Risk–benefit of antiemetics in prevention and treatment of chemotherapy-induced nausea and vomiting

The development of effective antiemetic prophylaxis is one of the most significant steps forward in the area of supportive care. Fifteen years ago, patients receiving chemotherapy had to face the fact that nausea and vomiting were inevitable adverse effects, which could only be partially prevented by treatment with antiemetics such as dopamine (DA) D2 receptor antagonists and corticosteroids. The first group of drugs specifically developed as antiemetics was the serotonin (5-hydroxytryptamine [5-HT]₃) receptor antagonists. These drugs have dramatically improved prophylaxis of chemotherapy-induced emesis, particularly when used in combination with a corticosteroid. This combination has resulted in a significant decrease in the number of patients vomiting, whereas the improvement in the prophylaxis of nausea has been less successful. Another group of antiemetics, the neurokinin (NK)₁ receptor antagonists, has recently been developed, and the first drug in this class, aprepitant, has been approved by the FDA and the EU authorities. Studies have showed that patients benefit from the use of this drug in combination with standard antiemetic therapy (5-HT₃ receptor antagonist plus a corticosteroid), both in the acute and delayed phase of nausea and vomiting induced by cisplatin-based chemotherapy. This development has not only led to improved efficacy but also to a decreased risk associated with the use of antiemetics. One of the problems with traditional antiemetics, for example, the DA D2 receptor antagonists, is the risk of unpleasant adverse effects including restlessness and dystonic reactions. To avoid these adverse effects, combination with benzodiazepines or antihistamines was necessary, often resulting in sedation. Modern research also includes pharmacogenomic investigations. This has led to speculation about the importance of drug–drug interactions involving antiemetics through competition for metabolism by the cytochrome P450 isoenzymes. The worst possible interaction would be a decrease in the effect of different cytotoxins but there is no evidence that such interactions are of importance in daily clinical practice. Guidelines are useful tools in the optimisation of antiemetic prophylaxis but, unfortunately, implementation of the evidence-based recommendations is far from successful. A prerequisite for further optimisation of antiemetic prophylaxis is updating of the guidelines, including recommendations for the use of NK₁ receptor antagonists (aprepitant), followed by implementation of these recommendations in the clinic. Future research must include ‘the difficult trials’ focusing on the remaining groups of patients with severe chemotherapy-induced nausea and vomiting, including patients with refractory and breakthrough emesis.     

Preparation and characterization of HA–PEG–PCL intelligent core–corona nanoparticles for delivery of doxorubicin

The objective of the present study was to synthesize core–corona nanoparticles of doxorubicin (DOX) using hyaluronic acid–polyethyleneglycol–polycaprolactone (HA–PEG–PCL) copolymer for tumor targeting. Targeting efficiency of HA–PEG–PCL nanoparticles was compared with non-HA-containing nanoparticles (methoxy poly ethylene glycol (MPEG)–PCL). The copolymers were chemically synthesized and characterized by IR and NMR spectroscopies. The nanoparticles were characterized for shape and morphology by transmission electron microscopy, particle size, percentage of drug entrapment, and in vitro drug release profile. Differential scanning calorimetry and X-ray diffraction studies were also performed to appraise the crystalline or amorphous nature of DOX inside the polymer matrix. Formulations were prepared using different DOX:polymer ratios (1:1–1:3 w/w) and the optimum formulation with the drug:polymer ratio of 1:1 showed the mean particle size of 95 ± 5 nm and entrapment efficiency of 95.56% in the case of HA–PEG–PCL nanoparticles, while the values were 115 nm and 95.50%, respectively, in the case of MPEG–PCL nanoparticles. The HA–PEG–PCL nanoparticles could release DOX for up to 17 days, whereas the MPEG–PCL nanoparticles could release it for up to 14 days. The hemolytic toxicity and hematological studies confirmed that both DOX-loaded HA–PEG–PCL and MPEG–PCL nanoparticles were safe and suitable for sustained and targeted drug delivery. The tissue distribution study and tumor growth inhibition were performed after intravenous injection of nanoparticles in Ehrlich ascites tumor (EAT)-bearing mice. The nanoparticles of HA–PEG–PCL copolymer accomplishes efficient delivery of DOX in EAT tumor when compared with the MPEG–PCL nanoparticles by the process of receptor-mediated endocytosis, as well as enhanced permeability and retention effect.     

