Low dose lipid formulations: effects on gastric emptying and biliary secretion

Impact of Composition of Lipid-Based Formulations on First-Pass Drug Metabolism after Oral Administration

This study aimed to elucidate the drug absorption mechanisms after oral administration of lipid-based formulations (LBFs), emphasizing the impact of their composition on first-pass drug metabolism. Ketoconazole (KTZ), a CYP3A substrate, was loaded into two types of LBFs: a long-chain LBF (type II-LC) and a lipid-free formulation (type IV). Following oral administration of type II-LC, the systemic exposure of KTZ was lower compared to that for the type IV and a control suspension. However, pretreatment with 1-aminobenzotriazole, a nonspecific CYP inhibitor, revealed equivalent in vivo exposure among the formulations tested. The absorption of KTZ from type II-LC in the early period was slower than that from the suspension and type IV. Experiments on in vitro digestion in sequence with in vitro permeation across a dialysis membrane showed that the drug permeation rate for type II-LC was extremely low. This was probably due to the reduction in free drug molecules in the donor compartment via the incorporation of KTZ into mixed micelles comprising digestion products derived from type II-LC and bile components. Furthermore, luminal concentration measurements revealed that gastric emptying was delayed when a type II-LC was administered. The reduced free drug concentration and transient delay in gastric emptying of KTZ resulted in the slower absorption of KTZ for type II-LC. The product of the fraction of drug absorbed and fraction of the drug not metabolized in the gut wall (Fa × Fg) calculated from the systemic and portal plasma concentration-time courses of KTZ was 0.185 for type II-LC and 0.327 for suspension. Since the luminal concentration measurement demonstrated complete absorption of KTZ from the gastrointestinal tract (Fa ≅ 1), the Fa × Fg values can be regarded as Fg. In conclusion, the lower in vivo exposure following oral administration of type II-LC was attributed to reduced Fg, that is, slower drug absorption from the jejunum resulted in low KTZ concentration in enterocytes, leading to enhanced metabolic efficiency. Our findings can be valuable when selecting excipients for designing LBFs with the preferred in vivo performance for highly metabolized drugs.

Enhancing the pharmacokinetics of abiraterone acetate through lipid-based formulations: addressing solubility and food effect challenges

Abiraterone acetate, a prodrug of abiraterone, is an effective antiandrogen for treating metastatic prostate cancer. However, its poor aqueous solubility restricts oral bioavailability to under 10% in fasted conditions. Additionally, its pharmacokinetics are significantly influenced by food intake, leading to variable exposure that can impact treatment safety and efficacy. To overcome these challenges, we developed a series of lipid-based formulations aimed at reducing food effects and enhancing the fasted bioavailability of abiraterone acetate by incorporating the drug into colloidal delivery systems. Medium- and long-chain self-nanoemulsifying drug delivery systems (MC-SNEDDS and LC-SNEDDS) were formulated with abiraterone acetate loading at 80% of their respective preconcentrate equilibrium solubility. In-vitro gastrointestinal lipolysis experiments demonstrated that the SNEDDS formulations increased drug solubilisation by over 6-fold compared to pure abiraterone acetate and over 2-fold compared to the reference product after 60 min in the intestinal environment. In-vivo pharmacokinetic studies in rats revealed that both MC-SNEDDS and LC-SNEDDS formulations, along with their enteric-coated (EC) forms, exhibited enhanced bioavailability, with EC-LC-SNEDDS providing the highest performance, demonstrating a 7.32-fold increase in abiraterone exposure compared to the reference. Strong correlations were observed between in-vitro solubilisation and in-vivo AUC0 - 8 h (R2 = 0.980) and Cmax (R2 = 0.925). In-vivo pharmacokinetic studies in pigs demonstrated that EC-LC-SNEDDS improved drug systemic exposure in fasted conditions and mitigated positive food effects, showing a fed-to-fasted AUC0 - 8 h ratio of 108% compared to 334% with the reference. The developed lipid-based formulations hold promise in overcoming the pharmacokinetic challenges associated with abiraterone, potentially offering improved outcomes for patients.

Intestinal Lymphatic Biology, Drug Delivery, and Therapeutics: Current Status and Future Directions

Historically, the intestinal lymphatics were considered passive conduits for fluids, immune cells, dietary lipids, lipid soluble vitamins, and lipophilic drugs. Studies of intestinal lymphatic drug delivery in the late 20th century focused primarily on the drugs' physicochemical properties, especially high lipophilicity, that resulted in intestinal lymphatic transport. More recent discoveries have changed our traditional view by demonstrating that the lymphatics are active, plastic, and tissue-specific players in a range of biological and pathological processes, including within the intestine. These findings have, in turn, inspired exploration of lymph-specific therapies for a range of diseases, as well as the development of more sophisticated strategies to actively deliver drugs or vaccines to the intestinal lymph, including a range of nanotechnologies, lipid prodrugs, and lipid-conjugated materials that "hitchhike" onto lymphatic transport pathways. With the increasing development of novel therapeutics such as biologics, there has been interest in whether these therapeutics are absorbed and transported through intestinal lymph after oral administration. Here we review the current state of understanding of the anatomy and physiology of the gastrointestinal lymphatic system in health and disease, with a focus on aspects relevant to drug delivery. We summarize the current state-of-the-art approaches to deliver drugs and quantify their uptake into the intestinal lymphatic system. Finally, and excitingly, we discuss recent examples of significant pharmacokinetic and therapeutic benefits achieved via intestinal lymphatic drug delivery. We also propose approaches to advance the development and clinical application of intestinal lymphatic delivery strategies in the future. SIGNIFICANCE STATEMENT: This comprehensive review details the understanding of the anatomy and physiology of the intestinal lymphatic system in health and disease, with a focus on aspects relevant to drug delivery. It highlights current state-of-the-art approaches to deliver drugs to the intestinal lymphatics and the shift toward the use of these strategies to achieve pharmacokinetic and therapeutic benefits for patients.

Infant formula as a solid lipid dose form for enhancement of the oral bioavailability of cannabidiol for paediatric patients

Cannabinoids can save paediatric patients from harmful psychological conditions caused by epilepsy. However, the limited aqueous solubility of the drug presents a limitation to oral absorption and bioavailability. Previous studies have shown the enhancement of oral bioavailability for poorly water-soluble drugs using milk or milk-based products like infant formula as a novel lipid-based formulation, due to digestion of the lipids to enhance drug solubility that is particularly well suited to infants and in low economy settings. Therefore, this study has investigated the in vitro solubilisation enhancement of cannabidiol (CBD) in milk-based products during digestion using synchrotron small angle X-ray scattering, followed by pharmacokinetic studies to determine the relative oral bioavailability. The in vitro results, coupled with in vivo data, demonstrate a two-fold increase in the oral bioavailability of CBD in bovine milk as well as infant formula. The results of this study indicate the potential for infant formula to be considered as a novel formulation approach for CBD. Further study is encouraged for more drugs with infant formula to strengthen the correlation between the solubilisation of drug and their oral bioavailability.

