Simultaneous determination of bufadienolides in the traditional Chinese medicine preparation, liu-shen-wan, by liquid chromatography.

The bufadienolide compounds (bufalin, cinobufagin and resibufogenin), major constituents of Chansu in Liu-Shen-Wan (LSW), were determined by reverse phase high performance liquid chromatography. The procedure involves a preliminary extraction of the bufadienolides from LSW with chloroform using ultrasonication and subsequent evaporation to dryness of the chloroform extract. The residue of the chloroform extract was dissolved in methanol and separated on a Merck LiChrosorb RP-18 column. Methanol: water (74:26) was used as mobile phase. The compounds were satisfactorily separated with good chromatographic peaks. Good coefficients of correlation (r > 0.999) were obtained from the calibration of peak areas with concentrations for the 3 bufadienolides. Results of analysis showed that there were differences between the contents of bufadienolides in 11 LSW samples of different origin available to the public in Hong Kong where at present there is no legal control over the sale of traditional Chinese medicines. The variability of quantities of bufadienolides in Chansu may be a hazard to the public.     

一测多评法测定心可宁胶囊中6种蟾蜍二烯内酯类化合物

目的 建立一测多评法同时测定心可宁胶囊中6种蟾蜍二烯内酯类化合物的含量,并验证此方法在心可宁胶囊中应用的可行性和准确性。方法 以华蟾酥毒基为内参物,建立日蟾毒它灵、沙蟾毒精、蟾毒它灵、蟾毒灵和脂蟾毒配基与华蟾酥毒基的相对校正因子。分别采用外标法和一测多评法测定心可宁胶囊中6种蟾蜍二烯内酯类化合物的含量,比较2种方法的结果差异,验证一测多评法的可行性和准确性。结果 日蟾毒它灵、沙蟾毒精、蟾毒它灵、蟾毒灵和脂蟾毒配基与华蟾酥毒基的相对校正因子分别为1.06,0.862,0.897,1.09,0.915;2种方法结果无显著差异。结论 以华蟾酥毒基为内参物建立的相对校正因子重现性好,一测多评法可用于心可宁胶囊中多个蟾蜍二烯内酯类成分的质量评价。     

蟾皮中蟾毒配基类成分的分离与鉴定

目的研究中华大蟾蜍(Bufo bufo gargarizansCantor)皮中的蟾毒配基类成分。方法利用反复硅胶柱色谱、Sephadex LH-20凝胶柱色谱、半制备高效液相色谱、重结晶等手段分离纯化蟾皮中的蟾毒配基类成分,根据化合物的理化性质和各种波谱学数据鉴定其化学结构。结果分离得到11个蟾毒配基类化合物,分别鉴定为脂蟾毒配基(resibufogenin,1)、华蟾毒精(cinobufagin,2)、蟾毒灵(bufalin,3)、远华蟾毒精(telocinobufagin,4)、蟾毒它灵(bufotalin,5)、去乙酰华蟾毒它灵(desace-tylcinobufotalin,6)、嚏根草苷元(hellebrigenin,7)、沙蟾毒精(arenobufagin,8)、日蟾毒它灵(gam-abufotalin,9)、11β-羟基脂蟾毒配基(11β-hydroxylresibufogenin,10)、华蟾毒它灵(cinobufotalin,11)。结论化合物10和11为首次从中华大蟾蜍皮中分离得到。     

Determination and pharmacokinetics of isoferulic acid in rat plasma by high-performance liquid chromatography after oral administration of isoferulic acid and Rhizoma Cimicifugae extract

A simple and specific high-performance liquid chromatographic (HPLC) method with ultraviolet (UV) absorbance detection has been developed for the determination of isoferulic acid in rat plasma. The plasma samples were deproteinized with methanol after the addition of internal standard (IS) tinidazole. The analysis was performed on a Kromasil C18 column (250 mm x 4.6 mm i.d., 5 microm particle size) with acetonitrile-0.05% phosphoric acid (25:75, v/v) as mobile phase. The linear range was 0.0206-5.15 microg ml(-1) and the lower limit of quantification (LLOQ) was 0.0206 microg ml(-1). The intra- and inter-day relative standard deviations (R.S.D.s%) were less than 11.4 and 12.3%, respectively, and accuracy as relative error (R.E.%) between -6.7 and -1.1%. Mean extraction recovery was above 80%. The validated method was successfully applied to the pharmacokinetic study of isoferulic acid in rat plasma after oral administration of isoferulic acid and Rhizoma Cimicifugae extract.     

