Investigating herb–drug interactions: the effect of Citrus aurantium fruit extract on the pharmacokinetics of amiodarone in rats

Citrus aurantium extract has been largely used in weight loss and sports performance dietary supplements. However, the safety of C. aurantium-containing products has been questioned mainly due to the association of its use with adverse events in the cardiovascular system. Therefore, this work aimed to assess the potential for herb–drug interactions among a standardized C. aurantium extract (GMP certificate) and amiodarone (narrow therapeutic index drug) in rats. In a first pharmacokinetic study, rats were simultaneously co-administered with a single-dose of C. aurantium (164 mg/kg, p.o.) and amiodarone (50 mg/kg, p.o.); in a second study, rats were pre-treated during 14 days with C. aurantium (164 mg/kg/day, p.o.) and received amiodarone (50 mg/kg, p.o.) on the 15th day. Rats of the control groups received the corresponding volume of vehicle. Overall, after analysis of the pharmacokinetic data, it deserves to be highlighted the significant increase of the peak plasma concentration of amiodarone in rats pre-treated with C. aurantium extract, while the extent of systemic exposure was comparable between both groups. This paper reports, for the first time, data on the potential of herb–drug interaction between C. aurantium extract and amiodarone. However, specific clinical trials should be performed to confirm these results in humans

A Rapid and Sensitive HPLC–DAD Assay to Quantify Lamotrigine, Phenytoin and Its Main Metabolite in Samples of Cultured HepaRG Cells

A sensitive and fast high-performance liquid chromatography-diode-array detection assay was developed and validated for the simultaneous quantification of 5-(4-hydroxyphenyl)-5-phenylhydantoin (HPPH), phenytoin (PHT) and lamotrigine (LTG) in samples of cultured HepaRG cells. Chromatographic separation of analytes and internal standard (IS) was achieved in ∼15 min on a C18-column, at 35°C, using acetonitrile (6%), methanol (25%) and a mixture (69%) of water-triethylamine (99.7:0.3, v/v; pH 6.0), pumped at 1 mL/min. The analytes and IS were detected at 215 or 235 nm. Calibration curves were linear with regression coefficients >0.994 over the concentration ranges of 0.1-15 µg/mL for HPPH; 0.15-30 µg/mL for PHT and 0.2-20 µg/mL for LTG. The method showed to be accurate (bias value of ±10.5 or ±17.6% in the lower limit of quantification, LLOQ) and precise (coefficient variation ≤8.1 or ≤15.4% in the LLOQ), and the absolute recovery of the analytes ranged from 62.5 to 96.9%. HepaRG cells have emerged as a very promising in vitro model to evaluate metabolic, drug interaction and/or pharmacokinetic studies, and this methodology will be suitable to support subsequent studies involving the antiepileptic drugs PHT and LTG

Influence of the dual combination of silymarin and (-)-epigallocatechin gallate, natural dietary flavonoids, on the pharmacokinetics of oxcarbazepine in rats

Considering the potential of flavonoids in reversing the P-glycoprotein (P-gp)–mediated multidrug resistance, this work aimed to assess the combined effects of silymarin and (-)-epigallocatechin gallate (EPG) on the pharmacokinetics of the P-gp substrates oxcarbazepine (OXC) and licarbazepine (LIC). Rats were pre-treated intraperitoneally with silymarin (25 mg/kg), EPG (25 mg/kg), silymarin/EPG (12.5/12.5 mg/kg; 6.25/18.75 mg/kg; 18.75/6.25 mg/kg) or verapamil (25 mg/kg, reference P-gp inhibitor) before the intraperitoneal administration of OXC (50 mg/kg). Pre-treatment with dual silymarin/EPG combinations originated peak plasma concentrations of OXC and LIC (pharmacologically active metabolite of OXC) similar to those achieved in the presence of verapamil (positive control). Moreover, the effects promoted by silymarin/EPG combinations on the magnitude of systemic drug exposure to OXC and LIC were also reflected in the corresponding drug levels attained in the brain (biophase). These findings evidence the synergistic effect of silymarin and EPG in enhancing the degree of systemic exposure to OXC and LIC in rats, which occurred in a comparable extent to that observed with verapamil. Hence, our findings support the combination of flavonoid-type P-gp inhibitors and P-gp substrate antiepileptic drugs as a potential therapeutic strategy for the management of pharmacoresistant epilepsy.The authors are grateful to FCT - Foundation for Science and Technology (Lisbon, Portugal) for the PhD fellowship of Ana Ferreira (SFRH/BD/84936/2012). This work was also supported by FEDER funds through the POCI - COMPETE 2020 - Operational Programme Competitiveness and Internationalization in Axis I - Strengthening research, technological development and innovation (Project POCI-01-0145-FEDER-007491) and National Funds by FCT (Project UID/Multi/00709/2013)