Physiological, Anatomical and Physicochemical Characteristics of Children Affecting Food-Drug Interaction-Review

The drug-food interaction has a great interest in nutrition research to minimize unfavorable reactions to nutritional treatment. Failure to supply appropriate nutrition to the child can harm both body development and growth. This review aimed to examine available data on the impact of diet on medication absorption in pediatric populations. Mechanisms underlying food-drug interactions were investigated to explore possible distinctions between adult and pediatric populations and to gain insight into how this may impact the pharmacokinetic profile in a child. Several changes in physiology, anatomy and physicochemical properties among children are likely to result in food-drug interactions that cannot be anticipated based on adult studies. The influence of food on medications results in decreased bioavailability and altered drug elimination. Drugs, on the other hand, can affect dietary intake, digestion, absorption and excretion. Literature shows that differences in gastrointestinal physiology and anatomy between pediatric and adult populations can have a major impact on drug absorption and bioavailability. A higher splanchnic blood flow may result in decreased drug bioavailability due to increased loss in first-pass metabolism. To overcome the overall lack of knowledge on analyzing food-drug interactions among pediatric populations, comprehensive procedures and recommendations must be developed.

Exploring LIPIDs for their potential to improves bioavailability of lipophilic drugs candidates: A review

This review aims to provide a thorough examination of the benefits, challenges, and advancements in utilizing lipids for more effective drug delivery, ultimately contributing to the development of innovative approaches in pharmaceutical science. Lipophilic drugs, characterized by low aqueous solubility, present a formidable challenge in achieving effective delivery and absorption within the human body. To address this issue, one promising approach involves harnessing the potential of lipids. Lipids, in their diverse forms, serve as carriers, leveraging their unique capacity to enhance solubility, stability, and absorption of these challenging drugs. By facilitating improved intestinal solubility and selective lymphatic absorption of porously permeable drugs, lipids offer an array of possibilities for drug delivery. This versatile characteristic not only bolsters the pharmacological efficacy of drugs with low bioavailability but also contributes to enhanced therapeutic performance, ultimately reducing the required dose size and associated costs. This comprehensive review delves into the strategic formulation approaches that employ lipids as carriers to ameliorate drug solubility and bioavailability. Emphasis is placed on the critical considerations of lipid type, composition, and processing techniques when designing lipid-based formulations. This review meticulously examines the multifaceted challenges that come hand in hand with lipid-based formulations for lipophilic drugs, offering an insightful perspective on future trends. Regulatory considerations and the broad spectrum of potential applications are also thoughtfully discussed. In summary, this review presents a valuable repository of insights into the effective utilization of lipids as carriers, all aimed at elevating the bioavailability of lipophilic drugs.

Formulation and processing of solid self-emulsifying drug delivery systems (HME S-SEDDS): A single-step manufacturing process via hot-melt extrusion technology through response surface methodology

The objective of the current study is the formulation development and manufacturing of solid self-emulsifying drug delivery systems (HME S-SEDDS) via a single-step continuous hot-melt extrusion (HME) process. For this study, poorly soluble fenofibrate was selected as a model drug. From the results of pre-formulation studies, Compritol® HD5 ATO, Gelucire® 48/16, and Capmul® GMO-50 were selected as oil, surfactant and co-surfactant respectively for manufacturing of HME S-SEDDS. Neusilin® US2 was selected as a solid carrier. The design of experiments (response surface methodology) was employed to prepare formulations via a continuous HME process. The formulations were evaluated for emulsifying properties, crystallinity, stability, flow properties and drug release characteristics. The prepared HME S-SEDDS showed excellent flow properties, and the resultant emulsions were stable. The globule size of the optimized formulation was 269.6 nm. The DSC and XRD studies revealed the amorphous nature of the formulation and FTIR studies showed no significant interaction between fenofibrate and excipients. The drug release studies showed significant (p < 0.05) improvement in solubility compared to the pure drug (DE15 = 45.04 for the optimized formulation), as >90% of drug release was observed within 15 min. The stability studies for the optimized formulation were conducted for 3 months at 40 °C/75% RH.

Chrysin-phospholipid complex-based solid dispersion for improved anti-aging and neuroprotective effects in mice

The present study aimed to improve the neuroprotective effect of chrysin (CHR) by combining two formulation techniques, phospholipid (PL) complexation and solid dispersion (SD). CHR-phospholipid complex (CHR-PLC) was prepared through solvent evaporation. The molar ratio CHR/PL (1:3), which exhibited the highest complexation efficiency, was selected for the preparation of CHR-PLC loaded SD (CHR-PLC-SD) with 2-hydroxypropyl β cyclodextrin (2-HPβCD) and polyvinylpyrrolidone 8000. CHR-PLC/2-HPβCD (1:2, w/w) displayed the highest aqueous solubility of CHR (5.86 times more than that of plain CHR). CHR-SD was also prepared using 2-HPβCD for comparison. The in vitro dissolution of CHR-PLC-SD4 revealed an enhancement in the dissolution rate over CHR-PLC (1:3), CHR-SD, and plain CHR by six times. The optimum formulations and plain CHR were evaluated for their neuroprotective effect on brain aging induced by D-galactose in mice. The results demonstrated a behavioral activity elevation, an increase of AMPK, LKB1, and PGC1α brain contents as well as a reduction of AGEs, GFAP, NT-3, TNF-α, and NF-κβ brain contents when compared with those of the D-galactose control group. Thus, the developed formulations stimulated neurogenesis and mitochondrial biogenesis as well as suppressed neuroinflammation and neurodegeneration. The order of activity was as follows: CHR-PLC-SD4 > CHR-PLC (1:3) > CHR-SD > plain CHR.

A self-emulsifying omega-3 fatty acids delivery system for enhanced gastro-intestinal absorption in rats

Omega-3 fatty acids have many health benefits as they help to prevent and treat coronary artery disease, hypertension, diabetes mellitus, arthritis, and autoimmune disorders. Omega-3 fatty acids miscible in lecithin were found to spontaneously form microemulsions in water. The particle sizes of emulsions ranged from 300 to 800 nm and their morphologies were observed by optical microscopy. In vitro testing showed that the amounts of omega-3 fatty acids released by self-emulsifying delivery (SED) formulations containing lecithin, were higher than that released by a commercial formulation without lecithin. The Cmax values of docosahexaenoic acid (DHA) or eicosapentaenoic acid (EPA) were approximately 1.38-1.40-fold for the optimized SED formulation than for the control group (P < 0.01). Similarly, the mean AUC0 - 48 values of DHA or EPA in the SED group were 1.27-1.29-fold higher than in the control group (P < 0.05). Phospholipids and lecithin were found to have considerable potentials as bioavailability enhancing excipients for SED systems.

Lipid-based solubilization technology via hot melt extrusion: promises and challenges

INTRODUCTION

Self-emulsifying drug delivery systems (SEDDS) are a promising strategy to improve the oral bioavailability of poorly water-soluble drugs (PWSD). The excipients of SEDDS enable permeation through the mucus and gastro-intestinal barrier, inhibiting efflux transporters (e.g. P-glycoprotein) of drugs. Poor drug loading capacity and formulation instability are the main setbacks of traditional SEDDS. The use of polymeric precipitation inhibitors was shown to create supersaturable SEDDS with increased drug payload, and their solidification can help to overcome the instability challenge. As an alternative to several existing SEDDS solidification technologies, hot melt extrusion (HME) holds the potential for lean and continuous manufacturing of supersaturable solid-SEDDS. Despite being ubiquitously applied in solid lipid and polymeric processing, HME has not yet been widely considered for the preparation of SEDDS.