The mode of cardiac action of cardiotonic steroids isolated from Toad Cake in perfused working guinea-pig heart and effect of cinobufagin on experimental heart failure

The effects of bufadienolides (bufalin, bufotalin, cinobufagin, cinobufotalin, gamabufotalin and resibufogenin) isolated from Toad Cake was compared to that of cardenolides (digitoxin and ouabain) on cardiac function in a guinea-pig working heart preparation. All the steroids showed the cardiotonic effect in a concentration-dependent manner, and the minimum threshold concentration was 10(-8) M for bufalin, cinobufagin, gamabufotalin and digitoxin and 10(-7) M for bufotalin, cinobufotalin and ouabain. In addition, the order of maximum efficacy of cardiotonic action was as follows: cinobufagin (3 X 10(-7) M) = ouabain (3 X 10(-7) M) greater than digitoxin (1 X 10(-7) M) = gamabufotalin (3 X 10(-7) M) greater than cinobufotalin (3 X 10(-7) M) greater than bufotalin (1 X 10(-7) M). The effect of cinobufagin was examined on experimentally induced heart failure caused by acute local ischemia through ligation of the left anterior descending coronary artery in perfused guinea-pig heart. Cinobufagin (3 X 10(-7) M) and digitoxin (1 X 10(-7) M) reestablished the coronary flow of perfused guinea-pig heart to 90% and 98% of the level prior to the coronary artery ligation. The cardiac output and left ventricular pressure of perfused heart were increased to the level prior to the acute local ischemia, and the left ventricular work was increased by cinobufagin (3 X 10(-7) M) and digitoxin (1 X 10(-7) M) to 108% and 106%, respectively, of the pre-ligation level. These results indicate that cinobufagin possesses strong cardiotonic action, similar, to digitoxin, in experimentally induced heart failure due to acute local ischemia.     

Effects of bufadienolides and some kinds of cardiotonics on guinea pig hearts]

Effects of bufadienolides such as bufalin (BF) and cinobufagin (CB), the main components of Senso (Ch'an Su), on myocardial Na+,K(+)-ATPase activity, the cardiotonic activity in vivo and the action potential of isolated guinea pig papillary muscle cells were compared with those of other cardiotonic drugs. 1) The rank order of potency for inhibition of myocardial Na+,K(+)-ATPase activity was BF greater than digoxin (DG) greater than digitoxin (DT) greater than telocinobufagin greater than gamabufotalin greater than cinobufotalin greater than CB greater than g-strophanthin (GS) greater than digitoxigenin (DTG) greater than resibufogenin (RB) when compared at the 50% inhibitory concentration. 2) In isolated papillary muscle cells, CB shortened the action potential duration (APD) dose-dependently. The order of potency for shortening of APD was GS greater than CB greater than DTG much greater than DT. 3) In open-chest guinea pigs, intraduodenal administration of BF or CB increased the myocardial contractile force (MCF), but did not affect the heart rate. The order of potency for increase in MCF was as follows: methyldigoxin, proscillaridin greater than BF greater than CB greater than DG greater than Senso much greater than DT, DTG, RB. These results indicate that CB has a shortening effect on APD and an inhibitory effect on Na+,K(+)-ATPase activity along with its cardiotonic effect, like GS.     

