Biomedical subjects

Xing Tang

Publications and source records attributed to Xing Tang.

At least 19 recordsLinked to original sources

PubMed2006

Preparation and in vitro/in vivo evaluation of sustained-release metformin hydrochloride pellets.

In this study, metformin hydrochloride (MH) sustained-release pellets were successfully prepared by centrifugal granulation. Seed cores preparation, drug layering, talc modification and coating of polymeric suspensions were carried out in a centrifugal granulator. Talc modification was performed before coating in order to overcome the high water solubility of metformin. The influence of surface modification by talc, the effects of Eudragit types and ratios, as well as the correlation between in vitro release and in vivo absorption were investigated in detail. Experimental results indicated that talc modification made a decisive contribution to controlling the drug release by avoiding drug dumping. Three dissolution media: 0.1 M HCl, distilled water and pH 6.8 phosphate buffer were employed to determine the in vitro release behaviors of the above metformin hydrochloride pellets. The relative bioavailability of the sustained-release pellets was studied in 12 healthy volunteers after oral administration in a fast state using a commercially available immediate release tablet (Glucophage) as a reference. Following coating with a blend of Eudragit L30D-55 and Eudragit NE30D (1:20), at 7% or 10% coating level, respectively (referred to as F-2, F-3), the pellets acquired perfect sustained-release properties and good relative bioavailability. The Cmax, Tmax and relative bioavailability for F-2 and F-3 coated pellets were 1.21 microg/ml, 6 h, 97.6% and 1.65 microg/ml, 8 h, 165%, respectively. Combined use of two Eudragit polymers with different features as coating materials produced the desired results. Restricted delivery of metformin hydrochloride to the small intestine from differently coated pellets resulted in increased relative bioavailability and a sustained release effect. The adoption of several different pH dissolution media established a better relationship between the in vitro release and in vivo absorption of the sustained-release pellets.

Administration, Oral↗

PubMed2006

Evaluation of brain-targeting for the nasal delivery of estradiol by the microdialysis method.

The uptake of estradiol into the cerebrospinal fluid (CSF) after intranasal and intravenous administration in rats was investigated to study whether direct nose-CSF transport of estradiol exits or not. Animals received 0.48 mg kg(-1) estradiol randomly methylated beta-cyclodextrin (RAMEB) inclusion complex intranasally and intravenously. Following nasal delivery, estradiol reached a C(max) value (mean+/-S.D.) in plasma (26.70+/-11.37 ng ml(-1)) and CSF (54.76+/-32.84 ng ml(-1)) after 20 min in each case, while after intravenous infusion, estradiol reached a C(max) value in plasma (170.08+/-64.67 ng ml(-1)) and CSF (26.48+/-11.34 ng ml(-1)) at 5 min and 60 min, respectively. The AUC(CSF)/AUC(plasma) ratio (1.60+/-0.67) after intranasal delivery differed significantly from the ratio (0.61+/-0.16) observed after intravenous infusion (P<0.05). All these results indicate that estradiol is transported into CSF via olfactory neurons, and, hence, there is a direct transport route from the nasal cavity into the CSF for estradiol.

Administration, Intranasal↗

PubMed2006

Formulation and evaluation of nimodipine-loaded lipid microspheres.

The purpose of this study was to develop an alternative, improved and better tolerated formulation and investigate the pharmacokinetic profile of the new formulation of nimodipine (NM) compared with nimodipine ethanol solutions. Lipid microspheres (LMs) prepared using lecithin and vegetable oils have attracted a lot of interest owing to their versatile properties, such as non-immunogenicity, being easily biodegradable and exhibiting high entrapment efficiency. NM incorporated in LMs could reduce irritation by avoiding the use of ethanol as a solubilizer. The solubility of NM was also increased by dissolving it in the oil phase. The particle size distribution, zeta potential, entrapment efficacy and assay of the NM-loaded LMs were found to be 188.2+/-5.4 nm, -31.6 mV, 94.2% and 1.04 mg mL(-1), respectively. The preparation was stable for 1 year at 4-10 degrees C. The formulation and some physicochemical properties of NM-loaded LMs were investigated. The pharmacokinetic and biodistribution studies were performed in rats at a dose of 1.2 mg kg(-1). From the observed data, there is no obvious retention of NM-loaded LMs in plasma. Moreover, incorporation of NM in LMs did not alter the tissue distribution significantly except for the relatively greater drug accumulation in the liver and spleen. The stimulation studies demonstrate that LMs of NM reduce irritation markedly compared with NM solutions. These results suggest that the LM system is a promising option to replace NM ethanol solutions as an intravenous treatment.