AREAS COVERED

The review begins with the rationale why SEDDS as the preferred lipid-based delivery systems (LBDS) is suitable for the oral delivery of PWSD and discusses the common barriers to oral administration. The potential of LBDS to surmount them is discussed. SEDDS as the flagship of LBDS for PWSD is proposed with a special emphasis on solid-SEDDS. Finally, the opportunities and challenges of HME from the lipid-based excipient (LBE) processing and product performance standpoint are highlighted.

EXPERT OPINION

HME can be a continuous, solvent-free, cost-effective, and scalable technology for manufacturing solid supersaturable SEDDS. Several critical formulations and process parameters in successfully preparing SEDDS via HME are identified.

Rationale utilization of phospholipid excipients: a distinctive tool for progressing state of the art in research of emerging drug carriers

Phospholipids have a high degree of biocompatibility and are deemed ideal pharmaceutical excipients in the development of lipid-based drug delivery systems, because of their unique features (permeation, solubility enhancer, emulsion stabilizer, micelle forming agent, and the key excipients in solid dispersions) they can be used in a variety of pharmaceutical drug delivery systems, such as liposomes, phytosomes, solid lipid nanoparticles, etc. The primary usage of phospholipids in a colloidal pharmaceutical formulation is to enhance the drug's bioavailability with low aqueous solubility [i.e. Biopharmaceutical Classification System (BCS) Class II drugs], Membrane penetration (i.e. BCS Class III drugs), drug uptake and release enhancement or modification, protection of sensitive active pharmaceutical ingredients (APIs) from gastrointestinal degradation, a decrease of gastrointestinal adverse effects, and even masking of the bitter taste of orally delivered drugs are other uses. Phospholipid-based colloidal drug products can be tailored to address a wide variety of product requirements, including administration methods, cost, product stability, toxicity, and efficacy. Such formulations that are also a cost-effective method for developing medications for topical, oral, pulmonary, or parenteral administration. The originality of this review work is that we comprehensively evaluated the unique properties and special aspects of phospholipids and summarized how the individual phospholipids can be utilized in various types of lipid-based drug delivery systems, as well as listing newly marketed lipid-based products, patents, and continuing clinical trials of phospholipid-based therapeutic products. This review would be helpful for researchers responsible for formulation development and research into novel colloidal phospholipid-based drug delivery systems.

Practical and operational considerations related to paediatric oral drug formulation: an industry survey

For over 15 years, US and EU regulations ensure that medicines developed for children are explicitly authorised for such use with age-appropriate forms and formulations, implying dedicated research. To shed light on how these regulations have been adopted by pharmaceutical companies and how various aspects of paediatric oral drug formulation development are currently handled, an exploratory survey was conducted. Topics included: general company policy, regulatory aspects, dosage form selection, in-vitro, in-silico and (non-)clinical in-vivo methods, and food effects assessment. The survey results clearly underline the positive impact of the paediatric regulations and their overall uptake across the pharmaceutical industry. Even though significant improvements have been made in paediatric product development, major challenges remain. In this respect, dosage form selection faces a discrepancy between the youngest age groups (liquid products preference) and older subpopulations (adult formulation preference). Additionally, concerted research is needed in the development and validation of in-vitro tools and physiology based pharmacokinetic models tailored to the paediatric population, and in estimating the effect of non-standard and paediatric relevant foods. The current momentum in paediatric drug development and research should allow for an evolution in standardised methodology and guidance to develop paediatric formulations, which would benefit pharmaceutical industry and regulators.

Simulation Models for Prediction of Bioavailability of Medicinal Drugs-the Interface Between Experiment and Computation

The oral drug bioavailability (BA) problems have remained inevitable over the years, impairing drug efficacy and indirectly leading to eventual human morbidity and mortality. However, some conventional lab-based methods improve drug absorption leading to enhanced BA, and the recent experimental techniques are up-and-coming. Nevertheless, some have inherent drawbacks in improving the efficacy of poorly insoluble and low impermeable drugs. Drug BA and strategies to overcome these challenges were briefly highlighted. This review has significantly unravelled the different computational models for studying and predicting drug bioavailability. Several computational approaches provide mechanistic insights into the oral drug delivery system simulation of descriptors like solubility, permeability, transport protein-ligand interactions, and molecular structures. The in silico techniques have long been known still are just being applied to unravel drug bioavailability issues. Many publications have reported novel applications of the computational models towards achieving improved drug BA, including predicting gastrointestinal tract (GIT) drug absorption properties and passive intestinal membrane permeability, thus maximizing time and resources. Also, the classical molecular simulation models for free solvation energies of soluble-related processes such as solubilization, dissolutions, supersaturation, and precipitation have been used in virtual screening studies. A few of the tools are GastroPlus^TM that supports biowaiver for drugs, mainly BCS class III and predicts drug compounds' absorption and pharmacokinetic process; SimCyp® simulator for mechanistic modelling and simulation of drug formulation processes; pharmacodynamics analysis on non-linear mixed-effects modelling; and mathematical models, predicting absorption potential/maximum absorption dose. This review provides in silico-experiment annexation in the drug bioavailability enhancement, possible insights that lead to critical opinion on the applications and reliability of the various in silico models as a growing tool for drug development and discovery, thus accelerating drug development processes.

Solidification of Self-Emulsifying Drug Delivery Systems as a Novel Approach to the Management of Uncomplicated Malaria

Malaria affects millions of people annually, especially in third-world countries. The mainstay of treatment is oral anti-malarial drugs and vaccination. An increase in resistant strains of malaria parasites to most of the current anti-malarial drugs adds to the global burden. Moreover, existing and new anti-malarial drugs are hampered by significantly poor aqueous solubility and low permeability, resulting in low oral bioavailability and patient noncompliance. Lipid formulations are commonly used to increase solubility and efficacy and decrease toxicity. The present review discusses the findings from studies focusing on specialised oral lipophilic drug delivery systems, including self-emulsifying drug delivery systems (SEDDSs). SEDDSs facilitate the spontaneous formation of liquid emulsions that effectively solubilise the incorporated drugs into the gastrointestinal tract and thereby improve the absorption of poorly-soluble anti-malaria drugs. However, traditional SEDDSs are normally in liquid dosage forms, which are delivered orally to the site of absorption, and are hampered by poor stability. This paper discusses novel solidification techniques that can easily and economically be up-scaled due to already existing industrial equipment that could be utilised. This method could, furthermore, improve product stability and patient compliance. The possible impact that solid oral SEDDSs can play in the fight against malaria is highlighted.

