Enteric solid dispersion of cyclosporin A (CyA) having potential to improve availability of CyA in rabbit

The availability of cyclosporin A (CyA) administered as an enteric solid dispersion preparation of which the composition is CyA:HCO-60:HP-55 = 1:2:8 was evaluated in rabbits. The additives are surfactant (polyoxyethylated, 60 mumol, castor oil derivative, HCO-60) and enteric coating material (hydroxypropylmethyl cellulose phthalate, HP-55), which are generally used as pharmaceutical additives. Both the systemic and lymphatic availabilities of CyA from this solid preparation were measured in rabbits after intrastomach administration, 7 mg CyA/kg, and were compared with those from conventional oily solution, Sandimmun. The mean systemic availability of CyA from the solid preparation was 57% which is about 1.5 times greater than that obtained from Sandimmun. The amounts of CyA transferred into the thoracic lymphatics within 12 h from solid dosage form and Sandimmun are 0.62 +/- 0.16(S.D.)% and 0.13 +/- 0.05% of the administered CyA dose. These results support the usefulness of the new solid dosage form of CyA.     

Molecular weight determination of hypromellose phthalate (HPMCP) using size exclusion chromatography with a multi-angle laser light scattering detector

The molecular weight of hypromellose phthalate (HPMCP), a polymer used for enteric coating, was determined using size exclusion chromatography with a multi-angle laser light scattering detector. The values of weight-average molecular weight (Mw) of commercially available grades (HP-55, HP-55S, and HP-50) were 45600, 60200, and 37900, respectively. Their inter-day precisions expressed in terms of the coefficient of variation were less than 3%. A correlation curve between Mw and solution viscosity was prepared so that Mw could be easily estimated from the solution viscosity measured by the compendial method.     

Determination of amifloxacin and two of its principal metabolites in plasma and urine by high-performance liquid chromatography using automated column switching

The automated determination of amifloxacin and two of its principal metabolites in human plasma and urine by column-switching high-performance liquid chromatography is described. Plasma or urine samples, diluted 1:1 with 0.5 M sodium citrate buffer pH 2.5, were directly injected onto a cation-exchange pre-column. Following a 2.0-min wash of the pre-column with water at a flow-rate of 1.1 ml/min, the effluent from the pre-column was directed to the analytical column by a column-switching device. The precision of the plasma and urine methods ranged from a +/- 1.9 to +/- 3.6% for all compounds. The accuracies of the methods were within a range of -3.3% to 6.4% of the nominal values for all compounds. Linear responses were observed for all the standards in the range 0.10-5.0 micrograms/ml for plasma and 0.50-100 micrograms/ml for urine for all three compounds. The minimum quantifiable levels were 0.10 and 0.50 micrograms/ml for plasma and urine, respectively. The analytical methods may be used to quantify amifloxacin and the piperazinyl-N-desmethyl and piperazinyl-N-oxide metabolites in plasma and urine samples obtained from humans, monkeys, dogs and rats.     

Formulation study for lansoprazole fast-disintegrating tablet. I. Effect of compression on dissolution behavior

Lansoprazole fast-disintegrating tablet (LFDT) is a new patient-friendly formulation of lansoprazole. Since lansoprazole is an antiulcer agent and is unstable under acidic conditions, we have developed LFDT as an orally disintegrating tablet containing enteric-coated microgranules. The effect of compression on dissolution behavior was investigated, as compression affected cleavage and crushing of the enteric layer. To decrease cleavage and crushing of the enteric layer, the effects of the combined ratio of methacrylic acid copolymer dispersion to ethyl acrylate-methyl methacrylate copolymer dispersion and the concentration of triethyl citrate on the dissolution in the acid stage and the dissolution in the buffer stage were evaluated. By adjusting the ratio of methacrylic acid copolymer dispersion to ethyl acrylate-methyl methacrylate copolymer dispersion to 9 : 1 and adding a 20% triethyl citrate concentration, sufficient flexibility of the enteric layer and sufficient stability against compression forces were achieved. Agglomeration of enteric-coated microgranules during the coating process was decreased at the optimized concentration of triethyl citrate and glyceryl monostearate. We compared the absorption properties of LFDT and lansoprazole capsules in dogs. The absorption profiles of LFDT were similar to those of lansoprazole capsules.     

