Digestion of surfactants does not affect their ability to inhibit P-gp-mediated transport in vitro

While various non-ionic surfactants at low concentrations have been shown to increase the transport of P-gp substrates in vitro, in vivo studies in rats have shown that a higher surfactant concentration is needed to increase the oral absorption of e.g. the P-gp substrates digoxin and etoposide. The aim of the present study was to investigate if intestinal digestion of surfactants could be the reason for this deviation between in vitro and in vivo data. Therefore, Kolliphor EL, Brij-L23, Labrasol and polysorbate 20 were investigated for their ability to inhibit P-gp and increase digoxin absorption in vitro. Transport studies were performed in Caco-2 cells, while P-gp inhibition and cell viability assays were performed in MDCKII-MDR1 cells. Polysorbate 20, Kolliphor EL and Brij-L23 increased absorptive transport and decreased secretory digoxin transport in Caco-2 cells, whereas only polysorbate 20 and Brij-L23 showed P-gp inhibiting properties in the MDCKII-MDR1 cells. Polysorbate 20 and Brij-L23 were chosen for in vitro digestion prior to transport- or P-gp inhibiting assays. Brij-L23 was not digestible, whereas polysorbate 20 reached a degree of digestion around 40%. Neither of the two surfactants showed any significant difference in their ability to affect absorptive or secretory transport of digoxin after pre-digestion. Furthermore, the P-gp inhibiting effects of polysorbate 20 were not decreased significantly. In conclusion, the mechanism behind the non-ionic surfactant mediated in vitro P-gp inhibition seemed independent of the intestinal digestion and the results presented here did not suggest it to be the cause of the observed discrepancy between in vitro and in vivo.

Rationalizing Counterion Selection for the Development of Lipophilic Salts: A Case Study with Venetoclax

The use of lipid-based formulations (LBFs) can be hindered by low dose loading due to solubility limitations of candidate drugs in lipid vehicles. Formation of lipophilic salts through pairing these drugs with a lipophilic counterion has been demonstrated as a potential means to enhance dose loading in LBFs. This study investigated the screening of appropriate counterions to form lipophilic salts of the BCS class IV drug venetoclax. The physical properties, lipid solubility, and in vitro performance of the salts were analyzed. This study illustrated the versatility of alkyl sulfates and sulfonates as suitable counterions in lipophilic salt synthesis with up to ∼9-fold higher solubility in medium- and long-chain LBFs when compared to that of the free base form of venetoclax. All salts formulated as LBFs displayed superior in vitro performance when compared to the free base form of the drug due to the higher initial drug loadings in LBFs and increased affinity for colloidal species. Further, in vitro studies confirmed that venetoclax lipophilic salt forms using alkyl chain counterions demonstrated comparable in vitro performance to venetoclax docusate, thus reducing the potential for laxative effects related to docusate administration. High levels of the initial dose loading of venetoclax lipophilic salts were retained in a molecularly dispersed state during dispersion and digestion of the formulation, while also demonstrating increased levels of saturation in biorelevant media. The findings of this study suggest that alkyl chain sulfates and sulfonates can act as a suitable alternative counterion to docusate, facilitating the selection of counterions that can unlock the potential to formulate venetoclax as an LBF.

Exploring career choices of pharmacy graduates over 15 years: A cross-sectional evaluation

INTRODUCTION

Career opportunities for pharmacists beyond those commonly associated with the degree continue to emerge. A paucity of literature regarding evaluation of pharmacy graduate career paths over extended periods is apparent. Considering international pharmacy workforce capacity pressures, the primary study aim was to evaluate trends in career paths of pharmacy graduates.

METHODS

This study utilised a multimethod approach to access graduate career data using publicly accessible information from LinkedIn® profiles and an online survey. The survey was distributed to all pharmacy graduates of a university (2007-2022). Data from both methods was combined, cross-checked, coded and analysed quantitatively using descriptive and inferential statistics.

RESULTS

Data from 69.7% of the university's pharmacy graduates was collected. Community pharmacy was the most prevalent employment sector (47.7%), followed by industry (21.5%) and hospital (17.7%). A higher proportion of more recent graduates (≤5 years post-graduation) work in a community or hospital pharmacy role versus those who graduated greater than five years ago (χ2 = 8.44, df = 2, p < 0.05). Post-graduate education was undertaken by 41.3% of graduates. Career satisfaction was high (88.2%) but was lower (χ2 = 11.31, df = 1, p < 0.05) for those in community and hospital (82%) versus other sectors (97.5%).

CONCLUSION

This study provides the first analysis of graduate career paths over an extended period, highlighting a novel approach to track pharmacist workforce. While almost two thirds of pharmacy graduates occupy community or hospital roles, a trend of leaving these settings five years post-graduation was evident. Accordingly, this work represents a springboard for additional research to inform future pharmacist workforce planning worldwide.

Predictive computational models for assessing the impact of co-milling on drug dissolution

Co-milling is an effective technique for improving dissolution rate limited absorption characteristics of poorly water soluble drugs. However, there is a scarcity of models available to forecast the magnitude of dissolution rate improvement caused by co-milling. Therefore, this study endeavoured to quantitatively predict the increase in dissolution by co-milling based on drug properties. Using a biorelevant dissolution setup, a series of 29 structurally diverse and crystalline drugs were screened in co-milled and physically blended mixtures with Polyvinylpyrrolidone K25. Co-Milling Dissolution Ratios after 15 min (COMDR15 min) and 60 min (COMDR60 min) drug release were predicted by variable selection in the framework of a partial least squares (PLS) regression. The model forecasts the COMDR15 min (R2 = 0.82 and Q2 = 0.77) and COMDR60 min (R2 = 0.87 and Q2 = 0.84) with small differences in root mean square errors of training and test sets by selecting four drug properties. Based on three of these selected variables, applicable multiple linear regression equations were developed with a high predictive power of R2 = 0.83 (COMDR15 min) and R2 = 0.84 (COMDR60 min). The most influential predictor variable was the median particle size of the pure drug, followed by the calculated drug logD6.5 value, the calculated molecular descriptor Kappa 3 and the apparent solubility of pure drug after 24 h dissolution. The study demonstrates the feasibility of forecasting the dissolution rate improvements of poorly water solube drugs through co-milling. These models can be applied as computational tools to guide formulation in early stage development.

Developing an in vitro lipolysis model for real-time analysis of drug concentrations during digestion of lipid-based formulations

Understanding the effect of digestion on oral lipid-based drug formulations is a critical step in assessing the impact of the digestive process in the intestine on intraluminal drug concentrations. The classical pH-stat in vitro lipolysis technique has traditionally been applied, however, there is a need to explore the establishment of higher throughput small-scale methods. This study explores the use of alternative lipases with the aim of selecting digestion conditions that permit in-line UV detection for the determination of real-time drug concentrations. A range of immobilised and pre-dissolved lipases were assessed for digestion of lipid-based formulations and compared to digestion with the classical source of lipase, porcine pancreatin. Palatase® 20000 L, a purified liquid lipase, displayed comparable digestion kinetics to porcine pancreatin and drug concentration determined during digestion of a fenofibrate lipid-based formulation were similar between methods. In-line UV analysis using the MicroDISS ProfilerTM demonstrated that drug concentration could be monitored during one hour of dispersion and three hours of digestion for both a medium- and long-chain lipid-based formulations with corresponding results to that obtained from the classical lipolysis method. This method offers opportunities exploring the real-time dynamic drug concentration during dispersion and digestion of lipid-based formulations in a small-scale setup avoiding artifacts as a result of extensive sample preparation.

