The ABC superfamily of transporters consists of 51 human genes in 7 subfamilies. The ABC transporters involved in drug transport are found in many tissues in the body including the liver, kidney, brain, and intestine. The liver and the intestine are the tissues most important in the oral bioavailability of drugs. This chapter focuses on the ABC efflux transporters present in liver and intestine and their roles in the oral bioavailability and hepatobiliary excretion of xenobiotics. It discusses factors that affect the expression and function of efflux transporters in the liver and intestine. ABCB11 is a monovalent bile salt efflux protein located predominantly on the canalicular membrane in liver hepatocytes. Excretion of bile salts from liver hepatocytes into bile canaliculi is a major driving force for bile flow and can be a rate-limiting step. The ABC family of efflux transporters are determinants of the absorption and disposition of substrates for the transporters.

: Present study investigated the possible role of P-glycoprotein in the intracellular exposure of active substance (robinin) of natural medicine Flaroninum™ and effect of robinin on the cellular accumulation of mitoxantrone in either BCRP-overexpressing and BCRP-negative cells. Robinin - kaempferol-3-O- -D-robinoside-7-O-α-L-rhamnopyranoside, has been obtained from over ground parts of Astragalus falcatus Lam., growing in Georgia. The compound possesses hypoazotemic and diuretic activities and is proposed for the complex therapy of kidney diseases. P-gp-overexpressing and P-gp-negative human breast cancer cells (MCF7) were used to examine the absorption character of kaempferol and robinin with or without of verapamil (P-gp inhibitor). Flavonoids concentrations were determined by LC/MS/MS. Robinin transport was P-gp-dependent and verapamil significantly increased the extent of uptake of robinin in cells, which is attributed in part to P-gp-inhibition by verapamil

Despite the understanding that renal clearance is pivotal for driving the pharmacokinetics of numerous therapeutic proteins and peptides, the specific processes that occur following glomerular filtration remain poorly defined. For instance, sites of catabolism within the proximal tubule can occur at the brush border, within lysosomes following endocytosis, or even within the tubule lumen itself. The objective of the current study was to address these limitations and develop methodology to study the kidney disposition of a model therapeutic protein. Exenatide is a peptide used to treat type 2 diabetes mellitus. Glomerular filtration and ensuing renal catabolism have been shown to be its principal clearance pathway. Here, we designed and validated a Förster resonance energy transfer-quenched exenatide derivative to provide critical information on the renal handling of exenatide. A combination of in vitro techniques was used to confirm substantial fluorescence quenching of intact peptide that was released upon proteolytic cleavage. This evaluation was then followed by an assessment of the in vivo disposition of quenched exenatide directly within kidneys of living rats via intravital two-photon microscopy. Live imaging demonstrated rapid glomerular filtration and identified exenatide metabolism occurred within the subapical regions of the proximal tubule epithelia, with subsequent intracellular trafficking of cleaved fragments. These results provide a novel examination into the real-time, intravital disposition of a protein therapeutic within the kidney and offer a platform to build upon for future work.

Megalin and cubilin, endocytic proteins present in the proximal tubule of the kidney, are responsible for reabsorbing filtered proteins from urine. Our hypothesis was that potential substrates of megalin/cubilin could be identified by examining urinary protein differences between control (WT) mice and kidney-specific megalin knockdown (KD) mice. Using the IonStar proteomics approach, 877 potential megalin/cubilin substrates were discovered, with 23 of these compounds representing known megalin/cubilin substrates. Some of the proteins with the largest fold changes in the urine between KD and WT included the known megalin substrates retinol-binding protein and vitamin D-binding protein. Of the total proteins identified as novel substrates, about three-quarters of compounds had molecular weights (MWs) below 69 kDa, the MW of albumin, and the remaining had higher MWs, with about 5% of the proteins having MWs greater than 150 kDa. Sex differences in the number of identified substrates occurred, but this may be due to differences in kidney megalin expression between both male and female megalin KD and WT animals, with the ratio of megalin between WT and KD being 2.76 and 2.14 for female and male mice, respectively. The top three ingenuity canonical pathways based on the urinary proteins in both female and male KD mice were acute phase response signaling, liver X receptor/retinoid X receptor activation, and intrinsic prothrombin activation pathways. In conclusion, analysis of urine samples from kidney-specific megalin KD and WT mice was found to be useful for the identification of potential endogenous substrates for megalin and cubilin.

