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1.
J Pharmacol Exp Ther ; 2018 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-30361237

RESUMO

Plasma pyridoxic acid (PDA) and homovanillic acid (HVA) were recently identified as novel endogenous biomarkers of OAT1/3 function in monkeys. Consequently, this clinical study assessed the dynamic changes and utility of plasma PDA and HVA as an initial evaluation of OAT1/3 inhibition in early-phase drug development. The study was designed as a single dose randomized, three-phase, crossover study; 14 Indian healthy volunteers received probenecid (PROB) (1,000 mg orally) alone, furosemide (FSM) (40 mg orally) alone, or FSM 1 h after receiving PROB (40 mg and 1,000 mg orally) on Days 1, 8, and 15, respectively. PDA and HVA plasma concentrations remained stable over time in the prestudy and FSM groups. Administration of PROB significantly increased AUC of PDA by 3.1-fold (dosed alone; p < 0.05), and 3.2-fold (coadministered with FSM; p < 0.01), as compared with the prestudy and FSM groups, respectively. The corresponding increase in HVA AUC was 1.8-fold (p > 0.05) and 2.1-fold (p < 0.05), respectively. The increases in PDA AUC are similar to those in FSM AUC whereas those of HVA are smaller (3.1-3.2 and 1.8-2.1 versus 3.3, respectively). PDA and HVA CLR were decreased by PROB to smaller extents compared to FSM (0.35-0.37 and 0.67-0.73 versus 0.23, respectively). These data demonstrate that plasma PDA is a promising endogenous biomarker for OAT1/3 function and its plasma exposure respond in a similar fashion to FSM upon OAT1/3 inhibition by PROB. The magnitude and variability of response in PDA AUC and CLR between subjects is more favourable relative to HVA.

2.
Xenobiotica ; : 1-9, 2018 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-29898636

RESUMO

1-Aminobenzotriazole (ABT) is a mechanism-based inactivator of major cytochrome P450 (CYP) enzymes, which is used in multiple mechanistic studies. The purpose was to evaluate the effect of 2 and 16-h pretreatment regimens of ABT on the exposures of triazolam in rat. Another objective was to evaluate the effect of ABT on gastric emptying of acetaminophen. Plasma area under the curve (AUC) of triazolam was increased by 101-fold and 81-fold for the rats pretreated with ABT at 2 and 16 h, respectively, compared to control rats. Time to reach maximum concentration was 0.3, 4.8 and 3.7 h in control, 2 and 16-h pretreatment animals, respectively. In the case of acetaminophen, where Tmax was not delayed, the mean absorption time (MAT) in control, 2 and 16 h ABT pretreatment groups were 0.3, 4.6 and 2.9 h, respectively, suggesting delayed absorption. This hypothesis was further supported by GastroPlusTM simulation. In summary, extent of triazolam absorption was increased to a similar extent with both 2 and 16 h ABT pretreatment regimens, suggesting that either of the regimen can be used to increase parent exposures in rat. With ABT pretreatment, delayed absorption of triazolam and acetaminophen was observed, as suggested by delay in Tmax and MAT, respectively.

