Cobalt-assisted route to rare carbocyclic C-ribonucleosides.

(Re)emerging RNA viruses have been major threats to public health in the past years, and from the few drugs available, nucleoside analogues are still at the cornerstone of the antiviral therapy. Among them, the synthesis of carbocyclic C-nucleosides is suffering from long syntheses and poor yields. Herein we report a concise stereoselective synthesis of rare carbocyclic C-nucleosides (11a-l) bearing non-canonical nucleobases through a cobalt-assisted-route as key step starting from the optically pure (-)-cyclopentenone 1. This approach paves the route for novel carbocyclic C-nucleoside discovery.

Synthesis of a molecularly imprinted polymer to isolate glucosamine from plant extracts by an ionic-non-covalent dual approach.

OBJECTIVE: The objective of this study was to synthesize a novel glucosamine-imprinted sorbent based on ionic and non-covalent dual approach to purify glucosamine from chicory root extracts. METHODS: The synthesis of the molecularly imprinted polymer was optimized in terms of choice of monomers, porogen, cross-linker and initiator to have the best recognition as possible for targeted molecule. The sorbent obtained was characterized by nitrogen sorption (BET), scanning electron microscopy (SEM) and solid-phase extraction (SPE) to plot adsorption isotherms. The selectivity of polymer between glucosamine and interfering salt as ammonium sulphate was calculated. Extraction procedure was optimized in terms of loading, washing and elution solvents, to have the best recovery of glucosamine. Compounds were analysed by HPLC-UV after chemical derivatization. RESULTS: The results showed that the optimal conditions of extracting glucosamine on this new type of sorbent were as follows: percolation of plant extract in EtOH/aqueous HCl pH 3, washing of cartridge with water and elution of compound of interest with aqueous acetic acid solution at 5%. The recoveries of glucosamine were around 53% and 70%, from aqueous standard solution and aqueous chicory roots extracts, respectively, on the molecularly imprinted polymer. And, only 11% and 7% of the ammonium sulphate were recovered from standard solution and chicory roots extract, respectively. CONCLUSION: The use of the MIP as solid-phase extraction sorbent was able to extract preferentially glucosamine from structural analogues and ammonium salt. Assays on chicory roots extracts were carried out, and the MIP showed good results allowing the transfer methodology at semi-industrial scale for cosmetic companies. The optimized protocol of extraction of glucosamine allowed using only eco-friendly solvents, as ethanol, water and acetic acid.

Application of drug repositioning strategy to TOFISOPAM.

Drug repositioning strategy is an interesting approach for pharmaceutical companies; especially to increase their productivity. SELNERGY(tm) is a reverse docking based-program able to virtually screen thousands of compounds on more than 2000 3D biological targets. This program was successfully applied to tofisopam and revealed that the isomers of tofisopam are able to fit with phosphodiesterase 4. This old drug was used as a racemic mixture to treat anxiety in the eighties and was recently shown to act as a PDE4 inhibitor. Thanks to this strategy we demonstrated that tofisopam acts via the inhibition of PDE4 in the submicromolar range. Moreover, we firstly showed that the S-enantiomer of tofisopam is ten times more active than R-enantiomer. The identification of the biochemical mechanism of tofisopam isomers now allows to reposition this drug in new therapeutic indications where modulation of cAMP via PDE4 inhibitors are possible.

Quantitative measurement of propofol and in main glucuroconjugate metabolites in human plasma using solid phase extraction-liquid chromatography-tandem mass spectrometry.

A high-performance liquid chromatographic method coupled with tandem mass spectrometry detection has been developed for the determination of propofol and its main glucuroconjugate metabolites (propofol-glucuronide (PG), 1-quinol-glucuronide (1-QG) and 4-quinol-glucuronide (4-QG) in human plasma. All compounds were extracted with a single solid phase extraction procedure using Max Oasis cartridges. Propofol and thymol (internal standard) were analyzed using a C8 reversed-phase column with a mobile phase consisting of methanol-water (75:25, v/v) containing 0.025% NH(4)OH. Chromatography of glucuroconjugate metabolites and phenyl-beta-d-glucuronide (internal standard) was performed using a hydrophilic interaction liquid chromatography (HILIC) and a mixture of acetonitrile/water/ammonium acetate buffer (100 mM, pH 5, 87/1/12, v/v/v). Both chromatographic separations were achieved in isocratic mode allowing a rapid analysis without re-equilibration of the phase. The method is specific and sensitive with a range of 10-1500 ng mL(-1) for propofol and 1-QG, 20-3000 ng mL(-1) for PG and 25-3750 ng mL(-1) for 4-QG. The regression curves were linear for all compounds. The method is accurate and precise with intra-assay and inter-assay precision <8% and bias < or =6% for all compounds. This assay has allowed the successful measurement of propofol and its main glucuroconjugate metabolites in human plasma from 24 patients undergoing anaesthesia for elective partial hepatectomy surgery.