Flavonoid compounds as reversing agents of the P-glycoprotein-mediated multidrug resistance: An in vitro evaluation with focus on antiepileptic drugs

The pharmacoresistance to antiepileptic drugs (AEDs) remains a major unsolved therapeutic need. The overexpression of multidrug transporters, as the P-glycoprotein (P-gp), at the level of the blood-brain barrier of epileptic patients has been suggested as a key mechanism underlying the refractory epilepsy. Thus, efforts have been made to search for therapeutically useful P-gp inhibitors. Herein, the strategy of flavonoid/AED combined therapy was exploited as a possible approach to overcome the P-gp-mediated pharmacoresistance. For this purpose, several in vitro studies were performed using Madin-Darby canine kidney II (MDCK II) cells and those transfected with the human multidrug resistance-1 (MDR1) gene, overexpressing the P-gp (MDCK-MDR1). Overall, the results showed that baicalein, (−)-epigallocatechin gallate, kaempferol, quercetin and silymarin, at 200 μM, produced a marked increase on the intracellular accumulation of rhodamine 123 in MDCK-MDR1 cells, potentially through inhibiting the P-gp activity. In addition, with the exception of lamotrigine, all other AEDs tested (phenytoin, carbamazepine and oxcarbazepine) and their active metabolites (carbamazepine-10,11-epoxide and licarbazepine) demonstrated to be P-gp substrates. Furthermore, the most promising flavonoids as Pgp inhibitors promoted a significant increase on the intracellular accumulation of the AEDs (excluding lamotrigine) and their active metabolites in MDCK-MDR1 cells, evidencing to be important drug candidates to reverse the AED-resistance. Thus, the co-administration of AEDs with baicalein, (−)-epigallocatechin gallate, kaempferol, quercetin and silymarin should continue to be explored as adjuvant therapy for refractory epilepsy

Determination of lamotrigine in human plasma and saliva using microextraction by packed sorbent and high performance liquid chromatography–diode array detection: An innovative bioanalytical tool for therapeutic drug monitoring

A ground-breaking high-performance liquid chromatography-diode array detection method based on microextraction by packed sorbent (MEPS) as sample preparation approach is described herein for determination of lamotrigine (LTG), a narrow therapeutic index drug, in human plasma and saliva. MEPS variables and chromatographic conditions were optimized to achieve appropriate selectivity and sensitivity using small sample volumes (100 μL). The chromatographic separation of LTG and chloramphenicol [internal standard (IS)] was accomplished in < 5 min on a C18-column, at 35 °C, using a mobile phase composed by acetonitrile/methanol/water-triethylamine 0.3% at pH 6.0 (13:13:74, v/v/v) pumped isocratically at 1 mL/min. LTG and IS were detected at 215 nm. A good linearity was obtained for LTG (r² ≥ 0.9936) in the range of 0.1–20 μg/mL in plasma and saliva, with the limit of quantification of 0.1 μg/mL. The method was shown to be precise (RSD ≤ 14.5%) and accurate (bias ± 13.4%), and the absolute recovery ranged from 64.9% to 73.6%. The stability of LTG was demonstrated in plasma and saliva samples in all studied conditions. The proposed assay was applied to the analysis of real human plasma and saliva samples from epilepsy patients under LTG therapy and the results support its usefulness for therapeutic drug monitoring

Clinical pharmacists interventions in the management of type 2 diabetes mellitus: a systematic review