Animals↗

PubMed2006

Pharmacokinetic study of ketoprofen isopropyl ester-loaded lipid microspheres in rat blood using microdialysis.

A blood microdialysis technique coupled with high-performance liquid chromatography was used to investigate the pharmacokinetics of unbound ketoprofen in rats after intravenous administration of a lipid-soluble ketoprofen derivate, ketoprofen isopropyl ester (KPI), loaded into lipid microspheres (LM) and ketoprofen solution. A microdialysis probe was inserted into the jugular vein of male Wistar rats. KPI-loaded LM or ketoprofen solution (24 mg/kg, i.v.) was then administrated via a femoral vein. Dialysate samples were analyzed using HPLC. The in vitro and in vivo recovery rate of the microdialysis probe was 30.42+/-0.74% (n=3) and 40.27+/-2.74% (n=3), respectively. The pharmacokinetic parameters for ketoprofen after intravenous administration of KPI-loaded LM and ketoprofen solution exhibited no statistically significant differences. The results of this pharmacokinetic study indicate that the microdialysis technique can be widely applicable to investigations of in vivo free-drug of microcarrier systems.

Animals↗

PubMed2006

Simple and effective method for generating single-stranded DNA targets and probes.

A simple and efficient PCR method was developed for generating dye- or radiolabeled single-stranded DNA targets or probes used for hybridization studies. The method involved the use of a pair of long primers with high annealing temperatures and a short, labeled primer with a low annealing temperature in a PCR consisting of two cycles at different temperatures. We used this method to generate dye Cy 5-labeled and [32P]-radiolabeled single-stranded DNA targets and probes. These labeled probes were used successfully for the microarray identification of point mutations in Mycobacterium tuberculosis genes and for the Northern blot detection of expression changes of the GATA-2 gene in Pneumocystis carinii-infected rat lungs.

Animals↗

PubMed2006

[Pharmacokinetic study of ketoprofen in rat by blood microdialysis technique].

AIM: To investigate the in vitro recovery and influencing factors of ketoprofen in microdialysis probe, and study the pharmacokinetic of unbound ketoprofen in rat after iv administration. METHODS: The recovery of ketoprofen was detected by a concentration difference method. After microdialysis probe was inserted into the jugular vein of male Wistar rats, the probe was infused with various concentrations perfusate. The in vivo recovery and the pharmacokinetics of unbound ketoprofen in rat were investigated. Dialysate samples were determined by HPLC. RESULTS: The recovery detected by gain was as the same as that by loss; the recovery was independent of the drug concentration surrounding the probe. The in vitro recovery was 28.75% by concentration difference method and the in vivo recovery was (40.3 +/- 2.7) % by retrodialysis method. After i.v. administration of ketoprofen in rat, T 1/2, AUC and CL of unbound ketoprofen were (181 +/- 16) min, (112 +/- 27) microg x min x mL(-1) and (0.22 +/- 0.05) L x min(-1), respectively. CONCLUSION: Microdialysis sampling can be used for the pharmacokinetic study of unbound ketoprofen in rat.

Animals↗

PubMed2006

[In vitro and in vivo assesemet of sodium norcantharidin lipid microsphere].