In vitro and in vivo correlation for lipid-based formulations: Current status and future perspectives

Lipid-based formulations (LBFs) have demonstrated a great potential in enhancing the oral absorption of poorly water-soluble drugs. However, construction of in vitro and in vivo correlations (IVIVCs) for LBFs is quite challenging, owing to a complex in vivo processing of these formulations. In this paper, we start with a brief introduction on the gastrointestinal digestion of lipid/LBFs and its relation to enhanced oral drug absorption; based on the concept of IVIVCs, the current status of in vitro models to establish IVIVCs for LBFs is reviewed, while future perspectives in this field are discussed. In vitro tests, which facilitate the understanding and prediction of the in vivo performance of solid dosage forms, frequently fail to mimic the in vivo processing of LBFs, leading to inconsistent results. In vitro digestion models, which more closely simulate gastrointestinal physiology, are a more promising option. Despite some successes in IVIVC modeling, the accuracy and consistency of these models are yet to be validated, particularly for human data. A reliable IVIVC model can not only reduce the risk, time, and cost of formulation development but can also contribute to the formulation design and optimization, thus promoting the clinical translation of LBFs.

Structured edible lipid-based particle systems for oral drug-delivery

Oral administration is the most popular and patient-compliant route for drug delivery, though it raises great challenges due to the involvement of the gastro-intestine (GI) system and the drug bioavailability. Drug bioavailability is directly related to its ability to dissolve, transport and/or absorb through the physiological environment. A great number of drugs are characterized with low water solubility due to their hydrophobic nature, thus limiting their oral bioavailability and clinical use. Therefore, new strategies aiming to provide a protective shell through the GI system and improve drug solubility and permeability in the intestine were developed to overcome this limitation. Lipid-based systems have been proposed as good candidates for such a task owing to their hydrophobic nature which allows high drug loading, drug micellization ability during intestinal digestion due to the lipid content, and the vehicle physical protective environment. The use of edible lipids with high biocompatibility paves the bench-to-bedside translation. Four main types of structured lipid-based drug delivery systems differing in the physical state of the lipid phase have been described in the literature, namely emulsions, solid lipid nanoparticles, nanostructured lipid carriers, and oleogel-based particles. The current review provides a comprehensive overview of the different structured edible lipid-based oral delivery systems investigated up to date and emphasizes the contribution of each system component to the delivery performance, and the oral delivery path of lipids.

Food effects on the formulation, dosing, and administration of cannabidiol (CBD) in humans: A systematic review of clinical studies

Cannabidiol (CBD), a non-psychotropic phytocannabinoid from the Cannabis plant, is increasingly being pursued as a treatment for differing ailments. The bioavailability and pharmacokinetics of CBD are not well understood, and proper dosing schemes have not been adequately developed for its clinical use. CBD is a lipophilic molecule and exhibits low water solubility, so its formulation expectedly impacts its gastrointestinal absorption and subsequent blood plasma concentrations. In this review article, the food effects on CBD pharmacokinetics were analyzed. Clinical trials focusing on the performance of Epidiolex, the FDA-approved CBD formulation, were found in several databases and systematically analyzed in terms of administration method, dosing schedules, and patient characteristics. 44 data sets from clinical trials were found to be useful in the quantitative analysis. Following the normalization of all the pharmacokinetic data sets by dose and patient weight, CBD exhibited a much greater bioavailability in fed patients. For Epidiolex, administration in the fed state led to lower interindividual variability and more predictable pharmacokinetics. Considering all the different oral formulations of CBD, further analysis points to the main excipient of oral CBD formulations (refined sesame seed oil) as a major contributor to the dose-dependent variations in CBD pharmacokinetics, especially affecting the fasted state. We discuss the implications of these results on the downstream pharmacodynamics of endocannabinoid receptor modulation and its broad physiological implications.

Investigating the Impact of Crohn's Disease on the Bioaccessibility of a Lipid-Based Formulation with an In Vitro Dynamic Gastrointestinal Model

The aim of the study was to investigate the impact of Crohn's disease (CD) on the performance of a lipid-based formulation of ciprofloxacin in a complex gastrointestinal simulator (TIM-1, TNO) and to compare the luminal environment in terms of bile salt and lipid composition in CD and healthy conditions. CD conditions were simulated in the TIM-1 system with a reduced concentration of porcine pancreatin and porcine bile. The bioaccessibility of ciprofloxacin was similar in simulated CD and healthy conditions considering its extent as well as its time course in the jejunum and ileum filtrate. Differences were observed in terms of the luminal concentration of triglycerides, monoglycerides, and fatty acids in the different TIM-1 compartments, indicating a reduction and delay in the lipolysis of formulation excipients in CD. The quantitative analysis of bile salts revealed higher concentrations for healthy conditions (standard TIM-1 fasted-state protocol) in the duodenum and jejunum TIM-1 compartments compared to published data in human intestinal fluids of healthy subjects. The reduced concentrations of bile salts in simulated CD conditions correspond to the levels observed in human intestinal fluids of healthy subjects in the fasted state.A lipidomics approach with ultra performance liquid chromatography (UPLC)/mass spectrometry (MS) has proven to be a time-efficient method to semiquantitatively analyze differences in fatty acid and bile salt levels between healthy and CD conditions. The dynamic luminal environment in CD and healthy conditions after administration of a lipid-based formulation can be simulated using the TIM-1 system. For ciprofloxacin, an altered luminal lipid composition had no impact on its performance indicating a low risk of altered performance in CD patients.

New insights into in vivo gastroduodenal digestion of oil-in-water emulsions: gastric stability and in vitro digestion modeling

In this paper, effect of emulsion stability on gastroduodenal emptying/secretion was reviewed and differentiated. Moreover, novel perspectives on physiology of gastric lumen, duodenum, and gall bladder were achieved using mathematical models, being useful for designing artificial digestive systems. In this regard, numerical data for dynamic gastric emptying/secretion were offered for gastric-stable and gastric-unstable emulsion intakes. It was shown that alterations in human gastric and duodenal volume follow, respectively, linear and sinusoidal curves, with high correlation coefficients (r² > 0.93). For both emulsions, about 30-40 mL ingesta discharged rapidly from stomach upon ingestion; However, further gastric emptying was regulated for the rest of digestion period, so that 0.1 mL/min oil was passing through duodenum. Intragastric evacuation of both emulsions started with a lag phase during which stomach stored secretions incrementally by slow gastric discharge. Lag phase ended with fat layering, when emptying considerably enhanced. This reduction was gradual for stable emulsion while unstable emulsion experienced a rapid emptying before slow declining trend. Along with initial gastric emptying, 87% of gallbladder content discharged into duodenum, prolonged up to the gradual reduction phase of stomach. Supplementary investigations are needed to quantify gastroduodenal secretions, particularly pepsin and pancreas in response to emulsion ingesta.