3.
Drug Metab Dispos ; 45(8): 908-919, 2017 08.
Artigo em Inglês | MEDLINE | ID: mdl-28576766

RESUMO

Multiple endogenous compounds have been proposed as candidate biomarkers to monitor organic anion transporting polypeptide (OATP) function in preclinical species or humans. Previously, we demonstrated that coproporphyrins (CPs) I and III are appropriate clinical markers to evaluate OATP inhibition and recapitulate clinical drug-drug interactions (DDIs). In the present study, we investigated bile acids (BAs) dehydroepiandrosterone sulfate (DHEAS), hexadecanedioate (HDA), and tetradecanedioate (TDA) in plasma as endogenous probes for OATP inhibition and compared these candidate probes to CPs. All probes were determined in samples from a single study that examined their behavior and their association with rosuvastatin (RSV) pharmacokinetics after administration of an OATP inhibitor rifampin (RIF) in healthy subjects. Among endogenous probes examined, RIF significantly increased maximum plasma concentration (Cmax) and area under the concentration-time curve (AUC)(0-24h) of fatty acids HDA and TDA by 2.2- to 3.2-fold. For the 13 bile acids in plasma examined, no statistically significant changes were detected between treatments. Changes in plasma DHEAS did not correlate with OATP1B inhibition by RIF. On the basis of the magnitude of effects for the endogenous compounds that demonstrated significant changes from baseline over interindividual variations, the overall rank order for the AUC change was found to be CP I > CP III > HDA ≈ TDA ≈ RSV > > BAs. Collectively, these results reconfirmed that CPs are novel biomarkers suitable for clinical use. In addition, HDA and TDA are useful for OATP functional assessment. Since these endogenous markers can be monitored in conjunction with pharmacokinetics analysis, the CPs and fatty acid dicarboxylates, either alone or in combination, offer promise of earlier diagnosis and risk stratification for OATP-mediated DDIs.


Assuntos
Ácidos e Sais Biliares/sangue , Biomarcadores/sangue , Coproporfirinas/sangue , Sulfato de Desidroepiandrosterona/sangue , Transportadores de Ânions Orgânicos/antagonistas & inibidores , Ácidos Palmíticos/sangue , Adolescente , Adulto , Área Sob a Curva , Transporte Biológico/efeitos dos fármacos , Linhagem Celular , Interações de Medicamentos/fisiologia , Células HEK293 , Voluntários Saudáveis , Humanos , Masculino , Pessoa de Meia-Idade , Rifampina/farmacologia , Rosuvastatina Cálcica/farmacologia , Adulto Jovem
4.
Eur J Pharm Biopharm ; 117: 212-223, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28438550

RESUMO

Self-emulsifying drug delivery systems (SEDDS) have been used to solubilize poorly water-soluble drugs to improve exposure in high-dose pharmacokinetic (PK) and toxicokinetic (TK) studies. However, the absorbable dose is often limited by drug solubility in the lipidic SEDDS vehicle. This study focuses on increasing solubility and drug loading of ionizable drugs in SEDDS vehicles using lipophilic counterions to prepare lipophilic salts of drugs. SEDDS formulations of two lipophilic salts-atazanavir-2-naphthalene sulfonic acid (ATV-2-NSA) and atazanavir-dioctyl sulfosuccinic acid (ATV-Doc)-were characterized and their performance compared to atazanavir (ATV) free base formulated as an aqueous crystalline suspension, an organic solution, and a SEDDS suspension, using in vitro, in vivo, and in silico methods. ATV-2-NSA exhibited ∼6-fold increased solubility in a SEDDS vehicle, allowing emulsion dosing at 12mg/mL. In rat PK studies at 60mg/kg, the ATV-2-NSA SEDDS emulsion had comparable exposure to the free-base solution, but with less variability, and had better exposure at high dose than aqueous suspensions of ATV free base. Trends in dose-dependent exposure for various formulations were consistent with GastroPlus™ modeling. Results suggest use of lipophilic salts is a valuable approach for delivering poorly soluble compounds at high doses in Discovery.


Assuntos
Sistemas de Liberação de Medicamentos/métodos , Descoberta de Drogas/métodos , Emulsificantes/administração & dosagem , Lipídeos/administração & dosagem , Animais , Composição de Medicamentos/métodos , Emulsificantes/sangue , Emulsificantes/química , Lipídeos/sangue , Lipídeos/química , Masculino , Ratos , Ratos Sprague-Dawley , Solubilidade
5.
Eur J Pharm Sci ; 99: 272-278, 2017 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-28034694