Discovery and investigation of natural Diels–Alderases

It has been proposed that biosyntheses of many natural products involve pericyclic reactions, including Diels–Alder (DA) reaction. However, only a small set of enzymes have been proposed to catalyze pericyclic reactions. Most surprisingly, there has been no formal identification of natural enzymes that can be defined to catalyze DA reactions (DAases), despite the wide application of the reaction in chemical syntheses of complex organic compounds. However, recent studies began to accumulate a growing body of evidence that supports the notion that enzymes that formally catalyze DA reactions, in fact exist. In this review, I will begin by describing a short history behind the discovery and characterization of macrophomate synthase, one of the earliest enzymes that was proposed to catalyze an intermolecular DA reaction during the biosynthesis of a substituted benzoic acid in a phytopathogenic fungus Macrophoma commelinae. Then, I will discuss representative enzymes that have been chemically authenticated to catalyze DA reactions, with emphasis on more recent discoveries of DAases involved mainly in fungal secondary metabolite biosynthesis except for one example from a marine streptomycete. The current success in identification of a series of DAases and enzymes that catalyze other pericyclic reactions owes to the combined efforts from both the experimental and theoretical approaches in discovering natural products. Such efforts typically involve identifying the chemical features derived from cycloaddition reactions, isolating the biosynthetic genes that encode enzymes that generate such chemical features and deciphering the reaction mechanisms for the enzyme-catalyzed pericyclic reactions.

     

Antinociceptive activity and chemical composition of Wei–Chang–An–Wan extracts

Abstract

Context: Currently, famous traditional Chinese medicine formulas have undergone re-evaluation and development in China. Wei–Chang–An–Wan (WCAW) as one of them has been used for treating various gastrointestinal diseases for several decades. The secondary development of WCAW is in progress so as to interpret the effective material basis or find new pharmacological activity.

Objective: To evaluate the antinociceptive effect of methanol extract of WCAW (ME) as well as four fractions (P.E., EtOAc, n-BuOH, H₂O) and obtain information on the correlation between the contents of the fractions and antinociceptive effect.

Materials and methods: ME was divided into four parts extracted by petroleum ether, ethyl acetate and n-butanol. Antinociceptive activity was evaluated by three models of acetic acid–induced writhing, formalin and hot-plate test in mice after repetitive administration of ME at 200, 400 or 800?mg/kg, P.E. 132?mg/kg, EtOAc 106?mg/kg, n-BuOH 176?mg/kg and H₂O 176?mg/kg for six days. The chemical compounds were analyzed by HPLC-ESI-MS.

Results: ME at 800?mg/kg inhibited acid-induced writhing by 84.69%, and reduced the licking time of second phase in formalin test by 53.23%. The inhibition rates in acid-induced writhing of P.E., EtOAc, n-BuOH and H₂O were 27.79, 33.85, 38.97 and 37.69%, respectively, and in formalin test about 50%. They had no effect on the hot-plate test. HPLC-ESI-MS analysis showed that 68 chemical compounds were detected and 41 compounds were identified from ME.

Discussion and conclusion: The results obtained herein indicate that WCAW possesses the antinociceptive activity that provides a new aspect in clinical application.     

Mother–Daughter and Father–Daughter Attachment of College Student ACOAs

This 2005 study compared parent–child attachment in 89 American female Adult Children of Alcoholics (ACOAs) as compared to 201 non-ACOAs. Women attended a large university in the southeastern United States. Participants categorized as ACOA on the Children of Alcoholics Screen Test (CAST; ) reported significantly more negative affect and less support from their fathers as indicated on the Parental Attachment Questionnaire (). When results were examined by the gender of the alcohol-abusing parent, participants who suspected their fathers were problem drinkers did not differ from non-ACOAs in their attachment to either parent. As compared to non-ACOAs, women who self-identified as daughters of problem-drinking mothers reported poorer attachment both to mothers and fathers.     