Advancing algorithmic drug product development: Recommendations for machine learning approaches in drug formulation

Artificial intelligence is a rapidly expanding area of research, with the disruptive potential to transform traditional approaches in the pharmaceutical industry, from drug discovery and development to clinical practice. Machine learning, a subfield of artificial intelligence, has fundamentally transformed in silico modelling and has the capacity to streamline clinical translation. This paper reviews data-driven modelling methodologies with a focus on drug formulation development. Despite recent advances, there is limited modelling guidance specific to drug product development and a trend towards suboptimal modelling practices, resulting in models that may not give reliable predictions in practice. There is an overwhelming focus on benchtop experimental outcomes obtained for a specific modelling aim, leaving the capabilities of data scraping or the use of combined modelling approaches yet to be fully explored. Moreover, the preference for high accuracy can lead to a reliance on black box methods over interpretable models. This further limits the widespread adoption of machine learning as black boxes yield models that cannot be easily understood for the purposes of enhancing product performance. In this review, recommendations for conducting machine learning research for drug product development to ensure trustworthiness, transparency, and reliability of the models produced are presented. Finally, possible future directions on how research in this area might develop are discussed to aim for models that provide useful and robust guidance to formulators.

Lipid based formulations as supersaturating oral delivery systems: From current to future industrial applications

Lipid-based formulations, in particular supersaturated lipid-based formulations, are important delivery approaches when formulating challenging compounds, as especially low water-soluble compounds profit from delivery in a pre-dissolved state. In this article, the classification of lipid-based formulation is described, followed by a detailed discussion of different supersaturated lipid-based formulations and the recent advances reported in the literature. The supersaturated lipid-based formulations discussed include both the in situ forming supersaturated systems as well as the thermally induced supersaturated lipid-based formulations. The in situ forming drug supersaturation by lipid-based formulations has been widely employed and numerous clinically available products are on the market. There are some scientific gaps in the field, but in general there is a good understanding of the mechanisms driving the success of these systems. For thermally induced supersaturation, the technology is not yet fully understood and developed, hence more research is required in this field to explore the formulations beyond preclinical studies and initial clinical trials.

Leveraging the use of in vitro and computational methods to support the development of enabling oral drug products: An InPharma commentary

Due to the strong tendency towards poorly soluble drugs in modern development pipelines, enabling drug formulations such as amorphous solid dispersions, cyclodextrins, co-crystals and lipid-based formulations are frequently applied to solubilize or generate supersaturation in gastrointestinal fluids, thus enhancing oral drug absorption. Although many innovative in vitro and in silico tools have been introduced in recent years to aid development of enabling formulations, significant knowledge gaps still exist with respect to how best to implement them. As a result, the development strategy for enabling formulations varies considerably within the industry and many elements of empiricism remain. The InPharma network aims to advance a mechanistic, animal-free approach to the assessment of drug developability. This commentary focuses current status and next steps that will be taken in InPharma to identify and fully utilize 'best practice' in vitro and in silico tools for use in physiologically based biopharmaceutic models.

P-glycoprotein-mediated transport in a mucus-supplemented Caco-2 cell model in the presence of different surfactants

The aim of the present study was to investigate if mucus applied to Caco-2 cell monolayers protects cells from high concentrations of surfactants, while still allowing for an identification of the surfactant's inhibitory effects on P-glycoprotein (P-gp). Two types of porcine mucin and six surfactants (Polysorbate 20 (PS20) and 80 (PS80), Kolliphor EL (Kol. EL) and RH40 (Kol. RH40), Labrafil M 2125 CS (L.fil) and Labrasol (L.sol)) were applied to Caco-2 cells, and TEER, paracellular transport and P-gp mediated digoxin transport was measured. The results showed that 15% porcine mucin type II was incompatible with Caco-2 cell monolayer integrity, resulting in a dramatic drop in monolayer TEER and increased mannitol transport. In contrast, mucin type III was compatible with Caco-2 cell monolayers in the concentration range of 2.5-15% without substantially disturbing barrier properties. The highest concentration of mucin type III impaired the ability of all six surfactants to decrease P-gp mediated digoxin transport. Subsequently lowering the mucin concentration to 5% facilitated adequate protection of cells and enabled e.g., 5% PS20 to inhibit P-gp mediated digoxin transport. Overall, the present work is useful for early-stage permeability investigations on how mucus affects P-gp mediated transport in the presence of formulation excipients.

Gut microbiota-drug interactions in cancer pharmacotherapies: implications for efficacy and adverse effects

INTRODUCTION

The gut microbiota is involved in host physiology and health. Reciprocal microbiota-drug interactions are increasingly recognized as underlying some individual differences in therapy response and adverse events. Cancer pharmacotherapies are characterized by a high degree of interpatient variability in efficacy and side effect profile and recently, the microbiota has emerged as a factor that may underlie these differences.

AREAS COVERED

The effects of cancer pharmacotherapy on microbiota composition and function are reviewed with consideration of the relationship between baseline microbiota composition, microbiota modification, antibiotics exposure and cancer therapy efficacy. We assess the evidence implicating the microbiota in cancer therapy-related adverse events including impaired gut function, cognition and pain perception. Finally, potential mechanisms underlying microbiota-cancer drug interactions are described, including direct microbial metabolism, and microbial modulation of liver metabolism and immune function. This review focused on preclinical and clinical studies conducted in the last 5 years.

EXPERT OPINION

Preclinical and clinical research supports a role for baseline microbiota in cancer therapy efficacy, with emerging evidence that the microbiota modification may assist in side effect management. Future efforts should focus on exploiting this knowledge towards the development of microbiota-targeted therapies. Finally, a focus on specific drug-microbiota-cancer interactions is warranted.

Machine learning methods for prediction of food effects on bioavailability: A comparison of support vector machines and artificial neural networks

Despite countless advances in recent decades across various in vitro, in vivo and in silico tools, anticipation of whether a drug will show a human food effect (FE) remains challenging. One means to predict potential FE involves probing any dependence between FE and drug properties. Accordingly, this study explored the potential for two machine learning (ML) algorithms to predict likely FE. Using a collated database of drugs licensed from 2016-2020, drugs were classified into three groups; positive, negative or no FE. Greater than 250 drug properties were predicted for each drug which were used to train predictive models using Support Vector Machine (SVM) and Artificial Neural Network (ANN) algorithms. When compared, ANN outperformed SVM for FE classification upon training (82%, 72%) and testing (72%, 69%). Both models demonstrated higher FE prediction accuracy than the Biopharmaceutics Classification System (BCS) (46%). This exploratory work provided new insights into the connection between FE and drug properties as the Octanol Water Partition Coefficient (S+logP), Number of Hydrogen Bond Donors (HBD), Topological Polar Surface Area (T_PSA) and Dose (mg) were all significant for prediction. Overall, this study demonstrated the utility of ML to facilitate early anticipation of likely FE in pre-clinical development using four well-known drug properties.

