Quantitation of diltiazem and desacetyldiltiazem in dog plasma by high-performance liquid chromatography

A high-performance liquid chromatographic procedure was developed for the determination of diltiazem and desacetyldiltiazem in dog plasma. Two milliliters of plasma is extracted with a hexane-2-propanol mixture. The assay uses a reverse-phase column maintained at 55 degrees C with a silica saturation column and a pellicular precolumn. The mobile phase is acetonitrile-water (50:50) at pH 6.6 with 1.5-g/L heptanesulfonic acid added as the ion-pair reagent. The procedure is sensitive to 5 ng/mL for both compounds in dog plasma and is linear up to 2000 ng/mL for diltiazem and 1000 ng/mL for desacetyldiltiazem . Preliminary dog mean plasma profiles of diltiazem and desacetyldiltiazem are presented.     

Quantitation of amphotericins by reverse-phase high-performance liquid chromatography

A reverse-phase high-performance liquid chromatographic (HPLC) method was developed for simultaneous potency determination of amphotericin A and amphotericin B in bulk amphotericin B preparations. This single, rapid, specific, and simple method can be used for qualitative and quantitative analyses and is proposed to replace a combination of cumbersome official tests presently in use. This new HPLC method employs an isocratic acidic phosphate bufhotericin A and amphotericin B in bulk amphotericin B preparations. This single, rapid, specific, and simple method can be used for qualitative and quantitative analyses and is proposed to replace a combination of cumbersome official tests presently in use. This new HPLC method employs an isocratic acidic phosphate buffer-methanol mixture in a reverse mode on an octade-cylsilane-bonded silica column at ambient temperature, using UV detection at 313 nm. Results obtained by HPLC compare favorably with the official assay results. During these studies, an apparent heptaenic component, not previously described, was detected in commercial amphotericin B preparations at concentrations ranging from approximately 6 to 14%.     

Analysis of ritonavir in plasma/serum and tissues by high-performance liquid chromatography

A method has been developed to quantify ritonavir concentrations in human plasma and in mouse serum, liver, and brain using high-performance liquid chromatography. Extraction recoveries for ritonavir and its internal standard averaged greater than 95%. Within-day variability, expressed as a coefficient of variation, averaged 6% over the concentration range 0.5 μg/mL to 15 μg/mL ritonavir, and between-day variability averaged 5.6% over 5 μg/mL to 15 μg/mL ritonavir. The method was applied to quantitation of ritonavir in mouse serum and tissue. Measured values deviated less than 5% from the actual values in mouse serum, liver, and brain samples containing 5 μg/mL ritonavir. The slopes of calibration curves for extracted calf serum, mouse serum, mouse liver and mouse brain standards were nearly identical to the calibration slope of standards which were not extracted. All curves were linear through zero, and r² was no less than 0.998 for any form of calibration. In addition, there was no chromatographic interference from commonly prescribed medications.     

HPLC测定己酮可可碱氯化钠注射液

目的　建立HPLC法测定己酮可可碱氯化钠注射液中己酮可可碱含量的方法。方法　用十八烷基硅烷键合硅胶柱 (4 6× 15 0mm) ;以甲醇 -水 -冰醋酸 (4 5∶ 5 5∶5 )为流动相 ;检测波长为 2 74nm。结果　线性回归方程为 y =- 10 2 80 +392 975 2 1x ,r=0 9999,平均回收率为 10 0 4 0 %。结论　该法简便、准确、快捷 ,可用于该注射剂质量控制的方法     

Quantitation of acetazolamide in rat plasma, brain tissue and cerebrospinal fluid by high-performance liquid chromatography

A simple and sensitive high-performance liquid chromatographic method for the analysis of acetazolamide (AZ) in rat blood (plasma/serum, whole blood and serum ultrafiltrate), brain tissue and cerebrospinal fluid (CSF) was described. Quantitative extraction of AZ with ethyl acetate from both buffered plasma and brain tissue homogenate (pH 8.0) was achieved. Each extract was evaporated to dryness and the residue was chromatographed on a reversed-phase column. CSF was directly analysed without extraction step. The limits of detection were 0.05 μg ml⁻¹ for plasma, 0.02 μg g⁻¹ for brain tissue and 0.004 μg ml⁻¹ for CSF. Calibration curves were linear over the working ranges of 0.1–100 μg ml⁻¹ for plasma, 0.05–50 μg g⁻¹ for brain tissue and 0.025–50 μg ml⁻¹ for CSF. The reproducibility of AZ assay in the rat biologic media indicated very low relative standard deviations (RSDs). The recoveries of AZ added to plasma and brain tissue were more than 96% with an RSD of less than 5%. The present method was applied to studies of plasma concentration profiles of the drug after administration and its distribution into central nervous system.     