Comparative examination of adsorption of serum proteins on HSA- and PLGA-based nanoparticles using SDS–PAGE and LC–MS

The behavior of nanosized drug carrier systems under cell culture conditions and therefore also the destiny in the body are highly influenced by the protein corona, which is formed upon entering a biological environment. Some of the adsorbed proteins, named opsonins, lead to a shortened plasma circulation half-life of the nanoparticles. Others are attributed to promote the transport of nanoparticles into other compartments of the body, just to mention two examples. Hence, detailed knowledge concerning the composition of the protein corona is of great importance. The aim of this work was to investigate the influence of the nanoparticle starting material and the surface modification on the composition of the adsorbed serum proteins in a cell culture environment. Therefore, positively charged nanoparticles based on the biodegradable polymer poly(dl-lactide-co-glycolide) (PLGA) stabilized with didodecyldimethylammonium bromide (DMAB) and negatively charged nanoparticles based on human serum albumin (HSA) were prepared and modified with hydrophilic polymers. By incubating the nanoparticles with fetal bovine serum (FBS) the adsorption of serum proteins on the colloidal system was investigated. Using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS–PAGE) a semi-quantitative analysis of the protein corona was performed and after enzymatic in-solution-digestion the adsorbed proteins were identified using high resolution LC–MS. Our study accentuates the influence of the core material, surface charge, and surface modification on the amount and nature of the adsorbed proteins. The combination of SDS–PAGE and LC–MS turns out to be a simple and reliable method to investigate the protein corona of nanoparticles.     

Pharmacokinetic–Pharmacodynamic Modeling of the Effectiveness and Safety of Buprenorphine and Fentanyl in Rats

Objective Respiratory depression is a serious and potentially life-threatening side-effect of opioid therapy. The objective of this investigation was to characterize the relationship between buprenorphine or fentanyl exposure and the effectiveness and safety outcome in rats. Methods Data on the time course of the antinociceptive and respiratory depressant effect were analyzed on the basis of population logistic regression PK–PD models using non-linear mixed effects modeling software (NONMEM). The pharmacokinetics of buprenorphine and fentanyl were described by a three- and two-compartment model, respectively. A logistic regression model (linear logit model) was used to characterize the relationship between drug exposure and the binary effectiveness and safety outcome. Results For buprenorphine, the odds ratios (OR) were 28.5 (95% CI, 6.9–50.1) and 2.10 (95% CI, 0.71–3.49) for the antinociceptive and respiratory depressant effect, respectively. For fentanyl these odds ratios were 3.03 (95% CI, 1.87–4.21) and 2.54 (95% CI, 1.26–3.82), respectively. Conclusion The calculated safety index (OR_{antinociception}/OR_{respiratory depression}) for fentanyl of 1.20 suggests that fentanyl has a low safety margin, implicating that fentanyl needs to be titrated with caution. For buprenorphine the safety index is 13.54 suggesting that buprenorphine is a relatively safe opioid.     

Physical–chemical characterization of binary and ternary systems of ketoprofen with cyclodextrins and phospholipids

Binary and ternary interaction products of ketoprofen (an anti-inflammatory drug very poorly water soluble) with phospholipids (phosphatidylcholine (EPC3) and phosphatidylglycerol (EPG)) and cyclodextrins (β-cyclodextrin and its methylated derivative (MeβCd)), were prepared to evaluate their ability in improving drug dissolution properties. The different binary and ternary drug–carrier(s) systems were obtained by microwave irradiation, in order to investigate the effectiveness of such a newly proposed preparation technology in bringing about effective solid-state interactions among the components. The effect of different experimental conditions such as microwave irradiation power (500 and 750 W) and treatment time (5, 10 and 15 min) on the physicochemical properties of the products has been also assessed. All solid systems were characterized by differential scanning calorimetry (DSC) analysis, supported by X-ray powder diffractometry, and examined for dissolution properties. The study pointed out the better performance of ternary systems than the binary ones and allowed selection of the best drug–phospholipid–Cd combination and of the most effective preparation conditions. In particular drug–EPC3–MeβCd ternary systems obtained by using the greatest microwave irradiation energy and the longest treatment time exhibited complete drug amorphization and allowed achievement after 60 min of almost 80% dissolved drug, with an increase in dissolution efficiency of 10.7 and 1.4 times in comparison with drug alone and the corresponding drug–Cd binary system, respectively. The synergistic effect between cyclodextrin and phospholipid in enhancing the drug dissolution properties has been attributed to the combination of the surfactant properties of phospholipids and the wetting and solubilizing power of cyclodextrins and/or the possible formation of a “multicomponent” complex.     

