Vijay V Upreti

Clinical pharmacology of Miami, Miami, Florida, United States

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Publications (16)44.4 Total impact

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    ABSTRACT: BACKGROUND: As compared with individual tablets, saxagliptin/metformin immediate release (IR) fixed-dose combination (FDC) tablets offer the potential for increased convenience, compliance, and adherence for patients requiring combination therapy. OBJECTIVES: Two bioequivalence studies assessed the fed-state and the fasted-state bioequivalence of saxagliptin/metformin IR 2.5 mg/500 mg FDC (study 1) and saxagliptin/metformin IR 2.5 mg/1,000 mg FDC (study 2) relative to the same dosage strengths of the individual component tablets [saxagliptin (Onglyza™) and metformin IR (Glucophage(®))] administered concurrently. STUDY DESIGNS: These were randomized, open-label, single-dose, four-period, four-treatment, crossover studies in healthy subjects (n = 24 in each study). The treatments in study 1 were a saxagliptin/metformin IR 2.5 mg/500 mg FDC tablet in the fed and fasted states on separate occasions, and saxagliptin 2.5 mg and metformin IR 500 mg tablets co-administered in the fed state and fasted states on separate occasions. The treatments in study 2 were a saxagliptin/metformin IR 2.5 mg/1,000 mg FDC tablet in the fed and fasted states on separate occasions, and saxagliptin 2.5 mg and metformin IR 1,000 mg co-administered in the fed state and fasted states on separate occasions. The pharmacokinetics, safety, and tolerability of each treatment were evaluated. RESULTS: For both studies, saxagliptin and metformin in the FDCs were bioequivalent to the individual components in both the fed and the fasted states as the limits of the 90 % confidence interval of the ratio of adjusted geometric means for all key pharmacokinetic parameters were contained within the predefined 0.800 to 1.250 bioequivalence criteria. Co-administration of saxagliptin and metformin IR was generally safe and well tolerated as the FDCs or as individual tablets. CONCLUSIONS: Saxagliptin/metformin IR 2.5 mg/500 mg and saxagliptin/metformin IR 2.5 mg/1,000 mg FDCs were bioequivalent to individual tablets of saxagliptin and metformin of the same strengths in both the fed and the fasted states. No unexpected safety findings were observed with saxagliptin/metformin IR administration. The tolerability of the FDC of saxagliptin/metformin IR was comparable to that of the co-administered individual components. These results indicate that the safety and efficacy profile of co-administration of saxagliptin and metformin can be extended to the saxagliptin/metformin IR FDC tablets.
    Clinical Drug Investigation 04/2013; · 1.70 Impact Factor
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    ABSTRACT: Apixaban is an oral, direct, factor-Xa inhibitor approved for thromboprophylaxis in patients who have undergone elective hip or knee replacement surgery. This open-label, parallel-group study investigated effect of extremes of body weight on apixaban pharmacokinetics, pharmacodynamics, safety and tolerability. METHODS: Fifty-four healthy subjects were enrolled (18 each into low (≤ 50 kg), reference (65-85 kg) and high (≥ 120 kg) body weight groups. Following administration of a single oral dose of 10 mg apixaban, plasma and urine samples were collected for determination of apixaban pharmacokinetics and anti-factor Xa activity. Adverse events, vital signs and laboratory assessments were monitored. RESULTS: Compared with the reference body weight group, low body weight had approximately 27% and 20% higher apixaban maximum observed plasma concentration (Cmax) and area under the concentration-time curve extrapolated to infinity (AUC(0,∞)), respectively; and high body weight had approximately 31% and 23% lower apixaban Cmax and AUC(0,∞), respectively. Apixaban renal clearance was similar across weight groups. Plasma anti-factor Xa activity showed a direct, linear relationship with apixaban plasma concentration, regardless of body weight group. Apixaban was well tolerated in this study. CONCLUSIONS: The modest change in apixaban exposure is unlikely to require dose adjustment for apixaban based on body weight alone; however, caution is warranted in the presence of additional factors (such as severe renal impairment) that could increase apixaban exposure.