AIM: To prepare lipid microsphere of sodium norcantharidin (NCTD) and then study their characters and pharmacokinetic behavior. METHODS: Dynamic Light Scattering, HPLC and retrodialysis technique were used to determine the in vitro characters of the NCTD loaded lipid microsphere (LM), such as the particle size, xi-potential, content, incorporation ratio, release profile and changes after dilute. And the plasma concentration was determined by HPLC-MS, compared with NCTD aqueous solution at the same time. RESULTS: Every property showed that the LM was preferable. The average diameter was about 200 nm. The xi-potential was - 38 mV. The content was close to 100%. And the incorporation ratio exceeded 80%. After i. v. administration of single dose, the pharmacodynamic parameter of LM AUC was 111.28 microg x mL(-1) x h(-1). The data of plasma concentrations showed that the NCTD LM was of two compartment. There was no obvious difference between in vivo parameters of LM and reference solution. CONCLUSION: The NCTD LM was eligible and the character of it in vivo was not changed.

Animals↗

PubMed2006

[Preparation and evaluation of clarithromycin emulsion for injection].

AIM: To prepare clarithromycin emulsion and investigate its pharmacokinetics in rats. And to do irritation test of the emulsion. METHODS: High pressure homogenization method was used to prepare clarithromycin emulsion, and the Nicomp380 machine was used to test the mean particle size and zeta-potential of clarithromycin emulsion. Irritation of emulsion was also evaluated compared with the positive control of clarithromycin solution using rat paw lick test and rabbit ear vein irritation test. Microbiological assay method was used for determining the drug concentration in plasma. Pharmacokinetics of two dosage forms in rats was also studied. RESULTS: The mean particle size and zeta potential of clarithromycin emulsion were 156 nm and -31.8 mV, respectively. The emulsion was stable during the storage time at 4 degrees C for 6 month. The pain caused by emulsion reduced significantly compared with that of clarithromycin solution based on the results of rat paw lick test and rabbit ear vein test. The drug concentration-time curves of clarithromycin emulsion and clarithromycin solution were similar and could be described by two compartment model. AUC(0-1) of clarithromycin emulsion and clarithromycin solution were (66.76 +/- 16.34) and (59.00 +/- 11.20) microg x h x mL(-1), respectively. CONCLUSION: Stable emulsion could be prepared using high pressure homogenization method, and irritation caused by i.v. injection could be reduced significantly by using clarithromycin emulsion.

Animals↗

PubMed2005

Microarray and allele specific PCR detection of point mutations in Mycobacterium tuberculosis genes associated with drug resistance.

Global public health is threatened by the emergence of potentially dangerous antibiotic drug-resistant strains of Mycobacterium tuberculosis. Point mutations in certain M. tuberculosis genes are associated with the resistance of M. tuberculosis strains to antibiotic drugs. The purpose of this study was to develop a suitable microarray-based protocol for the detection of point mutations in M. tuberculosis genes associated with drug resistance. We initially developed a conventional, oligonucleotide microarray protocol and used it to detect and identify on a single microarray slide a number of point mutation-containing rpoB and katG gene target sequences. However, the occurrence of some non-specific hybridization led us to the development of an improved protocol based on allele specific PCR combined with tags/anti-tags and microarrays. This protocol was evaluated by detecting point mutations in M. tuberculosis katG and rpoB gene templates produced by recombinant PCR. The methodology allowed sequences containing single point mutations to be readily distinguished from wild type sequences. The data obtained with the improved protocol had strong and specific signals and relatively low amounts of non-specific hybridization. We successfully used this protocol to detect and identify (<8 h) a number of clinically relevant point mutations in the rpoB, katG and rpsL genes of M. tuberculosis clinical isolates. Our allele specific PCR/tags and anti-tags/microarray protocol has several advantages over our conventional oligonucleotide microarray protocol, and it may have broad applications for point mutation detection.

Alleles↗

PubMed2005

Study on the bioavailability of puerarin from Pueraria lobata isoflavone self-microemulsifying drug-delivery systems and tablets in rabbits by liquid chromatography-mass spectrometry.