Exploring porcine gastric and intestinal fluids using microscopic and solubility estimates: Impact of placebo self-emulsifying drug delivery system administration to inform bio-predictive in vitro tools

Validation and characterisation of in vitro and pre-clinical animal models to support bio-enabling formulation development is of paramount importance. In this work, post-mortem gastric and small intestinal fluids were collected in the fasted, fed state and at five sample-points post administration of a placebo Self-Emulsifying Drug Delivery System (SEDDS) in the fasted state to pigs. Cryo-TEM and Negative Stain-TEM were used for ultrastructure characterisation. Ex vivo solubility of fenofibrate was determined in the fasted-state, fed-state and post-SEDDS administration. Highest observed ex vivo drug solubility in intestinal fluids after SEDDS administration was used for optimising the biorelevant in vitro conditions to determine maximum solubility. Under microscopic evaluation, fasted, fed and SEDDS fluids resulted in different colloidal structures. Drug solubility appeared highest 1 hour post SEDDS administration, corresponding with presence of SEDDS lipid droplets. A 1:200 dispersion of SEDDS in biorelevant media matched the highest observed ex vivo solubility upon SEDDS administration. Overall, impacts of this study include increasing evidence for the pig preclinical model to mimic drug solubility in humans, observations that SEDDS administration may poorly mimic colloidal structures observed under fed state, while microscopic and solubility porcine assessments provided a framework for increasingly bio-predictive in vitro tools.

In Silico, In Vitro, and In Vivo Evaluation of Precipitation Inhibitors in Supersaturated Lipid-Based Formulations of Venetoclax

The concept of using precipitation inhibitors (PIs) to sustain supersaturation is well established for amorphous formulations but less in the case of lipid-based formulations (LBF). This study applied a systematic in silico–in vitro–in vivo approach to assess the merits of incorporating PIs in supersaturated LBFs (sLBF) using the model drug venetoclax. sLBFs containing hydroxypropyl methylcellulose (HPMC), hydroxypropyl methylcellulose acetate succinate (HPMCAS), polyvinylpyrrolidone (PVP), PVP-co-vinyl acetate (PVP/VA), Pluronic F108, and Eudragit EPO were assessed in silico calculating a drug–excipient mixing enthalpy, in vitro using a PI solvent shift test, and finally, bioavailability was assessed in vivo in landrace pigs. The estimation of pure interaction enthalpies of the drug and the excipient was deemed useful in determining the most promising PIs for venetoclax. The sLBF alone (i.e., no PI present) displayed a high initial drug concentration in the aqueous phase during in vitro screening. sLBF with Pluronic F108 displayed the highest venetoclax concentration in the aqueous phase and sLBF with Eudragit EPO the lowest. In vivo, the sLBF alone showed the highest bioavailability of 26.3 ± 14.2%. Interestingly, a trend toward a decreasing bioavailability was observed for sLBF containing PIs, with PVP/VA being significantly lower compared to sLBF alone. In conclusion, the ability of a sLBF to generate supersaturated concentrations of venetoclax in vitro was translated into increased absorption in vivo. While in silico and in vitro PI screening suggested benefits in terms of prolonged supersaturation, the addition of a PI did not increase in vivo bioavailability. The findings of this study are of particular relevance to pre-clinical drug development, where the high in vivo exposure of venetoclax was achieved using a sLBF approach, and despite the perceived risk of drug precipitation from a sLBF, including a PI may not be merited in all cases.

Combining species specific in vitro & in silico models to predict in vivo food effect in a preclinical stage - case study of Venetoclax

The pig has been increasingly used as a reliable preclinical model for assessing and predicting the in vivo bioavailability of different formulation strategies. Nevertheless, differences in the composition between porcine and human intestinal fluids, may impact on the solubility and dissolution behaviour of drugs, in particular BCS II/IV drugs. Recently, a porcine fasted simulated intestinal fluid (FaSSIFp) was developed to mimic the composition in the lumen of landrace pigs under fasted state conditions. In this work, we present the utilization of FaSSIFp to compare solubility against human FaSSIF & FeSSIF and further combine species specific in vitro testing with in silico predictive modelling. Venetoclax was chosen as a model drug, representing a BCS class IV drug, with a reported clinically significant positive food effect, where bioavailability is increased up to approximately five-fold when administered with a high-fat meal. Biorelevant species specific in vitro testing was a promising tool for integrating in vitro data into in silico models, using FaSSIFp resulted in reliable predictions of the plasma concentration profile in fasted pigs, based on a porcine physiologically based absorption model. The porcine physiologically based absorption model was used to prospectively simulate the impact of food on the bioavailability of venetoclax. The use of luminal solubility estimates in combination with dissolution data for venetoclax, measured in species specific simulated fluids, correctly predict the observed pig plasma concentration profile and food effect. Overall, integrating species specific in vitro - in silico models led to accurate prediction of in vivo absorption of venetoclax in a preclinical stage, which can support guidance in early decisions of drug product development. In addition, the study further demonstrated the utility of the pig model to predict the food effects of venetoclax in humans.

The gut microbiome influences the bioavailability of olanzapine in rats

Background

The role of the gut microbiome in the biotransformation of drugs has recently come under scrutiny. It remains unclear whether the gut microbiome directly influences the extent of drug absorbed after oral administration and thus potentially alters clinical pharmacokinetics.

Methods

In this study, we evaluated whether changes in the gut microbiota of male Sprague Dawley rats, as a result of either antibiotic or probiotic administration, influenced the oral bioavailability of two commonly prescribed antipsychotics, olanzapine and risperidone.

Findings

The bioavailability of olanzapine, was significantly increased (1.8-fold) in rats that had undergone antibiotic-induced depletion of gut microbiota, whereas the bioavailability of risperidone was unchanged. There was no direct effect of microbiota depletion on the expression of major CYP450 enzymes involved in the metabolism of either drug. However, the expression of UGT1A3 in the duodenum was significantly downregulated. The reduction in faecal enzymatic activity, observed during and after antibiotic administration, did not alter the ex vivo metabolism of olanzapine or risperidone. The relative abundance of Alistipes significantly correlated with the AUC of olanzapine but not risperidone.

Interpretation

Alistipes may play a role in the observed alterations in olanzapine pharmacokinetics. The gut microbiome might be an important variable determining the systemic bioavailability of orally administered olanzapine. Additional research exploring the potential implication of the gut microbiota on the clinical pharmacokinetics of olanzapine in humans is warranted.

Funding

This research is supported by APC Microbiome Ireland, a research centre funded by Science Foundation Ireland (SFI), through the Irish Government's National Development Plan (grant no. 12/RC/2273 P2) and by Nature Research-Yakult (The Global Grants for Gut Health; Ref No. 626891).