Exploring the Impact of Intestinal Fluid Components on the Solubility and Supersaturation of Danazol

Eleven simulated intestinal fluids (SIF) were designed using a Design of Experiment (DoE) approach. The DoE SIF covered a range of compositions of fasted state human intestinal fluid (FaHIF) with regard to pH, bile salt (BS), and phospholipid (PL). Using the model compound danazol, the apparent crystalline solubility (aCS) and apparent amorphous solubility (aAS), as well as the supersaturation propensity was determined in the DoE SIF media. The aCS of danazol was dependent on the composition of the SIF, with PL as the main factor, and a small effect from BS and an interaction between BS and PL. From the DoE solubility data a model was derived, which could predict aCS in commercially available SIF (FaSSIF-V1 and -V2) and in a range of FaHIF. The aAS of danazol was differently affected by the SIF composition than the aCS; PL was again the main factor influencing the aAS, but interactions between BS and pH, as well as pH and PL were also important. The supersaturation propensities of danazol in the DoE SIF media were affected by the same factors as the aCS. Hence, the supersaturation behaviour and aCS of danazol, were found to be closely related.

Characterization of solid lipid dispersions prepared by hot fusion containing a double-fixed dose combination of artemether and lumefantrine

OBJECTIVE

The World Health Organization has called for the development of novel drug delivery systems to combat malaria - the fourth most prevalent cause of death globally. The plausibility of utilizing hot fusion to prepare solid lipid dispersions containing the prescribed first-line, double-fixed dose combination (artemether and lumefantrine), proposed for inclusion in directly compressed lipid matrix tablets, was investigated. Significance: Currently, no anti-malarial product is commercially available that employs lipid technology in a solid oral dosage form that contains this double-fixed dose combination. Through developing lipid matrix tablets, the stability, solubility and subsequent bioavailability of these drugs could be significantly enhanced in the presence of lipids or oils.

METHODS

Hot fusion encompasses encompassed melt mixing of a selected lipid base and the dispersion of the active ingredient(s) therein below their glass transition temperatures. Solid-state characterization, particle size analysis and pharmacotechnical properties were evaluated, with particular focus given to powder flowability.

RESULTS

Stearic acid in a 0.5:1 lipid:drug ratio demonstrated the best powder flow properties of the investigated solid lipid dispersion for inclusion into prospective lipid-matrix tablets duly based on an increase in overall particle size, a more spherical particle shape and improved powder flow properties compared to the individual active ingredients.

CONCLUSION

Good powder flow is critical for powders destined for inclusion into tablets - especially when employing direct compression as method of manufacture - in this case, lipid matrix tablets, which have demonstrated huge promise as a prospective dosage form for future use in malarial treatment.

Supersaturated-Silica Lipid Hybrids Improve in Vitro Solubilization of Abiraterone Acetate

PURPOSE

Abiraterone acetate (AbA) is a poorly water-soluble drug with an oral bioavailability of <10% and a significant pharmaceutical food effect. We aimed to develop a more efficient oral solid-state lipid-based formulation for AbA using a supersaturated silica-lipid hybrid (super-SLH) approach to achieve high drug loading, improve in vitro solubilization and mitigate the food effect, while gaining a mechanistic insight into how super-SLH are digested and release drug.

METHODS

The influence of super-SLH saturation level and lipid type on the physicochemical properties and in vitro solubilization during lipolysis of the formulations was investigated and compared to the commercial product, Zytiga.

RESULTS

Super-SLH achieved significantly greater levels of AbA solubilization compared to Zytiga. Solubilization was influenced by the AbA saturation level, which determined the solid state of AbA and the relative amount of lipid, and the lipid utilized, which determined its degree of digestion and the affinity of the lipid and digestion products to the silica. A fine balance existed between achieving high drug loads using supersaturation and improving performance using the lipid-based formulation approach. The non-supersaturated SLH prepared with Capmul PG8 mitigated the 3-fold in vitro food effect.

CONCLUSION

SLH and super-SLH improve in vitro solubilization of AbA, remove the food effect and demonstrate potential to improve oral bioavailability in vivo. Graphical Abstract Abiraterone acetate was formulated as silica-lipid hybrids and demonstrated enhanced in vitro solubilization in comparison to pure abiraterone acetate and commercial product, Zytiga.

Ginkgolides-loaded soybean phospholipid-stabilized nanosuspension with improved storage stability and in vivo bioavailability

The purpose of this study was to investigate the effects of soybean phospholipid, as a steric stabilizer, on improving dissolution rate, storage stability and bioavailability of ginkgolides. The ginkgolides coarse powder, hydroxypropyl methylcellulose (HPMC), soybean phospholipid and sodium dodecyl sulfate (SDS) were mixed and wet-milled to prepare nanosuspension S1. Nanosuspension S2 was obtained by the same technique except adding the soybean phospholipid. Results of particle size showed that particle size (D50) of S1 significantly decreased from 44.25 μm to 0.373 μm. Results of differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD) and transmission electron microscope (TEM) showed that ginkgolides in nanosuspension still maintained its crystallinity, and the nanoparticles were all nearly circular and uniformly dispersed. Then, pellets F1 and F2 were prepared by layering S1 and S2 onto the microcrystalline cellulose (MCC) spheres, respectively. The dissolution rate of ginkgolide A (GA) and ginkgolide B (GB) in F1 was 98.3% and 97.7% in 30 min, respectively. It was much higher than F2 (89.0% and 86.5%) and coarse powder of ginkgolides (22.3% and 24.6%). According to the results of stability test, the storage stability of F1 was improved compared with F2. In addition, compared with coarse powder of ginkgolides, the relative bioavailability of GA and GB in F1 were up to (221.84 ± 106.67) % and (437.45 ± 336.43) %, respectively. The above results demonstrated that soybean phospholipid added to the nanosuspension played an important role in improving drug dissolution rate, storage stability and in vivo bioavailability: (1) The amphiphilic soybean phospholipid interacted with the drug, with the hydrophobic part adsorbed on the surface of the poorly soluble drug and the hydrophilic part exposed to the aqueous medium. This increases the wettability of the nanoparticles, which ensure a good redispersibility of the drug particles. (2) It could self-assemble to form an interfacial phospholipid film by surrounding the individual nanoparticles, which can produce enough steric hindrance to prevent nanoparticles from aggregation and ensure a rapid dissolution rate. (3) Soybean phospholipid and its hydrolysate formed strong micellar solubilizing vehicles with bile salts in vivo, stimulated the absorption process of ginkgolides. Thus, soybean phospholipid was a promising steric stabilizer in nanosuspension drug delivery system.

Comparisons of in vitro Fick's first law, lipolysis, and in vivo rat models for oral absorption on BCS II drugs in SNEDDS

Purpose

The objective of this study was to compare the in vitro Fick’s first law, in vitro lipolysis, and in vivo rat assays for oral absorption of Biopharmaceutical Classification Systems Class II (BCS II) drugs in self-nanoemulsifying drug delivery system (SNEDDS), and studied drugs and oils properties effects on the absorption.

Methods

The transport abilities of griseofulvin (GRI), phenytoin (PHE), indomethacin (IND), and ketoprofen (KET) in saturated water solutions and SNEDDS were investigated using the in vitro Madin-Darby canine kidney cell model. GRI and cinnarizine (CIN) in medium-chain triglycerides (MCT)-SNEDDS and long-chain triglycerides (LCT)-SNEDDS were administered in the in vivo SD rat and in vitro lipolysis models to compare the oral absorption and the distribution behaviors in GIT and build an in vitro-in vivo correlation (IVIVC).

