Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A sensitive and rapid liquid chromatography-tandem mass spectrometry method has been developed for to assess therapeutic exposures of aprepitant in HIV-infected patients and rhesus macaques. The method utilized a simple sample-preparation procedure of protein precipitation with methanol. Chromatographic separation was performed on a reversed phase C(8) column (Hypersil Gold, 50 mm x 2.1 mm, 3 microm) using a mobile phase composed of acetonitrile and water in 0.5% formic acid through gradient elution. Electro-spray ionization in positive mode was incorporated in the tandem mass spectrometric detection. The lower limit of quantitation of aprepitant in plasma of rhesus macaques and human and cerebral spinal fluid of rhesus macaques were 1, 1, and 0.1 ng/mL, respectively. The method has been successfully employed to measure aprepitant in preclinical and clinical samples collected from three SIV-infected rhesus macaques and ten patients with HIV infection. In conclusion, this liquid chromatography-tandem mass spectrometry method is suitable for preclinical-clinical translational research exploring exposure-response relationships with aprepitant as well as therapeutic drug monitoring of aprepitant.
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PMID:A sensitive and rapid liquid chromatography-tandem mass spectrometry method for the quantification of the novel neurokinin-1 receptor antagonist aprepitant in rhesus macaque plasma, and cerebral spinal fluid, and human plasma with application in translational NeuroAIDs research. 1916 82

The purpose of this study was to develop reversed-phase HPLC method for the simultaneous determination of the flavonoids from the leaves of Nelumbo nucifera, which have been known to exhibit antioxidant, anti-HIV, antihyperlipidemic and antiobesity effects. HPLC separation was achieved on C(18) column using gradient elution with mobile phase consisting of acetonitrile-water containing 0.1% formic acid. The separated peaks were identified by electrospray ionization mass spectrometry. The HPLC method was validated and applied for the simultaneous determination of the bioactive flavonoids from the leaves of Nelumbo nucifera. In the methanol extract, six flavonoids, quercetin, rutin, quercetin 3-O-beta-D-galactopyranoside (Qc-3-Gal), quercetin 3-O-beta-D-glucopyranoside (Qc-3-Glc), quercetin 3-O-beta-D-glucuronide (Qc-3-Gln) and quercetin 3-O-alpha-arabinopyranosyl-(1-->2)-beta-galactopyranoside (Qc-3-AraGal), were identified. Among them, Qc-3-Glc and Qc-3-Gln were found to be major component in the methanol extract of Nelumbo nucifera leaves.
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PMID:Simultaneous determination of quercetin and its glycosides from the leaves of Nelumbo nucifera by reversed-phase high-performance liquid chromatography. 1928 Jan 49

Therapeutic drug monitoring is pivotal to improve the management of HIV infection. Here, a new HPLC-UV method to quantify simultaneously maraviroc and raltegravir levels in human plasma is reported. Remarkably, this is the first method for maraviroc determination in human plasma. The volume of the plasma sample was 600 microL. This method involved automated solid-phase extraction with Oasis HLB Cartridge 1 cc (30 mg divinylbenzene and N-vinylpyrrolidone) and evaporation in a water bath under nitrogen stream. The extracted samples were reconstituted with 200 microL 50/50 of mobile-phase solution (0.01 M KH(2)PO(4) and acetonitrile). Twenty microliters of these samples were injected into a HPLC-UV system, the analytes were eluted on an analytical dC18 Atlantis column (150 mm x 4.6 mm I.D.) with a particle size of 5 microm. The mobile phase (0.01 M KH(2)PO(4) and acetonitrile) was delivered at 1.0 mL/min with isocratic elution. The total run time for a single analysis was 10 min; maraviroc and raltegravir were detected by UV at 197 and 300 nm. The calibration curves were linear up to 2,500 ng/mL. The absolute recovery ranged between 93 and 100%. The HPLC-UV method reported here has been validated and is currently applied to monitor plasma levels of maraviroc and raltegravir in HIV-infected patients.
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PMID:Simultaneous determination of maraviroc and raltegravir in human plasma by HPLC-UV. 1931 71

