The Effect of Digestion and Drug Load on Halofantrine Absorption from Self-nanoemulsifying Drug Delivery System (SNEDDS)

Absorption of cinnarizine from type II lipid-based formulations: Impact of lipid chain length, supersaturation, digestion, and precipitation inhibition

Lipid-based formulations (LBFs) are an enabling-formulation approach for lipophilic poorly water-soluble compounds. In LBFs, drugs are commonly pre-dissolved in lipids, and/or surfactants/cosolvents, hereby avoiding the rate-limiting dissolution step. According to the Lipid formulation classification system, proposed by Pouton in 2006, in type II LBFs a surfactant with an HLB-value lower than 12 is added to the lipids. If high drug doses are required, e.g. for preclinical toxicity studies, supersaturated LBFs prepared at elevated temperatures may be a possibility to increase drug exposure. In the present study, the impact of digestion on drug absorption in rats was studied by pre-dosing of the lipase inhibitor orlistat. The lipid chain length of the type II LBFs was varied by administration of a medium-chain- (MC) and a long-chain (LC)-based formulation. Different drug doses, both non-supersaturated and supersaturated, were applied. Due to an inherent precipitation tendency of cinnarizine in supersaturated LBFs, the effect of the addition of the precipitation inhibitor Soluplus® was also investigated. The pharmacokinetic results were also evaluated by multiple linear regression. In most cases LC-based LBFs did not perform better in vivo, in terms of a higher area under the curve (AUC0-24 h) and maximal plasma concentration (Cmax), than MC-based LBFs. The administration of supersaturated LBFs resulted in increased AUC0-24 h (1.5 - 3.2-fold) and Cmax (1.1 - 2.6-fold)-values when compared to the non-supersaturated equivalents. Lipase inhibition led to a decreased drug exposure in most cases, especially for LC formulations (AUC0-24 h reduced to 47 - 67%, Cmax to 46 - 62%). The addition of Soluplus® showed a benefit to drug absorption from supersaturated type II LBFs (1.2 - 1.7-fold AUC0-24 h), due to an increased solubility of cinnarizine in the formulation. Upon dose-normalization of the pharmacokinetic parameters, no beneficial effect of Soluplus® could be demonstrated.

Digestion is a critical element for absorption of cinnarizine from supersaturated lipid-based type I formulations

Enabling formulations, such as lipid-based formulations (LBFs), are means to deliver challenging-to-formulate, poorly soluble drugs. LBFs may be composed of lipids, surfactants and/or cosolvents and can be classified depending on the proportions of the components and the hydrophilicity of the surfactant according to the Lipid Formulations Classification System, ranging from type I (very lipophilic) to type IV (hydrophilic). In cases where drug solubility in LBFs does not suffice, e.g. for preclinical toxicity studies, supersaturated LBFs can be used in order to increase the drug load. However, the effect of digestion on drug absorption from supersaturated type I formulations (consisting exclusively of lipids) still remains relatively unexplored and unclear. In the present study, the impact of lipid digestion on absorption of cinnarizine-loaded supersaturated lipid-based formulations of type I was investigated in rats by pre-dosing of the lipase inhibitor orlistat. The lipid chain length and the drug dose were varied by testing medium-chain triglycerides (MCT) and long-chain triglycerides (LCT), both supersaturated and non-supersaturated. Due to the physical instability of supersaturated formulations of cinnarizine, i.e. a potential of precipitation of cinnarizine, the impact of the addition of the amphiphilic polymer Soluplus®, as a potential precipitation inhibitor, was also investigated. The supersaturated systems resulted in a 2.3 - 3.3-fold higher Area Under the Curve (AUC0-24 h, not dose-normalized) and 1.4 - 2.2-fold higher maximum plasma concentration (Cmax, not dose-normalized) than non-supersaturated formulations (statistically significant with p = 0.05), whereas the addition of Soluplus® did not reveal any benefit. Results indicated that lipase inhibition affected the in vivo performance of LBFs: Co-administration of the lipase inhibitor significantly reduced Cmax and AUC0-24 h (both to 33-39 %, not dose-normalized) for the LCT formulations and, though not significant, a similar trend was observed for the AUC0-24 h of the MCT formulations (to 53-87 %), suggesting a higher dependency on lipolysis for LCT. Also, tmax tended to decrease to 20-60 % when compared to the animals not dosed with orlistat but lacking statistical significance. Without lipase inhibition, the LCT in general lead to better absorption of cinnarizine as compared to MCT, with 1.2-1.7-fold higher AUC0-24 h and 1.4-1.8-fold higher Cmax, but without showing statistical significance. Overall, the study revealed that lipolysis plays a major role in drug absorption from supersaturated lipid-based formulations type I.

