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X D Tu

Publications and source records attributed to X D Tu.

14 recordsLinked to original sources
PubMed2000

[Determination of bromhexine in plasma by gas chromatography-electron capture detection and pharmacokinetic studies].

This paper reports a gas chromatography-electron capture detection(GC-ECD) method for the study of pharmacokinetics of bromhexine in healthy human body. A2 m x 3 mm i.d. silanized glass column packed with 5% SE-30 was used. The carrier gas was nitrogen. The internal standard was 5-chloro-2-amino-diphenyl ketone. After NaH2PO4-Na2HPO4 buffer (pH 6.0) being added, the plasma was extracted with n-hexane-dichloromethane (9:1, V/V). A good linearity was obtained from 1.0 microgram/L to 50.0 micrograms/L of bromhexine in human plasma, r = 0.9994. The detection limit of bromhexine in plasma was 0.5 microgram/L. The average recovery was 97.5%. The pharmacokinetics of bromhexine was determined by this method after a single oral dose of 8 mg bromhexine capsule given to each of 8 volunteers. The results showed that the plasma concentration-time courses conformed to one compartment model. The established GC-ECD method is a good method for the determination of bromhexine in human plasma. The method is rapid, simple, precise and sensitive.

Bromhexine↗
PubMed1996

[Studies on ethmozine sustained-release tablet remaining-floating in stomach].

An oral sustained-release system of ethmozine (E-HBS) was developed. The in vitro release characteristics of E-HBS were shown primarily to be of the first order of kinetics (Kr = 0.2436 h-1). The gamma-scintiphotographic study showed that E-HBS remained in the human stomach for more than 6 hours after ingestion, much longer than the conventional tablet (1-1.5 h). The plasma concentration-time curve of E-HBS exhibited typical sustained-release characteristics. The percentage of drug released in vitro vs the percentage of drug release in vivo of E-HBS indicated excellent linearity.

Adult↗
PubMed1994

[Studies on formulation and bioavailability of benorilate tablets].

A new formulation tablet B was developed and compared with tablet A with the purpose of improving the bioavailability of benorilate by reducing its particle size. The dissolution rate in vitro was determined by paddle method and using surfactant solution medium. The plasma concentrations of hydrolyzates which are salicylic acid and paracetamol from benorilate in vivo were measured by HPLC. The dissolution rates of ground and unground drug are 0.0337 min-1 and 0.0152 min-1 (P < 0.001) respectively. Compared with tablet A, the cumulative dissolution percentage of B is higher. The mean dissolution time of B and A are 15.77 min and 42.25 min (P < 0.001) respectively. The study in vivo showed that the Cmax, Tp and AUC of salicylic acid for these two formulations have no significant difference (P > 0.1). The relative bioavailability of B to A is 125.59%. Their in vivo process fits one-compartment model and first order elimination.

Acetanilides↗
PubMed1994

[Determination of ethmozine in human plasma by high performance liquid chromatography and its pharmacokinetics].

Following detailed study, a rapid and sensitive assay for ethmozine in human plasma has been developed using reversed phase high performance liquid chromatography (HPLC). Plasma samples were prepared for analysis by addition of internal standard (5-chloro-2-amino-benzophenone) followed by protein precipitation using acetonitrile. Analytical column was a C18 Spherisorb. The mobile phase consisted of mathanol-water-triethylamine (70:30:0.4, v/v/v, pH 6.5). The column effluent was monitored at 268 nm. The calibration curve was linear in the range from 20 ng/ml to 4000 ng/ml with r = 0.9994. The detection limit of this method was 3 ng/ml. The method showed good precision and the analytical recovery of ethmozine from plasma was 90-105%. The relative standard deviations for within-day and between-day were 2.4-6.3% and 4.5-10.2% respectively. The plasma drug concentration-time course in man after oral administration of 400 mg after conformed to a 1-compartment open model with a first order absorption phase. Mean T1/2 value was 1.75 +/- 0.45 h.

Adult↗
PubMed1993

[Determination of pseudoephedrine in human plasma by gas chromatography with a mass selective detector (GC-MSD)].

A specific and sensitive method has been established for the analysis of pseudoephedrine (PE) in human plasma by gas chromatography with a mass selective detector (GC-MSD). PE and ephedrine (E, internal standard) reacted with trifluoroacetic anhydride (TFAA) and the derivatives were separated by a HP-5 capillary column. PE-TFA and E-TFA were quantitatively measured by selected ion monitoring (m/z = 154). The detection limits for E and PE were 1 ng/ml plasma. The recoveries were about 99%.

Delayed-Action Preparations↗
PubMed1992

[Studies on the dissolution and bioavailability of trimethoprim-sulfadiazine-sulfamethoxazole tablets].