Raltegravir (RAL), maraviroc (MVC), darunavir (DRV), and etravirine (ETV) are new antiretroviral agents with significant potential for drug interactions. This work describes a sensitive and accurate liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of plasma drug levels. Single-step extraction of RAL, MVC, DRV, ETV and RTV from plasma (100 microl) is performed by protein precipitation using 600 microl of acetonitrile, after the addition of 100 microl darunavir-d(9) (DRV-d(9)) at 1000 ng/ml in MeOH/H(2)O 50/50 as internal standard (I.S.). The mixture is vortexed, sonicated for 10 min, vortex-mixed again and centrifuged. An aliquot of supernatant (150 microl) is diluted 1:1 with a mixture of 20 mM ammonium acetate/MeOH 40/60 and 10 microl is injected onto a 2.1 x 50 mm Waters Atlantis-dC18 3 microm analytical column. Chromatographic separations are performed using a gradient program with 2 mM ammonium acetate containing 0.1% formic acid and acetonitrile with 0.1% formic acid. Analytes quantification is performed by electrospray ionisation-triple quadrupole mass spectrometry using the selected reaction monitoring detection in the positive mode. The method has been validated over the clinically relevant concentrations ranging from 12.5 to 5000 ng/ml, 2.5 to 1000 ng/ml, 25 to 10,000 ng/ml, 10 to 4000 ng/ml, and 5 to 2000 ng/ml for RAL, MRV, DRV, ETV and RTV, respectively. The extraction recovery for all antiretroviral drugs is always above 91%. The method is precise, with mean inter-day CV% within 5.1-9.8%, and accurate (range of inter-day deviation from nominal values -3.3 to +5.1%). In addition our method enables the simultaneous assessment of raltegravir-glucuronide. This is the first analytical method allowing the simultaneous assay of antiretroviral agents targeted to four different steps of HIV replication. The proposed method is suitable for the Therapeutic Drug Monitoring Service of these new regimen combinations administered as salvage therapy to patients having experienced treatment failure, and for whom exposure, tolerance and adherence assessments are critical.
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PMID:A LC-tandem MS assay for the simultaneous measurement of new antiretroviral agents: Raltegravir, maraviroc, darunavir, and etravirine. 1933 96

A pharmacokinetic interaction study between efavirenz (EFV), a non-nucleoside reverse transcriptase inhibitor used in the treatment of HIV-1 infection, and an African traditional medicine, African potato in human subjects was undertaken. This necessitated the development and validation of a quantitative method for the analysis of EFV in plasma. A simple mobile phase consisting of 0.1M formic acid, acetonitrile and methanol (43:52:5) was pumped at a low flow rate of 0.3 ml/min through a reverse phase Phenomenex Luna C(18) (2) (5 microm, 150 mm x 2.0mm i.d.) column maintained at 40 degrees C. Diclofenac sodium was used as an internal standard (IS) and EFV and IS were monitored at 247 nm and 275 nm, respectively. A simple and rapid sample preparation involved the addition of mobile phase to 100 microl of plasma to precipitate plasma proteins followed by direct injection of 10 microl of supernatant onto the column. The procedures were validated according to international standards with good reproducibility and linear response (r=0.9990). The intra- and inter-day accuracies were between 12.3 and 17.7% at the LLOQ and between -5.8 and 9.1% for the QC samples. The intra- and inter-day precision of EFV determinations were 5.1 or less and 7.2% RSD or less, respectively across the entire QC concentration range. Mean recovery based on high, medium and low quality control standards ranged between 92.7 and 94.1% with %RSD values better than 3%. Plasma samples were evaluated for short-term (ambient temperature for 6h) and long-term (-10+/-2 degrees C for 60 days) storage conditions and were found to be stable. The method described is cost-effective and has the necessary accuracy and precision for the rapid quantitative determination of EFV in human plasma.
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PMID:Rapid method for the quantitative determination of efavirenz in human plasma. 1937 62