Pancreatic lipase digestion: The forgotten barrier in oral administration of lipid-based delivery systems?

This review highlights the importance of controlling the digestion process of orally administered lipid-based delivery systems (LBDS) and their performance. Oral LBDS are prone to digestion via pancreatic lipase in the small intestine. Rapid or uncontrolled digestion may cause the loss of delivery system integrity, its structural changes, reduced solubilization capacity and physical stability issues. All these events can lead to uncontrolled drug release from the digested LBDS into the gastrointestinal environment, exposing the incorporated drug to precipitation or degradation by luminal proteases. To prevent this, the digestion rate of orally administered LBDS can be estimated by appropriate choice of the formulation type, excipient combinations and their ratios. In addition, in vitro digestion models like pH-stat are useful tools to evaluate the formulation digestion rate. Controlling digestion can be achieved by conventional lipase inhibitors like orlistat, sterically hindering of lipase adsorption on the delivery system surface with polyethylene glycol (PEG) chains, lipase desorption or saturation of the interface with surfactants as well as formulating LBDS with ester-free excipients. Recent in vivo studies demonstrated that digestion inhibition lead to altered pharmacokinetic profiles, where Cmax and Tmax were reduced in spite of same AUC compared to control or even improved oral bioavailability.

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.

Self-Nanoemulsifying Drug Delivery System for Enhanced Bioavailability of Madecassic Acid: In vitro and in vivo Evaluation

Purpose

Madecassic acid (MCA) is a natural triterpenoid isolated from centellae herba that has diverse biological effects, such as anti-inflammatory, antioxidant, and anticancer activities. However, the efficacy of MCA is limited by low oral bioavailability caused by its extremely poor aqueous solubility. This study aimed to develop a self-nanoemulsifying drug delivery system (SNEDDS) for MCA to improve its oral absorption.

Methods

The utilized oil phases, surfactants, and co-surfactants for SNEDDS were selected based on the solubility of MCA and emulsification efficiency. The optimized formulation was characterized for pharmaceutical properties and its pharmacokinetic behavior was examined in rats. Besides, the intestinal absorption property of MCA was investigated using in situ single-pass intestinal perfusion and intestinal lymphatic transport.

Results

The optimized nanoemulsion formula consists of Capryol 90:Labrasol:Kolliphor ELP:Transcutol HP in a weight ratio of 1:2.7:2.7:3.6 (w/w/w/w). MCA-loaded SNEDDS presented a small droplet size (21.52 ± 0.23 nm), with a zeta potential value of -3.05 ± 0.3 mV. Compared with pure MCA, SNEDDS had a higher effective permeability coefficient and showed 8.47-fold and 4.01-fold of maximum plasma concentration (C_max) and area under the plasma concentration-time curve (AUC), respectively. Cycloheximide was pretreated before the experiment to evaluate the degree of lymphatic uptake. The results showed that cycloheximide greatly influenced the absorption of SNEDDS, resulting in 82.26% and 76.98% reduction in C_max and AUC, respectively.

Conclusion

This study reports the MCA-loaded SNEDDS with distinctly enhanced in vitro and in vivo performance compared with pure MCA and concludes that the SNEDDS formulation could be a viable and effective strategy for improving the dissolution rate and bioavailability of poor aqueous-soluble ingredients.

Fast-Fed Variability: Insights into Drug Delivery, Molecular Manifestations, and Regulatory Aspects

Among various drug administration routes, oral drug delivery is preferred and is considered patient-friendly; hence, most of the marketed drugs are available as conventional tablets or capsules. In such cases, the administration of drugs with or without food has tremendous importance on the bioavailability of the drugs. The presence of food may increase (positive effect) or decrease (negative effect) the bioavailability of the drug. Such a positive or negative effect is undesirable since it makes dosage estimation difficult in several diseases. This may lead to an increased propensity for adverse effects of drugs when a positive food effect is perceived. However, a negative food effect may lead to therapeutic insufficiency for patients suffering from life-threatening disorders. This review emphasizes the causes of food effects, formulation strategies to overcome the fast-fed variability, and the regulatory aspects of drugs with food effects, which may open new avenues for researchers to design products that may help to eliminate fast-fed variability.