Quantitative determination of spinosin in rat plasma by liquid chromatography-tandem mass spectrometry method

A sensitive method for the quantitative determination of spinosin in rat plasma was developed and validated using high-performance liquid chromatographic separation with tandem mass spectrometric detection. The analytes of interest were extracted from rat plasma samples by methyl tert-butyl ether (MTBE) after acidification with 1.0% acetic acid aqueous solution. Chromatographic separation was achieved on an Agilent Zorbax SB-C(18) (50 mm x 4.6 mm, 5 microm) using a isocratic mobile phase consisting of acetonitrile-water (30:70, v/v) with 1% isopropyl alcohol and 0.01% heptafluorobutyric acid. The flow rate was 0.2 ml/min. The column temperature was maintained at 25 degrees C. Detection was performed on a triple quadrupole tandem mass spectrometer by selected reaction monitoring (SRM) mode via electrospray ionization (ESI). The calibration curve was linear over the range of 1.00-400 ng/ml in rat plasma, with 1.00 ng/ml of the lower limit of quantification (LLOQ). The inter- and intra-day precisions and accuracy for all samples were satisfactory. The validated method was successfully applied for the pharmacokinetic study of spinosin in rat. After oral administration of 20mg/kg spinosin to rats, the main pharmacokinetic parameters of T(max), C(max), T(0.5) and AUC(0-T) were 5.33+/-0.58 h, 132.2+/-10.6 ng/ml, 4.89+/-0.37 h, 1.02+/-0.09 microg h/l, respectively.     

Determination of deoxyschizandrin in rat plasma by LC-MS

A simple, rapid and sensitive LC-MS method was developed for quantification of deoxyschizandrin in rat plasma. A 50 miccrol plasma sample was extracted by ether and performed on Elite Hypersil C(18) column (200 mm x 4.6 mm, 5 microm) with the mobile phase of methanol-water (84:16, v/v) in a run time of 6.5 min. The analyte was monitored with positive atmospheric pressure chemical ionization (APCI) by selected ion monitoring (SIM) mode. A good linear relationship was obtained over the range of 1.0-50.0 ng/ml and the validated method was successfully applied for the pharmacokinetic studies of deoxyschizandrin in rat. After oral administration of 4 mg/kg deoxyschizandrin and Schisandra extract which contained the same dose of deoxyschizandrin to male rats, the C(max) of deoxyschizandrin were 15.8+/-3.1 and 34.3+/-16.8 ng/ml, T(max) were 0.51+/-0.13 and 3.83+/-1.83 h, T(1/2) were 5.3+/-2.2 and 6.5+/-3.4h.     

一测多评法测定六神丸中5种蟾毒配基类成分含量

目的：建立一测多评法测定六神丸中蟾毒配基类成分含量的分析方法,并验证此方法在六神丸中的可行性和适应性。方法：采用高效液相色谱法,以华蟾酥毒基（S）为内参物,建立日蟾毒它灵（A）、蟾毒它灵（B）、蟾毒灵（C）和脂蟾毒配基（D）的相对校正因子。分别采用外标法和一测多评法测定六神丸中5种蟾毒配基类成分的含量,并比较测定值和计算值之间的差异。结果：六神丸中蟾毒配基类成分间的相对校正因子分别为f_A/S=1.06,f_B/S=0.896,f_C/S=1.09,f_D/S=0.914,一测多评法的计算值与外标法的实测值的相对误差小于1%。结论：以华蟾酥毒基为内参物建立的相对校正因子准确、可行,一测多评法可用于六神丸中蟾毒配基类成分的质量评价。     

Determination of a novel angiotensin-AT1 antagonist CR 3210 in biological samples by HPLC