An LC/MS/MS assay we published for tenofovir (TFV) plasma levels is a useful tool for monitoring the pharmacotherapy of HIV-positive individuals [T. Delahunty, L. Bushman, C.V. Fletcher, J. Chromatogr. B 830 (2006) 6-12]. A new combination therapy consisting of the TFV pro-drug (300 mg) and another reverse transcriptase inhibitor, emtricitabine (FTC, 200 mg) has become available in a convenient once-daily dosage form (Truvada). This widely used medication has prompted us to develop and validate a convenient assay to determine simultaneously TFV and FTC plasma concentrations. In view of their chemical similarity to the analytes, stable isotope internal standards (IS) were chosen. These consisted of TFV labeled uniformly with (13)C in the adenine moiety (Iso-TFV) and FTC labeled with 13C and 15N in the cytosine moiety (Iso-FTC). Trifluoroacetic acid was added to the patient's EDTA plasma (containing the IS) to produce a de-proteinated extract after high speed centrifugation. The extracts were directly injected into the mobile phase (3% acetonitrile/1% acetic acid, aq.) stream flowing at 200 microL/min. A Synergi Polar-RP, 2.0 mm x 150 mm, reversed-phase analytical column was used to achieve the chromatographic separation. Detection of the analytes was achieved by ESI positive ionization tandem mass spectrometry. The precursor/product transitions (m/z) in the positive ion mode were 288/176 and 293/181 ions for TFV and Iso-TFV, respectively and the precursor/product transitions (m/z) were 248/130 and 251/133 ions for FTC and Iso-FTC, respectively. When the analyte/IS abundance ratios were plotted against the specified concentrations, the linearity of the concentration curves were in the range 10 ng/mL to 1500 ng/mL for both analytes (250 microL plasma extracted), with a minimum quantifiable limit of 10 ng/mL for both analytes. The inter- and intra-day accuracy and precision for both TFV and FTC were within +/-20% at the LLOQ and +/-15% at the other QC levels. We have expanded the method originally designed for the assay of TFV alone to incorporate the simultaneous determination of the latter and FTC using stable isotope IS. This assay has been successfully used for the periodic monitoring of 678 HIV-positive patients being treated with the combination therapy.
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PMID:The simultaneous assay of tenofovir and emtricitabine in plasma using LC/MS/MS and isotopically labeled internal standards. 1949 10

Lopinavir and ritonavir are co-formulated in Kaletra approved for the treatment of human immunodeficiency virus infection. A validated analytical method is mandatory for clinical development and therapeutic drug monitoring. Here we are reporting a method for rapid, simultaneous determination of lopinavir and ritonavir in human plasma with stacked protein precipitations and salting-out assisted extraction (SALLE), and ultrafast LC-MS/MS detection. With stacked protein precipitations and SALLE, the sample preparation for a 96-well plate can be completed within 20 min by an automated pipette. Due to the unique cleanliness of SALLE extracts post double protein precipitations, the extracts were injected into an ultrafast liquid chromatography and tandem mass spectrometry system (LC-MS/MS) after simple dilution. An Agilent Zobax Extend-C18 Rapid resolution HT column (1.8 microm, 2.1 mm x 30 mm) was used for the separation. A mixture of acetonitrile:water (55:45, v/v) with 0.1% formic acid was used as the mobile phase. LC ran for approximately 48 s at a flow rate of 0.5 mL min(-1), tandem mass spectrometric data collection started at 15 s and lasts for 30 s. The method was validated with reference to Industry Guidance for Bioanalytical Method Validation and then used for clinical samples. The method is ultrafast, and robust. Results of incurred samples demonstrated excellent method of reproducibility. This ultrafast analysis speed did not compromise with the data quality. To our knowledge, this is the fastest analytical method for simultaneous determination of lopinavir and ritonavir.
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PMID:Rapid, simultaneous determination of lopinavir and ritonavir in human plasma by stacking protein precipitations and salting-out assisted liquid/liquid extraction, and ultrafast LC-MS/MS. 1973 44