Background: Type 2 diabetes mellitus is a chronic disease that is reaching epidemic proportions worldwide. It is imperative to adopt an integrated strategy, which involves a close collaboration between the patient and a multidisciplinary team of which pharmacists should be integral elements. Objective: This work aims to identify and summarize the main effects of interventions carried out by clinical pharmacists in the management of patients with type 2 diabetes, considering clinical, humanistic and economic outcomes. Methods: PubMed and Cochrane Central Register of Controlled Trials were searched for randomized controlled trials assessing the effectiveness of such interventions compared with usual care that took place in hospitals or outpatient facilities. Results: This review included 39 studies, involving a total of 5,474 participants. Beneficial effects were observed on various clinical outcomes such as glycemia, blood pressure, lipid profile, body mass index and coronary heart disease risk. For the following parameters, the range for the difference in change from baseline to final follow-up between the intervention and control groups was: HbA1c, -0.05% to -2.1%; systolic blood pressure, +3.45 mmHg to -10.6 mmHg; total cholesterol, +10.06 mg/dL to -32.48 mg/dL; body mass index, +0.6 kg/m2 to -1.94 kg/m2; and coronary heart disease risk, -3.0% and -12.0% (among the studies that used Framinghan prediction method). The effect on medication adherence and health-related quality of life was also positive. In the studies that performed an economic evaluation, the interventions proved to be economically viable. Conclusions: These findings support and encourage the integration of clinical pharmacists into multidisciplinary teams, underlining their role in improving the management of type 2 diabete

Effectiveness of an intervention to improve antibiotic-prescribing behaviour in primary care: a controlled, interrupted time-series study

Background: High rates of antibiotic misprescribing in primary care, with alarming clinical and economic consequences, highlight the urgent need for interventions to improve antibiotic prescribing in this setting. Objectives: To assess the effectiveness on antibiotic prescribing quality indicators of a multifaceted intervention targeting health professionals' and patients' behaviour regarding antibiotic use. Methods: We conducted a pragmatic cluster-randomized controlled trial in the catchment area covered by Portugal's Central Regional Health Administration. The intervention consisted of a multidisciplinary, multifaceted programme involving physicians, pharmacists and patients, and comprising outreach visits for physicians and pharmacists, and educational materials for health professionals and patients. The following were assessed: relative ratios of prescription of penicillins sensitive to β-lactamase, penicillin combinations including β-lactamase inhibitors, third- and fourth-generation cephalosporins and fluoroquinolones; and the ratio of broad- to narrow-spectrum antibiotics. An interrupted time-series analysis for multiple-group comparisons was performed. The study protocol was registered on Clinical.trials.gov (NCT02173509). Results: The participation rate in the educational intervention was 64% (197/309 GPs) in a total of 25 counties. Statistically significant improvements were obtained, not only in the relative prescription of penicillins sensitive to β-lactamase (overall relative change of +896%) and penicillin combinations including β-lactamase inhibitors (-161%), but also in the ratio of broad- to narrow-spectrum antibiotics (-200%). Statistically significant results were also obtained for third- and fourth-generation cephalosporins, though only in the immediate term. Conclusions: This study showed that quality indicators of antibiotic prescribing can be improved by tackling influences on behaviour including knowledge and attitudes surrounding physicians' clinical practice. Accordingly, these determinants must be considered when implementing interventions aimed at improving antibiotic prescribing

Highlighting the Role of DC-NK Cell Interplay in Immunobiology and Immunotherapy

Dendritic cells (DCs) and natural killer (NK) cells are both part of the innate immune system, also playing crucial functions in the regulation of adaptive immune responses. In recent years, numerous works have demonstrated that DCs and NK cells mutually influence each other with major consequences in the type and effectiveness of elicited immune responses. Among other effects, DC-NK crosstalk can result in NK cell activation and DC maturation or deletion, depending on its activation status. In this chapter and after a brief overview of DCs and NK immunobiology, we focus on the process of DC-NK crosstalk, highlighting the relevance of rationally exploring this interplay in the development of more effective cancer immunotherapies