RESUMO

Rat is commonly used for pharmacokinetic screening during pharmaceutical lead optimization. To handle the large number of compounds, rats with a single jugular vein cannulation are commonly utilized for intravenous pharmacokinetic studies, where the same cannula is used both for dose administration and blood sampling. We demonstrate that the single cannula method is not suitable for all compounds, especially for high logP compounds. We propose an alternative dual cannulation technique in which two cannulas are placed in the same jugular vein, thus avoiding an additional surgery. Compounds were administered orally or via intravenous infusion to compare PK parameters, including bioavailability, using both procedures. For itraconazole and amiodarone, known to bind to the cannula, the measured plasma exposures were substantially higher in the single cannulated rats than those from dual cannulated rats. Area under the plasma concentration time curve differed by 79% and 74% for itraconazole and amiodarone, respectively. When compared to the single cannulation approach, clearance, volume of distribution and bioavailability determined by dual cannulation were 39%, 60% and 38% higher for itraconazole, and 46%, 34% and 42% higher for amiodarone, respectively. In contrast, all pharmacokinetic parameters were similar between single and dual-cannulated rats for the hydrophilic compound atenolol. Based on these results, we recommend the use of dual cannulated rats for intravenous pharmacokinetic studies when testing a series of hydrophobic compounds that may be prone to non-specific binding to the cannula. If single cannulated model is selected for pharmacokinetic screening, we recommend a bridging study with dual cannulated rats with representative compounds of a given chemical series.


Assuntos
Amiodarona/farmacocinética , Cateterismo/métodos , Itraconazol/farmacocinética , Veias Jugulares/metabolismo , Administração Intravenosa/métodos , Administração Oral , Animais , Disponibilidade Biológica , Coleta de Amostras Sanguíneas/métodos , Masculino , Ratos , Ratos Sprague-Dawley
6.
J Pharmacol Exp Ther ; 358(3): 371-86, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27411717

RESUMO

To identify novel targets for neuropathic pain, 3097 mouse knockout lines were tested in acute and persistent pain behavior assays. One of the lines from this screen, which contained a null allele of the adapter protein-2 associated kinase 1 (AAK1) gene, had a normal response in acute pain assays (hot plate, phase I formalin), but a markedly reduced response to persistent pain in phase II formalin. AAK1 knockout mice also failed to develop tactile allodynia following the Chung procedure of spinal nerve ligation (SNL). Based on these findings, potent, small-molecule inhibitors of AAK1 were identified. Studies in mice showed that one such inhibitor, LP-935509, caused a reduced pain response in phase II formalin and reversed fully established pain behavior following the SNL procedure. Further studies showed that the inhibitor also reduced evoked pain responses in the rat chronic constriction injury (CCI) model and the rat streptozotocin model of diabetic peripheral neuropathy. Using a nonbrain-penetrant AAK1 inhibitor and local administration of an AAK1 inhibitor, the relevant pool of AAK1 for antineuropathic action was found to be in the spinal cord. Consistent with these results, AAK1 inhibitors dose-dependently reduced the increased spontaneous neural activity in the spinal cord caused by CCI and blocked the development of windup induced by repeated electrical stimulation of the paw. The mechanism of AAK1 antinociception was further investigated with inhibitors of α2 adrenergic and opioid receptors. These studies showed that α2 adrenergic receptor inhibitors, but not opioid receptor inhibitors, not only prevented AAK1 inhibitor antineuropathic action in behavioral assays, but also blocked the AAK1 inhibitor-induced reduction in spinal neural activity in the rat CCI model. Hence, AAK1 inhibitors are a novel therapeutic approach to neuropathic pain with activity in animal models that is mechanistically linked (behaviorally and electrophysiologically) to α2 adrenergic signaling, a pathway known to be antinociceptive in humans.


Assuntos
Neuralgia/tratamento farmacológico , Inibidores de Proteínas Quinases/farmacologia , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Animais , Fenômenos Eletrofisiológicos/efeitos dos fármacos , Técnicas de Inativação de Genes , Células HEK293 , Humanos , Masculino , Camundongos , Neuralgia/metabolismo , Neuralgia/fisiopatologia , Nociceptividade/efeitos dos fármacos , Fenótipo , Inibidores de Proteínas Quinases/uso terapêutico , Proteínas Serina-Treonina Quinases/deficiência , Proteínas Serina-Treonina Quinases/genética , Ratos , Medula Espinal/efeitos dos fármacos , Medula Espinal/enzimologia , Medula Espinal/fisiopatologia
7.
J Pharmacol Exp Ther ; 358(3): 397-404, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27317801