Quantitation of oxycodone in human plasma using high-performance liquid chromatography with electrochemical detection

An original, highly sensitive and specific high-performance liquid chromatographic (HPLC) assay has been developed for the measurement of oxycodone in human plasma with a detection limit of 10 ng/ml using a 1.0-ml plasma sample. Plasma samples were initially acid-washed and then extracted twice at pH 10 with butyl chloride. Oxycodone and codeine (internal standard) were eluted with a mixture of methanol, acetonitrile, and 0.01 M pH 7 phosphate buffer to which 40 mg/l of cetyltrimethylammonium bromide (cetavlon) was added at ambient temperature and detected with electrochemical detection. The addition of cetavlon to the mobile phase markedly reduced the interaction between oxycodone and Si-OH groups on the stationary phase of the HPLC column, so that the organic content of the mobile phase could be reduced from 80 to 25%. Quantitation was achieved using the peak height ratio of oxycodone to codeine. The assay is currently being used for the study of oxycodone pharmacokinetics after single oral doses of 10 and 20 mg and single rectal doses of 30 mg.     

Quantitation of thiothixene in plasma by high-performance thin-layer chromatography and fluorometric detection

A specific and sensitive assay procedure to measure thiothixene (Navane) in plasma has been developed and used to measure plasma concentrations in patients receiving thiothixene. The procedure involves in situ fluorescent detection after separation by high-performance thin-layer chromatography. Fluorescent detection permits a limit of detectability of approximately 0.1 ng/ml in plasma and the coefficient of variation is less than 6% at 2 ng/ml. Thirty samples may be processed through the entire procedure in less than 6-h period and up to 60 samples may be simultaneously spotted and chromatographed with a larger-capacity spotter and plate. Plasma levels (n = 62) drawn 10-12 h after dosage ranged from 0 to 42 ng/ml from dosages of 4-100 mg/day.     

Determination of ranitidine in plasma by high-performance liquid chromatography

A high-performance liquid chromatographic method has been developed for the determination of ranitidine in plasma. Ranitidine was extracted with acetonitrile by adding it to the plasma and then salting it out with potassium carbonate. The chromatographic column was 5-microns ODS silica, the mobile phase being acetonitrile-7 mM triethylammonium ion in phosphoric acid (pH 3.00) (30:70, v/v). The ranitidine peak was monitored at a wavelength of 315 nm, the retention time for ranitidine being 4.6 min. A limit of detection of 3 ng ml-1 was obtained for a 100-microliters injection of ranitidine. The method was found to be reproducible with a relative standard deviation (RSD) between 0.8-5.3% (n = 5) over the concentration range 25-80 ng ml-1 in plasma. The ranitidine concentration was determined in 18 different patients' plasmas. Ranitidine and its metabolites ranitidine S-oxide, ranitidine N-oxide and desmethyl-ranitidine, were also studied for chromatographic resolution from each other. It was shown that a group of common drugs did not interfere with ranitidine determination.     

Determination of sematilide in plasma by high-performance liquid chromatography

A method for the determination of sematilide levels in human plasma is described. After the addition of an internal standard, plasma samples are adjusted to pH 8.5 and extracted with a solution of 7.5% isopropanol in methylene chloride. Separation from co-extracted matrix constituents is performed by reversed-phase HPLC followed by UV detection at 254 nm. The assay is linear in the concentration range 12-2400 ng/mL when 0.5-mL aliquots of plasma are extracted. Application of the method to the analysis of samples obtained from eight healthy volunteers given an oral dose of 100 mg of sematilide hydrochloride is shown.     

HPLC法测定原位肝脏隔离灌注猪血浆中丝裂霉素的浓度

目的建立一种简单、快捷的反相高效液相色谱法(RP-HPLC)测定猪血浆中丝裂霉素C(MMC)浓度的方法.方法用LC-6AHPLC仪,以μBondapak C1 8 column(5μm,3.9×300mm)为分析柱;流动相为CH3CN:H2O(30:70),柱温25℃,检测波长365 nm,流速0.5 ml@min-1;血浆样品用乙酸乙酯分两次直接萃取.结果线性范围为0.1～8.0 mg@L-1,r=0.9998,n=5;提取回收率为(79.71±2.97)%;日内、日间变异均小于10%;最低检测浓度为0.05 mg@L.结论该法简便、快速、可靠、特异性强,适用于生物样品中MMC监测及药代动力学研究.     