Results

In the cell model, the solubility of GRI, PHE, IND, and KET increased 6–8 fold by SNEDDS, but their permeability were only 18%, 4%, 8%, and 33% of those of their saturated water solutions, respectively. However, in vivo absorption of GRI-SNEDDS was twice that of the GRI suspension and those of CIN-SNEDDS were 15–21 fold those of the CIN suspension. In the lipolysis model, the GRI% in aqueous and pellet phases of MCT were similar to that in LCT. In contrast, the CIN% in the aqueous and pellet phases were decreased but that of the lipid phase increased. In addition, an IVIVC was found between the CIN% in the lipid phase and in vivo relative oral bioavailability (F_r).

Conclusion

The in vitro cell model was still a suitable tool to study drug properties effects on biofilm transport and SNEDDS absorption mechanisms. The in vitro lipolysis model provided superior oral absorption simulation of SNEDDS and helped to build correlation with in vivo rats. The oral drug absorption was affected by drug and oil properties in SNEDDS.

Solid lipid matrix mediated nanoarchitectonics for improved oral bioavailability of drugs

Introduction: Solid matrix mediated lipid nanoparticle formulations (LNFs) retain some of the best features of ideal drug carriers necessary for improving the oral absorption and bioavailability (BA) of both hydrophilic and hydrophobic drugs. LNFs with solid matrices may be typically categorized into three major types of formulations, viz., solid lipid nanoparticles (SLNs), nanostructured lipid carriers (NLCs) and lipid-drug conjugate nanoparticles (LDC-NPs). Solid matrix based LNFs are, potentially, the most appropriate delivery systems for poorly water soluble drugs in need of improved drug solubility, permeability, absorption, or increased oral BA. In addition, LNFs as matrices are able to encapsulate both hydrophobic and hydrophilic drugs in a single matrix based on their excellent ability to form cores and shells. Interestingly, LNFs also act as delivery devices to impart chemical stability to various orally administered drugs. Areas covered: Aim of the review is to forecast the presentation of pharmacokinetic characteristics of solid lipid matrix based nanocarriers which are typically biocompatible, biodegradable and non-toxic carrier systems for efficient oral delivery of various drugs. Efficient delivery is broadly mediated by the fact that lipophilic drugs are readily soluble in lipidic substrates that are capable of permeating across the gut epithelium following oral administration, subsequently delivering the moiety of interest more efficiently across the gut mucosal membrane. This enhances the overall BA of many drugs facing oral delivery challenges by improving their pharmacokinetic profile. This article specifically focuses on the biopharmaceutical and pharmacokinetic aspects of such solid lipid matrix based nanoformulations and possible mechanisms for better drug absorption and improved BA following oral administration. It also briefly reviews methods to access the efficacy of LNFs for improving oral BA of drugs, regulatory aspects and some interesting lipid-derived commercial formulations, with a concluding remark. Expert opinion: LNFs enhance the overall BA of many drugs facing oral delivery challenges by improving their pharmacokinetic profile.

Effect of lipids on absorption of carvedilol in dogs: Is coadministration of lipids as efficient as a lipid-based formulation?

Lipid-based formulations (LBFs) is a formulation strategy for enabling oral delivery of poorly water-soluble drugs. However, current use of this strategy is limited to a few percent of the marketed products. Reasons for that are linked to the complexity of LBFs, chemical instability of pre-dissolved drug and a limited understanding of the influence of LBF intestinal digestion on drug absorption. The aim of this study was to explore intestinal drug solubilization from a long-chain LBF, and evaluate whether coadministration of LBF is as efficient as a lipid-based drug formulation containing the pre-dissolved model drug carvedilol. Thus, solubility studies of this weak base were performed in simulated intestinal fluid (SIF) and aspirated dog intestinal fluid (DIF). DIF was collected from duodenal stomas after dosing of water and two levels (1 g and 2 g) of LBF. Similarly, the in vitro SIF solubility studies were conducted prior to, and after addition of, undigested or digested LBF. The DIF fluid was further characterized for lipid digestion products (free fatty acids) and bile salts. Subsequently, carvedilol was orally administered to dogs in a lipid-based drug formulation and coadministered with LBF, and drug plasma exposure was assessed. In addition to these studies, in vitro drug absorption from the different formulation approaches were evaluated in a lipolysis-permeation device, and the obtained data was used to evaluate the in vitro in vivo correlation. The results showed elevated concentrations of free fatty acids and bile salts in the DIF when 2 g of LBF was administered, compared to only water. As expected, the SIF and DIF solubility data revealed that carvedilol solubilization increased by the presence of lipids and lipid digestion products. Moreover, coadministration of LBF and drug demonstrated equal plasma exposure to the lipid-based drug formulation. Furthermore, evaluation of in vitro absorption resulted in the same rank order for the LBFs as in the in vivo dog study. In conclusion, this study demonstrated increased intestinal solubilization from a small amount of LBF, caused by lipid digestion products and bile secretion. The outcomes also support the use of coadministration of LBF as a potential dosing regimen in cases where it is beneficial to have the drug in the solid form, e.g. due to chemical instability in the lipid vehicle. Finally, the in vitro lipolysis-permeation used herein established IVIVC for carvedilol in the presence of LBFs.

Palm Oil in Lipid-Based Formulations and Drug Delivery Systems

Palm oil is natural oil packed with important compounds and fatty acids ready to be exploited in lipid-based formulations and drug delivery. Palm oil and palm kernel oil contain long-chain and medium-chain triglycerides, respectively, including phytonutrients such as tocotrienol, tocopherol and carotenes. The exploitation of these compounds in a lipid-based formulation would be able to address hydrophobicity, lipophilicity, poor bioavailability and low water-solubility of many current drugs. The utilisation of palm oil as part of the drug delivery system seemed to improve the bioavailability and solubility of the drug, stabilising emulsification of formulation between emulsifier and surfactant, promoting enhanced drug permeability and performance, as well as extending the shelf-life of the drug. Despite the complexity in designing lipid-based formulations, palm oil has proven to offer dynamic behaviour in providing versatility in drug design, form and delivery. However, the knowledge and application of palm oil and its fractions in lipid-based formulation are scarce and interspersed. Therefore, this study aims to focus on the research and outcomes of using palm oil in lipid-based formulations and drug delivery systems, due to the importance of establishing its capabilities and benefits.

Drug-Phospholipid Complex-a Go Through Strategy for Enhanced Oral Bioavailability

Among many, the oral route of delivery is considered to be the most favorable route with the highest patient compliance. The main issue with oral delivery is the environmental vulnerability of gastro intestinal tract (G.I.T). The bioavailability could further decrease when drug has poor aqueous solubility and permeability through biological membrane. This drawback could be resolved by employing drug-phospholipid complex strategy, as they utilize mechanism which is similar to the absorption mechanism of nutritional constituents form G.I.T. The drug-phospholipid complexes are considered ideal for oral delivery as they are biodegradable and non-toxic, which enable them to be employed as solubilizer, emulsifier, and as a matrix forming excipient for dugs with poor solubility and/or permeability. The present review compiles the basic know how about the phospholipids and the mechanism through which it improves the bioavailability of drugs. Further, it also compiles the crucial formulation aspects and methods of preparations of drug-phospholipid complex along with its physical and in silico characterization techniques. The increase in number of recent reports involving the utilization of drug-phospholipid complex to improve oral bioavailability of drugs thus explains how vital the strategy is for a successful oral delivery.

