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Topoisomerase I (Topo I) is a recognized target for ovarian, lung, and colorectal cancer therapy. The FDA-approved camptothecin (CPT) Topo I inhibitors, topotecan and irinotecan are labile and their effects are rapidly reversible. The indenoisoquinoline topoisomerase I inhibitors, NSC 743400 and NSC 725776, have been developed as a new generation of Topo I inhibitors and are being advanced to clinical evaluation. To support the clinical development of NSC 743400 and NSC 725776, we developed and validated, according to FDA guidelines, LC-MS/MS assays for the sensitive, accurate and precise quantitation of NSC 743400 and NSC 725776 in 0.2 mL human plasma. After ethyl acetate extraction, separation was achieved with a Synergi Polar RP column and a gradient of 0.1% formic acid in acetonitrile:water. NSC 743400 and NSC 725776 eluted at approximately 3 min, and the total run time was 14 min. Detection consisted of electrospray, positive-mode ionization mass spectrometry. Between 3 and 1000 ng/mL, accuracy was 96.9-108.2% for NSC 743400 and 95.1-106.7% for NSC 725776, and precision was <11.4% for NSC 743400 and <5.9% for NSC 725776. Extraction recovery was >80% for both analytes, and ion suppression ranged from -46.7 to 5.7%. The use of isotopically labeled internal standards and a wash phase at the end of the run were necessary to achieve adequate assay performance. Protein binding in human plasma as assessed by equilibrium dialysis showed both indenoisoquinolines to be more than 98% protein bound., (2010 Elsevier B.V. All rights reserved.)

A robust and sensitive ultra-low flow liquid chromatography (UFLC) method that can reproducibly, at reasonable cost, detect low concentrations of piperine from human plasma is necessary. Piperine in plasma was separated and quantified by a gradient method using ultraviolet detection at a maximal absorbance wavelength of 340 nm. An aliquot was injected onto a reversed-phase column Waters SymmetryShield, 2.1 x 100 mm, 3.5 microm, C(18) column, attached to a Waters absorbosphere, 4.6 x 30 mm, C(18) guard column and eluted with a mobile phase containing a mixture of acetonitrile/water/acetic acid (25:74.9:0.1, v/v/v) on line A and acetonitrile/acetic acid (99.9:0.1, v/v) on line B. The flow rate was 0.3 mL/min. The gradient method consisted of an opening condition of 20% pump B, with a linear increase to 37% pump B over 8 min, then a linear increase to 100% pump B at 11 min, 2 min at 100% pump B, and then a return to the opening condition (20% pump B) via a linear gradient over 2 min, followed by 5 min re-equilibration at opening conditions. The total run time was 20 min for each sample. All samples were processed protected from ambient light to avoid isomerization of piperine. The plasma assay was linear with R = 0.9995, with a lower limit of detection [signal-to-noise (S/N) > 5:1] of 100 pg of piperine loaded into the analytical system with acceptable accuracy and precision. Extraction recoveries of piperine from human plasma were 88% for quality control high (QCH), 93% for quality control medium (QCM), and 90% for quality control low (QCL), and the matrix effect was <12%. Piperine was quantifiable from a 50 mg oral dose given to human volunteers. A UFLC method for the rapid assay of human plasma with sensitivity to detect as low as 5 ng/mL piperine was developed. The method sensitivity equals that of liquid chromatography/tandem mass spectrometry (LC/MSMS) methods with much less cost.

In the present investigation, a UPLC-qTOF-MS/MS method has been developed for the simultaneous determination of etoposide and a piperine analogue, namely, 4-ethyl 5-(3,4-methylenedioxyphenyl)-2E,4E-pentadienoic acid piperidide (PA-1). The analytes were separated on a reverse phase C18 column using methanol-water (72:28, v/v) mobile phase with a flow rate of 250 microL/min. The qTOF-MS was operated under multiple reaction monitoring mode using electro-spray ionization (ESI) technique with positive ion polarity. The major product ions for etoposide and PA-1 were at m/z 185.1350 and 164.1581, respectively. The recovery of the analytes from mouse plasma was optimized using solid phase extraction technique. The total run time was 6 min and the elution of etoposide and PA-1 occurred at 1.24 and 2.84 min, respectively. The calibration curves of etoposide as well as PA-1 were linear over the concentration range of 2-1000 ng/mL (r(2), 0.9829), and 1-1000 ng/mL (r(2), 0.9989), respectively. For etoposide intra-assay and inter-assay accuracy in terms of % bias was in between -7.65 to +6.26, and -7.83 to +5.99, respectively. For PA-1 intra-assay and inter-assay accuracy in terms of % bias was in between -7.01 to +9.10, and -7.36 to +6.71, respectively. The lower limit of quantitation for etoposide and PA-1 were 2.0 and 1.0 ng/mL, respectively. Analytes were stable under various conditions (in autosampler, during freeze-thaw, at room temperature, and under deep-freeze conditions). The method was used for a pharmacokinetic study which showed that PA-1 enhanced the oral bioavailability of etoposide in mice by 2.32-fold., (2010 Elsevier B.V. All rights reserved.)