Current challenges and future perspectives in oral absorption research: An opinion of the UNGAP network

Although oral drug delivery is the preferred administration route and has been used for centuries, modern drug discovery and development pipelines challenge conventional formulation approaches and highlight the insufficient mechanistic understanding of processes critical to oral drug absorption. This review presents the opinion of UNGAP scientists on four key themes across the oral absorption landscape: (1) specific patient populations, (2) regional differences in the gastrointestinal tract, (3) advanced formulations and (4) food-drug interactions. The differences of oral absorption in pediatric and geriatric populations, the specific issues in colonic absorption, the formulation approaches for poorly water-soluble (small molecules) and poorly permeable (peptides, RNA etc.) drugs, as well as the vast realm of food effects, are some of the topics discussed in detail. The identified controversies and gaps in the current understanding of gastrointestinal absorption-related processes are used to create a roadmap for the future of oral drug absorption research.

Rational Selection of Bio-Enabling Oral Drug Formulations - A PEARRL Commentary

New drug candidates often require bio-enabling formation technologies such as lipid-based formulations, solid dispersions, or nanosized drug formulations. Development of such more sophisticated delivery systems generally requires higher resource investment compared to a conventional oral dosage form, which might slow down clinical development. To achieve the biopharmaceutical objectives while enabling rapid cost effective development, it is imperative to identify a suitable formulation technique for a given drug candidate as early as possible. Hence many companies have developed internal decision trees based mostly on prior organizational experience, though they also contain some arbitrary elements. As part of the EU funded PEARRL project, a number of new decision trees are here proposed that reflect both the current scientific state of the art and a consensus among the industrial project partners. This commentary presents and discusses these, while also going beyond this classical expert approach with a pilot study using emerging machine learning, where the computer suggests formulation strategy based on the physicochemical and biopharmaceutical properties of a molecule. Current limitations are discussed and an outlook is provided for likely future developments in this emerging field of pharmaceutics.

Oral biopharmaceutics tools: recent progress from partnership through the Pharmaceutical Education and Research with Regulatory Links collaboration

OBJECTIVES

To summarise key contributions of the Pharmaceutical Education and Research with Regulatory Links (PEARRL) project (2016-2020) to the optimisation of existing and the development of new biopharmaceutics tools for evaluating the in vivo performance of oral drug products during the development of new drugs and at the regulatory level.

KEY FINDINGS

Optimised biopharmaceutics tools: Based on new clinical data, the composition of biorelevant media for simulating the fed state conditions in the stomach was simplified. Strategies on how to incorporate biorelevant in vitro data of bio-enabling drug products into physiologically based pharmacokinetic (PBPK) modelling were proposed. Novel in vitro biopharmaceutics tools: Small-scale two-stage biphasic dissolution and dissolution-permeation setups were developed to facilitate understanding of the supersaturation effects and precipitation risks of orally administered drugs. A porcine fasted state simulated intestinal fluid was developed to improve predictions and interpretation of preclinical results using in vitro dissolution studies. Based on new clinical data, recommendations on the design of in vitro methodologies for evaluating the GI drug transfer process in the fed state were suggested. The optimized design of in vivo studies for investigating food effects: A food effect study protocol in the pig model was established which successfully predicted the food-dependent bioavailability of two model compounds. The effect of simulated infant fed state conditions in healthy adults on the oral absorption of model drugs was evaluated versus the fasted state and the fed state conditions, as defined by regulatory agencies for adults. Using PBPK modelling, the extrapolated fasted and infant fed conditions data appeared to be more useful to describe early drug exposure in infants, while extrapolation of data collected under fed state conditions, as defined by regulators for adults, failed to capture in vivo infant drug absorption.

SUMMARY

Substantial progress has been made in developing an advanced suite of biopharmaceutics tools for streamlining drug formulation screening and supporting regulatory applications. These advances in biopharmaceutics were achieved through networking opportunities and research collaborations provided under the H2020 funded PEARRL project.

Characterization of gastrointestinal transit and luminal conditions in pigs using a telemetric motility capsule

Within preclinical research, the pig has become an important model in regulatory toxicology and pharmacokinetics, to assess oral dosage forms and to compare different formulation strategies. In addition, there are emerging application of the pig model to asses clinical dosing conditions in the fasted and fed state. In this study, the gastrointestinal transit conditions in male landrace pigs were studied with a telemetric motility capsule under fasted and postprandial conditions. The whole gut transit time (WGTT) was determined by administering a SmartPill® capsule to four landrace pigs, under both fasted and fed state conditions in a cross-over study design. Overall, this study found that small intestinal transit in landrace pigs ranged from 2.3 - 4.0 h, and was broadly similar to reported human estimates and was not affected by the intake conditions. Gastric emptying was highly variable and prolonged in landrace pigs ranging from 20 - 233 h and up to 264 h in one specific case. Under dynamic conditions pigs have a low gastric pH comparable to humans, however a high variability under fasted conditions could be observed. The comparison of the data from this study with a recent similar study in beagle dogs revealed major differences between gastric maximum pressures observed in landrace pigs and dogs. In the porcine stomach maximum pressures of up to 402 mbar were observed, which are comparable to reported human data. Intestinal maximum pressures in landrace pigs were in the same range as in humans. Overall, the study provides new insights of gastrointestinal conditions in landrace pigs, which can lead to more accurate interpretation of in vivo results obtained of pharmacokinetic studies in preclinical models. While small intestinal transit conditions, GI pH and pressures were similar to humans, the prolonged gastric emptying observed in pigs need to be considered in assessing the suitability of the pig model for assessing in vivo performance of large non-disintegrated oral drug products.

Applying Computational Predictions of Biorelevant Solubility Ratio Upon Self-Emulsifying Lipid-Based Formulations Dispersion to Predict Dose Number

Computational approaches are increasingly utilised in development of bio-enabling formulations, including self-emulsifying drug delivery systems (SEDDS), facilitating early indicators of success. This study investigated if in silico predictions of drug solubility gain i.e. solubility ratios (SR), after dispersion of a SEDDS in biorelevant media could be predicted from drug properties. Apparent solubility upon dispersion of two SEDDS in FaSSIF was measured for 30 structurally diverse poorly water soluble drugs. Increased drug solubility upon SEDDS dispersion was observed in all cases, with higher SRs observed for cationic and neutral versus anionic drugs at pH 6.5. Molecular descriptors and solid-state properties were used as inputs during partial least squares (PLS) modelling resulting in predictive models for SR_MC (r² = 0.81) and SR_LC (r² = 0.77). Multiple linear regression (MLR) facilitated generation of simplified SR equations with high predictivity (SR_MC r² = 0.74; SR_LC r² = 0.69), requiring only three drug properties; partition coefficient at pH 6.5 (logD_6.5), melting point (Tm) and aromatic bonds as fraction of total bonds (F-AromB). Through using the equations to inform developability classification system (DCS) classes for drugs that have already been licensed as lipid-based formulations, merits for development with SEDDS was predicted for 2/3 drugs.

Toward simplified oral lipid-based drug delivery using mono-/di-glycerides as single component excipients

OBJECTIVE

This study aimed to systematically explore compositional effects for a series of lipid systems, on the in vitro drug solubilization and in vivo bioavailability of three poorly water-soluble drugs with different physico-chemical properties.