Balanced lipase interactions for degradation-controlled paclitaxel release from lipid cubic phase formulations

Lipid cubic phase (LCP) formulations enhance the intestinal solubility and bioavailability of hydrophobic drugs by reducing precipitation and facilitating their mass transport to the intestinal surface for absorption. LCPs with an ester linkage connecting the acyl chain to the glycerol backbone (monoacylglycerols), are susceptible to chemical digestion by several lipolytic enzymes including lipases, accelerating the release of hydrophobic agents from the lipid bilayers of the matrix. Unlike regular enzymes that transform soluble substrates, lipolytic enzymes act at the interface of water and insoluble lipid. Therefore, compounds that bind to this interface can enhance or inhibit the activity of enzymes to varying extent. Here, we explore how the lipolysis rate can be tuned by the interfacial interaction of porcine pancreatic lipase with monoolein LCPs containing a known lipase inhibitor, tetrahydrolipstatin. Release of the Biopharmaceutical Classification System (BCS) class IV drug, paclitaxel, from the inhibitor-modified LCP was examined in the presence of lipase and its effectors colipase and calcium. By combining experimental dynamic digestion studies, thermodynamic measurements and molecular dynamics simulations of the competitive inhibition of lipase by tetrahydrolipstatin, we reveal the role and mode of action of lipase effectors in creating a precisely-balanced degradation-controlled LCP release system for the poorly soluble paclitaxel drug.

Artificial Neural Networks to Predict the Apparent Degree of Supersaturation in Supersaturated Lipid-Based Formulations: A Pilot Study

In response to the increasing application of machine learning (ML) across many facets of pharmaceutical development, this pilot study investigated if ML, using artificial neural networks (ANNs), could predict the apparent degree of supersaturation (aDS) from two supersaturated LBFs (sLBFs). Accuracy was compared to partial least squares (PLS) regression models. Equilibrium solubility in Capmul MCM and Maisine CC was obtained for 21 poorly water-soluble drugs at ambient temperature and 60 °C to calculate the aDS ratio. These aDS ratios and drug descriptors were used to train the ML models. When compared, the ANNs outperformed PLS for both sLBF_Capmul^MC (r² 0.90 vs. 0.56) and sLBF_Maisine^LC (r² 0.83 vs. 0.62), displaying smaller root mean square errors (RMSEs) and residuals upon training and testing. Across all the models, the descriptors involving reactivity and electron density were most important for prediction. This pilot study showed that ML can be employed to predict the propensity for supersaturation in LBFs, but even larger datasets need to be evaluated to draw final conclusions.

An update on oral drug delivery via intestinal lymphatic transport

Orally administered drug entities have to survive the harsh gastrointestinal environment, penetrate the enteric epithelia and circumvent hepatic metabolism before reaching the systemic circulation. Whereas the gastrointestinal stability can be well maintained by taking proper measures, hepatic metabolism presents as a formidable barrier to drugs suffering from first-pass metabolism. The pharmaceutical academia and industries are seeking alternative pathways for drug transport to circumvent problems associated with the portal pathway. Intestinal lymphatic transport is emerging as a promising pathway to this end. In this review, we intend to provide an updated overview on the rationale, strategies, factors and applications involved in intestinal lymphatic transport. There are mainly two pathways for peroral lymphatic transport-the chylomicron and the microfold cell pathways. The underlying mechanisms are being unraveled gradually and nowadays witness increasing research input and applications.

Enhanced Bioavailability of AC1497, a Novel Anticancer Drug Candidate, via a Self-Nanoemulsifying Drug Delivery System

AC1497 is an effective dual inhibitor of malate dehydrogenase 1 and 2 targeting cancer metabolism. However, its poor aqueous solubility results in low bioavailability, limiting its clinical development. This study was conducted to develop an effective self-nanoemulsifying drug delivery system (SNEDDS) of AC1497 to improve its oral absorption. Based on the solubility of AC1497 in various oils, surfactants, and cosurfactants, Capryol 90, Kolliphor RH40, and Transcutol HP were selected as the components of SNEDDS. After testing various weight ratios of Capryol 90 (20–30%), Kolliphor RH40 (35–70%), and Transcutol HP (10–35%), SNEDDS-F4 containing 20% Capryol 90, 45% Kolliphor RH40, and 35% Transcutol HP was identified as an optimal SNEDDS with a narrow size distribution (17.8 ± 0.36 nm) and high encapsulation efficiency (93.6 ± 2.28%). Drug release from SNEDDS-F4 was rapid, with approximately 80% of AC1497 release in 10 min while the dissolution of the drug powder was minimal (<2%). Furthermore, SNEDDS-F4 significantly improved the oral absorption of AC1497 in rats. The maximum plasma concentration and area under the plasma concentration–time curve of AC1497 were, respectively 6.82- and 3.14-fold higher for SNEDDS-F4 than for the drug powder. In conclusion, SNEDDS-F4 with Capryol 90, Kolliphor RH40, and Transcutol HP (20:45:35, w/w) effectively improves the solubility and oral absorption of AC1497.