This special topic theme issue focuses on the results of a global survey for doctoral and master's programs in the pharmaceutical sciences. The survey was supported by the International Pharmaceutical Federation (FIP) and the FIP Board of Pharmaceutical Sciences (BPS); FIP is an international organization that represents over 4 million pharmacists and pharmaceutical scientists globally. The survey was developed by an international and discipline-diverse committee of pharmaceutical science educators (listed as authors) and the Scientific Secretary of the FIP Board of Pharmaceutical Sciences. While there have been a range of publications addressing doctoral programs in the pharmaceutical sciences in the United States, there are few examining international doctoral programs, and, to our knowledge, none that have reported on master's programs in the pharmaceutical sciences. These publications provide the results of the first survey to address global graduate programs in the pharmaceutical sciences.

Competency-based education (CBE) is a viable educational approach to close a training gap between ever-changing health challenges and pharmacy and pharmaceutical education curricula. However, the implementation of CBE into initial professional education and training (IPET) for pharmacists is slow. Thus, the development of a handbook to guide academics, educators, and practitioners in implementing CBE would be beneficial. This paper describes the process of developing a handbook to support educators in implementing CBE principles in IPET for pharmacists and pharmaceutical scientists. The project involves three phases: (1) a systematic review, (2) a global survey, and (3) the development of a handbook. The handbook provides guidance and a stepwise approach to implementing CBE in pharmacy curricula, which is particularly useful in resource-limited settings where curriculum overhaul using CBE principles might be challenging.

This publication represents the first to report global information on characteristics and requirements of doctoral programs in the pharmaceutical sciences in schools/colleges of Pharmacy. Survey responses (140 responses) were received from doctoral programs in 23 countries, with the greatest number of responses obtained from Japan, followed by India and the United States. Program characteristics and requirements, and student and faculty information, including graduate placement, in programs in Asia, North America, Europe, Africa and Australia were compared. Survey responses indicated differences in entrance requirements for doctoral programs with minimum requirements being a bachelor's degree, pharmacy degree or master's degree, including a M.Phil. degree. Programs differed widely in size in all geographical areas, but there was a similar emphasis on core educational learning outcomes (core competencies) and Ph.D. graduation requirements including qualifying examinations, thesis defense with internal and external reviewers and requirements for peer-reviewed publications. Additionally, three-quarters of programs indicated that there was external review of their programs every 2-4 or 5-7 years. Female students and female faculty mentors represented about 50% of students/faculty in programs in most geographical areas. Placement of students after graduation indicated that the highest percentage went into the pharmaceutical industry in Asia (predominantly India) and North America, with a lower percentage in Europe, Africa and Australia.

Abstract Monocarboxylate transporter 6 (MCT6; SLC16A5) is an orphan transporter protein with expression in multiple tissues. The endogenous function of MCT6 related to human health and disease remains unknown. Our previous transcriptomic and proteomic analyses in Mct6 knockout (KO) mice suggested that MCT6 may play a role in lipid and glucose homeostasis, but additional evidence is required. Thus, the objective of this study was to further explore the impact of MCT6 on metabolic function using untargeted metabolomic analysis in Mct6 KO mice. The plasma from male and female mice and livers from male mice were submitted for global metabolomics analysis to assess the relative changes in endogenous small molecules across the liver and systemic circulation associated with absence of Mct6. More than 782 compounds were detected with 101 and 51 metabolites significantly changed in plasma of male and female mice, respectively, and 100 metabolites significantly changed in the livers of male mice (p < .05). Significant perturbations in lipid metabolism were annotated in the plasma and liver metabolome, with additional alterations in the amino acid metabolism pathway in plasma samples from male and female mice. Elevated lipid diacylglycerol and altered fatty acid metabolite concentrations were found in liver and plasma samples of male Mct6 KO mice. Significant reduction of N‐terminal acetylated amino acids was found in plasma samples of male and female Mct6 KO mice. In summary, the present study confirmed the significant role of MCT6 in lipid and amino acid homeostasis, suggesting its contribution in metabolic diseases.

Dietary and nutrient-containing mixtures of phytochemicals may alter drug pharmacokinetics. Previous food–drug interaction studies have focused primarily on the effects of diet on drug-metabolizing enzymes. In recent years, the role of drug transporters in diet–drug interactions have been increasingly recognized. Modulation of drug transporters by diet/dietary supplements, such as St. John's Wort, grapefruit juice, and green tea, may result in clinically important drug interactions. Flavonoids and isothiocyanates have also been identified as potent inhibitors/inducers of major efflux or uptake transporters. However, it remains difficult to predict alterations in drug disposition due to the complex components in foods/dietary supplements and multiple factors influencing drug disposition. In the present chapter, we focus on the molecular mechanisms of drug–dietary component interactions involving drug transporters, based on in vitro and in vivo studies, with specific emphasis on several major efflux transporters (P-glycoprotein, MRP, and BCRP) and uptake transporters (OATP, OAT).