An in vitro and in vivo investigation into the suitability of bacterially triggered delivery system for colon targeting

The colon specific drug delivery systems based on polysaccharides; locust bean gum and chitosan in the ratio of 2 : 3, 3 : 2 and 4 : 1 were evaluated using in vitro and in vivo methods. The in vitro studies in pH 6.8 phosphate buffer containing 2% w/v rat caecal contents showed that the cumulative percentage release of mesalazine after 26 h were 31.25+/-0.56, 46.25+/-0.96, 97.5+/-0.26 (mean+/-S.D.), respectively. The in vivo studies conducted in nine healthy male human volunteers for the various formulations revealed that, the drug release was initiated only after 5 h (i.e.) transit time of small intestine and the bioavailability (AUC(0-->t*)) of the drug was found to be 85.24+/-0.10, 196.08+/-0.12, 498.62+/-0.10 microg x h/ml 26 (mean+/-S.D.), respectively. These studies on the polysaccharides demonstrated that the combination of locust bean gum and chitosan as a coating material proved capable of protecting the core tablet containing mesalazine during the condition mimicking mouth to colon transit. In particular, the formulation containing locust bean gum and chitosan in the ratio of 4 : 1 held a better dissolution profile, higher bioavailability and hence a potential carrier for drug targeting to colon.     

High-performance liquid chromatographic analysis of isoxicam in human plasma and urine

A sensitive, selective, and rapid high-performance liquid chromatographic procedure was developed for the determination of isoxicam in human plasma and urine. Acidified plasma or urine were extracted with toluene. Portions of the organic extract were evaporated to dryness, the residue dissolved in tetrahydrofuran (plasma) or acetonitrile (urine) and chromatographed on a mu Bondapak C18 column preceded by a 4-5 cm X 2 mm I.D. column packed with Corasil C18. Quantitation was obtained by UV spectrometry at 320 nm. Linearity in plasma ranged from 0.2 to 10 micrograms/ml. Recoveries from plasma samples seeded with 1.8, 4 and 8 micrograms/ml isoxicam were 1.86 +/- 0.077, 4.10 +/- 0.107 and 8.43 +/- 0.154 micrograms/ml with relative standard deviations of 3.3%, 2.5% and 5.4%, respectively. The linearity in urine ranged from 0.125 to 2 micrograms/ml. The precision of the method was 3.3-9.0% relative standard deviation over the linear range.     

三重串联四级杆气质联用法测定化妆品中的三种邻苯二甲酸酯类增塑剂

建立了一种快速、灵敏、准确的三重串联四级杆气质联用(GC-MS/MS)法,将其用于同时检测化妆品中的三种邻苯二甲酸酯(邻苯二甲酸二丁酯、邻苯二甲酸丁基苄基酯、邻苯二甲酸二乙基己酯)增塑剂.化妆品经甲醇提取,HP-5MS柱分离,采用GC-MS/MS的多反应监测模式,以保留时间和离子对(母离子和子离子)信息比较定性,以母离子和响应值高的子离子进行定量.结果表明,该方法的检出限为12～28ng/g,相对标准偏差为1.6%～7.54%,目标物的加标回收率为86.4%～121.1%;该方法可用于检测日常化妆品中邻苯二甲酸酯的含量.     

Effect of protein binding on the disposition of cephalexin and cefazolin in a simultaneous perfusion system of rat liver and kidney

The effect of protein binding on the disposition of cephalexin (CEX) and cofazolin (CEZ) was investigated in a simultaneous perfusion system of rat liver and kidney. In the present study, we used bovine serum albumin (BSA) or human serum albumin (HSA) as plasma protein to control the degree of perfusate protein binding of drugs. Total clearance (CLt) of CEX perfused with BSA (0.70 +/- 0.27 ml/min) was slightly smaller than that with HSA (0.89 +/- 0.08 ml/min), corresponding to the unbound fraction of the drug in the perfusate plasma. On the other hand, CLt of CEZ perfused with BSA (0.90 +/- 0.20 ml/min) was significantly larger than that with HSA (0.32 +/- 0.10 ml/min). The unbound fraction of CEZ to BSA (0.703 +/- 0.052) was much larger than that to HSA (0.253 +/- 0.017) and the clearance of the unbound drug did not differ significantly between two kinds of albumin perfusate (1.30 +/- 0.40 ml/min for BSA and 1.26 +/- 0.40 ml/min for HSA). These results suggest that plasma protein binding is an important factor determining the biliary clearance as well as the urinary clearance of drugs.     