Formulation optimization, anesthetic activity, skin permeation, and transportation pathway of Alpinia galanga oil SNEDDS in zebrafish (Danio rerio)

Alpinia galanga oil (AGO) has an anesthetic activity but its water insoluble property limits its clinical applications. The aim of the present study was to develop a self-nanoemulsifying drug delivery system of AGO (SNEDDS-AGO) to avoid the use of organic solvent and investigate AGO transportation pathway and anesthetic activity. Three optimized formulations from a contour plots of droplet size; SNEDDS-AGO-1, SNEDDS-AGO-2, and SNEDDS-AGO-3, composed of AGO, Miglyol 812, Cremophor RH 40, Capmul MCM EP, and ethanol at the ratios of 40:10:35:10:5, 40:20:15:20:5, and 60:10:15:10:5, respectively were selected as they possessed different droplet size of 62 ± 0.5, 107 ± 2.8, and 207 ± 4.3 nm, respectively. It was found that the droplet size played an important role in fish anesthesia. SNEDDS-AGO-3 showed the longest anesthetic induction time (270 sec) (p < 0.03). Transportation pathway and skin permeation of SNEDDS-AGO-2 were investigated using nile red labelled AGO and detected by fluorescence microscope. AGO was found mostly in brain, gills, and skin suggesting that the transportation pathway of AGO in zebrafish is passing through the gills and skin to the brain. SNEDDS-AGO formulations showed significantly higher permeation through the skin than AGO ethanolic solution. In conclusion, SNEDDS is a promising delivery system of AGO.

Estimating the Oral Absorption from Self-Nanoemulsifying Drug Delivery Systems Using an In Vitro Lipolysis-Permeation Method

The aim of this study was to design an in vitro lipolysis-permeation method to estimate drug absorption following the oral administration of self-nanoemulsifying drug delivery systems (SNEDDSs). The method was evaluated by testing five oral formulations containing cinnarizine (four SNEDDSs and one aqueous suspension) from a previously published pharmacokinetic study in rats. In that study, the pharmacokinetic profiles of the five formulations did not correlate with the drug solubilization profiles obtained during in vitro intestinal lipolysis. Using the designed lipolysis-permeation method, in vitro lipolysis of the five formulations was followed by in vitro drug permeation in Franz diffusion cells equipped with PermeaPad^® barriers. A linear in vivo–in vitro correlation was obtained when comparing the area under the in vitro drug permeation–time curve (AUC_0–3h), to the AUC_0–3h of the plasma concentration–time profile obtained from the in vivo study. Based on these results, the evaluated lipolysis-permeation method was found to be a promising tool for estimating the in vivo performance of SNEDDSs, but more studies are needed to evaluate the method further.

Exploring precipitation inhibitors to improve in vivo absorption of cinnarizine from supersaturated lipid-based drug delivery systems

Supersaturated lipid-based drug delivery systems are increasingly being explored as a bio-enabling formulation approach, particularly in preclinical evaluation of poorlywater-soluble drugs. While increasing the drug load through thermally-induced supersaturation resulted in enhanced in vivo exposure for some drugs, for others, such as cinnarizine, supersaturated lipid-based systems have not been found beneficial to increase the in vivo bioavailability. We hypothesized that incorporation of precipitation inhibitors to reduce drug precipitation may address this limitation. Therefore, pharmacokinetic profiles of cinnarizine supersaturated lipid-based drug delivery systems with or without precipitation inhibitors were compared. Five precipitation inhibitors were selected for investigation based on a high throughput screening of twenty-one excipients. In vivo results showed that addition of 5% precipitation inhibitors to long chain monoglyceride (LCM) or medium chain monoglyceride (MCM) formulations showed a general trend of increases in cinnarizine bioavailability, albeit only statistically significantly increased for Poloxamer 407 + LCM system (i.e. 2.7-fold increase in AUC_0-24h compared to LCM without precipitation inhibitors). It appeared that precipitation inhibitors mitigated the risk of in vivo precipitation of cinnarizine from sLBDDS and overall, bioavailability was comparable to that previously reported for cinnarizine after dosing of non-supersaturated lipid systems. In summary, for drugs which are prone to precipitation from supersaturated lipid-based drug delivery systems, such as cinnarizine, inclusion of precipitation inhibitors mitigates this risk and provides the opportunity to maximize exposure which is ideally suited in early efficacy and toxicology evaluation.

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.