To evaluate the bioavailability of puerarin from Pueraria lobata isoflavone self-microemulsifying drug delivery systems (SMEDDS) and Yufengningxin tablets, a rapid and specific liquid chromatography--mass spectrometric method was developed and validated to determine puerarin in rabbit serum. The analyte was extracted from serum samples by precipitating the serum proteins, separated on a Diamonsil C(18) column and detected by mass spectrometry with an electrospray ionization interface. 4-Hydroxybenzaldehyde was used as the internal standard. The method has a limit of quantitation of 10 ng/mL using 200 microL serum. The intra-day relative standard deviations (RSDs) ranged from 3.7 to 6.9% and inter-day RSDs were within 6.5%. After administration of SMEDDS and tablets to rabbits, a significant difference was observed in main pharmacokinetic parameters of t(max), C(max) and AUC(0--infinity) between SMEDDS and tablets, and a 2.2-fold increase in the relative bioavailability of puerarin was observed with the SMEDDS compared with Yufengningxin tablets. It was concluded that the absorption of puerarin from Pueraria lobata isoflavone SMEDDS was enhanced.

Administration, Oral↗

PubMed2005

Evaluation of in-vitro dissolution and in-vivo absorption for two different film-coated pellets of clarithromycin.

The aim of this study was to compare two formulations of film-coated pellets containing clarithromycin after single oral dose study in healthy male volunteers. Two formulations with different coating polymers were prepared: formulation-1 (F-1) was prepared by incorporating three kinds of pH-dependent gradient-release coated pellets into capsules and formulation-2 (F-2) was prepared by coated with an insoluble semiosmotic film. Release profiles of film-coated pellets were evaluated using paddle method under different conditions. Pharmacokinetic profiles of these formulations were obtained in three healthy male volunteers and compared to commercially available immediate release (IR) tablets. The relative bioavailability based on the AUC0-24h was found to be 96.2% and 58.7% for F-1 and F-2 compared with IR, and the Tmax was delayed.

Anti-Bacterial Agents↗

PubMed2005

[Preparation of solid lipid nanoparticles loaded with all-trans retinoic acid and their evaluation in vitro and in vivo].

AIM: To prepare solid lipid nanoparticles (SLN) loaded with all trans retinoic acid using an ultrasonic technique with Compritol 888 ATO as matrix material, and investigate properties of nanoparticles in vitro and in vivo. METHODS: Ultrasonic technique was adopted to prepare solid lipid nanoparticles in an aqueous system using all-trans retinoic acid (ATRA) as a model drug. Physicochemical proterties of SLN were investigated in detail. Drug release from two sorts of ATRA-SLN was investigated using a dialysis bag method. Compared with ATRA solution, the in vivo pharmacokinetics of two sorts of ATRA-SLN after intravenous injection to rats were studied. RESULTS: Solid lipid nanoparticles loaded with all-trans retinoic acid was readily and quickly prepared by ultrasonic technique. The morphological investigation by Transmission Electron Microscopy (TEM) showed that the particles had round and uniform shapes. The mean diameters of them were (158 +/- 9) nm and (89 +/- 11) nm separately. The SLN dispersion was stable at 4 degrees C for more than one year. Drug loading was 3.3%, drug entrapment efficiency was more than 95%, the in vitro release was well in accordance with Weibull distribution. Compared with ATRA control solution, SLN could stay in the blood circulation for a longer time after intravenous injection. CONCLUSION: The ultrasonic technique was appropriate for the preparation of solid lipid nanoparticles.

Animals↗

PubMed2005

[Pharmacodynamics of compound danshen pH-dependent delayed release pellets in dogs].