    British Journal of Clinical Pharmacology 03/2013; · 3.69 Impact Factor
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    ABSTRACT: Apixaban is an oral, selective, direct factor Xa inhibitor approved for thromboprophylaxis after orthopedic surgery and stroke prevention in patients with atrial fibrillation, and under development for treatment of venous thromboembolism. This study investigated the effect of a gastric acid suppressant, famotidine (a histamine H2-receptor antagonist), on the pharmacokinetics of apixaban in healthy subjects. This two-period, two-treatment crossover study randomized 18 healthy subjects to receive a single oral dose of apixaban 10 mg with and without a single oral dose of famotidine 40 mg administered 3 hours before dosing with apixaban. Plasma apixaban concentrations were measured up to 60 hours post-dose and pharmacokinetic parameters were calculated. Famotidine did not affect maximum apixaban plasma concentration (Cmax) or area under the plasma concentration-time curve from zero to infinite time (AUC∞). Point estimates for ratios of geometric means with and without famotidine were close to unity for Cmax (0.978) and AUC∞ (1.007), and 90% confidence intervals were entirely contained within the 80%-125% no-effect interval. Administration of apixaban alone and with famotidine was well tolerated. Famotidine does not affect the pharmacokinetics of apixaban, consistent with the physicochemical properties of apixaban (lack of an ionizable group and pH-independent solubility). Apixaban pharmacokinetics would not be affected by an increase in gastrointestinal pH due to underlying conditions (eg, achlorhydria), or by gastrointestinal pH-mediated effects of other histamine H2-receptor antagonists, antacids, or proton pump inhibitors. Given that famotidine is also an inhibitor of the human organic cation transporter (hOCT), these results indicate that apixaban pharmacokinetics are not influenced by hOCT uptake transporter inhibitors. Overall, these results support that apixaban can be administered without regard to coadministration of gastric acid modifiers.
    Clinical Pharmacology: Advances and Applications 01/2013; 5:59-66.
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    ABSTRACT: Saxagliptin (Onglyza™) is a dipeptidyl peptidase-4 (DPP4) inhibitor for treating type 2 diabetes mellitus. This open-label, randomized, 2-way crossover study in 20 healthy female subjects investigated the effect of saxagliptin on the pharmacokinetics (PK) of the active components of a combined oral contraceptive (COC). Subjects received either COC (Ortho-Cyclen®) QD for 21 days, then 5 mg saxagliptin QD + COC QD for 21 days, or vice versa. Coadministration of saxagliptin and COC did not alter the steady-state PK of the primary active estrogen (ethinyl estradiol) or progestin (norelgestromin) COC components. The area under the concentration time curve (AUC) and peak plasma concentration (C(max) ) of an active metabolite of norelgestromin (norgestrel) were increased by 13% and 17%, respectively, a magnitude that was not considered clinically meaningful. Coadministration of saxagliptin and COC in this study was generally well tolerated. Saxagliptin can be co-prescribed with an estrogen/progestin combination for women taking oral contraceptive.
    Diabetes Obesity and Metabolism 07/2012; 9999(999A). · 5.18 Impact Factor
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    ABSTRACT: The dependency of metformin in vivo disposition on the rate and extent of dissolution was studied. The analysis includes the use of fundamental principles of drug input, permeability, and intestinal transit time within the framework of a compartmental absorption transit model to predict key pharmacokinetic (PK) parameters and then compare the results to clinical data. The simulations show that the maximum plasma concentration (C(max) ) and area under the curve (AUC) are not significantly affected when 100% of drug is released within 2 h of oral dosing, which was confirmed with corresponding human PK data. Furthermore, in vitro dissolution profiles measured in aqueous buffers at pH values of 1.2, 4.5, and 6.8 were slower than in vivo release profiles generated by deconvolution of metformin products that were bioequivalent. On the basis of this work, formulations of metformin that release 100% in vitro in a   time period equal to or less than two hours are indicated to be bioequivalent. The use of modeling offers a mechanistic-based approach for demonstrating acceptable bioperformance for metformin formulations without having to resort to in vivo bioequivalence studies and may be more robust than statistical comparison of in vitro release profiles. This work further provides a strategy for considering Biopharmaceutics Classification System (BCS) Class 3 compounds to be included under biowaiver guidelines as for BCS Class 1 compounds.