Development of Self-Nanoemulsifying Drug Delivery Systems Containing 4-Allylpyrocatechol for Treatment of Oral Infections Caused by Candida albicans

Clinical use of 4-Allylpyrocatechol (APC), a potential antifungal agent from Piper betle, is limited because of its low water solubility. The current study explores the development of the self-nanoemulsifying drug delivery system (SNEDDS) containing APC (APC-SNEDDS) to enhance APC solubility. Results demonstrated that excipient type and concentration played an important role in the solubility of APC in the obtained SNEEDS. SNEDDS, comprising 20% Miglyol 812N, 30% Maisine 35-1, 40% Kolliphor RH40, and 10% absolute ethanol, provided the highest loading capacity and significantly increased water solubility of APC. Oil-in-water nanoemulsions (NE) with droplet sizes of less than 40 nm and a narrow size distribution were obtained after dispersing this APC-SNEDDS in water. The droplets had a negative zeta potential between -10 and -20 mV. The release kinetics of APC from APC-SNEDDS followed the Higuchi model. The NE containing 1.6 mg APC/mL had effective activity against Candida albicans with dose-dependent killing kinetics and was nontoxic to normal cells. The antifungal potential was similar to that of 1 mg nystatin/mL. These findings suggest that APC-SNEDDS are a useful system to enhance the apparent water solubility of APC and are a promising system for clinical treatment of oral infection caused by C. albicans.

Impact of bile salts and a medium chain fatty acid on the physical properties of self-emulsifying drug delivery systems

The aim of this study was the evaluation of the influence of bile salts and fatty acids, important components of intestinal fluids, on physical characteristics of self-emulsifying drug delivery systems (SEDDS) such as size, polydispersity (PDI), zeta potential (Zp), turbidity (T%), cloud point temperature (CPT) and drug release. At this purpose, nonionic (ni-SEDDS) and cationic (c-SEDDS) were emulsified in aqueous media containing increasing concentrations of bile salts (BS) and decanoate (Dec). Zp of ni-SEDDS and c-SEDDS became highly negative at 15 mM BS and Dec. Size of ni-SEDDS decreased of 112 nm and of 76 nm at 15 mM BS and Dec, respectively. Size of c-SEDDS decreased of 53 nm at 15 mM BS, but it was not affected by 15 mM Dec. PDI and T% of ni- and c-SEDDS were lowered as well. CPT of ni-SEDDS increased from 70 °C to 97 °C and 84 °C at 15 mM BS and Dec. CPT of c-SEDDS decreased from above 100 °C to 80 °C and to 85 °C at 1.5 mM BS and at 5 mM Dec, respectively. Generally, BS had a more pronounced effect on SEDDS Zp, size, PDI, T %, and CPT than Dec. The release of the model drug quinine was accelerated by BS and Dec. As BS and fatty acids affect the physical characteristics and drug release behavior of SEDDS, their impact should be addressed during the development process.

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.

Modulating the release of pharmaceuticals from lipid cubic phases using a lipase inhibitor

Lipid cubic phase formulations have gained recognition as potential controlled delivery systems for a range of active pharmaceutical and biological agents on account of their desirable physiochemical properties and ability to encapsulate both hydrophobic and hydrophilic molecules. The most widely studied lipid cubic systems are those of the monoacylglycerol lipid family. These formulations are susceptible to lipolysis by a variety of enzymes, including lipases and esterases, which attack the ester bond present on the lipid chain bridging the oleic acid component to the glycerol backbone. The release of poorly soluble molecules residing in the lipid membrane portions of the phase is limited by the breakdown of the matrix; thus, presenting a potential means for further controlling and sustaining the release of therapeutic agents by targeting the matrix stability and its rate of degradation. The aims of the present study were twofold: to evaluate an approach to regulate the rate of degradation of lipid cubic phase drug delivery systems by targeting the enzyme interactions responsible for their demise; and to study the subsequent drug release profiles from bulk lipid cubic gels using model drugs of contrasting hydrophobicity. Here, hybrid materials consisting of cubic phases with monoacylglycerol lipids of different chain lengths formulated with a potent lipase inhibitor tetrahydrolipstatin were designed. Modulation of the release of a hydrophobic model pharmaceutical, a clofazimine salt, was obtained by exploiting the matrices' enzyme-driven digestion. A stable cubic phase is described, displaying controlled degradation with at least a 4-fold improvement compared to the blank systems shown in inhibitor-containing cubic systems. Sustained release of the model hydrophobic pharmaceutical was studied over 30 days to highlight the advantage of incorporating an inhibitor into the cubic network to achieve tunable lipid release systems. This is done without negatively affecting the structure of the matrix itself, as shown by comprehensive small-angle x-ray scattering experiments.

Oral formulation strategies to improve the bioavailability and mitigate the food effect of abiraterone acetate

Abiraterone acetate, marketed as Zytiga®, is an antiandrogen medication used in the treatment of prostate cancer. Abiraterone acetate is a BCS Class IV compound associated with several oral delivery challenges. Its low solubility and high lipophilicity lead to poor oral bioavailability (<10%) and a dramatic positive food effect (5-10-fold). Hence, a large dose of abiraterone acetate (1000 mg per day) is prescribed to patients who must fast for at least 1 h before and 2 h after administration. The recent expiry of Zytiga®s' patent has led to the emergence of publications describing improved oral formulation strategies for abiraterone acetate. This review aims to discuss the characteristics of abiraterone acetate that lead to its unfavorable oral delivery, examine the oral formulation strategies that have been applied, and to describe potential alternative oral formulation strategies that have been used for other BCS Class IV drugs, to determine the most valuable strategies to develop novel and improved alternatives to the current commercial product. Specific emphasis of this review is placed on enabling oral formulation strategies that can improve solubilization and bioavailability, reduce the clinical dose and remove the pharmaceutical food effect to ultimately provide prostate cancer patients with a more efficient formulation with greater patient compliance.