AIM: To prepare the compound danshen pH-dependent delayed release pellets and filled them in capsules and then study thier pharmacodynamics. METHODS: The pH-dependent delayed release pellets were prepared by coating with HPMC, Eudragit L-30D-55 and Eudragit L100-Eudragit S100 (1:6), separately, and mixed in proper proportion to prepare the two pH-dependent delayed release systems T1 and T2. The release of delayed release pellets was determined according to the method of China Pharmacopoeia (2000) in the simulated gastrointestinal pH conditions. The pharmacodynamic,parameters were evaluated by serum pharmacology method. RESULTS: The compound danshen pH-dependent delayed release pellets were prepared with the characteristics of pH dependent delayed release profile in vitro. In single oral dose, the pharmacodynamic parameters of rapid release tablets R Emax (%) and Tmax (h) were 34.63% and 0.58 h, respectively. Tmax S of delayed-release pellets T1 and T2 were extended to 2.42, 3.17 h and Emax S (%) were declined to 13.57%, 14.52%. The relative bioavailabilities of T1 and T2 were 99.3%, 133.6% , respectively. In multiple oral doses of R the pharmacodynamic parameter of DF was 7.32 and those T1, T2 DF were 3.40, 3.03, respectively. CONCLUSION: The compound danshen pH-dependent delayed release capsules have characteristics of pH dependent releasing in vitro and characteristics of delayed release in vivo. In multiple oral (loses the DF of delayed release capsules was lower than that of rapid release tablet at steady state.

Animals↗

PubMed2004

Development of a dissolution medium for nimodipine tablets based on bioavailability evaluation.

A marked difference in the dissolution rate between two brands of nimodipine tablets was observed using a newly developed dissolution medium of pH 4.5 acetate buffer containing 0.05% sodium dodecyl sulfate (SDS). However, when pH 4.5 acetate buffer containing 0.3% SDS was used as dissolution medium, which was specified in the edition, the dissolution results of the both brands conformed to the BP requirements and no significant difference in dissolution was observed. The dissolution data obtained for two commercial brands of nimodipine tablets indicate the superiority of the proposed system as a discriminatory dissolution medium for nimodipine tablets. The relative bioavailability of the two brands of nimodipine tablets was determined in healthy adult volunteers after a single dose in a randomized crossover study. Plasma concentrations were determined by a liquid chromatography-tandem mass spectrometry method. Statistical comparison of the AUC(0-T), AUC(0- infinity), C(max), and T(max) indicated a significant difference in the two brands of nimodipine tablets.

Adult↗

PubMed2004

Preparation and evaluation of pH-dependent gradient-release pellets for TCM.

This paper is designed to investigate a novel sustained release system for Traditional Chinese Medicinal Compound Recipe (TCMCR) by incorporating three kinds of pH-dependent gradient-release coated pellets into capsules. In our study, dosage reform was conducted on the TCMCR model drug--Guanxin Suhe Wan (GSW), which is in the traditional form of honey bolus, comprising Styrax, Borneolumsyntheticum, Olbanum, Radix aristolochiae and Lignum santali albi. In this study, the beta-CD inclusion complexes were prepared separately for Styrax, Borneolumsyntheticum and the volatile oil extracted from the mixture of Olbanum, Radix aristolochiae and Lignum santali albi. Pellets were prepared in a centrifugal granulator using the powder layering technique and then divided into 3 equal weight portions and coated with HPMC, HPMCP HP-55 and Eudragit L100/S100 to obtain gradient release in stomach, duodenum and jejunum or ileum respectively. On this basis, a pH-dependent sustained-release pellets system, "Guanxin Suhe Sustained-release Capsules"(GSSC), was prepared by mixing the above three kinds of coated pellets at the weight ratio of 1:1:1. Pharmacokinetic (PK) studies between GSW and GSSC were made on male volunteers and isolated guinea pig hearts by plasma drug concentration method and serum pharmacology method respectively. In plasma drug concentration method, Tmax was 0.42 h and 1.08 h for GSW and GSSC respectively, while in the serum pharmacology method, Tmax was 0.56 h and 0.52 h respectively. The relative bioavailability of GSSC to GSW was 95.62% and 121.82% separately in the above two methods, indicating a similarity between the two methods in predicting the PK behavior of GSSC.

Animals↗

PubMed2004

Solid lipid nanoparticles (SLNs) to improve oral bioavailability of poorly soluble drugs.