High doses of the partial agonist of the GABAB receptor, γ-hydroxybutyric acid (GHB), cause respiratory depression that can lead to death. Previously, it has been shown that GABAB receptor antagonism is able to prevent respiratory depression and sedation when inhibitors are preadministered. To treat GHB overdoses, safety and efficacy of a treatment strategy at various times after GHB administration are necessary to more closely replicate a true overdose situation. Preliminary studies developed an assay for SGS742 and determined its pharmacokinetics in rats. The effects of SGS742 on GHB-induced respiratory depression were evaluated when SGS742 administration was delayed 1 and 2 hours after intravenous or oral administration of GHB or γ-butyrolactone, a GHB prodrug. SGS742 reversed GHB-induced respiratory depression in a dose-dependent manner at both time points tested, with no effects on its toxicokinetics. However, some of the dosing paradigms resulted in toxicity in the form of tremors, seizures, or abnormal movements. The tremors/seizures occurred in a manner that was dependent on both the dose and timing of SGS742 administration and were not altered with pretreatment with gabazine, a GABAA receptor inhibitor, and only partially reduced with pretreatment with NCS382, a selective GHB receptor antagonist. Additional studies with a second GABAB antagonist SCH50911 demonstrated similar effects, producing reversal of respiratory depression but producing tremors and abnormal movements. Further work is necessary to identify the potential use of GABAB antagonism as a treatment strategy for GHB overdoses. SIGNIFICANCE STATEMENT There is no current treatment for overdoses of the drug GHB. Since the toxicodynamic effects of GHB, namely sedation and respiratory depression, are mediated through GABAB receptor agonism, GABAB receptor antagonists may represent a therapeutic strategy to treat overdoses. This study demonstrates that although GABAB receptor antagonists are effective as a pretreatment, they are less effective when administered at times after GHB administration, and their administration is also associated with time- and dose-associated toxicity, namely tremors or seizures.

Patients with chronic kidney disease (CKD) and end-stage renal disease suffer from increased cardiovascular events and cardiac mortality. Prior studies have demonstrated that a portion of this enhanced risk can be attributed to the accumulation of microbiota-derived toxic metabolites, with most studies focusing on the sulfonated form of p-cresol (PCS). However, unconjugated p-cresol (uPC) itself was never assessed due to rapid and extensive first-pass metabolism that results in negligible serum concentrations of uPC. These reports thus failed to consider the host exposure to uPC prior to hepatic metabolism. In the current study, not only did we measure the effect of altering the intestinal microbiota on lipid accumulation in coronary arteries, but we also examined macrophage lipid uptake and handling pathways in response to uPC. We found that atherosclerosis-prone mice fed a high-fat diet exhibited significantly higher coronary artery lipid deposits upon receiving fecal material from CKD mice. Furthermore, treatment with uPC increased total cholesterol, triglycerides, and hepatic and aortic fatty deposits in non-CKD mice. Studies employing an in vitro macrophage model demonstrated that uPC exposure increased apoptosis whereas PCS did not. Additionally, uPC exhibited higher potency than PCS to stimulate LDL uptake and only uPC induced endocytosis- and pinocytosis-related genes. Pharmacological inhibition of varying cholesterol influx and efflux systems indicated that uPC increased macrophage LDL uptake by activating macropinocytosis. Overall, these findings indicate that uPC itself had a distinct effect on macrophage biology that might have contributed to increased cardiovascular risk in patients with CKD.