Mefenamic acid-loaded solid SMEDDS: an innovative aspect for dose reduction and improved pharmacodynamic profile

AIM

The current investigation is focused on solid self-microemulsifying drug-delivery systems (S-SMEDDS) of mefenamic acid (MFA) for improving pharmacodynamic activity. Methodology & results: Solubility assessment in various lipid excipients and optimization of pseudoternary plots were carried out for development of liquid SMEDDS. The optimized liquid SMEDD formulation was spray dried to solid dosage form and observed with enhanced amorphization or molecular dispersion of MFA in S-SMEDDS, as evident from x-ray diffractometry and differential scanning calorimetry studies. Enhanced in vitro dissolution rate of optimized formulation was observed, resulting in multifold enhancement in absorption profile of MFA, as compared with pure drug and marketed product. These studies further substantiate the dose reduction in SMEDDS by gaining equivalent therapeutic profile with marketed product. Enhanced analgesic and anti-inflammatory activity was observed with S-SMEDD formulations in acetic acid-induced writhings and carrageenan-induced paw edema models, respectively.

CONCLUSION

The optimized S-SMEDD formulation holds great promise for enhancement of its physiochemical and biological attributes.

Impact of Ferroquine on the Solubilization of Artefenomel (OZ439) during in Vitro Lipolysis in Milk and Implications for Oral Combination Therapy for Malaria

Milk is an attractive lipid-based formulation for the delivery of poorly water-soluble drugs to pediatric populations. We recently observed that solubilization of artefenomel (OZ439) during in vitro intestinal lipolysis was driven by digestion of triglycerides in full-cream bovine milk, reflecting the ability of milk to act as an enabling formulation in the clinic. However, when OZ439 was co-administered with a second antimalarial drug, ferroquine (FQ) the exposure of OZ439 was reduced. The current study therefore aimed to understand the impact of the presence of FQ on the solubilization of OZ439 in milk during in vitro intestinal digestion. Synchrotron small-angle X-ray scattering was used for in situ monitoring of drug solubilization (inferred via decreases in the intensity of drug diffraction peaks) and polymorphic transformations that occurred during the course of digestion. Quantification of the amount of each drug solubilized over time and analysis of their distributions across the separated phases of digested milk were determined using high-performance liquid chromatography. The results show that FQ reduced the solubilization of OZ439 during milk digestion, which may be due to competitive binding of FQ to the digested milk products. Interactions between the protonated FQ-H⁺ and ionized liberated free fatty acids resulted in the formation of amorphous salts, which removes the low-energy crystalline state as a barrier to dissolution of FQ, while inhibiting the solubilization of OZ439. We conclude that although milk could enhance the solubilization of poorly water-soluble OZ439 during in vitro digestion principally due to the formation of fatty acids, the solubilization efficiency was reduced by the presence of FQ by competition for the available fatty acids. Assessment of the solubilization of both drugs during digestion of fixed-dose combination lipid formulations (such as milk) is important and may rationalize changes in bioavailability when compared to that of the individual drugs in the same formulation.

Bridging the gaps between academic research and industrial product developments of lipid-based formulations

Lipid-based formulations, including self-emulsifying drug delivery systems (SEDDS), are an interesting formulation technology that enables the clinical use of compounds for which a low aqueous solubility may be a limitation. From an academic perspective, the technology is interesting on several levels: what drives solubility, what determines bioperformance, what is the potential for solidification etc. From an industrial perspective, >35 lipid-based formulations are available and there is an unknown number of projects in the pipeline. Hence, while there is scientific interest from both academic and industrial perspectives, the agendas/needs in the two settings are different. From an industrial perspective, risks are associated with uncertainty; hence the more that is known about a technology the better - knowledge that in principle can be generated in both the academia and industry. This focuses on the development of lipid-based formulations and the knowledge gaps that could be investigated -with the hope that all stakeholders in the field of lipid-based formulations, including academia, industry, CRO's, lipid excipient manufacturers etc., would share their insight, so that this technology can be even further developed. Some of the gaps discussed include the selection of compounds suited for lipid-based formulations, which potential modifications that could be investigated, e.g., lipophilic salts, what is a relevant definition of accelerated stability studies, how best to construct an industrial development program of a lipid-based formulation, etc.