SIGNIFICANCE

While many lipid-based drug products have successfully reached the market, there is still a level of uncertainty on the design guidelines for such drug products with limited understanding on the influence of composition on in vitro and in vivo performance.

METHODS AND RESULTS

Lipid-based drug delivery systems were prepared using either single excipient systems based on partially digested triglycerides (i.e. mono- and/or di-glycerides) or increasingly complex systems by incorporating surfactants and/or triglycerides. These lipid systems were evaluated for both in vitro and in vivo behavior. Results indicated that simple single component long chain lipid systems are more beneficial for the absorption of the weak acid celecoxib and the weak base cinnarizine compared to equivalent single component medium chain lipid systems. Similarly, a two-component system produced by incorporating small amount of hydrophilic surfactant yields similar overall pharmacokinetic effects. The lipid drug delivery systems based on medium chain lipid excipients improved the in vivo exposure of the neutral drug JNJ-2A. The higher in vivo bioavailability of long chain lipid systems compared to medium chain lipid systems was in agreement with in vitro dilution and dispersion studies for celecoxib and cinnarizine.

CONCLUSIONS

The present study demonstrated the benefits of using mono-/di-glycerides as single component excipients in LBDDS to streamline formulation screening and improve oral bioavailability for the three tested poorly water-soluble drugs.

Exploring impact of supersaturated lipid-based drug delivery systems of celecoxib on in vitro permeation across PermeapadⓇ membrane and in vivo absorption

Supersaturated lipid-based drug delivery systems have recently been investigated for oral administration for a variety of lipophilic drugs and have shown either equivalent or superior oral bioavailability compared to conventional non-supersaturated lipid-based drug delivery systems. The aim of the present work was to explore supersaturated versus non-supersaturated lipid-based systems at equivalent lipid doses, on in vivo bioavailability in rats and on in vitro permeation across a biomimetic Permeapad^Ⓡ membrane to establish a potential in vivo - in vitro correlation. A secondary objective was to investigate the influence of lipid composition on in vitro and in vivo performance of lipid systems. Results obtained indicated that increasing the celecoxib load in the lipid-based formulations by thermally-induced supersaturation resulted in increased bioavailability for medium and long chain mono-/di-glycerides systems relative to their non-supersaturated (i.e. 85%) reference formulations, albeit only significant for the medium chain systems. Long chain systems displayed higher celecoxib bioavailability than equivalent medium chain systems, both at supersaturated and non-supersaturated drug loads. In vitro passive permeation of celecoxib was studied using both steady-state and dynamic conditions and correlated well with in vivo pharmacokinetic results with respect to compositional effects. In contrast, permeation studies indicated that flux and percentage permeated of supersaturated systems, either at steady-state or under dynamic conditions, decreased or were unchanged relative to non-supersaturated systems. This study has shown that by using two cell-free Permeapad^Ⓡ permeation models coupled with rat-adapted gastro-intestinal conditions, bio-predictive in vitro tools can be developed to be reflective of in vivo scenarios. With further optimization, such models could be successfully used in pharmaceutical industry settings to rapidly screen various prototype formulations prior to animal studies.

Novel Biphasic Lipolysis Method To Predict in Vivo Performance of Lipid-Based Formulations

The absence of an intestinal absorption sink is a significant weakness of standard in vitro lipolysis methods, potentially leading to poor prediction of in vivo performance and an overestimation of drug precipitation. In addition, the majority of the described lipolysis methods only attempt to simulate intestinal conditions, thus overlooking any supersaturation or precipitation of ionizable drugs as they transition from the acidic gastric environment to the more neutral conditions of the intestine. The aim of this study was to develop a novel lipolysis method incorporating a two-stage gastric-to-intestinal transition and an absorptive compartment to reliably predict in vivo performance of lipid-based formulations (LBFs). Drug absorption was mimicked by in situ quantification of drug partitioning into a decanol layer. The method was used to characterize LBFs from four studies described in the literature, involving three model drugs (i.e., nilotinib, fenofibrate, and danazol) where in vivo bioavailability data have previously been reported. The results from the novel biphasic lipolysis method were compared to those of the standard pH-stat method in terms of reliability for predicting the in vivo performance. For three of the studies, the novel biphasic lipolysis method more reliably predicted the in vivo bioavailability compared to the standard pH-stat method. In contrast, the standard pH-stat method was found to produce more predictive results for one study involving a series of LBFs composed of the soybean oil, glyceryl monolinoleate (Maisine CC), Kolliphor EL, and ethanol. This result was surprising and could reflect that increasing concentrations of ethanol (as a cosolvent) in the formulations may have resulted in greater partitioning of the drug into the decanol absorptive compartment. In addition to the improved predictivity for most of the investigated systems, this biphasic lipolysis method also uses in situ analysis and avoids time- and resource-intensive sample analysis steps, thereby facilitating a higher throughput capacity and biorelevant approach for characterization of LBFs.

Perspectives of pharmacists on facilitating experiential learning placements for pharmacy students in non-patient facing settings

INTRODUCTION

Recently, the model of pharmacy education in Ireland changed to a five-year pharmacy degree, with three distinct blocks of experimental placements dispersed throughout the degree. The United Kingdom is also considering the introduction of a similar five-year pharmacy degree, while the United States is looking to further expand non-clinical experiential learning opportunities. This study was carried out to ascertain the perspectives of pharmacists working in non-patient facing roles on the barriers to and facilitators of placements to aid in identifying placement recruitment strategies for non-patient facing placements.

METHODS

A questionnaire was distributed to pharmacists employed in non-patient facing settings, including in pharmaceutical industry, education, and regulation. Quantitative responses were analyzed using descriptive statistics, while qualitative questions were analyzed thematically.

RESULTS

Regardless of experience in the practice setting or supervision, the majority expressed a preference for offering paid placements of six months' duration. There was divided opinion regarding whether students should be given study leave, whether the student's supervisor should be a pharmacist, and whether students should undertake specialized postgraduate training. The main barriers to placements were time, the placement structure, availability of suitable projects or supervisors, and awareness of placement opportunities. Prior experience in the practice area, developing the talent pipeline, and personal interests were all placement facilitators.

CONCLUSIONS

Given the increasing roles for pharmacists in non-patient facing practice settings, this study highlights the importance of stakeholder involvement during the implementation of a new model of education to ensure that placements in all settings are feasible.

Gut microbiome-mediated modulation of hepatic cytochrome P450 and P-glycoprotein: impact of butyrate and fructo-oligosaccharide-inulin

OBJECTIVES

Our objective was to demonstrate microbial regulation of hepatic genes implicated in drug metabolism and transport using germ-free (GF) mice and to explore the impact of a microbial metabolite, butyrate, and a prebiotic dietary intervention on hepatic gene expression in mice.

METHODS

Using reverse-transcriptase PCR, we investigated cytochrome P450 (CYP) and multidrug-resistance protein 1 (MDR1) expression in conventional, GF and colonised GF mice. To investigate the effects of butyrate, sodium butyrate (3 g/l) was administered for 21 days to conventional or GF mice. In the prebiotic study, young adult and middle-aged mice received diet enriched with 10% fructo-oligosaccharide (FOS)-inulin for 14 weeks.