A simple and sensitive method for the determination of a new angiotensin-AT(1) antagonist i.e. CR 3210, 4-[4-[(2-ethyl-5,7-dimethylimidazo[4,5-b]pyridin-3-yl)methyl]phenyl]-3-(2H-tetrazol-5-yl)quinoline, is described. The assay was utilised to describe the pharmacokinetic profile of the title compound after intravenous and intraperitoneal administration to Sprague Dawley rats. CR 3210 and the internal standard CR 1505 (loxiglumide, 4-[(3,4-dichlorobenzoyl)amino-5-[(3-methoxypropyl)pentylamino]-5-oxopentanoic acid) were isolated from rat plasma by solid-phase extraction. The sorbent extraction material along with the pH in the conditioning solution and the washing volume were considered pivotal parameters for the optimisation of the procedure. The separations were performed by reversed-phase high-performance liquid chromatography with ultraviolet detection. The samples were injected onto the analytical column (Tracer Extrasil ODS1) and detected at 238 nm, giving a retention time of 6.19 min for CR 3210 and 4.39 min for the internal standard, respectively. The selectivity of the method showed to be satisfactory. The mean recovery of CR 3210 from spiked rat plasma was 80.3 at 1 microg/ml and 79.9 at 2 microg/ml. The lower limit of detection (LOD) was taken as 0.014 microg/ml in plasma samples. The lower limit of quantification (LOQ) was taken as 0.02 microg/ml, the lowest calibration standard using 500 microg rat plasma. The procedures were validated according to international standards with a good reproducibility and linear response from 0.02 to 2 microg/ml. The sensitivity of the method allowed for its application to pharmacokinetic studies. The maximal concentration was detected 5' after the IV administration, whereas no significant absorption was evident after IP administration of CR 3210 to Sprague-Dawley rats. Our study suggests the absence of extensive bio-transformation of the drug in vivo, supported by the evidence that no metabolites were detected in plasma samples.     

Simultaneous determination of Gastrodin and Ligustrazine hydrochloride in dog plasma by gradient high-performance liquid chromatography

A novel reversed-phase HPLC method was developed for the simultaneous determination of Gastrodin (Gas) and Ligustrazine hydrochloride (LZH) in dog plasma after oral administration of the preparation 'Tianxiong Capsule'. The assay involves deproteinization, extraction and subsequent detection with a gradient solvent system at two different wavelengths. Retention times were 10.6 and 18.9 min for Gas and LZH, respectively. Linear responses were observed over a wide range (0.40-200.0 microg/ml for Gas and 0.0999-39.96 microg/ml for LZH) in plasma. The mean intra- and inter-assay variation coefficients were 2.7 and 3.4% for Gas and 3.4 and 4.2% for LZH, respectively. The average extract recoveries were 76.77% for Gas and 75.8% for LZH. This assay has been successfully used to provide pharmacokinetic data for Gastrodin with oral administration of Tianxiong capsules.     

Antimicrobial activity of the bufadienolides marinobufagin and telocinobufagin isolated as major components from skin secretion of the toad Bufo rubescens.

The increase in the emergence of antibiotic-resistant microorganisms and difficult to treat infections caused by these pathogens stimulate research aiming the identification of novel antimicrobials. Skin secretion of amphibian contains a large number of biologically active compounds, including compounds that performance defense mechanisms against microorganisms. In the present work, two antimicrobial bufadienolides, telocinobufagin (402.1609 Da) and marinobufagin (400.1515 Da), were isolated from skin secretions of the Brazilian toad Bufo rubescens. The specimens were collected in Brasilia (Distrito Federal, Brazil), the skin secretions extracted by electric stimulation, and submitted to purification by RP-HPLC. The molecular structure and mass determination were done by (1)H and (13)C NMR and mass spectrometry data, respectively. The antimicrobial activity was performed by liquid growth inhibition against Staphylococcus aureus and Escherichia coli. The minimum inhibitory concentrations of telocinobufagin and marinobufagin were, respectively, 64.0 and 16.0 microg/mL for E. coli and both 128 microg/mL for S. aureus. Besides the antimicrobial activity both bufadienolides promoted an increase of the contraction force in isolated frog ventricle strips.     