Development and application of an ex vivo fosphenytoin nasal bioconversion/permeability evaluation method

There is an increasing interest in the intranasal delivery of central nervous system-active drugs due to the existence of a direct nose-to-brain connection. However, poor solubility limits the amount of drug that can be administered within an aqueous solution. In the present work, the objectives were to develop an ex vivo bioconversion/ permeability evaluation method and to study the ex vivo bioconversion of the hydrophilic phosphate ester prodrug fosphenytoin (FOS) to the active drug phenytoin (PHT) and their comparative nasal permeation. Bioconversion/permeability studies were performed in excised porcine nasal mucosa mounted in Ussing chambers. The physical integrity of the tissues was evaluated by measurement of the transepithelial electrical resistance (TEER). The simultaneous quantitative assay of FOS, PHT and its major metabolite, 5-(4-hydroxyphenyl)- 5-phenylhydantoin (HPPH) was developed and validated according to international guidelines using a liquid chromatography analytical method. The FOS bioconversion rate and PHT and FOS apparent permeability coefficients (Papp) were determined at different time points. FOS bioconversion was also qualitatively investigated in human nasal mucus. The developed liquid chromatography method combines a fast and inexpensive sample preparation with inactivation of the enzymatic metabolism of the prodrug during sample manipulation and storage. It was linear, precise, accurate, and presented a high analyte recovery. FOS was converted ex vivo to PHT but the metabolite HPPHwas not detected. The bioconversion rate increasedwith FOS concentration and with time, which suggests a diffusion-limited process. FOSwas also converted to its active drug by human nasal mucus. A novel mathematical data analysis method was developed to reduce the bias introduced by variable mucosal TEER in the permeability results. At comparable FOS and PHT concentrations the ln(Papp PHT) of both compounds showed little difference,which indicates that the use of a hydrophilic and charged prodrug did not hinder overall drug permeation. At the highest tested FOS concentration it was possible to quantify FOS in the receiver chambers, meaning that at a sufficiently high concentration the FOS permeation rate overcame its bioconversion rate. The ln(Papp PHT) tended to similar equilibrium values as the assay progressed, but with higher FOS concentrations that equilibrium was attained faster. Acidic pH reduced the permeability of both PHT and FOS. The developed bioconversion/permeability evaluation method will constitute an important tool to select the most promising formulations before proceeding to in vivo studies. Importantly, it allowed the demonstration of phosphatase activity and FOS bioconversion in nasal mucosa, aswell as the prodrug's nasal permeation potential. Furthermore, this study demonstrates the possibility of formulating phosphate prodrugs of poorly soluble central nervous system-active drugs as a strategy to increase the solubilized drug doses administered through the nasal route

Enantioselective HPLC-UV method for determination of eslicarbazepine acetate (BIA 2-093) and its metabolites in human plasma

Eslicarbazepine acetate (BIA 2-093) is a novel central nervous system drug undergoing clinical phase III trials for epilepsy and phase II trials for bipolar disorder. A simple and reliable chiral reversed-phase HPLC-UV method was developed and validated for the simultaneous determination of eslicarbazepine acetate, oxcarbazepine, S-licarbazepine and R-licarbazepine in human plasma. The analytes and internal standard were extracted from plasma by a solid-phase extraction using Waters Oasis® HLB cartridges. Chromatographic separation was achieved by isocratic elution with water–methanol (88:12, v/v), at a flow rate of 0.7 mL/min, on a LichroCART 250-4 ChiraDex (β-cyclodextrin, 5 μm) column at 30°C. All compounds were detected at 225 nm. Calibration curves were linear over the range 0.4–8 μg/mL for eslicarbazepine acetate and oxcarbazepine, and 0.4 – 80 μg/ mL for each licarbazepine enantiomer. The overall intra- and interday precision and accuracy did not exceed 15%. Mean relative recoveries varied from 94.00 to 102.23% and the limit of quantification of the assay was 0.4 μg/mL for all compounds. This method seems to be a useful tool for clinical research and therapeutic drug monitoring of eslicarbazepine acetate and its metabolites S-licarbazepine, R-licarbazepine and oxcarbazepine