KEY FINDINGS

Colonisation of GF animals normalised expression of Cyp3a11 and Mdr1b to conventional levels. Butyrate upregulated Cyp2b10 in conventional mice (P < 0.05) but overall did not induce widespread changes in hepatic genes. FOS-inulin increased Cyp3a13 expression and had the opposite effect on Mdr1a expression in young adult mice (P < 0.05). Age, on the other hand, influenced the prebiotic effect on Cyp2a4 expression (P < 0.01).

CONCLUSION

The expression of hepatic genes implicated in drug metabolism and transport displays sensitivity to the microbiome, microbiome-derived metabolites and a microbial-targeted intervention. Our study may provide the impetus to explore microbiota-targeted interventions in normalising host metabolic activity and reducing inter-individual variability in drug pharmacokinetics.

Exploring the Impact of Surfactant Type and Digestion: Highly Digestible Surfactants Improve Oral Bioavailability of Nilotinib

The scientific rationale for selection of the surfactant type during oral formulation development requires an in-depth understanding of the interplay between surfactant characteristics and biopharmaceutical factors. Currently, however, there is a lack of comprehensive knowledge of how surfactant properties, such as hydrophilic-lipophilic balance (HLB), digestibility, and fatty acid (FA) chain length, translate into in vivo performance. In the present study, the relationship between surfactant properties, in vitro characteristics, and in vivo bioavailability was systematically evaluated. An in vitro lipolysis model was used to study the digestibility of a variety of nonionic surfactants. Eight surfactants and one surfactant mixture were selected for further analysis using the model poorly water-soluble drug nilotinib. In vitro lipolysis of all nilotinib formulations was performed, followed by an in vivo pharmacokinetic evaluation in rats. The in vitro lipolysis studies showed that medium-chain FA-based surfactants were more readily digested compared to long-chain surfactants. The in vivo study demonstrated that a Tween 20 formulation significantly enhanced the absolute bioavailability of nilotinib up to 5.2-fold relative to an aqueous suspension. In general, surfactants that were highly digestible in vitro tended to display higher bioavailability of nilotinib in vivo. The bioavailability may additionally be related to the FA chain length of digestible surfactants with an improved exposure in the case of medium-chain FA-based surfactants. There was no apparent relationship between the HLB value of surfactants and the in vivo bioavailability of nilotinib. The impact of this study's findings suggests that when designing surfactant-based formulations to enhance oral bioavailability of the poorly water-soluble drug nilotinib, highly digestible, medium chain-based surfactants are preferred. Additionally, for low-permeability drugs such as nilotinib, which is subject to efflux by intestinal P-glycoprotein, the biopharmaceutical effects of surfactants merit further consideration.

Impact of host and environmental factors on β-glucuronidase enzymatic activity: implications for gastrointestinal serotonin

The gastrointestinal tract houses a reservoir of bacterial-derived enzymes that can directly catalyze the metabolism of drugs, dietary elements and endogenous molecules. Both host and environmental factors may influence this enzymatic activity, with the potential to dictate the availability of the biologically-active form of endogenous molecules in the gut and influence inter-individual variation in drug metabolism. We aimed to investigate the influence of the microbiota, and the modulation of its composition, on fecal enzymatic activity. Intrinsic factors related to the host, including age, sex and genetic background, were also explored. Fecalase, a cell-free extract of feces, was prepared and used in a colorimetric-based assay to quantify enzymatic activity. To demonstrate the functional effects of fecal enzymatic activity, we examined β-glucuronidase-mediated cleavage of serotonin β-d-glucuronide (5-HT-GLU) and the resultant production of free 5-HT by HPLC. As expected, β-glucuronidase and β-glucosidase activity were absent in germ-free mice. Enzymatic activity was significantly influenced by mouse strain and animal species. Sex and age significantly altered metabolic activity with implications for free 5-HT. β-Glucuronidase and β-glucosidase activity remained at reduced levels for nearly two weeks after cessation of antibiotic administration. This effect on fecalase corresponded to significantly lower 5-HT levels as compared with incubation with pre-antibiotic fecalase from the same mice. Dietary targeting of the microbiota using prebiotics did not alter β-glucuronidase or β-glucosidase activity. Our data demonstrate that multiple factors influence the activity of bacterial-derived enzymes which may have potential clinical implications for drug metabolism and the deconjugation of host-produced glucuronides in the gut.NEW & NOTEWORTHY This article explores a comprehensive range of host and environmental factors that introduce variability in the expression of bacterial-derived metabolic enzymes. Our results demonstrate that altered β-glucuronidase activity has implications for the bioavailability of luminal serotonin. The experimental approach employed, fecalase, provides a mechanistic basis and translational platform to further delineate the functional outputs of altered metabolic activity, and the associated physiological effects of microbiota-targeted interventions on host response to drugs and host-produced glucuronides.

Toward the establishment of a standardized pre-clinical porcine model to predict food effects - Case studies on fenofibrate and paracetamol

A preclinical porcine model that reliably predicts human food effect of fenofibrate was developed. Fenofibrate was administered to pigs as model compound with a positive food effect. Two different types of fed conditions were explored: a FDA style breakfast and a standard pig pellet feed. In order to assess if complete stomach emptying had been achieved under the employed fasting protocol, the amount of gastric and intestinal content was evaluated post-mortem. In addition, the protocol was designed to evaluate gastric emptying in the pre- and postprandial state using paracetamol as a marker. The study confirmed that micronized fenofibrate displayed a positive food effect with a similar fold difference to humans in FDA style fed state. Post-mortem assessment of stomach and intestinal content confirmed significantly lower content in the fasted compared to the pig pellet fed state. In the case of paracetamol, a delayed gastric emptying in the fed state was not observed, which may suggest that the Magenstrasse phenomena reported in humans, may also occur in landrace pigs. The study demonstrated the utility of a food effect protocol in landrace pigs as a pre-clinical approach to predict human food effects and provided new insights into gastric emptying in pigs.

Knowledge of Adverse Drug Reaction Reporting and the Pharmacovigilance of Biological Medicines: A Survey of Healthcare Professionals in Ireland

Background

In Europe, changes to pharmacovigilance legislation, which include additional monitoring of medicines, aim to optimise adverse drug reaction (ADR) reporting systems. The legislation also makes provisions related to the traceability of biological medicines.

Objective

The objective of this study was to assess (i) knowledge and general experience of ADR reporting, (ii) knowledge, behaviours, and attitudes related to the pharmacovigilance of biologicals, and (iii) awareness of additional monitoring among healthcare professionals (HCPs) in Ireland.

Methods

Hospital doctors (n = 88), general practitioners (GPs) (n = 197), nurses (n = 104) and pharmacists (n = 309) completed an online questionnaire.

Results

There were differences in mean knowledge scores relating to ADR reporting and the pharmacovigilance of biologicals among the HCP groups. The majority of HCPs who use biological medicines in their practice generally record biologicals by brand name but practice behaviours relating to batch number recording differed between some professions. HCPs consider batch number recording to be valuable but also regard it as being more difficult than brand name recording. Most respondents were aware of the concept of additional monitoring but awareness rates differed between some groups. Among those who knew about additional monitoring, there was higher awareness of the inverted black triangle symbol among pharmacists (> 86.4%) compared with hospital doctors (35.1%), GPs (35.6%), and nurses (14.9%). Hospital pharmacists had more experience and knowledge of ADR reporting than other practising HCPs.