High-performance liquid chromatographic method for the determination and pharmacokinetic study of oxypeucedanin hydrate and byak-angelicin after oral administration of Angelica dahurica extracts in mongrel dog plasma

A high-performance liquid chromatographic method was developed and validated for the determination and pharmacokinetic study of oxypeucedanin hydrate and byak-angelicin after oral administration of Angelica dahurica extracts in mongrel dog plasma. The coumarin components and the internal standard isopsoralen were extracted from plasma samples with the mixture of tert-butyl methyl ether and n-hexane (4:1, v/v). Chromatographic separation was performed on a C(18) column (200 mm x 4.6mm, 5 microm) with the mobile phase acetonitrile-methanol-water-acetic acid (20:15:65:2, v/v/v/v) at a flow-rate of 1.0 ml/min. Only the peak of oxypeucedanin hydrate and byak-angelicin could be detected in dog plasma after oral administration of ethanol extracts of A. dahurica mainly containing xanthotoxol, osthenol, imperatorin, oxypeucedanin hydrate and byak-angelicin. The calibration curves of oxypeucedanin hydrate and byak-angelicin were linear over a range of 22.08-8830.00 and 6.08-2430.00 ng/ml in dog plasma, respectively. The quantification limit of oxypeucedanin hydrate and byak-angelicin in dog plasma was 22.08 and 6.08 ng/ml, respectively. The intra- and inter-day precision was less than 7.6% and 8.5% and the accuracy was from 91.9% to 106.1%. The lowest absolute recoveries of oxypeucedanin hydrate and byak-angelicin were 85.7% and 87.0%, respectively. The method was successfully applied to the pharmacokinetic studies of oxypeucedanin hydrate and byak-angelicin in dog plasma after oral administration of ethanol extracts from A. dahurica.     

Sensitive SPE-HPLC method to determine a novel angiotensin-AT1 antagonist in biological samples

A high-performance liquid chromatography (HPLC)-method after solid-phase extraction (SPE) has been developed in order to determine a new angiotensin-AT1 antagonist, i.e. CR 3210 (C27H24N8; MW = 460.54), 4-[4-[(2-ethyl-5,7-dimethylimidazo[4,5-b]pyridin-3-yl)methyl]phenyl]-3-(2H-tetrazol-5-yl)quinoline in rat plasma and urine after oral administration to Sprague-Dawley rats. CR 3210 and the internal standard (IS) CR 1505 (loxiglumide), i.e. 4-[(3,4-dichlorobenzoyl)amino]-5-[(3-methoxypropyl)pentylamino]-5-oxopentanoic acid, were isolated from rat urine and plasma by solid-phase extraction. The procedure was optimized regarding the sorbent extraction material, the pH in the conditioning solution, the washing step, the dry time and the type of elution solvent. The separation was performed by reversed-phase high-performance liquid chromatography with ultraviolet detection. The samples were injected onto the analytical column (Tracer Extrasil ODS1) and detected at 238 nm, giving a capacity factor of 1.87 for CR 3210 and 1.10 for the internal standard. The selectivity of the method was satisfactory. The mean recovery of CR 3210 from spiked rat plasma was 68.5 at 75 ng/ml and 80.9 at 3000 ng/ml; the mean recovery of CR 3210 from spiked rat urine was 69.9 at 75 ng/ml and 78.6 at 3000 ng/ml. The lower limit of detection (LOD) was 14 ng/ml in plasma and 22 ng/ml in urine samples. The lower limit of quantification (LOQ) was taken as 30 ng/ml, the lowest calibration standard using 500 microl rat plasma and urine. The procedures were validated according to international standards with a good reproducibility and linear response from 30 to 3000 ng/ml, for either plasma or urine. The sensitivity of the method allowed for its application to pharmacokinetic studies.     

Pharmacokinetic study of the novel, synthetic trioxane antimalarial compound 97-78 in rats using an LC-MS/MS method for quantification