Characterisation of iota-carrageenans oligosaccharides with high-performance liquid chromatography coupled with evaporative light scattering detection.

Enzymatically digested oligo-iota-carrageenans were separated with liquid chromatography, coupled to evaporative light scattering detection. As expected, compared to oligo-kappa-carrageenans, the additional sulphate group in the neocarrabiose unit of iota-carrageenans significantly modified the separation mechanisms on ion-exchange chromatography, porous graphitic carbon and ion-pair chromatography. The oligomers were then isolated and characterised off-line with electrospray ionisation mass spectrometry in positive-ion mode. The tetrasaccharide, hexasaccharide and octasaccharide that were identified were associated with protonated heptylamine molecules whose number depended on the number of sulphate groups.

Simple and rapid high-performance liquid chromatographic method for nelfinavir, M8 nelfinavir metabolite, ritonavir and saquinavir assay in plasma.

A simple reversed-phase liquid chromatographic method has been developed to determine protease inhibitors concentrations in plasma. Plasma samples (250 micro l) containing protease inhibitors were prepared by a simple deproteinization (recovery: 92, 91, 91 and 90.5% for ritonavir, saquinavir, nelfinavir and M8 nelfinavir metabolite, respectively). Chromatography was accomplished using a Hypersil octadecylsilyl column (100 x 4.6 mm I.D.) and a mobile phase composed of acetonitrile, tetrahydrofuran and dihydrogenophosphate buffer (pH 4) (32:10:58, v/v). Ultraviolet detection at 210 nm was used. The limit of detection was 200 ng/ml for ritonavir, saquinavir, nelfinavir and M8 nelfinavir metabolite. Calibration curves were linear up to 20000 ng/ml, with correlation coefficients better than 0.997 for all compounds. Intra- and inter-day coefficients of variation of the assay were

Propofol metabolites in man following propofol induction and maintenance.

BACKGROUND: The pharmacokinetics of propofol in man is characterized by a rapid metabolic clearance linked to glucuronidation of the parent drug to form the propofol-glucuronide (PG) and sulfo- and glucuro-conjugation of hydroxylated metabolite via cytochrome P450 to produce three other conjugates. The purpose of this study was to assess the urine metabolite profile of propofol following i.v. propofol anaesthesia in a Caucasian population. METHODS: The extent of phase I and phase II metabolism of propofol was studied in 18 female and 17 male patients after an anaesthesia induced and maintained for at least 4 h with propofol. The infusion rates (mg kg(-1) h(-1)) of propofol were (mean (SD)) 4.1 (1.0) and 4.5 (1.3) for males and females, respectively. Urine was collected from each patient for the periods 0-4, 4-8, 8-12, and 12-24 h after the start of propofol administration. In a preliminary study, the three main glucuro-conjugated metabolites were isolated from urine and characterized by magnetic resonance spectroscopy. The quantification of these metabolites for the different collection periods was then performed by a HPLC-UV assay. RESULTS: Total recovery of propofol in the metabolites studied amounts to 38%, of which 62% was via the PG metabolite and 38% via cytochrome P-450. This percentage is significantly higher than that previously reported from patients after a bolus dose of propofol. Extreme values for PG (0-24 h period) were included from 73 to 49%. There was no significant difference between female and male patients in the metabolite ratio. CONCLUSIONS: We conclude that the extent of hydroxylation in propofol metabolism was higher than in previous findings after administration of anaesthetic doses of propofol. Moreover, the ratio between hydroxylation and glucuronidation of propofol is subject to an inter-patient variability but this does not correlate with the dose of propofol. However, the variation of the metabolite profile observed in the present report does not seem to indicate an extended role of metabolism in pharmacokinetic variability.