Self-microemulsifying Drug Delivery System for Problematic Molecules: An Update

BACKGROUND

The poor bioavailability of a problematic molecule is predominantly due to its high lipophilicity, low solubility in gastric fluids and/or high fist pass metabolism. Self microemulsifying drug delivery system (SMEDDS), a lipidic type IV nano-formulation has been of interest in the field of pharmaceutical research due to its potential for tailoring the physicochemical properties of pharmaceutical molecules.

METHODS

This review provides insights on various recent innovations and reports from the past seven years (2012-2019) of self-emulsifying formulations for the delivery of various types of poorly soluble drugs, phytoconstituents and high molecular peptides and gives exhaustive details of the outcome of the endeavors in this field.

RESULTS

Various types of innovative formulations have been molded from SMEDDS like selfemulsifying powders, granules, tablets, pellets, eutectic and cationic formulations. Till date, many research reports and patents have been filed on self-emulsifying dosage forms and many formulations have gained US-FDA approvals which are summarized in the review article.

CONCLUSION

This review content highlighted the increasing scope of SMEDDS in augmenting the physiochemical properties of an API, the variegated formulation types and the attributes of API that can be improved by SMEDD based formulations.

Exploring the utility of the Chasing Principle: influence of drug-free SNEDDS composition on solubilization of carvedilol, cinnarizine and R3040 in aqueous suspension

This study assessed the influence of the composition of drug-free SNEDDS co-dosed with aqueous suspensions of carvedilol (CAR), cinnarizine (CIN) or R3040 on drug solubilization in a two-compartment in vitro lipolysis model. Correlation of drug logP or solubility in SNEDDS with drug solubilization during in vitro lipolysis in the presence of drug-free SNEDDS was assessed. SNEDDS with varying ratios of soybean oil:Maisine 35-1 (1:1, w/w) and Kolliphor RH40, with ethanol at 10% (w/w) were used. SNEDDS were named F65, F55 and F20 (numbers refer to the percentage of lipids) and aqueous suspensions without drug-free SNEDDS (F0) were also analyzed. While the ranking order of drug solubilization was F65=F55=F20>F0 for CAR; F65=F55>F20>F0 for CIN and F65=F55=F20>F0 for R3040 - with higher CAR solubilization than for R3040 and CIN - the ranking of S eq of CAR, CIN and R3040 in SNEDDS was F65F20 and F65>F55>F20, respectively. Therefore, the composition of SNEDDS influenced the solubilization of CIN, but not CAR and R3040. Furthermore, high S eq in SNEDDS did not reflect high drug solubilization. As CAR (logP 3.8) showed higher solubilization than CIN (logP 5.8) and R3040 (logP 10.4), a correlation between drug logP and drug solubilization was observed.

Self-assembly and directed assembly of lipid nanocarriers for prevention of liver fibrosis in obese rats: a comparison with the therapy of bariatric surgery

Aim: Whether the obesity prevention by chemicals or surgeries in already obese patients is the better choice remains controversial. We aimed to compare the effect of orally silibinin-loaded nanocarriers and Roux-en-Y gastric bypass surgery on hepatic fibrosis in high-fat feeding-induced obese rats. Methodology: The developed nanocarriers included self-emulsifying drug delivery system (SNEDDS) and nanostructured lipid carriers (NLC). Results: A significant decrease in collagen production and lipid droplet formation was observed upon nanosystem and bariatric surgery than the rats treated with silibinin control suspension. Stage 3 fibrosis was present in 33% of the obese rats. This percentage could be minimized to 0% by SNEDDS and NLC. Following oral administration, SNEDDS and NLC resulted in 3.5- and 2.9-fold increase, respectively, in bioavailability compared with the reference suspension. Conclusion: Nanomedicine prevention provided a comparable efficiency to ameliorate liver steatosis as Roux-en-Y gastric bypass due to the improvement of silibinin dissolution and gastrointestinal permeation.

Preparation and Optimization of Rivaroxaban by Self-Nanoemulsifying Drug Delivery System (SNEDDS) for Enhanced Oral Bioavailability and No Food Effect