The present study has been designed to investigate the pharmacokinetic parameters of the novel trioxane antimalarial 97-78 (US Patent 6316493 B1, 2001) in male and female rats after single oral and intravenous administration. The pharmacokinetic profile of 97-78 was investigated in the form of its completely converted metabolite 97-63 after dose administration. Quantification of metabolite 97-63 in rat plasma was achieved using a simple and rapid LC-MS/MS method. The LC-MS/MS method has been validated in terms of accuracy, precision, sensitivity and recovery for metabolite 97-63 in rat plasma. The intra- and interday accuracy (% bias) and precision (% RSD) values of the assay were less than 10% for metabolite 97-63. The chromatographic run time was 4.0 min and the weighted (1/x2) calibration curves were linear over the range 1.56-200 ng/ml. This method was successfully applied for analysis of pharmacokinetic study samples. Maximum plasma concentrations of 97-63 at 47 mg/kg oral administration in male and female rats were 1986.6 ng/ml and 4086.7 ng/ml at time (Tmax) 0.92 h and 0.58 h, respectively. The area under the curve (AUC(0-infinity)), elimination half-life (t(1/2) beta) and mean residence time (MRT) were 4669.98 ng x h/ml, 2.8 h and 4.2 h in male and 11786.0 ng x h/ml, 4.52 h and 4.32 h in female rats respectively. After single oral and intravenous administration of 97-78 to male and female rats significant differences were observed in pharmacokinetic parameters (AUC and t (1/2) beta) for metabolite 97-63.     

Antitumor activity of extracts and compounds from the skin of the toad Bufo bufo gargarizans Cantor

The skin of the toad Bufo bufo gargarizans Cantor is known to be rich in bufadienolides, peptides and alkaloids. It has been found to be a source of some extracts and biologically active compounds with antitumor activity. Cinobufacini (Huachansu), a Chinese medicine prepared from the dried toad skin, has been widely used in clinical therapy for various cancers in China. Bufadienolides, such as bufalin, cinobufagin, resibufogenin, and telocinobufagin, are the major active compounds derived from the toad skin. They are the maker biologically active compounds of cinobufagin while the antitumor activity of cinobufagin may be due to this kind of components. Experimental research has suggested that cinobufacini and its active compounds (e.g. bufalin and cinobufagin) exhibit significant antitumor activity, including inhibition of cell proliferation, induction of cell differentiation, induction of apoptosis, disruption of the cell cycle, inhibition of cancer angiogenesis, reversal of multi-drug resistance, and regulation of the immune response. Clinical data have indicated that cinobufacini may have effective anticancer activity with low toxicity and few side effects. Data to date suggest it may also enhance quality of life for patients with cancer. Thus, this review briefly summarizes recent studies on the anticancer activity of cinobufacini and some of its active compounds from the skin of the toad Bufo bufo gargarizans Cantor. This might provide additional evidence for further study of the extracts and active compounds from the toad skin in cancer treatment.     

Simultaneous determination of liensinine, isoliensinine and neferine from seed embryo of Nelumbo nucifera Gaertn. in rat plasma by a rapid HPLC method and its application to a pharmacokinetic study

A rapid and specific HPLC method has been developed and validated for the simultaneous determination of liensinine (CAS 2586-96-1), isoliensinine (CAS 6817-41-0) and neferine (CAS 2292-16-2) in rat plasma. The sample was prepared by a liquid-liquid extraction with diethyl ether and the recovery was above 80% from the plasma for the three compounds. Chromatographic separation was achieved with a Hypersil BDS C18 column (4.0 mm x 250 mm, particle size 5 microm). A mobile phase consisting of methanol: 0.2 M KH2PO4:0.2 M NaOH:triethylamine (71:17:12:0.002, v/v/v/v, pH 9.2-9.3) was slowly delivered at 0.8 ml/min in isocratic mode with a detection wavelength of 282 nm. The linearity of calibration curves were good (r > 0.999) in the concentration range of 0.031-2.00 microg/ ml. The lower limit of quantification can reach 0.03 microg/ml for the three compounds. The intra-day and inter-day variations estimated with QC samples were less than 8% for the three tested concentration levels. This developed method was applied in the plasma pharmacokinetic study of total bisbenzylisoquinoline alkaloids (TAL) of the lotus flower (Lian Zi Xin) following a single oral and intravenous administration of TAL in rats.     