    Journal of Pharmaceutical Sciences 02/2012; 101(5):1773-82. · 3.13 Impact Factor
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    ABSTRACT: To investigate the effect of co-administration of rifampicin, a potent inducer of cytochrome P450 (CYP) 3A4 enzymes, on the pharmacokinetics (PK) and pharmacodynamics (PD) of saxagliptin and 5-hydroxy saxagliptin in healthy subjects. Saxagliptin is metabolized by CYP3A4/3A5 to 5-hydroxy saxagliptin, its major pharmacologically active metabolite. In a non-randomized, open label, single sequence design, 14 healthy subjects received single oral doses of saxagliptin 5 mg with and without steady-state rifampicin (600 mg once daily for 6 days). PK (saxagliptin and 5-hydroxy saxagliptin) and PD (plasma DPP-4 activity) were measured for up to 24 h on days 1 and 7. Concomitant administration with rifampicin resulted in 53% (point estimate 0.47, 90% CI 0.38, 0.57) and 76% (point estimate 0.24, 90% CI 0.21, 0.27) decreases in the geometric mean C(max) and AUC values of saxagliptin, respectively, with a 39% (point estimate 1.39, 90% CI 1.23, 1.56) increase in the geometric mean C(max) and no change (point estimate 1.03, 90% CI 0.97, 1.09) in the AUC of 5-hydroxy saxagliptin. Similar maximum % inhibition and area under the % inhibition-time effect curve over 24 h for DPP-4 activity were observed when saxagliptin was administered alone or with rifampicin. The saxagliptin total active moieties exposure (AUC) decreased by 27% (point estimate 0.73, 90% CI 0.66, 0.81). Saxagliptin with or without rifampicin in this study was generally well tolerated. Lack of change of PD effect of saxagliptin is consistent with the observed 27% reduction in systemic exposure to the total active moieties, which is not considered clinically meaningful. Based on these findings, it is not necessary to adjust the saxagliptin dose when co-administered with rifampicin.
    British Journal of Clinical Pharmacology 07/2011; 72(1):92-102. · 3.69 Impact Factor
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    ABSTRACT: It is well established that 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) causes acute liver damage in animals and humans. The aim of this study was to identify and characterize oxidative modification and inactivation of cytosolic proteins in MDMA-exposed rats. Markedly increased levels of oxidized and nitrated cytosolic proteins were detected 12 h after the second administration of two consecutive MDMA doses (10 mg/kg each). Comparative 2-DE analysis showed markedly increased levels of biotin-N-methylimide-labeled oxidized cytosolic proteins in MDMA-exposed rats compared to vehicle-treated rats. Proteins in the 22 gel spots of strong intensities were identified using MS/MS. The oxidatively modified proteins identified include anti-oxidant defensive enzymes, a calcium-binding protein, and proteins involved in metabolism of lipids, nitrogen, and carbohydrates (glycolysis). Cytosolic superoxide dismutase was oxidized and its activity significantly inhibited following MDMA exposure. Consistent with the oxidative inactivation of peroxiredoxin, MDMA activated c-Jun N-terminal protein kinase and p38 kinase. Since these protein kinases phosphorylate anti-apoptotic Bcl-2 protein, their activation may promote apoptosis in MDMA-exposed tissues. Our results show for the first time that MDMA induces oxidative-modification of many cytosolic proteins accompanied with increased oxidative stress and apoptosis, contributing to hepatic damage.
    Proteomics 01/2011; 11(2):202-11. · 4.43 Impact Factor
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    ABSTRACT: Despite numerous reports about the acute and sub-chronic toxicities caused by MDMA (3,4-methylenedioxymethamphetamine, ecstasy), the underlying mechanism of organ damage is poorly understood. The aim of this review is to present an update of the mechanistic studies on MDMA-mediated organ damage partly caused by increased oxidative/nitrosative stress. Because of the extensive reviews on MDMA-mediated oxidative stress and tissue damage, we specifically focus on the mechanisms and consequences of oxidative-modifications of mitochondrial proteins, leading to mitochondrial dysfunction. We briefly describe a method to systematically identify oxidatively-modified mitochondrial proteins in control and MDMA-exposed rats by using biotin-N-maleimide (biotin-NM) as a sensitive probe for oxidized proteins. We also describe various applications and advantages of this Cys-targeted proteomics method and alternative approaches to overcome potential limitations of this method in studying oxidized proteins from MDMA-exposed tissues. Finally we discuss the mechanism of synergistic drug-interaction between MDMA and other abused substances including alcohol (ethanol) as well as application of this redox-based proteomics method in translational studies for developing effective preventive and therapeutic agents against MDMA-induced organ damage.