Comparison of ceftazidime degradation in glass bottles and plastic bags under various conditions.

OBJECTIVE: To study the effect of type of container on ceftazidime stability in intravenous solutions. METHODS: One hundred millilitre polypropylene (PP) and polyvinyl chloride (PVC) bags and 100-mL glass bottles were filled with 5% dextrose or 0.9% sodium chloride solutions containing ceftazidime (Fortumset) at 40 mg/mL. Three containers of each solution were stored at 20 and 35 degrees C. One millilitre samples were drawn from each container at 0 and 20 h and assayed. Pyridine concentrations, the main degradation product of ceftazidime, were determined by high-pressure liquid chromatography. RESULTS: Pyridine levels increased during storage and were higher in PVC and PP bags than in glass bottles in both diluents. Solutions stored in PP bags showed better stability than in PVC bags. CONCLUSION: This study shows that ceftazidime undergoes slower degradation in PP than PVC containers although the difference is small. Glass bottles seems to be the better container for storing ceftazidime solutions, whatever storage temperature and diluent used.

Fortum stability in different disposable infusion devices by pyridine assay.

The stability of ceftazidime in 5% dextrose injection and 0.9% sodium chloride injection when stored in a different disposable infusion device was determined. Solutions of ceftazidime 40 mg/ml were used to fill the drug administration devices. Stability was determined for both 5% dextrose injection and 0.9% sodium chloride injection solutions at 37 degrees C in four disposable infusion devices. Ceftazidime and its mean degradation product, pyridine, were simultaneously assayed in triplicate by a stability-indicating high-performance liquid chromatographic (HPLC) method. This method was simple, sensitive (limit of quantitation (LOQ), 2 ng injected for both compounds), rapid (run time was 7 min) and precise (mean recovery was 100.5+/-2.9 and 103.6+/-1.9% for pyridine and ceftazidime, respectively). The ceftazidime stability in the 5% dextrose solution was lower than in the 0.9% sodium chloride solution. When stored at 37 degrees C in a disposable infusion device, the stability of the ceftazidime is included in large hourly range, depending strongly on the manufacturer. The stability of ceftazidime exceed 19 h in none studied cases. The pyridine formed in 24 h was in the range of 100-400 mg depending on devices and infusions.

Stability of sufentanil in human plasma samples.

The stability of sufentanil in human plasma kept under various storage conditions was investigated. Extraction was performed using solid phase extraction with new mixed-mode cation exchange Oasis MCX columns; quantification was carried out using gas chromatography equipped with a mass spectrometry detector. When plasma was left at 4 degrees C in nonsilanized tubes, concentrations of sufentanil decreased significantly during the first hour. In plasma samples kept at -25 degrees C for 8 hours in nonsilanized glass tubes, a significant decrease of sufentanil concentrations was found, with an average loss of 10.1% of the initial concentration. A significant decrease occurred when plasma was kept in silanized glass tubes for 12 hours at -25 degrees C. The current study emphasizes the importance of sampling and storage conditions for an accurate determination of sufentanil concentration in plasma.

New sensitive assay of vancomycin in human plasma using high-performance liquid chromatography and electrochemical detection.

A method using reversed-phase high-performance liquid chromatography with electrochemical detection for the analysis of vancomycin in human plasma was developed. Chromatographic conditions included an octadecyl column, a mobile phase of acetonitrile-sodium phosphate buffer (pH 7) (12:88), a total run time of 12 min, and coulometric electrochemical detection at +700 mV. Linear detector response was found in the range 5-100 microg ml(-1) after a 1:80 dilution or from 0.5 to 50 microg ml(-1) after a 1:20 dilution of the samples. In both cases the correlation coefficient (r) of the calibration curve standard was better than 0.995. Vancomycin determination was based on a denaturation of plasma proteins with methanol, then a dilution with mobile phase was performed. Recovery of vancomycin from plasma was 103.1+/-3.9%, and no interference from commonly used drugs or endogenous compounds was observed. A significant correlation was shown with the EMIT assay (r=0.92, P<0.001) using clinical samples from children. This HPLC technique is simple, sensitive, rapid, precise, selective and requires only 100 microl of plasma for completion.