Quantitation of adriamycin in plasma and urine: comparative study of radioimmunoassay and high-performance liquid chromatography methods

The response of tumours to adriamycin, and the cardiotoxicity of the drug, may be related to its pharmacokinetics and plasma levels. Rapid and sensitive methods of adriamycin determination in plasma and urine samples are thus needed. A comparative study shows that high-performance liquid chromatography with fluorimetric detection is a reliable and specific method, but it is relatively slow and sometimes lacks sensitivity. A commercially-available radioimmunoassay kit is convenient, but there is a cross reaction with the major metabolise adriamycinol and unless the assay is combined with an extraction step, it gives erroneously high results.     

高效液相色谱法测定人血浆中左布比卡因的浓度

目的建立高效液相色谱法测定人血浆中左布比卡因的浓度。方法以罗哌卡因为内标,色谱柱为Hypersil C_(18)柱(200 mm×4.6 mm,5μm),流动相采用0.01 mol·L~(-1)磷酸二氢钾-乙腈(87:13,V:V,pH=3.4),流速2.0 mL·min~(-1),检测波长为210 nm,柱温40℃。结果标准曲线方程为Y=0.310 1 X+ 0.008 9,r=0.999 7,左布比卡因的质量浓度在0.012 5～2 mg·L~(-1)范围内呈良好的线性关系,最低检测限为0.01 mg·L~(-1);方法回收率在96%～105%之间;日间、日内精密度RSD均<5%。结论本方法可用于临床上左布比卡因血药浓度的监测和药动学研究。     

高效液相色谱测定比格犬血浆中的头孢唑啉与头孢曲松的浓度

目的：建立HPLC在多项测定参数相同的基础上,分别测定比格犬血浆中头孢唑啉、头孢曲松浓度的方法。方法色谱柱：头孢唑啉为ES industries Epic C18（4．6 mm ×150 mm,5μm）,头孢曲松为Phenomenex Gemini C18（4．6 mm ×150 mm,5μm ）,流动相：头孢唑啉为甲醇－0．05 mol? L－1乙酸铵缓冲液（ pH＝4．3）＝30∶70;头孢曲松为乙腈－0．05 mol? L－1 KH2 PO4缓冲液（ pH＝6．0）＝6∶94,流速均为1．0 mL? min－1,进样量均为40μL。结果头孢唑啉标准曲线回归方程为 y ＝－1．25×104 x ＋8479．37（ r ＝0．9974）,头孢曲松为y＝1．25×104 x ＋2．72×104（ r ＝0．9976）。头孢唑啉线性范围为2～300μg? mL－1,头孢曲松为2～200μg? mL－1;日内、日间精密度相对标准偏差均≤10％,提取回收率均≥85．78％。结论本法灵敏、准确、快速,可用于比格犬血浆头孢唑啉、头孢曲松浓度的测定和药物其他方面研究。     

高效液相色谱法测定血浆中氟哌啶醇浓度

目的：建立高效液相色谱法测定血浆中氟哌啶醇浓度的方法。方法：以乙腈甲醇０ ．０２５ｍｏｌ／Ｌ 磷酸二氢钾（４５∶５∶５０ ,ｖ／ｖ） 为流动相,氯氟哌啶醇作内标,紫外波长２４８ｎｍ 处检测。结果：血浆中氟哌啶醇的最低检测浓度为０ ．５ｎｇ／ｍｌ,平均提取回收率为８６ ．６ ％ ±４ ．９ ％ ,线性范围１ ～５０ｎｇ／ｍｌ（ｒ ＝ ０ ．９９９８） ,日内和日间ＲＳＤ 分别小于８ ％ 和９ ％ 。结论：方法灵敏、快速、准确,可满足临床治疗药物的监测工作     

Determination of bergenin in rat plasma by high-performance liquid chromatography