Maraviroc is the first commercialized CCR5 inhibitor for HIV therapy. A new high-performance liquid chromatography-ultraviolet method to quantify maraviroc concentrations in human plasma was developed and validated. The method is based on a protein precipitation procedure, with an acidic solution of acetonitrile (trifluoroacetic acid 0.1%) and quinoxaline as internal standard. The analytes were eluted using a gradient run in 15 minutes on an analytical C18 Luna column (150 mm x 4.6 mm ID) with a particle size of 5 mum. Maraviroc and internal standard were detected by UV at 193 nm and 352 nm, respectively. The calibration curve was linear up to 2500 ng/mL. The mean recovery of maraviroc was 96%. All validation data were in accordance with U.S. Food and Drug Administration requirements. The new high-performance liquid chromatography-ultraviolet method reported here could be used routinely to monitor plasma concentrations of maraviroc in healthy volunteers and HIV-infected patients.
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PMID:A validated high-performance liquid chromatography-ultraviolet method for quantification of the CCR5 inhibitor maraviroc in plasma of HIV-infected patients. 2004 Aug 98

Clinical pharmacokinetic studies of antiretrovirals require accurate and precise measurement of plasma drug concentrations. Here we describe a simple, fast and sensitive HPLC-MS/MS method for determination of the commonly used protease inhibitors (PI) amprenavir, atazanavir, darunavir, lopinavir, ritonavir, saquinavir and the non-nucleoside reverse transcriptase inhibitor (NNRTI) nevirapine, as well as the more recent antiretrovirals, the CCR5 antagonist maraviroc and the "second generation" NNRTI etravirine and rilpivirine. An internal standard (quinoxalone; QX) was added to plasma aliquots (100 microl) prior to protein precipitation with acetonitrile (500 microl) followed by centrifugation and addition of 0.05% formic acid (200 microl) to the supernatant. Chromatographic separation was achieved using a gradient (acetonitrile and 0.05% formic acid) mobile phase on a reverse-phase C18 column. Detection was via selective reaction monitoring (SRM) operating in positive ionization mode on a triple-quadrupole mass spectrometer. All compounds eluted within a 5 min run time. Calibration curves were validated over concentration ranges reflecting therapeutic concentrations observed in HIV-infected patients from pharmacokinetic data reported in the literature. Correlation coefficients (r2) exceeded 0.998. Inter- and intra-assay variation ranged between 1% and 10% and % recovery exceeded 90% for all analytes. The method described is being successfully applied to measure plasma antiretroviral concentrations from samples obtained from clinical pharmacokinetic studies.
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PMID:Validation of a rapid and sensitive high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) assay for the simultaneous determination of existing and new antiretroviral compounds. 2042 48

Using polystyrene as a fabrication material and pure acetonitrile as a bonding solvent, we have developed an innovative and inexpensive weak-solvent-based chip lamination process to produce highly functional, completely plastic, microfluidic chips with a 3-layer structure. This simple, scalable and rapid method allows active components, such as multiple valves and pumps, to be constructed on chip with a thin, deflectable film as the middle layer sandwiched between two polystyrene layers. Our irreversible bonding method achieves uniform lamination under mild conditions (35-45 degrees C and 10-50 KPa) without damage to the underlying micro-features. The on-chip valve and pump structures have been systematically characterized and the pumping rate has been compared against theoretical rates predicted by mathematical modeling studies. A wide range of pumping rates (0.33-10 microL/s) can be achieved, with the integral pumps maintaining a constant pumping rate and depending on pumping frequency and pump diaphragm size. Valve leakage of less than 0.02 microL/min is noted under pressures of 41 kPa. Utilizing various configurations of on-chip valves and pumps, the fully automated flow control of an integrated chip for sample lysis, nucleic acid purification and PCR is demonstrated. The present technology and chip have been heavily evaluated internally and externally for rapid biomedical diagnosis of HPV, HIV, etc., and they are currently in the process of commercialization.
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PMID:Weak solvent based chip lamination and characterization of on-chip valve and pump. 2052 80


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