In this paper, a novel self-nanoemulsifying drug delivery system (SNEDDS) was used to improve the oral bioavailability in fasted state and diminish the food effect for rivaroxaban. Oil, surfactant, and co-surfactant were selected by saturated solubility study. IPM, Tween80, and 1,2-propanediol were finally selected as oil, surfactant, and co-surfactant, respectively. The pseudo-ternary-phase diagram was utilized to optimize the preliminary composition of SNEDDS formulation. The optimized rivaroxaban-SNEDDS formulation was selected by central composite design (CCD) of response surface methodology. Optimized SNEDDS formulation was evaluated for drug content, self-emulsifying time, droplet size, zeta potential, polydispersity index, Fourier transform-infrared (FTIR) spectroscopy, and transmission electron microscope (TEM). The drug dissolution profile compared to the commercial formulation Xarelto® (20 mg rivaroxaban) was determined in four different media (pH 1.2HCl, pH 4.5NaAc-HAc, pH 6.8PBS, and water). The result indicated that the SNEDDS formulation had successfully increased the drug solubility in four different media. A HPLC-MS method that indicated a high sensitivity, strong attribute, and high accuracy characteristic was built to measure the drug concentration in plasma. The fast/fed in vivo pharmacokinetics studies of SNEDDS formulation and Xarelto® were carried out in adult beagle dog, rivaroxaban with no food effect was achieved in SNEDDS formulation compared with Xarelto® in fed state. The result suggested that SNEDDS formulation in this study is useful to increase the oral bioavailability and diminish the food effect in fasted state.

Analysis of 3D Prints by X-ray Computed Microtomography and Terahertz Pulsed Imaging

PURPOSE

A 3D printer was used to realise compartmental dosage forms containing multiple active pharmaceutical ingredient (API) formulations. This work demonstrates the microstructural characterisation of 3D printed solid dosage forms using X-ray computed microtomography (XμCT) and terahertz pulsed imaging (TPI).

METHODS

Printing was performed with either polyvinyl alcohol (PVA) or polylactic acid (PLA). The structures were examined by XμCT and TPI. Liquid self-nanoemulsifying drug delivery system (SNEDDS) formulations containing saquinavir and halofantrine were incorporated into the 3D printed compartmentalised structures and in vitro drug release determined.

RESULTS

A clear difference in terms of pore structure between PVA and PLA prints was observed by extracting the porosity (5.5% for PVA and 0.2% for PLA prints), pore length and pore volume from the XμCT data. The print resolution and accuracy was characterised by XμCT and TPI on the basis of the computer-aided design (CAD) models of the dosage form (compartmentalised PVA structures were 7.5 ± 0.75% larger than designed; n = 3).

CONCLUSIONS

The 3D printer can reproduce specific structures very accurately, whereas the 3D prints can deviate from the designed model. The microstructural information extracted by XμCT and TPI will assist to gain a better understanding about the performance of 3D printed dosage forms.

Influence of drug load and physical form of cinnarizine in new SNEDDS dosing regimens: in vivo and in vitro evaluations

The aim of this work was to evaluate the influence of drug load and physical form of cinnarizine (CIN) in self-nanoemulsifying drug delivery systems (SNEDDS) on absorption in rats. Further, the predictivity of the dynamic in vitro lipolysis model was evaluated. The following dosing regimens were assessed: (1) CIN dissolved in SNEDDS at 80% of equilibrium solubility (S_eq) (SNEDDS 80%); (2) supersaturated SNEDDS with CIN dissolved at 200% S_eq (super-SNEDDS solution); (3) SNEDDS suspension with CIN added at 200% S_eq (CIN partially dissolved and partially suspended) (super-SNEDDS suspension); (4) drug-free SNEDDS co-dosed with aqueous CIN suspension (Chasing principle), and (5) CIN aqueous suspension. The CIN dose was kept constant for all dosing regimens. Therefore, the super-SNEDDS solution and super-SNEDDS suspension contained 2.5-fold less SNEDDS pre-concentrate than SNEDDS 80% and the Chasing principle. In vivo, a higher AUC after dosing CIN in SNEDDS 80% and the Chasing principle was obtained when compared to the super-SNEDDS solution, super-SNEDDS suspension, and aqueous suspension. In vitro, a higher extent of CIN in the aqueous phase was observed for all SNEDDS-containing dosing regimens, compared to the aqueous suspension. Since the drug level in the aqueous phase is traditionally considered as the fraction available for absorption, a lack of in vitro-in vivo relation was observed. This study revealed that the physical form of CIN in the current SNEDDS does not affect CIN absorption and solubilization, whereas the drug load, or amount of co-dosed lipid, significantly influenced CIN bioavailability.

Responsive self-assembled nanostructured lipid systems for drug delivery and diagnostics

While stimuli-responsive polymers have received a huge amount of attention in the literature, responsive lipid-based mesophase systems offer unique opportunities in biomedical applications such as drug delivery and biosensing. The different mesophase equilibrium structures enables dynamic switching between nanostructures to facilitate drug release or as a transducer for recognition events. In drug delivery, this behavior offers researchers the means to deliver a therapeutic payload at a specific rate and time i.e. 'on-demand'. This review summarizes the distinctive features of these multifaceted materials and aggregates the current state of the art research from our groups and others into the use of these materials as bulk gels and nanostructured dispersions for drug delivery, biosensing and diagnostics.

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.