Conclusion

This study highlights the important role hospital pharmacists play in post-marketing surveillance. There is a need to increase pharmacovigilance awareness of biological medicines and improve systems to support their batch traceability.

Electronic supplementary material

The online version of this article (10.1007/s40259-018-0281-6) contains supplementary material, which is available to authorized users.

Regulation of biosimilar medicines and current perspectives on interchangeability and policy

Competition arising from the increasing availability of biosimilar medicines has resulted in healthcare savings and has provided greater patient access to high cost therapeutics in Europe. The biosimilar market in the USA is relatively new so the full impact of biosimilar availability remains to be seen. Educational initiatives relating to the use of biosimilar medicines are currently being undertaken by regulators, policy makers and industry. The debate on biosimilars has moved on from the appropriateness of the regulatory framework which governs their approval, to the practice of interchangeability. Interchangeability is an important issue for healthcare professionals but different definitions and regulatory frameworks exist in the USA and Europe. In the USA, an interchangeable biological product is a biosimilar which may be substituted by a pharmacist, subject to local State policies. The interchangeability of a biosimilar with its reference medicine will be evaluated by the United States Food and Drug Administration (FDA) in cases where approval as an 'interchangeable product' is sought. In contrast, the European Medicines Agency (EMA) does not assess or make recommendations on interchangeability, therefore, in Europe, interchangeability does not mean substitution but is generally physician-led or driven by national policy. This paper provides an overview of the regulation of biosimilar medicines. Challenges associated with the demonstration of interchangeability and practical considerations relating to switching are also discussed. Finally, we present policies that have been adopted to date in several European countries, the USA and Australia, which aim to promote the use of biosimilar medicines.

Drug-gut microbiota interactions: implications for neuropharmacology

The fate and activity of drugs are frequently dictated not only by the host per se but also by the microorganisms present in the gastrointestinal tract. The gut microbiome is known to, both directly and indirectly, affect drug metabolism. More evidence now hints at the effects that drugs can have on the function and composition of the gut microbiome. Both microbiota-mediated alterations in drug metabolism and drug-mediated alterations in the gut microbiome can have beneficial or detrimental effects on the host. Greater insights into the mechanisms driving these reciprocal drug-gut microbiota interactions are needed to guide the development of microbiome-targeted dietary or pharmacological interventions, which may have the potential to enhance drug efficacy or reduce drug side effects. In this review, we explore the relationship between drugs and the gut microbiome, with a specific focus on potential mechanisms underpinning the drug-mediated alterations on the gut microbiome and the potential implications for psychoactive drugs. LINKED ARTICLES: This article is part of a themed section on When Pharmacology Meets the Microbiome: New Targets for Therapeutics? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.24/issuetoc.

Food for thought: formulating away the food effect - a PEARRL review

OBJECTIVES

Co-ingestion of oral dosage forms with meals can cause substantial changes in bioavailability relative to the fasted state. Food-mediated effects on bioavailability can have significant consequences in drug development, regulatory and clinical settings. To date, the primary focus of research has focused on the ability to mechanistically understand the causes and predict the occurrence of these effects.

KEY FINDINGS

The current review describes the mechanisms underpinning the occurrence of food effects, sheds new insights on the relative frequency for newly licensed medicines and describes the various methods by which they can be overcome. Analysis of oral medicines licensed by either the EMA or FDA since 2010 revealed that over 40% display significant food effects. Due to altered bioavailability, these medicines are often required to be dosed, rather restrictively, in either the fed or the fasted state, which can hinder clinical usefulness.

SUMMARY

There are clinical and commercial advantages to predicting the presence of food effects early in the drug development process, in order to mitigate this risk of variable food effect bioavailability. Formulation approaches aimed at reducing variable food-dependent bioavailability, through the use of bio-enabling formulations, are an essential tool in addressing this challenge and the latest state of the art in this field are summarised here.

The pig as a preclinical model for predicting oral bioavailability and in vivo performance of pharmaceutical oral dosage forms: a PEARRL review

OBJECTIVES

In pharmaceutical drug development, preclinical tests in animal models are essential to demonstrate whether the new drug is orally bioavailable and to gain a first insight into in vivo pharmacokinetic parameters that can subsequently be used to predict human values. Despite significant advances in the development of bio-predictive in vitro models and increasing ethical expectations for reducing the number of animals used for research purposes, there is still a need for appropriately selected pre-clinical in vivo testing to provide guidance on the decision to progress to testing in humans. The selection of the appropriate animal models is essential both to maximise the learning that can be obtained from such experiments and to avoid unnecessary testing in a range of species.

KEY FINDINGS

The present review, provides an insight into the suitability of the pig model for predicting oral bioavailability in humans, by comparing the conditions in the GIT. It also contains a comparison between the bioavailability of compounds dosed to both humans and pigs, to provide an insight into the relative correlation and examples on why a lack of correlation may be observed.

SUMMARY

While there is a general trend towards predicting human bioavailability from pig data, there is considerable variability in the data set, most likely reflecting species specific differences in individual drug metabolism. Nonetheless, the correlation between pigs vs. humans was comparable to that reported for dogs vs. humans. The presented data demonstrate the suitability of the pig as a preclinical model to predict bioavailability in human.

Sustained-release multiparticulates for oral delivery of a novel peptidic ghrelin agonist: Formulation design and in vitro characterization

There is an impetus to provide appropriate sustained release oral delivery vehicles to protect biofunctional peptide loads from gastric degradation in vivo. This study describes the generation of a high load capacity pellet formulation for sustained release of a freely water-soluble dairy-derived hydrolysate, FHI-2571. The activity of this novel peptidic ghrelin receptor agonist is reported using in vitro calcium mobilization assays. Conventional extrusion spheronization was then used to prepare peptide-loaded pellets which were subsequently coated with ethylcellulose (EC) film coats using a fluid bed coating system in bottom spray (Wurster) mode. Aqueous-based EC coating dispersions produced mechanically brittle coats which fractured due to osmotic pressure build-up within pellets in simulated media. In contrast, an ethanolic-based EC coating solution provided robust, near zero-order release in both USP Type 1 and Type 4 dissolution studies. Interestingly, the functionality of aqueous-based EC film coats was restored by first layering pellets with a methacrylic acid copolymer (MA) subcoat, thereby hindering pellet core swelling in acidic media. Broadband Acoustic Resonance Dissolution Spectroscopy (BARDS) was utilised as a complementary technique to confirm the results seen in USP dissolution studies. Retention of activity of the ghrelinergic peptide hydrolysate in the final encapsulated product was confirmed as being greater than 80%. The described pellet formulation is amenable to oral dosing in small animal studies in order to assess in vivo efficacy of the whey-derived ghrelinergic hydrolysate. In more general terms, it is also suitable as a delivery vehicle for peptide-based bioactives to special population groups e.g paediatric and geriatric.

