Differential effects of metformin-mediated BSEP repression on pravastatin and bile acid pharmacokinetics in humans: A randomized controlled trial.

Metformin has been shown to repress transcription of the bile salt export pump (BSEP) in human primary hepatocytes. The primary objective of this study was to assess the effect of oral metformin on the human pharmacokinetics (PKs) of two BSEP probe substrates: pravastatin and chenodeoxycholic acid (CDCA; also known as chenodiol). Endogenous bile acid levels were assessed as a secondary measure of metformin impact. An open-label, randomized, single-dose, placebo-controlled, fasted, crossover PK study was conducted in 12 healthy adult volunteers. Metformin (500 mg b.i.d.) or placebo (b.i.d.) was administered orally for 6 days. On day 7, a single dose of the BSEP substrates pravastatin (80 mg) and CDCA (250 mg) were administered orally. Plasma samples were quantified for pravastatin, CDCA, and endogenous bile acids. Compared to placebo, metformin increased pravastatin plasma exposure, did not impact CDCA plasma exposure, and reduced conjugated primary bile acid levels in the blood. These results are consistent with metformin repressing BSEP expression. This differential effect reflects the degree of enterohepatic recirculation of victim substrates.

Lack of an Effect of Polysorbate 80 on Intestinal Drug Permeability in Humans.

PURPOSE: Despite no broad, direct evidence in humans, there is a potential concern that surfactants alter active or passive drug intestinal permeation to modulate oral drug absorption. The purpose of this study was to investigate the impact of the surfactant polysorbate 80 on active and passive intestinal drug absorption in humans. METHODS: The human (n = 12) pharmacokinetics (PK) of three probe substrates of intestinal absorption, valacyclovir, chenodeoxycholic acid (CDCA), and enalaprilat, were assessed. Endogenous bile acid levels were assessed as a secondary measure of transporter and microbiota impact. RESULTS: Polysorbate 80 did not inhibit peptide transporter 1 (PepT1)- or apical sodium bile acid transporter (ASBT)-mediated PK of valacyclovir and CDCA, respectively. Polysorbate 80 did not increase enalaprilat absorption. Modest increases in unconjugated secondary bile acid Cmax ratios suggest a potential alteration of the in vivo intestinal microbiota by polysorbate 80. CONCLUSIONS: Polysorbate 80 did not alter intestinal membrane fluidity or cause intestinal membrane disruption. This finding supports regulatory relief of excipient restrictions for Biopharmaceutics Classification System-based biowaivers.

Simultaneous quantification of lidocaine and prilocaine in human plasma by LC-MS/MS and its application in a human pharmacokinetic study.

OBJECTIVE: The aim of the work was to develop and validate a simple, sensitive and selective Liquid chromatography with Mass spectroscopic method for simultaneous quantification of lidocaine and prilocaine in human plasma. DESIGN AND METHODS: Analytes and the internal standards from human plasma were extracted by using solid- phase extraction technique using Waters Oasis® HLB 1 â€‹cc (30 â€‹mg) cartridges. The reconstituted samples were chromatographed on Phenomenex Kinetex EVO 4.6*100 â€‹mm 2.6 µ 100A column by using a mixture of acetonitrile and 5 â€‹mM ammonium acetate buffer (80:20, v/v) as the mobile phase at a flow rate of 0.6 â€‹mL/min. RESULTS: The method was validated over the concentration range of 0.10-201.80 ng/mL for lidocaine and 0.10-201.66 ng/mL for prilocaine. The calibration curve obtained was linear. CONCLUSION: Method validation was performed as per FDA guidelines and the results met the acceptance criteria. A run time of 3.0 min for each sample, make it possible to analyze more than 350 human plasma samples per day. The proposed method was found applicable for pharmacokinetic studies.

Bioanalytical technique for determination of tasimelteon in human plasma by LC-MS/MS and its application to pharmacokinetic study in humans.

A highly sensitive, specific and rapid liquid chromatography-tandem mass spectrometry technique for the quantification of tasimelteon in human plasma has been developed and validated using tasimelteon-d5 as internal standard. Liquid-liquid extraction technique with ethyl acetate was used for extraction of tasimelteon from the plasma. The chromatographic separation was achieved on an Agilent Zorbax, Eclipse, C18 (4.6 × 50 mm, 5 µm) column using a mobile phase of acetonitrile and 0.02% formic acid buffer (85:15, v/v) with a flow rate of 0.5 mL/min. A detailed method validation was performed as per the United States Food and Drug Administration guidelines. The linear calibration curve was obtained over the concentration range 0.30-299 ng/mL. The API-4000 liquid chromatography-tandem mass spectrometry was operated under multiple reaction monitoring mode during analysis. The validated method was successfully applied to estimate plasma concentration of tasimelteon after oral administration of a single dose of a 20 mg capsule in healthy volunteers under fasting conditions. The maximum concentration of the drug achieved in the plasma was 314 ± 147 ng/mL and the time at which this concentration was attained was 0.54 ± 0.22 h.

Liquid chromatography-tandem mass spectrometric assay for the light sensitive calcium channel antagonist lacidipine in human plasma.