Simultaneous determination of midazolam and its three hydroxy metabolites in human plasma by electron-capture gas chromatography without derivatization

Electron-capture gas chromatography was carried out to determine midazolam and its three hydroxy metabolites (1-hydroxymethylmidazolam, 4-hydroxymidazolam and 1-hydroxymethyl-4-hydroxymidazolam) in human plasma. The assay involves extraction from plasma, buffered to pH 9.3, into cyclohexane-dichloromethane (6:4) and analysis by gas chromatography. The use of an HP-17 cross-linked, capillary column makes derivatization unnecessary. The sensitivity of the method was 2-3 ng/ml for midazolam, 1-hydroxymethylmidazolam and 4-hydroxymidazolam, and 20 ng/ml for 1-hydroxymethyl-4-hydroxymidazolam. The extraction recovery of midazolam, 1-hydroxymethylmidazolam, 4-hydroxymidazolam and 1-hydroxymethyl-4-hydroxymidazolam was 99.3 +/- 2.4, 67.0 +/- 4.6, 92.7 +/- 4.7 and 28.7 +/- 6.3%, respectively. This gas chromatographic assay was used to assess the concentration-time profiles of midazolam and its metabolites in human plasma after rectal and intravenous administration of midazolam.     

高效液相色谱法测定土壤中6种邻苯二甲酸酯的含量及其生物有效性的评价

取土壤样品10.000g两份,其中一份用10mL甲醇超声提取30min使其所含6种邻苯二甲酸酯(PAEs)[包括邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二乙酯(DEP)、邻苯二甲酸二丁基苄酯(BBP)、邻苯二甲酸二丁酯(DBP)、邻苯二甲酸二(2-乙基)己酯(DEHP)及邻苯二甲酸二辛酯(DNOP)]溶于甲醇中。于提取液中加入硫酸镁和氯化钠,离心3 min。取上清液,定容至10.0mL。经0.45μm滤膜过滤,取滤液按色谱条件进行测定。以Zorbax Eclipse C18色谱柱为固定相,以不同比例的乙腈(A)和水(B)的混合液为流动相进行梯度洗脱,并用紫外检测器于245nm处测定。上述6种PAEs的质量浓度均在0.10~10.0mg·L^-1内与其对应的色谱峰面积呈线性关系,检出限在0.01~0.04mg·L^-1之间。另一份样品先用10mL胃液在37℃振荡提取1h,用碳酸氢钠调节消化液pH至7.0,加入55.0mg胆汁盐和15mg胰液素,在37℃振荡提取2h,完成体外胃肠模拟处理。经离心3min,取上清液,按上述方法加入甲醇提取,并用高效液相色谱法进行测定。所得结果表明:PAEs的脂溶性越高,其生物有效性越低。此外,土壤的理化参数对PAEs的生物有效性也有影响。     

Analysis of lamotrigine and lamotrigine 2-N-glucuronide in guinea pig blood and urine by reserved-phase ion-pairing liquid chromatography.