Preparation and in vivo evaluation of anti-plasmodial properties of artemisinin-loaded PCL–PEG–PCL nanoparticles

Abstract

Purpose: Artemisinin (ART) has anti-inflammatory, antimicrobial, antioxidant, anti-amyloid, and anti-malarial effects, but its application is limited due to its low water solubility and poor oral bioavailability. In this study, the bioavailability, water solubility, and anti-plasmodial property of ART were improved by PCL–PEG–PCL tri-block copolymers.

Methods: The structure of the copolymers was characterized by ¹H NMR, FT-IR, DSC, and GPC techniques. ART was encapsulated within micelles by a single-step nano-precipitation method, leading to the formation of ART-loaded PCL–PEG–PCL micelles. The obtained micelles were characterized by dynamic light scattering (DLS) and atomic force microscopy (AFM). The in vivo anti-plasmodial activity of ART-loaded micelles was measured against Plasmodium berghei infected Swiss albino mice.

Results: The results showed that the zeta potential of ART-loaded micelles was about ?8.37?mV and the average size was 91.87?nm. ART was encapsulated into PCL–PEG–PCL micelles with a loading capacity of 19.33?±?0.015% and encapsulation efficacy of 87.21?±?3.32%. In vivo anti-plasmodial results against P. berghei showed that multiple injections of ART-loaded micelles could prolong the circulation time and increase the therapeutic efficacy of ART.

Conclusion: These results suggested that PCL–PEG–PCL micelles would be a potential carrier for ART for the treatment of malaria.     

Polymer–drug interactions and wetting of solid dispersions

We demonstrate the ability of drugs to influence the wetting of solid dispersion tablets in unexpected ways. Five model drugs of different water solubility and ability to interact with the involved polymers were incorporated in hydrophilic polymer matrices, made of either hydroxypropyl methylcellulose (HPMC) or polyvinyl pyrrolidone (PVP). The physical mixtures of all combinations of drug and polymer presented surface hydrophobicities, as measured by the equilibrium advancing contact angle of water, which are expected for materials that do not influence the interactions of each other with water. However, the solid dispersions containing HPMC deviated from this regular behaviour and displayed contact angles below those of the pure compounds involved, either drug or polymer. This behaviour is explained by changed surface exposure of HPMC side groups, as a result of changes in intermolecular hydrogen bonds. In addition to water contact angle measurements, we employed NMR imaging to monitor the time course of water ingress and swelling.     

Polymorphisms of IL–13 and IL–4–IL–13–SNPs in patients with penicillins allergy

Objective: Although IL–4 and IL–13 share many biologic activities, IL–13manifests some unique activities. We genotype the IL–13 and IL–4–IL–13–SNPs genes for polymorphisms that could then be used to determine associations with IgE regulation as well as levels of IL–4 and IL–13. Methods: Eight kinds of specific IgE to penicillins were determined with radioallergosobent test (RAST) in the sera of 158 patients with penicillins allergy and 89 healthy subjects. Serum levels of IL–4 and IL–13 were measured by using enzyme-linked immunosorbent assay (ELISA). The IL–13Arg130Gln, IL–4–IL–13–SNP3 and IL–4–IL13–SNP4 genotyping were carried out by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. Results: Among patients with positive specific IgE, significant differences of IL–4–IL–13–SNP3 and IL–4–IL–13–SNP4 genotypes were observed between patients with positive BPA and control group (P<0.05, P<0.05). Additionally, we also found significant difference in IL–4–IL–13–SNP4 genotype between positive and negative BPA–IgE patients (P<0.05). However, we found no significant differences in the prevalence of these polymorphisms between any group studied (IR and NIR, shock and urticaria, etc.) and control group. The same was true between levels of IL–4 and IL–13, and any of genotypes. Conclusion: These data suggests that IL–4–IL–13–SNP genes between IL–4 and IL–13 play a role in regulation of specific IgE levels in patients with penicillins allergy.     