Determination of pravastatin by high performance liquid chromatography

BACKGROUND: Pravastatin is a hydrophilic liver-specific inhibitor of the enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase. It effectively lowers plasma cholesterol and low-density lipoprotein concentrations in humans. Pharmacokinetic studies of pravastatin have been mostly performed by means of radioactively labelled drug or by measuring plasma concentrations with gas chromatography and mass spectrometry. AIMS OF THE STUDY: Aim of our study was to develop a simple, but reliable method which allows the determination of pravastatin plasma concentrations under clinical routine conditions. SUBJECTS, MATERIALS AND METHODS: Samples were prepared by solid-phase extraction on cyclohexyl bond elut cartridges. Chromatography was carried out on an octyl matrix. Triamcinolone acetonide was used as internal standard. The method was linear within the range of 5 to 200 microg/l pravastatin. The coefficient of variation depended on the pravastatin concentration, but was less than 10% throughout. The pharmacokinetics of pravastatin were determined in healthy individuals. Five healthy subjects received single oral doses of pravastatin (60 mg) and one of these subjects additionally received a dose of 80 mg at three different study days. In all subjects blood was sampled 0, 30, 60, 90, 120, 150, 180, 240 and 300 min after drug intake. RESULTS: Peak plasma concentrations of pravastatin were found between 60 min and 120 min after oral administration of 60 mg and reached values between 37 microg/l and 126 microg/l. The calculated AUCs were between 52 ng/ml x h and 311 ng/ml x h and the corresponding plasma elimination half-life times were between 95 min and 165 min. In all subjects plasma concentrations of pravastatin 5 hours after oral drug administration were near the detection limit of the method (5 microg/l). Intraindividually, there was only little variation in the kinetics of pravastatin. However, marked differences were encountered between the subjects studied. CONCLUSION: The data suggest that the determination of pravastatin plasma concentrations by means of a HPLC system can be used for routine analysis of pravastatin plasma concentrations. The obtained pharmacokinetic data in healthy individuals stand in ample agreement with the results of prior studies in which the concentrations of pravastatin were determined by other more sophisticated methods.     

Effect of oral administration of crude aqueous extract of garlic on pharmacokinetic parameters of isoniazid and rifampicin in rabbits

AIM: To study the effect of oral administration of crude aqueous extract of garlic for 14 days on pharmacokinetic parameters of isoniazid and rifampicin. MATERIALS AND METHODS: Crude extract was prepared according to the method described by Fromtling and Bulmer. The study was done on 16 New Zealand white rabbits, divided into two groups of 8 animals each for two drugs. Baseline pharmacokinetic parameters for single-dose isoniazid and rifampicin were calculated from plasma drug concentrations obtained at various time intervals after dosing. The animals were given garlic extract orally for 14 days. Pharmacokinetic parameters were calculated again as done previously. OBSERVATIONS: Administration of crude aqueous extract of garlic significantly altered the pharmacokinetic parameters for isoniazid. C(max) was reduced from 15.4 +/- 5.6 to 5.4 +/- 3.3 microg/ml. AUC((0-24)) was reduced from 76.7 +/- 25.0 to 34.3 +/- 19.2 microg/ml.h. No significant change in T(max), k(el) and AUC((0-)(alpha)) was seen. Pharmacokinetic parameters of rifampicin were not significantly altered by administration of garlic extract. CONCLUSIONS: Oral administration of garlic extract decreased the bioavailability of isoniazid significantly with no change in rate of elimination. Bioavailability of rifampicin is not significantly altered by garlic extract.     

A rapid and reliable solid-phase extraction--LC/MS/MS assay for the determination of two novel human leukocyte elastase inhibitors, SYN-1390 and SYN-1396, in rat plasma

A rapid and rugged solid-phase extraction-liquid chromatographic-electrospray tandem mass spectrometric method has been developed to quantitate two novel human leukocyte elastase inhibitors, SYN-1390 and SYN-1396, in rat plasma. A reversed-phase column and an isocratic mobile phase consisting of acetonitrile-water-formic acid (70:30:0.2, v/v/v) were used. The mass spectrometer was operated in the multiple reaction monitoring mode. For both analytes, standard curves were linear over a working range of 0.1-20 microg ml(-1) (r> or =0.995) and the limit of quantitation was 0.1 microg ml(-1) with a 150 microl plasma volume. This assay proved to be useful for the determination of SYN-1390 and SYN-1396 in plasma samples from pharmacokinetic study.