A simple, sensitive, selective and reproducible reversed-phase high-performance liquid chromatography (HPLC) method was developed for the determination of bergenin in rat plasma after intravenous administration. Acetaminophen was successfully used, as internal standard (IS) for calibration. The chromatographic separation was accomplished on a reversed-phase C18 column using a mobile phase consisting of methanol-water (20:80, v/v, pH 2.50) and a detection wavelength of 275 nm. Retention times of bergenin and acetaminophen were approximately 9.9 and 6.1 min and no interfering peak of the blank plasma chromatograms was observed. Good linearity was achieved in the range of 0.3 - 100 microg/ml (r2 = 0.9998). The extraction recoveries of bergenin from plasma was 70.82%, 69.44%, 70.98% at concentrations of 5, 50, 100 microg/ml. Intra-assay and inter-assay variabilities were 0.92 - 2.60% and 2.31 - 2.95%, respectively. The accuracy was validated by relative error (RE%), which was in the range of -0.05 - 1.74%. The capability of the assay to pharmacokinetic studies was demonstrated by the determination of bergenin in plasma after intravenous administration to rats in doses of 7.5 mg/kg, 15.0 mg/kg, and 30.0 mg/kg, using water as the solvent. The half-lives for distribution and elimination are not related to administered doses. A biphasic phenomenon with a rapid distribution followed by a slower elimination phase was observed from the plasma concentration-time curve and the pharmacokinetics was based on first order kinetics.     

Simplified assay of amrinone in plasma by high-performance liquid chromatography

An isocratic high-performance liquid chromatography method for the assay of plasma amrinone is described. Plasma amrinone is extracted using protein precipitation with an internal standard, separated with a reverse phase column, and detected using ultraviolet absorption. Each run is completed within 10 min. The assay can detect amrinone concentrations between 0.5 and 10.0 micrograms/ml, within the accepted therapeutic range. The assay has a within-day coefficient of variation of less than 5% and a day-to-day coefficient of variation of less than 10% in the therapeutic range of amrinone. This technique is an accurate, simple, and rapid method for the determination of amrinone concentrations in plasma.     

Determination of linezolid in plasma by reversed-phase high-performance liquid chromatography

An HPLC-UV method was developed for assay of linezolid in dog, rat, mouse, and rabbit plasma. Linezolid and the internal standard were extracted on a solid phase cartridge (SPE) and separated on a reversed-phase column (C8, 4.6x150 mm, 5 microm) with 20% acetonitrile in water as mobile phase. The SPE quantitatively recovered linezolid and the internal standard from plasma samples. The chromatographic peak height ratio or peak area ratio based on UV absorbency at 251 nm was used for quantitative analysis. The assay procedures were simple and the assay was specific and had adequate precision and accuracy. Calibration standards with concentrations over the range of 0.01 20 microg/ml were validated for routine sample analysis to support the pharmacokinetic and toxicology studies with linezolid in dog, rat, mouse, and rabbit. Analysis of quality control samples showed the coefficients of variation were usually <10% and the measured and theoretical concentrations differed by <10% in most assays. Linezolid in the plasma samples was stable when stored at below -20 degrees C for at least 63 days, at room temperature (22-23 degrees C) for up to 24 h, and after three freeze-thaw cycles. This HPLC method has been successfully used in multiple laboratories to assay plasma samples from pharmacokinetic and toxicology studies with linezolid in the animal species.     

Quantification of faropenem in human plasma by high-performance liquid chromatography

A simple, sensitive and specific high-performance liquid chromatography (HPLC) method with ultraviolet detection (315 nm) was developed and validated for quantitation of faropenem (CAS 106560-14-9), the newest addition to the group of beta-lactam antimicrobials, in human plasma. Following solid-phase extraction using Waters Oasis SPE cartridges, the analyte and internal standard (hydrochlorothiazide, CAS 58-93-5) were separated using an isocratic mobile phase of 10 mmol/L acetate buffer (pH adjusted to 7.0 with dilute acetic acid) / methanol / triethyl amine (70/30/0.03, v/v/v) on reverse phase Waters symmetry C18 column. The lower limit of quantitation was 200 ng/mL, with a relative standard deviation of less than 2 %. A linear range of 200 to 25000 ng/mL was established. This HPLC method was validated with between-batch and within-batch precision of 1.6 to 2.3 % and 0.4 to 1.6 %, respectively. The between-batch and within-batch bias was -3.1 to 5.3 % and -6.0 to 1.5 %, respectively. Frequently coadministered drugs did not interfere with the described methodology. The stability of faropenem in plasma was excellent, with no evidence of degradation during sample processing (autosampler) and 30 days storage in a freezer. This validated method is sensitive, simple and repeatable enough to be used in pharmacokinetic studies.