The purpose of this work was to improve the oral bioavailability of poorly soluble drugs by incorporation into solid lipid nanoparticles (SLNs). All-trans retinoic acid (ATRA) was used as a poorly soluble model drug. Different formulations of SLNs loaded with ATRA were successfully prepared by a high-pressure homogenization method and using Compritol 888 ATO as lipid matrix. The particle size and distribution, drug loading capacity, drug entrapment efficiency (EE %), zeta potential, and long-term physical stability of the SLNs were investigated in detail. Drug release from two sorts of ATRA-SLN was studied and compared with the diffusion from ATRA solution in 0.1 M HCl, distilled water and phosphate buffer (pH 7.40), using a dialysis bag method. A pharmacokinetic study was conducted in male rats after oral administration of 8 mg kg(-1) ATRA in different formulations and it was found that the relative bioavailability of ATRA in SLNs was significantly increased compared with that of an ATRA solution. The amount of surfactant also had a marked effect on the oral absorption of ATRA with SLN formulations. Although an emulsion formulation also increased ATRA absorption, it was too unstable for use in clinical situations. The absorption mechanism of the SLN formulations was discussed. These results indicate that ATRA absorption is enhanced significantly by employing SLN formulations. SLNs offer a new approach to improve the oral bioavailability of poorly soluble drugs.

Administration, Oral↗

PubMed2004

[Determination of ligustilide in volatile oil from rhizome of ligusticum chuanxiong by RP-HPLC].

OBJECTIVE: To determine Ligustilide in volatile oil from Ligustrcum chuanxiong with RP-HPLC. METHOD: ODS2 column (4.6 mm x 200 mm, 5 microm) was used and nitrendipine was used as internal standard. The mobil phase consisted methanol, acetontrile and water (33:21:46). The ligustilide was at 275 nm. RESULT: The linear range was 2.92-29.2 mg x L(-1) for ligustilide. The average recovery of ligustilide was 95.1% and RSD was 2.3%. CONCLUSION: This method is simple and can be used to determine ligustilide with satisfactory accuracy and reproducibility.

4-Butyrolactone↗

PubMed2003

Effect of transcription factor GATA-2 on phagocytic activity of alveolar macrophages from Pneumocystis carinii-infected hosts.

Alveolar macrophages from Pneumocystis carinii-infected hosts are defective in phagocytosis (W. Chen, J. W. Mills, and A. G. Harmsen, Int. J. Exp. Pathol. 73:709-720, 1992; H. Koziel et al., J. Clin. Investig. 102:1332-1344, 1998). Experiments were performed to determine whether this defect is specific for P. carinii organisms. The results showed that these macrophages were unable to phagocytose both P. carinii organisms and fluorescein isothiocyanate (FITC)-conjugated latex beads, indicating that alveolar macrophages from P. carinii-infected hosts have a general defect in phagocytosis. To determine whether this defect correlates with the recently discovered down-regulation of the GATA-2 transcription factor gene during P. carinii infection, alveolar macrophages from dexamethasone-suppressed or healthy rats were treated with anti-GATA-2 oligonucleotides and then assayed for phagocytosis. Aliquots of the alveolar macrophages were also treated with the sense oligonucleotides as the control. Cells treated with the antisense oligonucleotides were found to have a 46% reduction in phagocytosis of P. carinii organisms and a 65% reduction in phagocytosis of FITC-latex beads compared to those treated with the sense oligonucleotides. To determine whether the defect in phagocytosis in alveolar macrophages from P. carinii-infected hosts can be corrected by overexpression of GATA-2, a plasmid containing the rat GATA-2 gene in the sense orientation driven by the cytomegalovirus (CMV) promoter was introduced into alveolar macrophages from P. carinii-infected rats. Aliquots of the same cells transfected with a plasmid containing GATA-2 in the antisense orientation relative to the CMV promoter served as the control. Alveolar macrophages treated with the sense GATA-2 expression construct were found to increase their phagocytic activity by 66% in phagocytosis of P. carinii organisms and by 280% in phagocytosis of FITC-latex beads compared to those that received the antisense GATA-2 construct. The results of this study indicate that GATA-2 plays an important role in the regulation of phagocytosis in alveolar macrophages during P. carinii infection.

Animals↗