    Current pharmaceutical biotechnology 08/2010; 11(5):434-43. · 3.40 Impact Factor
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    ABSTRACT: Objectives: Saxagliptin/metformin XR fixed-dose combination (FDC) tablets offer potential for increased patient convenience and compliance compared with individual tablets. Two bioequivalence studies assessed: the fed-state bioequivalence of FDCs at doses of 5-mg saxagliptin/500-mg metformin XR (5/500) [Study 1] and 5-mg saxagliptin/1000-mg metformin XR (5/1000) [Study 2] to the same strengths of concomitantly administered individual tablets. The effect of food on the pharmacokinetics of the FDCs was also investigated. Methods: These were single-dose, open-label, randomized, 3-period, 3-treatment, crossover studies in healthy subjects (n=24 in each study). The treatments were: an FDC tablet in the fed state and fasted state on separate occasions, and the same strength tablets of saxagliptin and metformin coadministered in the fed state. Safety and tolerability of each treatment were evaluated. Results: One subject withdrew from Study 1 as a result of an adverse event (mild fever/sore throat during washout); all other subjects completed the study. For both studies, saxagliptin and metformin in the FDCs were bioequivalent to the individual components, as the limits of the 90% confidence interval of the ratio of adjusted geometric means for all key pharmacokinetic parameters were contained within 0.8, 1.25. Compared to the fasted state, food did not have a meaningful effect on the pharmacokinetics of saxagliptin and metformin XR when administered as FDCs. Coadministration of saxagliptin and metformin XR was generally safe and well tolerated as the FDCs or as individual tablets. Conclusion: 5/500 and 5/1000 FDCs were bioequivalent to individual tablets of saxagliptin and metformin of the same strengths. Additionally, food had little effect on the pharmacokinetics of saxagliptin and metformin administered in the FDCs. No unexpected safety concerns were observed with saxagliptin/metformin XR administration. The tolerability of the FDC of saxagliptin/metformin XR was comparable to that of the coadministered individual components.
    2010 American College of Clinical Pharmacy Spring Practice and Research Forum; 04/2010
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    ABSTRACT: Objectives: Saxagliptin/metformin IR fixed-dose combination (FDC) tablets offer potential for increased patient convenience, compliance, and adherence compared with individual tablets for patients requiring dual oral antidiabetic therapy. Two bioequivalence studies assessed the fed- and fasted-state bioequivalence of FDCs at doses of 2.5 mg saxagliptin/500 mg metformin IR (2.5/500) [Study 1] and 2.5 mg saxagliptin/1000 mg of metformin IR (2.5/1000) [Study 2] with the same strengths of concomitantly administered individual tablets. Methods: These were single-dose, open-label, randomized, 4-period, 4-treatment crossover studies in healthy subjects (n=24 in each study). The treatments included an FDC tablet in the fed and fasted state on separate occasions, and the same strength individual saxagliptin and metformin tablets coadministered in the fed and fasted state on separate occasions. The pharmacokinetics, safety, and tolerability of each treatment were evaluated. Results: All subjects completed Study 1. Eighteen subjects completed Study 2. Two subjects withdrew as a result of an adverse event during a washout period (1 ear pain, 1 sore throat); 4 withdrew for other reasons. In both studies, saxagliptin and metformin as the FDCs were bioequivalent to the individual components in the fed and fasted states; the limits of the 90% confidence interval of the ratio of adjusted geometric means for all key pharmacokinetic parameters (Cmax, AUC0-T, and AUCinf) were contained within the predefined 0.8 to 1.25 bioequivalence criteria. Coadministration of saxagliptin and metformin IR was generally safe and well tolerated as the FDCs or as individual tablets. Conclusion: 2.5/500 and 2.5/1000 FDCs were bioequivalent to individual tablets of saxagliptin and metformin of the same strengths in both the fed and fasted state. No unexpected safety concerns were observed with saxagliptin/metformin IR administration. The tolerability of the FDC of saxagliptin/metformin IR was comparable to that of the coadministered individual components.