The impact of food intake on the luminal environment and performance of oral drug products with a view to in vitro and in silico simulations: a PEARRL review

Objectives

Using the type of meal and dosing conditions suggested by regulatory agencies as a basis, this review has two specific objectives: first, to summarize our understanding on the impact of food intake on luminal environment and drug product performance and second, to summarize the usefulness and limitations of available in vitro and in silico methodologies for the evaluation of drug product performance after food intake.

Key findings

Characterization of the luminal environment and studies evaluating product performance in the lumen, under conditions suggested by regulatory agencies for simulating the fed state, are limited. Various in vitro methodologies have been proposed for evaluating drug product performance in the fed state, but systematic validation is lacking. Physiologically based pharmacokinetic (PBPK) modelling approaches require the use of in vitro biorelevant data and, to date, have been used primarily for investigating the mechanisms via which an already observed food effect is mediated.

Summary

Better understanding of the impact of changes induced by the meal administration conditions suggested by regulatory agencies on the luminal fate of the drug product is needed. Relevant information will be useful for optimizing the in vitro test methods and increasing the usefulness of PBPK modelling methodologies.

Armamentarium of nanoscaled lipid drug delivery systems customized for oral administration: In silico docking patronage, absorption phenomenon, preclinical status, clinical status and future prospects

Poor drug solubility and bioavailability remain a significant and frequently encountered concern for pharmaceutical scientists. Nanoscaled lipid drug delivery systems (NSLDDS) have exhibited great potentials in oral delivery of poorly water-soluble drugs, primarily for lipophilic drugs, with several successful clinical products. In the past few years, we have find out that optimized composition of drug in lipid, surfactant, or mixture of lipid and surfactant omits the solubility, permeability and bioavailability issues, which are potential limitations for oral absorption of poorly water-soluble drugs. Lipids not only vary in structures and physiochemical properties, but also in their digestibility and absorption pathway; therefore selection of lipid excipients and dosage form has a pronounced effect on biopharmaceutical aspects of drug absorption and distribution both in vitro and in vivo. Therefore, in current critical review, a comprehensive overview of the different lipid based nanostructured drug delivery systems intended for oral administration has been presented. In addition, implication of in silico docking in designing of NSLDDS as well as mechanism of absorption of different lipid based nanoformulations through intestinal absorption window has also been offered. Moreover, attention has also been paid to NSLDDS that are currently undergoing preclinical or clinical analysis.

Review - An update on the use of oral phospholipid excipients

The knowledge and experiences obtained with oral phospholipid excipients is increasing continuously. Nevertheless the present number of oral products using these excipients as essential excipient is very limited. This is remarkable to note, since phospholipids play a significant role in the food uptake mechanisms of the GI tract and these mechanisms could be translated into suitable dosage forms and corresponding drug delivery strategies. In addition, phospholipid excipients are multifunctional biodegradable, non-toxic excipients, which can be used in oral dosage forms as wetting agents, emulsifier, solubilizer and matrix forming excipients. Especially natural phospholipid excipients, made from renewable sources, may be considered as environmentally friendly excipients and as a viable alternative to synthetic phospholipid and non-phospholipid analogues. This review describes 1) essential physico-chemical properties of oral phospholipid excipients 2) the fate of orally administered phospholipids with respect to absorption and metabolism in the GI tract 3) the main dosage forms used for oral administration containing phospholipids. These elements are critically assessed and areas of future research of interest for the use of oral phospholipid excipients are summarized.

Oral and transdermal drug delivery systems: role of lipid-based lyotropic liquid crystals

Liquid crystal (LC) dosage forms, particularly those using lipid-based lyotropic LCs (LLCs), have generated considerable interest as potential drug delivery systems. LCs have the physical properties of liquids but retain some of the structural characteristics of crystalline solids. They are compatible with hydrophobic and hydrophilic compounds of many different classes and can protect even biologicals and nucleic acids from degradation. This review, focused on research conducted over the past 5 years, discusses the structural evaluation of LCs and their effects in drug formulations. The structural classification of LLCs into lamellar, hexagonal and micellar cubic phases is described. The structures of these phases are influenced by the addition of surfactants, which include a variety of nontoxic, biodegradable lipids; these also enhance drug solubility. LLC structure influences drug localization, particle size and viscosity, which, in turn, determine drug delivery properties. Through several specific examples, we describe the applications of LLCs in oral and topical drug formulations, the latter including transdermal and ocular delivery. In oral LLC formulations, micelle compositions and the resulting LLC structures can determine drug solubilization and stability as well as intestinal transport and absorption. Similarly, in topical LLC formulations, composition can influence whether the drug is retained in the skin or delivered transdermally. Owing to their enhancement of drug stability and promotion of controlled drug delivery, LLCs are becoming increasingly popular in pharmaceutical formulations.

Monoacyl phosphatidylcholine inhibits the formation of lipid multilamellar structures during in vitro lipolysis of self-emulsifying drug delivery systems

The colloidal structures formed during lipolysis of self-emulsifying drug delivery systems (SEDDS) might affect the solubilisation and possibly the absorption of drugs. The aim of the current study is to elucidate the structures formed during the in vitro lipolysis of four SEDDS containing medium-chain glycerides and caprylocaproyl polyoxyl-8 glycerides (Labrasol), with or without monoacyl phosphatidylcholine (MAPC). In situ synchrotron small-angle X-ray scattering (SAXS) was combined with ex situ cryogenic transmission electron microscopy (cryo-TEM) and dynamic light scattering (DLS) to elucidate the generated structures. The SAXS scattering curves obtained during the lipolysis of MAPC-free SEDDS containing 43-60% w/w Labrasol displayed a lamellar phase peak at q=2.13nm^-1 that increased with Labrasol concentration, suggesting the presence of multilamellar structures (MLS) with a d-spacing of 2.95nm. However, SEDDS containing 20-30% w/w MAPC did not form MLS during the lipolysis. The cryo-TEM and DLS studies showed that MAPC-free SEDDS formed coarse emulsions while MAPC-containing SEDDS formed nanoemulsions during the dispersion in digestion medium. From the first minute and during the entire lipolysis process, SEDDS both with and without MAPC generated uni-, bi-, and oligo-lamellar vesicles. The lipolysis kinetics in the first minutes of the four SEDDS correlated with an increased intensity of the SAXS curves and the rapid transformation from lipid droplets to vesicles observed by cryo-TEM. In conclusion, the study elucidates the structures formed during in vitro lipolysis of SEDDS and the inhibitory effect of MAPC on the formation of MLS.