Lamotrigine is an investigational anticonsulvant drug undergoing clinical trials. A simultaneous assay was developed to quantitate lamotrigine and its major metabolite, lamotrigine 2-N-glucuronide, from guinea pig whole blood. The extraction procedure and reversed-phase high-performance liquid chromatographic (HPLC) assay employed sodium dodecylsulfate (SDS) as an ion-pairing reagent to selectively separate lamotrigine and lamotrigine 2-N-glucuronide from endogenous blood components, other anti-convulsant drugs, and their metabolites. The mobile phase was composed of acetonitrile-50 mM phosphoric acid (pH 2.2) containing 10 mM SDS (33:67, v/v), and components were detected at 277 nm. The total coefficients of variance (C.V.) for the blood assay were less than or equal to 9.4% for lamotrigine (0.25-20.0 micrograms/ml) and less than or equal to 13.4% for the glucuronide metabolite (0.25-10.0 micrograms/ml). Separate assays for lamotrigine and its glucuronide in urine were developed. In order to quantitate low levels of lamotrigine in guinea pig urine, lamotrigine was extracted with tert.-butyl methyl ether-ethyl acetate (1:1). The total C.V. for lamotrigine quantitation in urine was less than or equal to 7.5% (0.10-10.0 micrograms/ml). For the determination of lamotrigine 2-N-glucuronide, urine was diluted with an SDS-phosphoric acid buffer (1:4) and injected directly onto the HPLC system, total C.V. less than or equal to 4.2% (0.5-50 micrograms/ml).     

Simultaneous determination of clarithromycin and 14(R)-hydroxyclarithromycin in plasma and urine using high-performance liquid chromatography with electrochemical detection.

A sensitive method for the simultaneous high-performance liquid chromatographic determination of clarithromycin and its active metabolite in plasma and urine is described. Alkalinized samples were coextracted with an internal standard and analyzed on a C8 column using electrochemical detection. Recoveries were greater than or equal to 85% and consistent. Standard curves for plasma were linear in the range 0-2 micrograms/ml for both compounds (r greater than 0.99), with limits of quantification of approximately 10.03 micrograms/ml (0.5-ml sample). Within-day and day-to-day precision were good, with coefficients of variation mostly within +/- 5%; accuracy for both compounds were routinely within 90-110% of theoretical values. Standard curves for urine were linear in the range 0-100 micrograms/ml with limits of quantification of 0.5 micrograms/ml (0.2-ml sample). Urine assays also had similar within-day and day-to-day precisions and accuracy.     

Determination of denzimol, a new anticonvulsant agent, and its main metabolite in biological material by gas chromatography and high-performance liquid chromatography

Two methods, using gas chromatography (GC) and high-performance liquid chromatography (HPLC), were developed in order to investigate the pharmacokinetics of denzimol hydrochloride, N-[beta-[4-(beta-phenylethyl)phenyl]-beta-hydroxyethyl] imidazole hydrochloride, which is a new anticonvulsant drug, and of its main metabolite, N-[beta-[4-(beta-phenyl-beta(alpha)-hydroxyethyl)phenyl] -beta-hydroxyethyl]-imidazole (referred to as M2), in humans. Both methods involve the use of a homologue of denzimol as an internal standard. The GC method is more sensitive (sensitivity limit 2.5 ng/ml for denzimol and 15 ng/ml for M2) and was utilized for the determination of denzimol and M2 in plasma. The GC method is specific, precise (relative standard deviations are 3.26, 2.12 and 1.72% at 10, 100 and 1000 ng/ml for denzimol and 6.45, 4.17 and 3.38% at 50, 500 and 1000 ng/ml for M2) and accurate (mean recovery +/- S.D. is 102.58 +/- 4.10% for denzimol and 99.72 +/- 7.75% for M2). The HPLC method is very simple and quick to perform. This method has a sensitivity limit of 0.5 micrograms/ml for denzimol and 1 microgram/ml for M2, and allows the determination of both compounds in urine with high selectivity, reproducibility (relative standard deviations are 2.05, 3.50 and 1.02% for denzimol and 2.78, 2.80 and 1.73% for M2, at concentrations of 15, 35 and 70 micrograms/ml) and accuracy (mean recovery +/- S.D. is 103.57 +/- 2.97% for denzimol and 95.91 +/- 1.59% for M2). The common anticonvulsants, when present in plasma, do not interfere with the monitoring of denzimol levels.     

Rapid determination of creatine, phosphocreatine, purine bases and nucleotides (ATP, ADP, AMP, GTP, GDP) in heart biopsies by gradient ion-pair reversed-phase liquid chromatography.