    2010 American College of Clinical Pharmacy Spring Practice and Research Forum; 04/2010
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    ABSTRACT: Alcohol (ethanol) and 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) are frequently co-abused, but recent findings indicate a harmful drug interaction between these two agents. In our previous study, we showed that MDMA exposure inhibits the activity of the acetaldehyde (ACH) metabolizing enzyme, aldehyde dehydrogenase2 (ALDH2). Based on this finding, we hypothesized that the co-administration of MDMA and ethanol would reduce the metabolism of ACH and result in increased accumulation of ACH. Rats were treated with MDMA or vehicle and then administered a single dose of ethanol. Liver ALDH2 activity decreased by 35% in the MDMA-treated rats compared to control rats. The peak concentration and the area under the concentration versus time curve of plasma ACH were 31% and 59% higher, respectively, in the MDMA-ethanol group compared to the ethanol-only group. In addition, the MDMA-ethanol group had 80% higher plasma transaminase levels than the ethanol-only group, indicating greater hepatocellular damage. Our results not only support a drug interaction between MDMA and ethanol but a novel underlying mechanism for the interaction.
    Toxicology Letters 08/2009; 188(2):167-72. · 3.15 Impact Factor
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    ABSTRACT: Salvinorin A is an unregulated potent hallucinogen isolated from the leaves of Salvia divinorum. It is the only known non-nitrogenous kappa-opioid selective agonist and rivals synthetic lysergic acid diethylamide (LSD) in potency. The objective of this study was to characterize the in vitrotransport, in vitro metabolism, and pharmacokinetic properties of Salvinorin A. The transport characteristics of Salvinorin A were assessed using MDCKMDR1 cell monolayers. The P-gp affinity status was assessed by the P-gp ATPase assay. In vitro metabolism studies were performed with various specific human CYP450 isoforms and UGT2B7 to assess the metabolic characteristics of Salvinorin A. Cohorts (n=3) of male Sprague Dawley rats were used to evaluate the pharmacokinetics and brain distribution of Salvinorin A (10 mg/kg, intraperitonal (i.p.) over a 240 minute period. A validated UVHPLC and LC/MS/MS method was used to quantify the hallucinogen concentrations obtained from the in vitro and in vivo studies, respectively. Salvinorin A displayed a high secretory transport in the MDCK-MDR1 cells (4.07+/-1.34x10(-5) cm/sec). Salvinorin A also stimulated the P-gp ATPase activity in a concentration (5 and 10 muM) dependant manner, suggesting that it may be a substrate of P-glycoprotein (P-gp). A significant decrease in Salvinorin A concentration ranging from 14.7+/-0.80 % to 31.1+/-1.20 % was observed after incubation with CYP2D6, CYP1A1, CYP2C18, and CYP2E1, respectively. A significant decrease was also observed after incubation with UGT2B7. These results suggest that Salvinorin A maybe a substrate of UGT2B7, CYP2D6, CYP1A1, CYP2E1 and CYP2C18. The in vivo pharmacokinetic study showed a relatively fast elimination with a half-life (t(1/2)) of 75 min and a clearance (Cl/F) of 26 L/h/kg. The distribution was extensive (Vd of 47.1 L/kg), however the brain to plasma ratio was 0.050. Accordingly, the brain half life was relatively short, 36 minutes. Salvinorin A is rapidly eliminated after i.p. dosing, in accordance with its fast onset and short duration of action. Further, it appears to be a substrate for various oxidative enzymes and multi-drug resistant protein, P-gp.