Screening and confirmation methods of the major urinary metabolite of finasteride–carboxy-finasteride by liquid chromatography–mass spectrometry and liquid chromatography–tandem mass spectrometry

Screening and confirmation methods of the major urinary metabolite of finasteride–carboxy-finasteride for doping control purpose were developed. Liquid–liquid extraction was adopted for the sample preparation. Analytes were detected by positive electrospray ionization in single quadrupole and triple quadrupole mass spectrometer. In the screening method, selected ion monitoring (SIM) mode was used to monitor m/z 403 for carboxy-finasteride. In the confirmation method, product ion mode was used to monitor the precursor ion m/z 403. The limit of detection was below 2 ng/mL for the screening method. Good linearity was obtained in the range 10.0–500.0 ng/mL. The intra-run and inter-run precision calculated from quality control (QC) samples was less than 5.3%. The accuracy as determined from QC samples was within ±6.6%. The screening method was applied for the analysis of excretion samples, allowing the detection of carboxy-finasteride for up to 49 h in urine specimen collected after an oral administration of 5 mg of finasteride.     

Terpenes and the Lipid–Protein–Partitioning Theory of Skin Penetration Enhancement

A series of terpenes has been assessed as skin penetration enhancers towards the model polar penetrant 5-fluorouracil (5-FU). Cyclic terpenes were selected from the chemical classes of hydrocarbons (e.g., -pinene), alcohols (e.g., -terpineol), ketones (e.g., carvone), and oxides (e.g., 1,8-cineole, ascaridole). Permeation experiments were performed on excised human epidermal membranes and the terpenes varied in their activities; -pinene only doubled the permeability coefficient of aqueous 5-FU, whereas 1,8-cineole caused a near 95-fold increase. Essential oils, e.g., chenopodium (70% ascaridole), were less effective than the corresponding isolated terpenes. 5-FU is less soluble in the terpenes than in water, and the terpenes did not exert their action by increasing partitioning of the drug into the membranes as illustrated by stratum corneum:water partitioning studies. The penetration enhancers increased drug diffusivity through the membranes, an effect which correlated empirically with the enhancer activities. The principal mode of action of these accelerants may be described by the lipid–protein–partitioning theory; the terpenes interacted with intercellular stratum corneum lipids to increase diffusivity, and the accelerant effects were not due to partitioning phenomena. Keratin interaction was assumed negligible.     

Analysis of the constituents of aqueous preparations of Stachys recta by HPLC–DAD and HPLC–ESI-MS

In the present study a method based on liquid chromatography with diode array detection (HPLC/DAD) coupled to an electrospray ionization (ESI) interface for the simultaneous determination of phenolic constituents in three aqueous preparations of the herbal medicinal drug Stachys recta. The developed assay was simple and effective and permitted the quality control of S. recta decoctions and infusion. Overall, 30 constituents were detected and identified, belonging mainly to three classes of compounds: caffeoylquinic acids, phenylethanol glycosides and flavonoids. 15 of them were quantified having a lower limit not less than 0.02% of the lyophilized extracts. Only seven of them were previously reported in this species, while 23 were identified for the first time as constituents of S. recta. HPLC–DAD–ESI-MS analysis provided evidence for the certain identification of the main constituents and in some cases of their isomers. Eight constituents were isolated and their structure elucidated by HPLC–ESI-MS and 1D- and 2D-NMR spectroscopy. Among the investigated preparations, the infusion seems to be the best method to extract the native constituents of the plant, while decoction is a more aggressive treatment and causes partial degradation of some acylated flavonoids.     