A simple binary solvent method has been developed for the simultaneous determination of creatine (Cr), phosphocreatine (PCr), ATP, ADP, AMP, GTP, GDP, IMP, NAD, inosine, adenosine, hypoxanthine and xanthine. This allows separation of the most important nucleotides present in myocardial biopsies as, for example, in studies using 31P NMR spectroscopy. In NMR spectra ATP and PCr are the only visible high-energy phosphates, therefore the status of other nucleotides and bases cannot be determined. The nucleotides, AMP degradation products, PCr and Cr in pig and rat heart muscle were resolved with 35 mM K2HPO4, 6 mM tetrabutylammonium hydrogensulfate buffer, pH 6.0, and a binary acetonitrile gradient on medium-bore, 250 mm or 125 mm x 3.9-4.6 mm I.D. steel octadecyl-bonded (C18) columns at a flow-rate of 1.5 or 1.0 ml/min. This method, optimized for use with older high-performance liquid chromatography pumps (100 microliters displacement heads), resolves the major porcine and rat myocardial nucleotides and degradation products within 22 min. The amounts found in normoxic porcine muscle are: Cr 9.21 +/- 0.75; hypoxanthine 1.40 +/- 0.14; PCr 7.20 +/- 1.2; IMP 1.34 +/- 0.13; beta NAD 1.82 +/- 0.23; AMP 0.10 +/- 0.04; GDP 0.05 +/- 0.02; ADP 1.23 +/- 0.09; GTP 0.19 +/- 0.01; ATP 4.45 +/- 0.32 mumol/g wet weight. The method, incorporating adenosine tetraphosphate as an internal standard, allows the documentation of changes in both the high-energy phosphates and their degradation products in a single analysis of myocardial samples as small as 200 micrograms (wet weight).     

Stability and bioequivalence studies of two marketed formulations of coenzyme Q10 in beagle dogs.

Coenzyme Q10 (CoQ10), a highly lipophilic compound present in the inner mitochondrial membrane, is essential for production of cellular energy in the form of ATP. CoQ10 is used as an antioxidant and also in the treatment of various cardiovascular disorders. The relative bioavailabilities of powder filled capsule (I) and oil-based formulation (II) of CoQ10 were compared in beagle dogs in an open, randomized, multiple dose, cross-over design. Poor and slow absorption characteristics were observed for both the formulations. The AUC, Cmax, and Tmax for formulation I and II are comparable (p < 0.05) where the values for formulation I are 22.84 +/- 6.3 micrograms ml-1 h, 0.51 +/- 0.11 microgram/ml, and 6.1 +/- 2.0 h whereas the values for formulation II are 24.32 +/- 5.6 micrograms ml-1 h, 0.55 +/- 0.16 microgram/ml, and 6.6 +/- 2.3 h, respectively. Stability of CoQ10 at various temperature and humidity conditions and its photostability were studied. Various antioxidants were evaluated to determine the type and amount of antioxidant(s) required to improve the stability of CoQ10. Large extent of degradation was observed at 45 degrees C and 55 degrees C. The effect of humidity conditions on degradation was insignificant. Among the various antioxidants studied, mixture of ascorbic acid (5%) and EDTA (0.1%) offered better protection than phenolic antioxidants such as butylated hydroxy anisole (BHA), butylated hydroxy toluene (BHT), or propyl gallate (PG). Further, increasing concentrations of phenolic antioxidants (from 0.1 to 0.3%) accelerated the degradation.     

HPLC analysis of orlistat and its application to drug quality control studies

In this study, a high performance liquid chromatography method with UV detection was developed for determination of orlistat. The chromatographic system consisted of a Nova-Pack C18 column, an isocratic mobile phase of phosphoric acid 0.1%-acetonitrile (10 : 90, v/v) and UV detection at 205 nm. Orlistat was eluted at about 6 min with no interfering peak from excipients used for preparation of dosage form. The method was linear over the range of 10-160 microg/ml orlistat (r2 > 0.9999). The within-day and between-day precision values were also in the range of 0.10-0.59%. The appropriate dissolution conditions were also determined and applied to evaluate the dissolution profile of orlistat capsules. Optimal conditions were 1000 ml of 3% SLS in water as dissolution medium and paddle at 100 rotation per minute. The proposed method was applied successfully to the determination of orlistat content in capsules and in vitro dissolution studies.     