A reverse-phase high performance liquid chromatographic method was established for the simultaneous determination of trimethoprim (TMP), sulfadiazine (SD) and sulfamethoxazole (SMZ) in dissolution media. Meanwhile, another reverse-phase high performance liquid chromatographic method was developed for the simultaneous determination of the three drugs mentioned above and their metabolites, N4-acetyl-SD and N4-acetyl-SMZ in serum. The in vitro dissolution and in vivo bioavailability of two commercial trimethoprim-sulfadiazine-sulfamethoxazole tablets (A and B) were studied. Drugs were released far more rapidly from A than from B. Significant difference (P less than 0.001) was observed between the T50 s of the same active principles released from A and B. The in vivo processes of all three active principles in 8 healthy subjects taking two tablets each could be described by one-compartment model with first-order absorption and elimination. Compared with A, the relative bioavailabilities of B were 0.83, 0.73 and 0.78 for TMP, SD and SMZ, respectively. Drugs were absorbed more rapidly from A than from B.

Adult↗
PubMed1991

[Development of gentamicin sulfate sustained release tablet remaining-floating in stomach].

Gentamicin sulfate sustained-release tablet remaining-floating in stomach (G-HBS) was developed based on the hydrodynamically balanced system. The dissolution rate of G-HBS was determined by rotary basket method (100 r/min, 37 +/- 0.5 degrees C, 0.1 mol/L HCl). The release characteristics of G-HBS showed basically first order kinetics with the dissolution rate constant (Kr) of 0.3992 h-1. The mean dissolution time (MDT) of G-HBS was 2.53 h-1. The density of G-HBS was found to have no significant influence on dissolution of G-BHS. The gamma-scintiphoto technique was used to examine the gastric retention time of G-HBS and GCT (gentamicin sulfate conventional tablet). It was shown that the gastric retention time of all subjects taking G-HBS under fed and fasted conditions were all over 4 h, in contrast with GCT, only 1-2 h. The stability of G-HBS was investigated and a tentative two-year expiration date was established. Spectrophotometry for the determination of gentamicin was established. The effect of G-HBS on Campylobacter pyloridis-associated chronic gastritis was examined through clinical trials.

Adult↗
PubMed1991

[Development and pharmacokinetic study of miocamycin sustained-release tablet remaining--floating in stomach].

A novel sustained-release tablet of miocamycin was developed based on the hydrodynamically balanced controlled drug delivery system (HBS). It was prepared to contain fast-release and sustained-release granules. The gamma-scintiphotographic study after oral ingestion showed that MOM-HBS remained in human stomach for more than 7 hours, much longer than the conventional tablet (3-4 h). The in vitro release characteristics showed basically first-order kinetics (Kr = 0.1619 h-1). The serum concentration-time course of MOM-HBS exhibited typical sustained-release characteristics. Moreover, The percentage of drug released in vitro versus the percentage of drug released in vivo of MOM-HBS indicated excellent linearity. Its relative bioavailability was increased greatly compared with MOM dry syrup produced in Japan.

Adult↗
PubMed1990

[Determination of metoprolol in plasma by gas chromatography and electron-capture detection].

A method is described to determine metoprolol in plasma by GC-ECD. Metoprolol and alprenolol (internal standard) reacted rapidly with heptafluorobutyric anhydride under the catalysis of tetrahydrofuran (THF) after being extracted from plasma with cyclohexane. The derivatives produced quantitatively were identified by GC-MSD to be diheptafluorobutyl metoprolol and dihepatafluorobutyl alpredolol which were then separated and detected by 3% SE-30 packed glass column (2m x 3 mm) equipped with ECD. The detection limit was 1 ng/ml and the linear range was 10-1500 ng/ml (r = 0.9993). Average recovery from spiked plasma was 97.30%. The coefficient of variation of day-to-day and within-day were less than 8% and 7%, respectively. The method has been applied to investigate the pharmacokinetics and bioavailability of metoprolol and also applied to clinical monitoring of metoprolol levels in patients.

Chromatography, Gas↗
PubMed1989

[Development and pharmacokinetic study of metoprolol tartrate controlled-release tablet remaining-floating in stomach].

An oral controlled-release system (M-HBS) of metoprolol was developed based on the hydrodynamically balanced controlled drug delivery system. It was found that the in vitro release characteristics showed basically first-order kinetics (K'r = 0.1651 h-1); a tentative two-year expiration date on M-HBS was established; the gamma-scintiphotographic study after oral ingestion showed that M-HBS was retained in human stomach for longer time (5-6 h) than the conventional metoprolol tablet (1-1.5 h). The blood concentration-time course of M-HBS was demonstrated to fit a one-compartment model with apparent first order absorption and first order elimination. The parameters were calculated using a NONLIN computer program with the values of Ka, K, Vd, tmax, cmax, being 0.1944 h-1, 0.1867 h-1, 2.813, 5.247 h, 125.1 ng/ml, respectively. Moreover, the fraction of the dose absorbed from M-HBS in vivo well correlated with dissolution rate in vitro.

Adult↗