History of knowledge and evolution of occupational health and regulatory aspects of asbestos exposure science: 1900–1975

The understanding by industrial hygienists of the hazards of asbestos and appropriate ways to characterize and control exposure has evolved over the years. Here, a detailed analysis of the evolution of industrial hygiene practices regarding asbestos and its health risks, from the early 1900s until the advent of the national occupational health and safety regulatory structure currently in place in the US (early-to-mid 1970s) is presented. While industrial hygienists recognized in the early 1900s that chronic and high-level exposures to airborne concentrations of asbestos could pose a serious health hazard, it was not until the mid-1950s that the carcinogenic nature of asbestos began to be characterized and widespread concern followed. With the introduction of the membrane filter sampling method in the late 1960s and early 1970s, asbestos sampling and exposure assessment capabilities advanced to a degree which allowed industrial hygienists to more precisely characterize the exposure–response relationship. The ability of industrial hygienists, analytical chemists, toxicologists, and physicians to more accurately define this relationship was instrumental to the scientific community’s ability to establish Occupational Exposure Levels (OELs) for asbestos. These early developments set the stage for decades of additional study on asbestos exposure potential and risk of disease. This was followed by the application of engineering controls and improved respiratory protection which, over the years, saved thousands of lives. This paper represents a state-of-the-art review of the knowledge of asbestos within the industrial hygiene community from about 1900 to 1975.     

Acid–base equilibria and solubility of loratadine and desloratadine in water and micellar media

Acid–base equilibria in homogeneous and heterogeneous systems of two antihistaminics, loratadine and desloratadine were studied spectrophotometrically in Britton–Robinson’s buffer at 25 °C. Acidity constant of loratadine was found to be pK_a 5.25 and those of desloratadine pK_a1 4.41 and pK_a2 9.97. The values of intrinsic solubilities of loratadine and desloratadine were 8.65 × 10⁻⁶ M and 3.82 × 10⁻⁴ M, respectively. Based on the pK_a values and intrinsic solubilities, solubility curves of these two drugs as a function of pH were calculated. The effects of anionic, cationic and non-ionic surfactants applied in the concentration exceeding critical micelle concentration (cmc) on acid–base properties of loratadine and desloratadine, as well as on intrinsic solubility of loratadine were also examined. The results revealed a shift of pK_a values in micellar media comparing to the values obtained in water. These shifts (ΔpK_a) ranged from −2.24 to +1.24.     

Theoretical and Practical Approaches for Prediction of Drug–Polymer Miscibility and Solubility

Purpose Crystallization of drugs formulated in the amorphous form may lead to reduced apparent solubility, decreased rate of dissolution and bioavailability and compromise the physical integrity of the solid dosage form. The purpose of this work was to develop thermodynamic approaches, both practical and theoretical, that will yield a better understanding of which factors are most important for determining the ability of polymers to stabilize amorphous active pharmaceutical ingredients (API).Materials and Methods Lattice based solution models were used to examine miscibility criteria in API-polymer blends. Different methods were used to estimate the Flory‐Huggins interaction parameter for model API-polymer systems consisting of felodipine or nifedipine with poly(vinylpyrrolidone) (PVP). These were melting point depression and determination of solubility parameters using group contribution theory. The temperature and enthalpy of fusion of crystalline API alone and the fusion temperature of the API in the presence of the polymer were measured by differential scanning calorimetry. The resultant thermal data were used to estimate the reduced driving force for crystallization and the solubility of the API in the polymer.Results Flory‐Huggins theory predicts that, for typical API-polymer systems, the entropy of mixing is always favorable and should be relatively constant. Due to the favorable entropy of mixing, miscibility can still be achieved in systems with a certain extent of unfavorable enthalpic interactions. For the model systems, interaction parameters derived from melting point depression were negative indicating that mixing was exothermic. Using these interaction parameters and Flory‐Huggins theory, miscibility was predicted for all compositions, in agreement with experimental data. A model was developed to estimate the solubility of the API in the polymer. The estimated solubility of the model APIs in PVP is low suggesting that kinetic rather than thermodynamic stabilization plays a significant role in inhibiting crystallization.Conclusions The thermodynamics of API-polymer systems can be modeled using solution based theories. Such models can contribute towards providing an understanding of the compatibility between API and polymer and the mechanisms of physical stabilization in such systems.     