High-performance liquid chromatographic determination of lansoprazole and its metabolites in human serum and urine.

A simple and sensitive high-performance liquid chromatographic method with ultraviolet detection is described for the simultaneous determination of lansoprazole and its metabolites in human serum and urine. The analytes in serum or urine were extracted with diethyl ether-dichloromethane (7:3, v/v) followed by evaporation, dissolution and injection into a reversed-phase column. The recoveries of authentic analytes added to serum at 0.05-2 micrograms/ml or to urine at 1-20 micrograms/ml were greater than 88%, with the coefficients of variation less than 7.1%. The minimum determinable concentrations of all analytes were 5 ng/ml in serum and 50 ng/ml in urine. The method was successfully applied to a pharmacokinetic study of lansoprazole in human.     

Molecularly imprinted solid-phase extraction method for the high-performance liquid chromatographic analysis of fungicide pyrimethanil in wine

A method for molecularly imprinted solid-phase extraction (MISPE) of the fungicide pyrimethanil from wine samples has been investigated. The molecular imprinted polymer was obtained by iniferter-mediated grafting on porous chloromethylated polystyrene beads, using methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross-linker. The imprinted beads were evaluated for use as a solid-phase extraction sorbent, in order to develop the extraction protocol in aqueous standards and red wine samples. The optimised extraction protocol resulted in a reliable MISPE method suitable for HPLC analysis (stationary phase: Cromolith Performance C18 column, 100 mm x 4.6 mm; mobile phase: acetonitrile-water (3:2, v/v), flow-rate: 1.00 ml/min; detection 270 nm). It was selective for pyrimethanil and the related pyrimidinic fungicides cyprodinil and mepanipyrim, while the non-pyrimidinic fungicides benalaxyl, chlozolinate, furalaxyl, iprodione, metalaxyl, nuarimol, procymidone and vinclozolin were not extracted. Recoveries performed on a wine matrix spiked with pyrimethanil at three different concentration levels were reproducible and were in good agreement with the recoveries performed on buffer, coming out between 80 and 90% (85+/-7.0% at 0.50 microg/ml, 79+/-1.6% at 2.0 microg/ml and 87+/-5.6% at 20 microg/ml). Preconcentration and quantitative extraction of pyrimethanil from wine samples was shown to be feasible down to 0.1 microg/ml.     

气相色谱-氮磷检测法检测尿中劳拉西泮

 报道了尿中劳拉西泮的气相色谱 氮磷检测器的检测方法。检测时以 2 羟乙基氟西泮为内标 ,用 β 葡萄糖醛酸苷酶水解后于碱性条件下用乙醚萃取 ,将萃取液浓缩后进行检测。劳拉西泮的萃取率 (mean±SD)为 ( 83 4±3 1) % ,检出限为 5 μg/L。萃取物用N ,O 双 (三甲硅烷基 )三氟乙酰胺 (BSTFA)衍生化后进行三甲基硅烷 (TMS)衍生物检测。     

QuEChERS-气相色谱-三重四极杆质谱法检测黄瓜中的19种邻苯二甲酸酯

建立了QuEChERS结合气相色谱-三重四极杆质谱联用仪同时检测黄瓜中19种邻苯二甲酸酯残留的方法。黄瓜样品采用乙腈超声提取,经无水硫酸镁和氯化钠盐析离心后减压蒸馏富集,然后用C18吸附剂净化,经HP-5ms UI色谱柱分离后在多反应监测模式下进行测定。该方法在10~5000 μg/kg范围内线性关系良好(r ≥ 0.9995),检出限为0.2~3.5 μg/kg。按照建立的方法分别进行了10、100和500 μg/kg 3个添加水平的19种邻苯二甲酸酯的加标回收率试验,回收率为63.3%~127.8%,相对标准偏差为0.5%~13.3%。该方法灵敏度高、准确度好,符合多残留检测的技术要求,适用于黄瓜等蔬菜中邻苯二甲酸酯残留的检测。