterized by an initial burst of 20% of incorporated prodrug and a continuous slow release thereafter. The microparticles were able to stabilize DVD in its solid form. In human plasma, DVD encapsulated in microparticles hydrolyzed with a markedly reduced rate in comparison with free prodrug: after 15 min, 35.8% of DVD was still detectable. The DVD-loaded microparticles could represent a potential system for dopamine uptake in the brain, following nasal administration. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:4730–4737, 2010     

Residual fraction of the area under the curve as a qualitative criterion in pharmacokinetic studies

The aim of the present study was to determine whether the residual area under the curve (AUC_res%; expressed as % of total value of AUC) could be used as a parameter for the qualitative evaluation of pharmacokinetic studies. We propose new criteria for the qualitative evaluation of pharmacokinetic analysis. Two sets of hypothetical data that illustrate the relationship between concentration and time were used for the analysis of drug pharmacokinetics. Non-compartmental analysis was applied for the calculations. The results obtained from the hypothetical data were compared with those obtained from an in vivo study in which 3-week-old broiler chickens were administered 10 mg/kg b.w. enrofloxacin intravenously (iv) or per os (po). In the first set of data (A–D), AUC_res% values were as follows: A= 16.29% and B = 20.79% for iv administration and C = 29.61% and D = 27.90% for po administration. In the next set of data (E–G), AUC_res% values after oral administration were 25.30% (E), 23.18% (F), and 20.79% (G). The AUC_res% values after iv administration of enrofloxacin were similar to po administration; the range of iv and po administration values were 14.35% to 17.50% and 11.14% to 28.33% of the total AUC, respectively. The analysis of the hypothetical data indicates that AUC_res% is not an optimal method for the evaluation of pharmacokinetic studies.     

A new and simple HPLC method for determination of etamsylate in human plasma and its application to pharmacokinetic study in healthy adult male volunteers

A new and simple HPLC assay method was developed and validated for the determination of etamsylate in human plasma. After protein precipitation with 6% perchloric acid, satisfactory separation was achieved on a HyPURITY C₁₈ column (250 mm × 4.6 mm, 5 μm) using a mobile phase comprising 20 mM sodium dihydrogen phosphate-2 hydrate (pH was adjusted to 3.5 by phosphoric acid) and acetonitrile at a ratio of 95:5 v/v. The elution was isocratic at ambient temperature with a flow rate of 0.75 ml/min. Allopurinol was used as internal standard. The calibration curve was linear over the range from 0.25 to 20 μg/ml (r² = 0.999). The limit of quantification for etamsylate in plasma was 0.25 μg/ml. The within day coefficient of variance (%CV) ranged from 3.9% to 10.2%, whereas the between-day %CV ranged from 3.1% to 8.7%. The assay method has been successfully used to estimate the pharmacokinetics of etamsylate after oral administration of a 500 mg tablet under fasting conditions to 24 healthy Egyptian human male volunteers. Various pharmacokinetic parameters including AUC_0–t, AUC_0–∞, C_max, T_max, t_1/2, MRT, Cl/F, and V_d/F were determined from plasma concentration–time profile of etamsylate.     

Characterisation of the roles of ABCB1, ABCC1, ABCC2 and ABCG2 in the transport and pharmacokinetics of actinomycin D in vitro and in vivo

Actinomycin D plays a key role in the successful treatment of Wilms tumour. However, associated liver toxicities remain a drawback to potentially curative treatment. We have used MDCKII cells over-expressing ABCB1, ABCC1, ABCC2 and ABCG2, alongside knockout mouse models to characterise actinomycin D transport and its impact on pharmacokinetics. Growth inhibition, intracellular accumulation and cellular efflux assays were utilised. A 59-fold difference in GI₅₀ was observed between MDCKII-WT and MDCKII-ABCB1 cells (12.7 nM vs. 745 nM, p < 0.0001). Reduced sensitivity was also seen in MDCKII-ABCC1 and ABCC2 cells (GI₅₀ 25.7 and 40.4 nM respectively, p < 0.0001). Lower intracellular accumulation of actinomycin D was observed in MDCKII-ABCB1 cells as compared to MDCKII-WT (0.98 nM vs. 0.1 nM, p < 0.0001), which was reversed upon ABCB1 inhibition. Lower accumulation was also seen in MDCKII-ABCC1 and ABCC2 cells. Actinomycin D efflux over 2 h was most pronounced in MDCKII-ABCB1 cells, with 5.5-fold lower intracellular levels compared to WT. In vivo studies showed that actinomycin D plasma concentrations were significantly higher in Abcb1a/1b^?/? as compared to WT mice following administration of 0.5 mg/kg actinomycin D (AUC_0–6 h 242 vs. 152 μg/L h respectively). While comparable actinomycin D concentrations were observed in the kidneys and livers of Abcb1a/1b^?/? and Abcc2^?/? mice, concentrations in the brain were significantly higher at 6 h following drug administration in Abcb1a/1b^?/? mice compared to WT. Results confirm actinomycin D as a substrate for ABCB1, ABCC1 and ABCC2, and indicate that Abcb1a/1b and Abcc2 can influence the in vivo disposition of actinomycin D. These data have implications for ongoing clinical pharmacology trials involving children treated with actinomycin D.