    European journal of pharmaceutics and biopharmaceutics: official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V 02/2009; · 3.15 Impact Factor
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    ABSTRACT: Despite numerous reports citing the acute hepatotoxicity caused by 3,4-methylenedioxymethamphetamine (MDMA) (ecstasy), the underlying mechanism of organ damage is poorly understood. We hypothesized that key mitochondrial proteins are oxidatively modified and inactivated in MDMA-exposed tissues. The aim of this study was to identify and investigate the mechanism of inactivation of oxidatively modified mitochondrial proteins, prior to the extensive mitochondrial dysfunction and liver damage following MDMA exposure. MDMA-treated rats showed abnormal liver histology with significant elevation in plasma transaminases, nitric oxide synthase, and the level of hydrogen peroxide. Oxidatively modified mitochondrial proteins in control and MDMA-exposed rats were labeled with biotin-N-maleimide (biotin-NM) as a sensitive probe for oxidized proteins, purified with streptavidin-agarose, and resolved using 2-DE. Comparative 2-DE analysis of biotin-NM-labeled proteins revealed markedly increased levels of oxidatively modified proteins following MDMA exposure. Mass spectrometric analysis identified oxidatively modified mitochondrial proteins involved in energy supply, fat metabolism, antioxidant defense, and chaperone activities. Among these, the activities of mitochondrial aldehyde dehydrogenase, 3-ketoacyl-CoA thiolases, and ATP synthase were significantly inhibited following MDMA exposure. Our data show for the first time that MDMA causes the oxidative inactivation of key mitochondrial enzymes which most likely contributes to mitochondrial dysfunction and subsequent liver damage in MDMA-exposed animals.
    Proteomics 10/2008; 8(18):3906-18. · 4.43 Impact Factor
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    ABSTRACT: Odiparcil is a novel, orally active beta-d-thioxyloside analog with antithrombotic activity associated with a reduced risk of adverse bleeding events. Its unique mechanism of action is postulated by means of an elevation in circulating endogenous chondroitin sulfate-related glycosaminoglycans (GAGs) levels. The purpose of these 2 separate clinical studies was to evaluate plasma GAG levels in healthy subjects administered odiparcil with either aspirin (ASA) or enoxaparin. Clinical plasma samples were processed and analyzed using validated HPLC bioassays that indirectly estimate GAG levels based on the simultaneous detection of the chondroitin disaccharide derivatives. The concomitant administration of odiparcil with or without ASA resulted in a significant elevation in GAG levels over baseline for both treatment groups. In the other clinical study, the concomitant administration of odiparcil with or without enoxaparin displayed significant increases in plasma DeltaDi-OS, DeltaDi-4S, and total disaccharide levels versus control group. Neither plasma GAG levels nor odiparcil plasma levels were correlated with a rise in hepatic transaminases, an adverse drug event observed in several subjects; and plasma odiparcil levels were indirectly correlated with plasma GAG levels. These clinical studies were proof of concept of preclinical rat studies indicating that chronic odiparcil treatment elevates endogenous GAG levels in human subjects.
    The Journal of Clinical Pharmacology 09/2008; 48(10):1158-70. · 2.84 Impact Factor
  • Vijay V Upreti, Natalie D Eddington
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    ABSTRACT: Fluoxetine has been shown to provide protection from MDMA induced long term neurotoxicity. The purpose of this investigation is to evaluate the pharmacokinetic drug interaction between MDMA and fluoxetine and also to determine the role of P-glycoprotein (P-gp) on mediating drug-drug interactions with MDMA. Bi-directional transport studies were conducted across MDCK-MDR1 and Caco-2 monolayers. MDMA brain and plasma levels were measured in P-gp deficient [mdr1a(-/-)] and normal [mdr1a(+/+)] mice after a 5 mg/kg i.p. dose of MDMA. Sprague-Dawley rats were pretreated with fluoxetine (4 days, 10 mg/kg, i.p.) or saline followed by MDMA (10 mg/kg, p.o.) and brain and plasma samples were collected over 10 h. MDMA and its active metabolite MDA were quantified using a HPLC method with fluorescence detection. In transport studies MDMA exhibited high permeability with essentially unpolarized transport. No significant difference in MDMA and MDA brain levels were seen in P-gp deficient versus normal mice. Pretreatment of rats with fluoxetine resulted in an increase in MDMA (1.4-fold) and MDA (1.5-fold) exposure in both brain and plasma. Elimination half-life was increased for MDMA (2.4 vs. 4.9 h) and MDA (1.8 vs. 8.2 h) with fluoxetine pretreatment. P-gp does not play a physiologically relevant role in absorption and distribution of MDMA, hence this transporter may not have a role in drug-drug interactions with MDMA. Fluoxetine pretreatment to provide protection from MDMA induced long term neurotoxicity decreases elimination of MDMA and MDA and may lead to enhanced risk of MDMA acute toxic effects. Overall, our results indicate that caution need to be practiced when recommending fluoxetine as an agent to provide protection from MDMA induced long term neurotoxicity.