The drug of abuse, γ-hydroxybutyric acid (GHB), is commonly co-ingested with ethanol, resulting in a high incidence of toxicity and death. Our laboratory has previously reported that GHB is a substrate for the monocarboxylate transporters (MCTs), necessary for its absorption, renal clearance, and tissue distribution, including across the blood-brain barrier. Our goal was to investigate the drug-drug interaction (DDI) between GHB and ethanol and to evaluate MCT1 inhibition as a strategy to reverse toxicity. The toxicokinetics of this DDI were investigated, including brain-to-plasma concentration ratios, in the presence and absence of ethanol. The toxicodynamic parameters examined were respiratory depression (breathing frequency, tidal volume) and sedation (time of return-of-righting reflex). Ethanol was administered (2 g/kg i.v.) 5 minutes before the intravenous or oral administration of GHB, and MCT1 inhibitors AZD-3965 and AR-C155858 (5 mg/kg i.v.) were administered 60 minutes after GHB administration. Ethanol administration did not alter the toxicokinetics or respiratory depression caused by GHB after intravenous or oral administration; however, it significantly increased the sedation effect, measured by return-to-righting time. AZD-3965 or AR-C155858 significantly decreased the effects of the co-administration of GHB and ethanol on respiratory depression and sedation of this DDI and decreased brain concentrations and the brain-to-plasma concentration ratio of GHB. The results indicate that ethanol co-administered with GHB increases toxicity and that MCT1 inhibition is effective in reversing toxicity by inhibiting GHB brain uptake when given after GHB-ethanol administration. SIGNIFICANCE STATEMENT These studies investigated the enhanced toxicity observed clinically when γ-hydroxybutyric acid (GHB) is co-ingested with alcohol and evaluated strategies to reverse this toxicity. The effects of the novel monocarboxylate transporter 1 (MCT1) inhibitors AR-C155858 and AZD-3965 on this drug-drug interaction have not been studied before, and these preclinical studies indicate that MCT1 inhibitors can decrease brain concentrations of GHB by inhibiting brain uptake, even when administered at times after GHB-ethanol. AZD-3965 represents a potential treatment strategy for GHB-ethanol overdoses.

Therapeutic immunoglobulin G (IgG) antibodies comprise the largest class of protein therapeutics. Several factors that influence their overall disposition have been well-characterized, including target-mediated mechanics and convective flow. What remains poorly defined is the potential for non-targeted entry into various tissues or cell types by means of uptake via cell surface receptors at those sites. Megalin and cubilin are large endocytic receptors whose cooperative function plays important physiological roles at the tissues in which they are expressed. One such example is the kidney, where loss of either results in significant declines in proximal tubule protein reabsorption. Due to their diverse ligand profile and broad tissue expression, megalin and cubilin represent potential candidates for receptor-mediated uptake of IgG into various epithelia. Therefore, the objective of the current work was to determine if IgG was a novel ligand of megalin and/or cubilin. Direct binding was measured for human IgG with both megalin and the cubilin/amnionless complex. Additional work focusing on the megalin-IgG interaction was then conducted to build upon these findings. Cell uptake studies using megalin ligands for competitive inhibition or proximal tubule cells stably transduced with megalin-targeted shRNA constructs supported a role for megalin in the endocytosis of human IgG. Furthermore, a pharmacokinetic study using transgenic mice with a kidney-specific mosaic knockout of megalin demonstrated increased urinary excretion of human IgG in megalin knockout mice when compared to wild-type controls. These findings indicate that megalin is capable of binding and internalizing IgG via a high affinity interaction.

Gamma hydroxybutyric acid (GHB) has been approved clinically to treat excessive daytime sleepiness and cataplexy in patients with narcolepsy, alcohol and opioid withdrawal, and as an anesthetic. The use of GHB clinically is limited due to its high abuse potential. The absorption, clearance and tissue uptake of GHB is mediated by proton-dependent and sodium-coupled monocarboxylate transporters (MCTs and SMCTs) and inhibition of these transporters may result in a change in GHB pharmacokinetics and pharmacodynamics. Previous studies have reported that non-steroidal anti-inflammatory drugs (NSAIDs) may inhibit these monocarboxylate transporters. Therefore, the purpose of this work was to analyze the interaction between GHB (at a dose of 600 mg/kg i. v.) and the NSAID, diclofenac, by examining the effects of this drug on the in vivo pharmacokinetics and pharmacodynamics in rat studies. The pharmacodynamic effect evaluated was respiratory depression, a measure of toxicity observed by GHB at this dose. There was an improvement in the respiratory rate with diclofenac administration suggesting an effect of diclofenac on GHB toxicity. In vitro studies with rat blood brain endothelial cells (RBE4) that express MCT1 indicated that diclofenac can inhibit GHB transport with an IC50 of 10.6 μM at pH 7.4. In vivo studies found a decrease in brain GHB concentrations and a decrease in the brain-to-plasma concentration ratio following diclofenac treatment. With this study we can conclude that diclofenac and potentially other NSAIDs can inhibit the transport of GHB into the brain, therefore decreasing GHB's pharmacodynamic effects and toxicity.