Detection of new propofol metabolites in human urine using gas chromatography/mass spectrometry and liquid chromatography/mass spectrometry techniques.

Using hyphenated analytical techniques, gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS), a study on minor propofol metabolites in human urine was conducted. These techniques allowed identification of two new phase I metabolites (2-(omega-propanol)-6-isopropylphenol and 2-(omega-propanol)-6-isopropyl-1,4-quinol). In addition, their four corresponding conjugates (three glucuronides and one sulphate) were detected. Thus in human urine at least eight conjugate metabolites are produced, derived from four different aglycones (propofol; 2, 6-diisopropyl-1,4-quinol; 2-(omega-propanol)-6-isopropylphenol and 2-(omega-propanol)-6-isopropyl-1,4-quinol).

High-performance liquid chromatographic assay to detect hydroxylate and conjugate metabolites of propofol in human urine.

This paper describes a HPLC method for the simultaneous detection of phase I (2,6-diisopropyl-1-4-quinol and 2,6-diisopropyl-1-4-quinone) and phase II (4-(2,6-diisopropyl-1-4-quinol)-sulphate, 1-(2,6-diisopropyl-1-4-quinol)-glucuronide, 4-(2,6-diisopropyl-1-4-quinol)-glucuronide, and propofol-glucuronide) metabolites of propofol in human urine samples. Separation was based on a simple mobile phase and a reversed-phase chromatographic column. Metabolite identification was performed by UV spectrum on a diode-array detector and by LC-APCI-MS. The identification was also carried out using in vitro incubation mixtures (cytosol and microsomes prepared from liver) from several species: human, rat and rabbit. This assay was performed using UV, fluorescence and electrochemical detection modes. Each of these was analyzed and discussed.

[Pharmacologic prevention of Mendelson syndrome. A controlled clinical trial]. / Prevenzione farmacologica della sindrome di Mendelson. Studio clinico controllato.

This controlled study considers the effect of ranitidine, both alone and in association with metoclopramide, on the acidity and volume of the gastric content of 75 patients requiring caesarean section. Ranitidine, when used alone (50 mg intravenously 30-60 minutes before the operation) significantly reduced (p less than 0.01) the acidity (pH greater than 2.5) and the volume (less than 25 ml) of the gastric content of the patient thus treated. Ranitidine in association with metoclopramide may also reduce the pH and the volume, but did not show any significant statistical differences when compared with the use of ranitidine alone.

[Possible effects of pharmacologic prophylaxis for Mendelson's syndrome on newborns]. / Ricerca sul neonato di eventuali effetti della profilassi farmacologica della sindrome di Mendelson.

Forty-eight newborn infants whose mothers underwent both elective and urgent caesarean section were studied. Mothers were randomly assigned to one of the treatment groups for the prophylaxis of Aspiration Pneumonitis: group A was treated with ranitidine, 50 mg i.v.; group B with ranitidine, 50 mg, and metoclopramide, 10 mg i.v.; group C no medication. Neonatal assessment included Apgar score and various haematological laboratory tests: haemogasanalysis, glycemia, electrolites, hematocrit, hemoglobin, bilirubinemia, SGOT, SGPT. Nor clinical or statistic differences were noted among the three infant groups.

[Atracurium, vecuronium and pancuronium. Results of a polygraphic study]. / Atracurio, vecuronio e pancuronio. Risultati di uno studio poligrafico.

The Authors have studied three nondepolarizing muscle relaxants widely used: pancuronium v/s atracurium and vecuronium. The Train of Four was used to detect the magnitude of the neuromuscular blockade. The intubation follows 90 minutes after administration of the drugs and for each patient the Authors valued: 1) the T1 and TR values at intubation; 2) the onset-time; 3) the duration of neuromuscular blockade; 4) the recovery time. Furthermore, the degree of neuromuscular blockade was clinically checked both at the time of induction and at recovery. The results of the present study show, in accordance with the literature, that all three drugs tested are capable of obtaining complete muscle relaxation. Atracurium and vecuronium particularly allow an adequate intubation at the adopted doses (0.6 mg/kg and 0.1 mg/kg respectively) with a relatively short onset-time (medium values 136" in the group of atracurium and 146" in the group of vecuronium) and a restoration time faster than pancuronium.