Laetispicine, which is a novel amide alkaloid isolated from the stem of Piper laetispicum, has been proven to possess antidepressant and antinociceptive effects. This study examined the pharmacokinetic characteristics of laetispicine in plasma and brain distribution in rats by a simple sensitive HPLC-UV method. The separation was performed on a reverse-phase ODS column (250 mm x 4.6 mm, i.d., 5 microm) with a mobile phase composed of acetonitrile-water (75:25, v/v) as the mobile phase at a flow rate of 1.0 ml/min with UV detection at 259 nm. The calibration curve of laetispicine in rat plasma showed excellent linear behavior between 0.005-5.0 microg/ml (r2 = 0.9992), and between 0.02-0.5 microg/ml (r2 = 0.9952) in rat brain samples. The lower limit of quantification (LLOQ) was found to be 0.005 microg/ml in rat plasma and 0.02 microg/ml in rat brain samples. This HPLC assay was a precise and reliable method for the analysis of laetispicine in pharmacokinetic studies. Laetispicine was rapidly and extensively transported across the blood-brain barrier (BBB) and distributed into different brain regions.

Brecanavir (BCV) is a novel, potent protease inhibitor in development for the treatment of human immunodeficiency virus (HIV-1) infection with low nM in vitro 50% inhibitory concentrations (IC50s) against many multiprotease inhibitor resistant viruses. This study was a double-blind, randomized, placebo-controlled repeat-dose escalation to evaluate the safety, tolerability, and pharmacokinetics of BCV, with or without ritonavir (RTV), in 68 healthy subjects. Seven sequential cohorts (n=10) received BCV (50 to 600 mg) in combination with 100 mg RTV (every 12 h [q12h] or q24h) or alone at 800 mg q12h for 15 days. BCV alone or in combination with RTV was well tolerated, with no serious adverse events reported. The most common drug-related adverse event was headache. BCV was readily absorbed with median time to maximum concentration of drug in serum values ranging from 2.5 to 5.0 h postdose following single- and repeat-dose administration of BCV alone and BCV with RTV 100 mg. Geometric mean BCV accumulation ratios ranged from 1.4 to 1.56 following BCV-RTV q24h regimens and from 1.84 to 4.93 following BCV q12h regimens. BCV steady state was generally achieved by day 13 in all groups. All day 15 BCV-RTV trough concentration values in q12h regimens reached or surpassed the estimated protein-binding corrected in vitro IC50 target BCV concentration of 28 ng/ml for highly resistant isolates. The pharmacokinetic and safety profile of BCV-RTV supports continued investigation in HIV-1-infected subjects.

Brecanavir (BCV, 640385) is a novel, potent protease inhibitor (PI) with low nanomolar 50% inhibitory concentrations against PI-resistant human immunodeficiency virus (HIV) in vitro. This phase I, double-blind, randomized, placebo-controlled, two-part single-dose study (first time with humans) was conducted to determine the safety, tolerability, and pharmacokinetics of BCV administered at 10 mg/ml in a tocopherol-polyethylene glycol succinate-polyethylene glycol 400-ethanol 50:40:10 solution. In part 1 of the study, single oral doses of BCV ranged from 25 mg to 800 mg. In part 2, single oral doses of BCV ranged from 10 mg to 300 mg and were coadministered with 100-mg oral ritonavir (RTV) soft gel capsules. Single doses of BCV and BCV/RTV were generally well tolerated. There were no severe adverse events (SAEs), and no subject was withdrawn due to BCV. The most commonly reported drug-related AEs during both parts of the study combined were gastrointestinal disturbances (similar to placebo) and headache. BCV was readily absorbed following oral administration with mean times to maximum concentration from >1 h to 2.5 h in part 1 and from 1.5 h to 3 h in part 2. Administration of BCV without RTV resulted in BCV exposures predicted to be insufficient to inhibit PI-resistant virus based on in vitro data. Coadministration of 300 mg BCV with 100 mg RTV, however, significantly increased the plasma BCV area under the concentration-time curve and maximum concentration 26-fold and 11-fold, respectively, achieving BCV concentrations predicted to inhibit PI-resistant HIV.