    Journal of Pharmaceutical Sciences 05/2008; 97(4):1593-605. · 3.13 Impact Factor
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    ABSTRACT: SB-424323 is a new, orally active anti-thrombotic agent presently in phase-II clinical development, with limited hemorrhagic risk and a unique mechanism of action involving the induction of glycosaminoglycans (GAGs) biosynthesis. The objective of the present study was to develop a simple and rapid high performance liquid chromatography (HPLC) method for determination of endogenous GAGs derived disaccharides in plasma samples from a phase-II clinical study of SB-424323. Sample preparation was a simple heat treatment of the diluted plasma followed by digestion of endogenous GAGs with chondroitinase ABC to yield unsaturated disaccharides, 2-acetamido-2-deoxy-3-O-(beta-D-gluco-4-enepyranosyluronic acid)-D-galactose (DeltaDi-0S), 2-acetamido-2-deoxy-3-O-(beta-D-gluco-4-enepyranosyluronic acid)-4-O-sulfo-D-galactose (DeltaDi-4S), and 2-acetamido-2-deoxy-3-O-(beta-D-gluco-4-enepyranosyluronic acid)-6-O-sulfo-D-galactose (DeltaDi-6S). These disaccharides were recovered and purified using centrifugal filtration through a filter with 3000 molecular weight cut-off along with externally added internal standard 2-acetamido-2-deoxy-3-O-(2-O-sulfo-beta-D-gluco-4-enepyranosyluronic acid)-D-galactose (DeltaDi-UA2S). A gradient reverse phase HPLC separation was developed on a Waters Symmetry C(18) column (4.6 mm x 150 mm, 5 microm) with a gradient mobile phase system consisting of 0.8 mM tetrabutylammonium hydrogen sulfate and 2mM sodium chloride and acetonitrile at a flow rate of 1.0 mL/min. The eluate was monitored with an ultraviolet detector set at 230 nm. Plasma standard curves were linear (r(2)> or =0.994) in the concentration range 1.0-20 microg/mL with a lower limit of quantification (LLOQ) of 1.0 microg/mL for each of the disaccharide. The mean measured quality control (QC) concentrations for the disaccharides deviated from the nominal concentrations in the range of -8.92 to 5.61% and -16.3 to 16.7%, for inter and intra-day, respectively. The inter and intra-day precision in the measurement of QC samples, were in the range of 3.21 to 18.2% relative standard deviation (R.S.D.) and 0.32 to 20.9% R.S.D., respectively. The inter and intra-day precision in the measurement of endogenous GAGs derived disaccharides in human control plasma, were in the range of 5.8 to 15.9% R.S.D. and 1.17 to 7.74% R.S.D., respectively. Stability of the processed samples was confirmed up to 48 h in the auto-sampler. The method is simple, reliable, and easily adaptable to analysis of large number of samples under logistics of a clinical study. The present method has been used to investigate the GAGs levels in the plasma of patients in a phase II clinical study of SB-424323.
    Journal of Chromatography B 03/2006; 831(1-2):156-62. · 2.49 Impact Factor

Publication Stats

116 Citations
44.40 Total Impact Points

Institutions

  • 2013
    • Clinical pharmacology of Miami
      Miami, Florida, United States
  • 2011–2013
    • Bristol-Myers Squibb
      • Discovery Medicine and Clinical Pharmacology
      New York City, NY, United States
  • 2006–2011
    • University of Maryland, Baltimore
      • Department of Pharmaceutical Sciences (PSC)
      Baltimore, MD, United States