A novel, rapid and sensitive liquid chromatography/tandem mass spectrometry method was developed and validated for the quantification of calcium channel antagonist lacidipine in human plasma. Carbamazepine was used as an internal standard. Analyte and the internal standard were extracted from human plasma by solid-phase extraction technique. The reconstituted samples were chromatographed on a C(18) column by using a mixture of acetonitrile-ammonium acetate buffer (5 mM) (80:20, v/v) as the mobile phase at a flow rate of 1.0 mL/min. The calibration curve obtained was linear (r(2)≥0.9990) over the concentration range of 0.05-12.5 ng/mL. The multiple reaction-monitoring mode was used for quantification of ion transitions at m/z 456.2/354.2 and 237.1/194.1 for the drug and the internal standard, respectively. The results of the intra- and inter-day precision and accuracy studies were well within the acceptable limits. A run time of 2.2 min for each sample made it possible to analyze more than 300 plasma samples per day. The proposed method was found to be applicable to clinical studies.

A rapid and sensitive liquid chromatography-tandem mass spectrometric assay for moexipril, an angiotensin-converting enzyme inhibitor in human plasma.

A simple, rapid and sensitive liquid chromatography/tandem mass spectrometry method was developed and validated for the quantification of angiotensin-converting enzyme inhibitor, moexipril, in human plasma. Benazepril was used as an internal standard (IS). Analyte and IS were extracted from the human plasma by liquid-liquid extraction technique using ethyl acetate. The reconstituted samples were chromatographed on a C18 column by using a mixture of methanol and 0.1% formic acid buffer (85:15, v/v) as the mobile phase at a flow rate of 0.5 mL/min. The calibration curve obtained was linear (r ≥ 0.99) over the concentration range of 0.2-204 ng/mL. The multiple reaction-monitoring mode was used for quantification of ion transitions at m/z 499.4/234.2 and 425.2/351.1 for moexipril and IS, respectively. The results of the intra- and inter-day precision and accuracy studies were well within the acceptable limits. A run time of 2.0 min for each sample made it possible to analyze more than 400 plasma samples per day. The proposed method was found to be applicable to clinical studies.

Simultaneous determination of losartan, losartan acid and amlodipine in human plasma by LC-MS/MS and its application to a human pharmacokinetic study.

INTRODUCTION: A simple, rapid and sensitive liquid chromatography-tandem mass spectrometric assay method has been developed and fully validated for simultaneous quantification of losartan and its active metabolite, losartan carboxylic acid, and amlodipine in human plasma. Irbesartan was used as an internal standard. MATERIALS AND METHODS: The analytes were extracted from human plasma samples by solid-phase extraction technique using Oasis HLB cartridges, (Waters Corporation, Mumbai, India). The reconstituted samples were chromatographed on a C18 column by using an 85:15, v/v mixture of methanol and 0.1% v/v formic acid as the mobile phase at a flow rate of 1.0 mL/min. A detailed validation of the method was performed as per the FDA guidelines. RESULTS: The calibration curves obtained were linear (r ≥ 0.99) over the concentration range of 0.5-1000 ng/mL for losartan and for its active metabolite losartan acid and 0.05-10.1 ng/mL for amlodipine. The results of the intra- and inter-day precision and accuracy studies were well within the acceptable limits. CONCLUSIONS: A run time of 2.5 min for each sample made it possible to analyze more than 300 plasma samples per day. The proposed method was found to be applicable to clinical studies.

A rapid and sensitive LC-MS/MS method for quantification of donepezil and its active metabolite, 6-o-desmethyl donepezil in human plasma and its pharmacokinetic application.

A rapid and sensitive liquid chromatography-tandem mass spectrometric (LC-MS/MS) assay method has been developed and fully validated for simultaneous quantification of donepezil and its active metabolite, 6-o-desmethyl donepezil in human plasma. Analytes and the internal standard were extracted from human plasma by liquid-liquid extraction technique using a 30:70 v/v mixture of ethyl acetate and n-hexane. The reconstituted samples were chromatographed on a C(18) column by using a 70:30 v/v mixture of acetonitrile and ammonium formate (5 mm, pH 5.0) as the mobile phase at a flow rate of 0.6 mL/min. The calibration curve obtained was linear (r ≥ 0.99) over the concentration range of 0.09-24.2 ng/mL for donepezil and 0.03-8.13 ng/mL for 6-o-desmethyl donepezil. The results of the intra-day and inter-day precision and accuracy studies were well within the acceptable limits. The proposed method was successfully applied for the estimation of the drug in real time plasma samples for pharmacokinetic studies.

Simultaneous determination of atorvastatin, amlodipine, ramipril and benazepril in human plasma by LC-MS/MS and its application to a human pharmacokinetic study.

A rapid, simple, sensitive and specific LC-MS/MS method has been developed and validated for the simultaneous estimation of atorvastatin (ATO), amlodipine (AML), ramipril (RAM) and benazepril (BEN) using nevirapine as an internal standard (IS). The API-4000 LC-MS/MS was operated under the multiple-reaction monitoring mode using electrospray ionization. Analytes and IS were extracted from plasma by simple liquid-liquid extraction technique using ethyl acetate. The reconstituted samples were chromatographed on C(18) column by pumping 0.1% formic acid-acetonitrile (15:85, v/v) at a flow rate of 1 mL/min. A detailed validation of the method was performed as per the FDA guidelines and the standard curves were found to be linear in the range of 0.26-210 ng/mL for ATO; 0.05-20.5 ng/mL for AML; 0.25-208 ng/mL for RAM and 0.74-607 ng/mL for BEN with mean correlation coefficient of ≥0.99 for each analyte. The intra-day and inter-day precision and accuracy results were well with in the acceptable limits. A run time of 2.5 min for each sample made it possible to analyze more than 400 human plasma samples per day. The developed assay method was successfully applied to a pharmacokinetic study in human male volunteers.