Computational prediction of formulation strategies for beyond-rule-of-5 compounds

The physicochemical properties of some contemporary drug candidates are moving towards higher molecular weight, and coincidentally also higher lipophilicity in the quest for biological selectivity and specificity. These physicochemical properties move the compounds towards beyond rule-of-5 (B-r-o-5) chemical space and often result in lower water solubility. For such B-r-o-5 compounds non-traditional delivery strategies (i.e. those other than conventional tablet and capsule formulations) typically are required to achieve adequate exposure after oral administration. In this review, we present the current status of computational tools for prediction of intestinal drug absorption, models for prediction of the most suitable formulation strategies for B-r-o-5 compounds and models to obtain an enhanced understanding of the interplay between drug, formulation and physiological environment. In silico models are able to identify the likely molecular basis for low solubility in physiologically relevant fluids such as gastric and intestinal fluids. With this baseline information, a formulation scientist can, at an early stage, evaluate different orally administered, enabling formulation strategies. Recent computational models have emerged that predict glass-forming ability and crystallisation tendency and therefore the potential utility of amorphous solid dispersion formulations. Further, computational models of loading capacity in lipids, and therefore the potential for formulation as a lipid-based formulation, are now available. Whilst such tools are useful for rapid identification of suitable formulation strategies, they do not reveal drug localisation and molecular interaction patterns between drug and excipients. For the latter, Molecular Dynamics simulations provide an insight into the interplay between drug, formulation and intestinal fluid. These different computational approaches are reviewed. Additionally, we analyse the molecular requirements of different targets, since these can provide an early signal that enabling formulation strategies will be required. Based on the analysis we conclude that computational biopharmaceutical profiling can be used to identify where non-conventional gateways, such as prediction of 'formulate-ability' during lead optimisation and early development stages, are important and may ultimately increase the number of orally tractable contemporary targets.

50years of oral lipid-based formulations: Provenance, progress and future perspectives

Lipid based formulations (LBF) provide well proven opportunities to enhance the oral absorption of drugs and drug candidates that sit close to, or beyond, the boundaries of Lipinski's 'rule-of-five' chemical space. Advantages in permeability, efflux and presystemic metabolism are evident; however, the primary benefit is in increases in dissolution and apparent intestinal solubility for lipophilic, poorly water soluble drugs. This review firstly details the inherent advantages of LBF, their general properties and classification, and provides a brief retrospective assessment of the development of LBF over the past fifty years. More detailed analysis of the ability of LBF to promote intestinal solubilisation, supersaturation and absorption is then provided alongside review of the methods employed to assess formulation performance. Critical review of the ability of simple dispersion and more complex in vitro digestion methods to predict formulation performance subsequently reveals marked differences in the correlative ability of in vitro tests, depending on the properties of the drug involved. Notably, for highly permeable low melting drugs e.g. fenofibrate, LBF appear to provide significant benefit in all cases, and sustained ongoing solubilisation may not be required. In other cases, and particularly for higher melting point drugs such as danazol, where re-dissolution of crystalline precipitate drug is likely to be slow, correlations with ongoing solubilisation and supersaturation are more evident. In spite of their potential benefits, one limitation to broader use of LBF is low drug solubility in the excipients employed to generate formulations. Techniques to increase drug lipophilicity and lipid solubility are therefore explored, and in particular those methods that provide for temporary enhancement including lipophilic ionic liquid and prodrug technologies. The transient nature of these lipophilicity increases enhances lipid solubility and LBF viability, but precludes enduring effects on receptor promiscuity and off target toxicity. Finally, recent efforts to generate solid LBF are briefly described as a means to circumvent the need to encapsulate in soft or hard gelatin capsules, although the latter remain popular with consumers and a proven means of LBF delivery.

Effect of food intake and co-administration of placebo self-nanoemulsifying drug delivery systems on the absorption of cinnarizine in healthy human volunteers

Positive food effects may be observed for low aqueous soluble compounds, these effects could potentially be circumvented using lipid based formulations. However, as all compounds are not chemically stable in lipid based systems, alternative dosage regimes could be investigated to evade the stability issue. The two aims for this present study were therefore; i) to investigate if a nutritional drink, Fresubin Energy®, could induce food effect in humans for the poorly soluble compound cinnarizine; and ii) to investigate if co-administration of a self-nano-emulsifying drug delivery systems (SNEDDS) with a conventional cinnarizine tablet could reduce the observed food-effect. A commercial conventional cinnarizine tablet was dosed to 10 healthy volunteers in a cross-over design in both fasted and fed state, with and without co-administration of a SNEDDS, with a one week wash-out period between dosing. The fed state was induced using a nutritional drink (Fresubin Energy®) and gastric emptying was assessed by administration of paracetamol as a marker. The pharmacokinetic analysis showed that the nutritional drink delayed the uptake and increased the fraction of absorbed cinnarizine, indicative of a food effect on the compound. This was in agreement with a previous dog study and indicates that the nutritional drink can be used for inducing the same level of food effect in humans. Though not statistically significant, the co-administration of SNEDDS exhibited a tendency towards a reduction of the observed food effect and an increased absorption of cinnarizine in the fasted state; based upon the individual ratios, which was not reflected in the mean data. However, the co-administration of SNEEDS in the fasted state, also induce a slower gastric emptying rate, which was observed as a delayed tmax for both cinnarizine and paracetamol.

Excipient Nanoemulsions for Improving Oral Bioavailability of Bioactives

The oral bioavailability of many hydrophobic bioactive compounds found in natural food products (such as vitamins and nutraceuticals in fruits and vegetables) is relatively low due to their low bioaccessibility, chemical instability, or poor absorption. Most previous research has therefore focused on the design of delivery systems to incorporate isolated bioactive compounds into food products. However, a more sustainable and cost-effect approach to enhancing the functionality of bioactive compounds is to leave them within their natural environment, but specifically design excipient foods that enhance their bioavailability. Excipient foods typically do not have functionality themselves but they have the capacity to enhance the functionality of nutrients present in natural foods by altering their bioaccessibility, absorption, and/or chemical transformation. In this review article we present the use of excipient nanoemulsions for increasing the bioavailability of bioactive components from fruits and vegetables. Nanoemulsions present several advantages over other food systems for this application, such as the ability to incorporate hydrophilic, amphiphilic, and lipophilic excipient ingredients, high physical stability, and rapid gastrointestinal digestibility. The design, fabrication, and application of nanoemulsions as excipient foods will therefore be described in this article.

Influence of Food on Paediatric Gastrointestinal Drug Absorption Following Oral Administration: A Review

The objective of this paper was to review existing information regarding food effects on drug absorption within paediatric populations. Mechanisms that underpin food-drug interactions were examined to consider potential differences between adult and paediatric populations, to provide insights into how this may alter the pharmacokinetic profile in a child. Relevant literature was searched to retrieve information on food-drug interaction studies undertaken on: (i) paediatric oral drug formulations; and (ii) within paediatric populations. The applicability of existing methodology to predict food effects in adult populations was evaluated with respect to paediatric populations where clinical data was available. Several differences in physiology, anatomy and the composition of food consumed within a paediatric population are likely to lead to food-drug interactions that cannot be predicted based on adult studies. Existing methods to predict food effects cannot be directly extrapolated to allow predictions within paediatric populations. Development of systematic methods and guidelines is needed to address the general lack of information on examining food-drug interactions within paediatric populations.