RESUMO

In the present study, an open-label, three-treatment, three-period clinical study of rosuvastatin (RSV) and rifampicin (RIF) when administered alone and in combination was conducted in 12 male healthy subjects to determine if coproporphyrin I (CP-I) and coproporphyrin III (CP-III) could serve as clinical biomarkers for organic anion transporting polypeptide 1B1 (OATP1B1) and 1B3 that belong to the solute carrier organic anion gene subfamily. Genotyping of the human OATP1B1 gene was performed in all 12 subjects and confirmed absence of OATP1B1*5 and OATP1B1*15 mutations. Average plasma concentrations of CP-I and CP-III prior to drug administration were 0.91 ± 0.21 and 0.15 ± 0.04 nM, respectively, with minimum fluctuation over the three periods. CP-I was passively eliminated, whereas CP-III was actively secreted from urine. Administration of RSV caused no significant changes in the plasma and urinary profiles of CP-I and CP-III. RIF markedly increased the maximum plasma concentration (Cmax) of CP-I and CP-III by 5.7- and 5.4-fold (RIF) or 5.7- and 6.5-fold (RIF+RSV), respectively, as compared with the predose values. The area under the plasma concentration curves from time 0 to 24 h (AUC0-24h) of CP-I and CP-III with RIF and RSV increased by 4.0- and 3.3-fold, respectively, when compared with RSV alone. In agreement with this finding, Cmax and AUC0-24h of RSV increased by 13.2- and 5.0-fold, respectively, when RIF was coadministered. Collectively, we conclude that CP-I and CP-III in plasma and urine can be appropriate endogenous biomarkers specifically and reliably reflecting OATP inhibition, and thus the measurement of these molecules can serve as a useful tool to assess OATP drug-drug interaction liabilities in early clinical studies.


Assuntos
Coproporfirinas/sangue , Coproporfirinas/urina , Transportadores de Ânions Orgânicos/antagonistas & inibidores , Rifampina/farmacologia , Rosuvastatina Cálcica/farmacologia , Adulto , Biomarcadores/sangue , Biomarcadores/urina , Interações de Medicamentos , Humanos , Masculino , Pessoa de Meia-Idade , Rifampina/farmacocinética , Rosuvastatina Cálcica/farmacocinética , Adulto Jovem
8.
Biopharm Drug Dispos ; 36(6): 385-397, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25832562

RESUMO

In recent years prodrug strategy has been used extensively to improve the pharmacokinetic properties of compounds exhibiting poor bioavailability. Mechanistic understanding of the absorption and the role of intestine and liver in the activation of oral prodrugs is crucial. Enalapril, a carboxyl ester prodrug, is reported to be metabolized by human carboxylesterase-1 (CES1) but not by carboxylesterase-2 (CES2) to its active metabolite enalaprilat. Further, it has been reported that the small intestines of both rat and human contain mainly CES2. The objective of this work was to understand whether enalapril remains unchanged as it is absorbed through the intestine into the portal circulation. This was evaluated using different intestinal preparations, an in situ intestinal perfusion experiment and a portal vein cannulated rat model. No turnover of enalapril was seen with commercial rat intestinal S9 and microsomes, but reasonable turnover was observed with freshly prepared rat intestinal and mucosal homogenate and S9. In the intestinal perfusion study, both enalapril and enalaprilat were observed in the mesenteric plasma with the data suggesting 32% hydrolysis of enalapril in the intestine. In the portal vein cannulated rat, about 51% of enalapril absorbed into intestine was converted to enalaprilat. Overall, it was demonstrated that even though enalapril has been shown to be a specific substrate for CES1, it is converted to enalaprilat to a significant extent in the intestine. Such experimental techniques can be applied by other scientific groups who are working on prodrugs to determine the region and extent of activation. Copyright © 2015 John Wiley & Sons, Ltd.

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