Mesoporous silica-based dosage forms improve bioavailability of poorly soluble drugs in pigs: case example fenofibrate

Objectives

Mesoporous silicas (SLC) have demonstrated considerable potential to improve bioavailability of poorly soluble drugs by facilitating rapid dissolution and generating supersaturation. The addition of certain polymers can further enhance the dissolution of these formulations by preventing drug precipitation. This study uses fenofibrate as a model drug to investigate the performance of an SLC-based formulation, delivered with hydroxypropyl methylcellulose acetate succinate (HPMCAS) as a precipitation inhibitor, in pigs. The ability of biorelevant dissolution testing to predict the in vivo performance was also assessed.

Key findings

Fenofibrate-loaded mesoporous silica (FF-SLC), together with HPMCAS, displayed significant improvements in biorelevant dissolution tests relative to a reference formulation consisting of a physical mixture of crystalline fenofibrate with HPMCAS. In vivo assessment in fasted pigs demonstrated bioavailabilities of 86.69 ± 35.37% with combination of FF-SLC and HPMCAS in capsule form and 75.47 ± 14.58% as a suspension, compared to 19.92 ± 9.89% with the reference formulation. A positive correlation was identified between bioavailability and dissolution efficiency.

Conclusions

The substantial improvements in bioavailability of fenofibrate from the SLC-based formulations confirm the ability of this formulation strategy to overcome the dissolution and solubility limitations, further raising the prospects of a future commercially available SLC-based formulation.

Pharmacokinetic, pharmacodynamic and biodistribution following oral administration of nanocarriers containing peptide and protein drugs

The influence of nanoparticle (NP) formulations on the pharmacokinetic, pharmacodynamic and biodistribution profiles of peptide- and protein-like drugs following oral administration is critically reviewed. The possible mechanisms of absorption enhancement and the effects of the physicochemical properties of the NP are examined. The potential advantages and challenges of physiologically-based pharmacokinetic (PBPK) modelling to help predict efficacy in man are discussed. The importance of developing and expanding the regulatory framework to help translate the technology into the clinic and accelerate the availability of oral nanoparticulate formulations is emphasized. In conclusion, opportunities for future work to improve the state of the art of oral nanomedicines are identified.

The Impact of the Gut Microbiota on Drug Metabolism and Clinical Outcome

The significance of the gut microbiota as a determinant of drug pharmacokinetics and accordingly therapeutic response is of increasing importance with the advent of modern medicines characterised by low solubility and/or permeability, or modified-release. These physicochemical properties and release kinetics prolong drug residence times within the gastrointestinal tract, wherein biotransformation by commensal microbes can occur. As the evidence base in support of this supplementary metabolic "organ" expands, novel opportunities to engineer the microbiota for clinical benefit have emerged. This review provides an overview of microbe-mediated alteration of drug pharmacokinetics, with particular emphasis on studies demonstrating proof of concept in vivo. Additionally, recent advances in modulating the microbiota to improve clinical response to therapeutics are explored.

Folate-targeted amphiphilic cyclodextrin.siRNA nanoparticles for prostate cancer therapy exhibit PSMA mediated uptake, therapeutic gene silencing in vitro and prolonged circulation in vivo

In this study, a folate targeted cyclodextrin (CD) nanoparticle was prepared by co-formulating CD.siRNA complexes with DSPE-PEG₅₀₀₀-folate to target the prostate specific membrane antigen (PSMA). Targeted formulations showed increased uptake, relative to untargeted controls, in two prostate cancer cell lines expressing PSMA (VCaP and LNCaP). Competitive uptake studies, using excess folate, significantly reduced uptake of targeted nanoparticles in PSMA positive cell lines (P<0.001). Relative to untreated controls, folate-targeted nanoparticles significantly reduced the levels of RelA mRNA in VCaP and LNCaP cells by 44% and 22% respectively (P<0.001). In contrast there was no significant reduction in RelA mRNA in these cell lines by untargeted complexes. Pharmacokinetic (PK) data indicated that the incorporation of PEG into the formulation increased the circulation time of siRNA 8-fold. This study highlights the ability of incorporating a folate ligand into CD.siRNA nanoparticles to allow for targeted delivery of siRNA to prostate cancer cells via the PSMA.

Treating disorders of the neonatal central nervous system: pharmacokinetic and pharmacodynamic considerations with a focus on antiepileptics

A major consideration in the treatment of neonatal disorders is that the selected drug, dose and dosage frequency is safe, effective and appropriate for the intended patient population. Thus, a thorough knowledge of the pharmacokinetics and pharmacodynamics of the chosen drug within the patient population is essential. In paediatric and neonatal populations two additional challenges can often complicate drug treatment - the inherently greater physiological variability, and a lack of robust clinical evidence of therapeutic range. There has traditionally been an overreliance in paediatric medicine on extrapolating doses from adult values by adjusting for bodyweight or body surface area, but many other sources of variability exist which complicate the choice of dose in neonates. The lack of reliable drug dosage data in neonates has been highlighted by regulatory authorities, as only ~50% of the most commonly used paediatric medicines have been examined in a paediatric population. Moreover, there is a paucity of information on the pharmacokinetic parameters which affect drug concentrations in different body tissues, and pharmacodynamic responses to drugs in the neonate. Thus, in the present review, we draw attention to the main pharmacokinetic factors that influence the unbound brain concentration of neuroactive drugs. Moreover, the pharmacodynamic differences between neonates and adults that affect the activity of centrally-acting therapeutic agents are briefly examined, with a particular emphasis on antiepileptic drugs.

Chronic P-glycoprotein inhibition increases the brain concentration of escitalopram: potential implications for treating depression

Recent preclinical studies have revealed a functionally important role for the drug efflux pump P‐glycoprotein (P‐gp) at the blood–brain barrier in limiting brain levels and thus antidepressant‐like activity of certain antidepressant drugs. Specifically, acute administration of P‐gp inhibitors, such as verapamil and cyclosporin A (CsA), has been shown to augment brain concentrations and functional activity of the antidepressant escitalopram in rodents. However, depression is a chronic disorder and current treatments require prolonged administration to elicit their full therapeutic effect. Thus, it is important to investigate whether acute findings in relation to P‐gp inhibition translate to chronic paradigms. To this end, the present study investigates whether chronic treatment with the P‐gp inhibitor verapamil and the antidepressant escitalopram results in enhanced brain distribution and antidepressant‐like effects of escitalopram. Verapamil (10 mg·kg⁻¹ i.p.) and escitalopram (0.1 mg·kg⁻¹ i.p.) were administered once daily for 22 days. On the final day of treatment, brain regions and plasma were collected for analysis of cortical and plasma escitalopram concentrations, and to determine the hippocampal expression of genes previously reported to be altered by chronic antidepressant treatment. Verapamil treatment resulted in a greater than twofold increase in brain levels of escitalopram, without altering plasma levels. Neither gene expression analysis nor behavioral testing revealed an augmentation of responses to escitalopram treatment due to verapamil administration. Taken together, these data demonstrate for the first time that P‐gp inhibition can yield elevated brain concentrations of an antidepressant after chronic treatment. The functional relevance of these increased brain levels requires further elaboration.