The Effects of pH and PEG 400–Water Cosolvents on Oxytetracycline–Magnesium Complex Formation and Stability

The effects of pH and PEG 400 on the stoichiometry, conformation, and stability of the magnesium–oxytetracycline (Mg⁺²–OTC) complex were evaluated. Circular dichroism (CD) and HPLC were used to investigate Mg⁺²–OTC complex formation and determine the stability of the complexes formed. The stoichiometry of the complex was determined to be a 1:1 molar ratio of Mg⁺² to OTC regardless of changes in pH, in the range 7–10, and regardless of the percentage of polyethylene glycol (PEG) 400 in solution. CD showed that the conformation assumed by Mg⁺²–OTC complex is sensitive to changes in pH, however, little to no effect was found when the PEG 400 concentration was varied. PEG 400 was found to effect the magnitude of complexation as evident by the dependence of CD peak intensity on the cosolvent concentration in solution. The Job's method confirmed that the formation of this complex increased with increasing PEG 400 concentration and was most favored at pH 8. HPLC analyses of OTC solutions at pH 9 revealed the formation of multiple degradation products after storage at 50°C. The incidence and magnitude of OTC degradation products were reduced in the presence of Mg⁺² and PEG 400. Despite the HPLC results of maintained OTC stability in magnesium-complexed solutions over time, visual inspection showed these solutions to have darkened, indicating that an oxidative process is responsible for initial degradation of OTC. Therefore, the need for additional measures (i.e., antioxidants) was established to ensure the long-term stability of OTC in solution.     

Determination of tramadol and metabolites by HPLC-FL and HPLC–MS/MS in urine of dogs

Tramadol is a centrally acting analgesic drug used in veterinary and human clinical practice. Its metabolism has been largely characterized in human being but is still long to be comprehended in several animal species, especially in the dog. The aim of the present study was to develop and validate a new analytical procedure to investigate HPLC the metabolization/elimination process tramadol in urine of dogs by HPLC-FL or HPLC–MS/MS. A single oral dose of tramadol (4 mg/kg) was administered to 4 male Beagle dogs and the urine was naturally collected. This matrix either hydrolyzed than un-hydrolyzed was extracted with different blends of solvents to detect the total or free form of the analytes, respectively.     

Influence of continuous veno–venous haemodiafiltration and continuous veno–venous haemofiltration on the pharmacokinetics of fluconazole

OBJECTIVE: To compare the elimination of fluconazole by continuous veno-venous haemodiafiltration (CVVHD) and continuous veno-venous haemofiltration (CVVH) at different dosages. INTERVENTION: Patients received doses of 400 mg (n=3), 600 mg (n=1) or 800 mg (n=2) fluconazole as a short-time infusion once a day. Patients underwent CVVHD the first day and CVVH the second day. CVVHD and CVVH were performed using an acrylonitrile hollow-fibre filter at a constant blood flow of 90 ml/min and a substitution flow of 1000 ml/h (predilution). During CVVHD, the dialysate flow was 1000 ml/h. Ultrafiltration rates were 1158+/-90.5 ml/h during CVVHD and 1167+/-81.6 ml/h. Serum and ultrafiltrate/dialysate concentrations of fluconazole were determined on nine occasions over 24 h. PARTICIPANTS: Six critically ill patients with acute renal failure (ARF) and serious fungal infection. RESULTS: Extracorporeal clearance (CVVHD 30.5+/-6.0 ml/min, CVVH 17.5+/-4.0 ml/min) and total clearance of fluconazole (CVVHD 37.9+/-4.4 ml/min, CVVH 25.3+/-6.5 ml/min) were significantly higher during CVVHD (P < 0.05). During CVVHD, the sieving coefficient (S(CVVHD)) was 0.88 (range 0.54-1) and the elimination half-life (t1/2) was 14.8-35.1 h. During CVVH, the S(CVVH) was 0.96 (range 0.56-1.02) and t1/2 was 24.0-51.6 h. CONCLUSIONS: A daily dosage of 400-800 mg fluconazole is recommended in the treatment of life-threatening fungal infections in critically ill patients undergoing CVVHD since the clearance of CVVHD may considerably exceed the clearance in patients with normal renal function, which is about 20 ml/min. Drug monitoring is highly recommended for these patients.