: The drug of abuse, γ-hydroxybutyric acid (GHB), is commonly co-ingested with ethanol, resulting in a high incidence of toxicity and death. Our laboratory has previously reported that GHB is a substrate for the monocarboxylate transporters (MCT), necessary for its absorption, renal clearance, and tissue distribution, including across the blood-brain barrier. Our goal was to investigate the drug-drug interaction (DDI) between GHB-ethanol and evaluate MCT1 inhibition as a strategy to reverse toxicity. The toxicokinetics of this DDI were investigated, including brain to plasma concentration ratios, in the presence and absence of ethanol. The toxicodynamic parameters examined were respiratory depression (breathing frequency, tidal volume) and sedation (time of return-of-righting reflex). Ethanol was administered (2 g/kg i.v.) 5 min before the i.v. or oral administration of GHB, and MCT1 inhibitors, AZD-3965 and AR-C155858 (5mg/kg i.v.) were administered 60 min after GHB administration. Ethanol administration did not alter the toxicokinetics or respiratory depression caused by GHB after i.v. or oral administration; however, it significantly increased the sedation effect, measured by return-to-righting time. AZD-3965 or AR-C155858 significantly decreased the effects of the co-administration of GHB and ethanol on respiratory depression and sedation of this DDI, and decreased brain concentrations and the brain/plasma concentration ratio of GHB. The results indicate that ethanol co-administered with GHB increases toxicity and MCT1 inhibition is effective in reversing toxicity by inhibiting GHB brain uptake when given post-GHB/ethanol administration.

γ-hydroxybutyric acid (GHB) is widely abused alone and in combination with other club drugs such as ketamine. GHB exhibits nonlinear toxicokinetics, characterized by saturable metabolism, saturable absorption and saturable renal reabsorption mediated by monocarboxylate transporters (MCTs). In this research, we characterized the effects of ketamine on GHB toxicokinetics/toxicodynamics (TK/TD) and evaluated the use of MCT inhibition and specific receptor antagonism as potential treatment strategies for GHB overdose in the presence of ketamine. Adult male Sprague-Dawley rats were administered GHB 600 mg/kg i.v. alone or with ketamine (6 mg/kg i.v. bolus plus 1 mg/kg/min i.v. infusion). Plasma and urine samples were collected and respiratory parameters (breathing frequency, tidal and minute volume) continuously monitored using whole-body plethysmography. Ketamine co-administration resulted in a significant decrease in GHB total and metabolic clearance, with renal clearance remaining unchanged. Ketamine prevented the compensatory increase in tidal volume produced by GHB, and this resulted in a significant decline in minute volume when compared to GHB alone. Sleep time and lethality were also increased after ketamine co-administration when compared to GHB. L-lactate and AR-C155858 (potent MCT inhibitor) treatment resulted in an increase in GHB renal and total clearance and improvement in respiratory depression. AR-C155858 administration also resulted in a significant decrease in GHB brain/plasma ratio. SCH50911 (GABAB receptor antagonist), but not naloxone, improved GHB-induced respiratory depression in the presence of ketamine. In conclusion, ketamine ingestion with GHB can result in significant TK/TD interactions. MCT inhibition and GABAB receptor antagonism can serve as potential treatment strategies for GHB overdose when it is co-ingested with ketamine.

Gamma-hydroxybutyrate (GHB) is a short-chain fatty acid present endogenously in the brain and used therapeutically for the treatment of narcolepsy, as sodium oxybate, and for alcohol abuse/withdrawal. GHB is better known however as a drug of abuse and is commonly referred to as the "date–rape drug"; current use in popular culture includes recreational "chemsex," due to its properties of euphoria, loss of inhibition, amnesia, and drowsiness. Due to the steep concentration–effect curve for GHB, overdoses occur commonly and symptoms include sedation, respiratory depression, coma, and death. GHB binds to both GHB and GABAB receptors in the brain, with pharmacological/toxicological effects mainly due to GABAB agonist effects. The pharmacokinetics of GHB are complex and include nonlinear absorption, metabolism, tissue uptake, and renal elimination processes. GHB is a substrate for monocarboxylate transporters, including both sodium-dependent transporters (SMCT1, 2; SLC5A8; SLC5A12) and proton-dependent transporters (MCT1–4; SLC16A1, 7, 8, and 3), which represent significant determinants of absorption, renal reabsorption, and brain and tissue uptake. This review will provide current information of the pharmacology, therapeutic effects, and pharmacokinetics/pharmacodynamics of GHB, as well as therapeutic strategies for the treatment of overdoses.