Lipid-based formulations for oral delivery of lipophilic drugs

Solid Self Nano-Emulsifying Drug Delivery System of Dasatinib: Optimization, In-vitro, Ex-vivo and In-vivo assessment

Aim: Dasatinib (DST) is an oral tyrosine kinase inhibitor with poor aqueous solubility. To outwit this issue, a solid self-nano emulsifying drug delivery system (S-SNEDDS) of DST was formulated.Methods: I-optimal mixture design was used for optimization of DST-loaded SNEDDS using Linalool, Cremophor RH40 and Transcutol P. S-SNEDDS underwent physicochemical characterization, in-vitro release and ex-vivo permeation, cell-based assays and pharmacokinetic study.Results: DST-S-SNEDDS showed globule size and PDI of 141.53 ± 5.371 nm and 0.282 ± 0.020, respectively. DST-S-SNEDDS revealed significantly lower IC50 (1.825 μg/mL) than free DST (7.298 μg/mL) in MDA-MB-231. In-vivo pharmacokinetic study revealed 1.94-fold increment in AUC0-t for the DST-S-SNEDDS group than free DST.Conclusion: S-SNEDDS could be promising approach for improving bioavailability and efficacy of DST.

Development of lipid-based SEDDS using digestion products of long-chain triglyceride for high drug solubility: Formulation and dispersion testing

A self-emulsifying drug delivery system (SEDDS) containing long chain lipid digestion products (LDP) and surfactants was developed to increase solubility of two model weakly basic drugs, cinnarizine and ritonavir, in the formulation. A 1:1.2 w/w mixture of glyceryl monooleate (Capmul GMO-50; Abitec) and oleic acid was used as the digestion product, and a 1:1 w/w mixture of Tween 80 and Cremophor EL was the surfactant used. The ratio between LDP and surfactant was 1:1 w/w. Since the commercially available Capmul GMO-50 is not pure monoglyceride and contained di-and-triglycerides, the digestion product used would provide 1:2 stoichiometric molar ratio of monoglyceride and fatty acid after complete digestion in gastrointestinal fluid. Both cinnarizine and ritonavir had much higher solubility in oleic acid (536 and 72 mg/g, respectively) than that in glyceryl monooleate and glyceryl trioleate. Therefore, by incorporating oleic acid in place of glyceryl trioleate in the formulation, the solubility of cinnarizine and ritonavir could be increased by 5-fold and 3.5-fold, respectively, as compared to a formulation without the fatty acid. The formulation dispersed readily in aqueous media, and adding 3 mM sodium taurocholate, which is generally present in GI fluid, remarkably improved the dispersibility of SEDDS and reduced particle size of dispersions. Thus, the use of digestion products of long-chain triglycerides as components of SEDDS can enhance the drug loading of weakly basic compounds and increase dispersibility in GI fluids.

Early evaluation of opportunities in oral delivery of PROTACs to overcome their molecular challenges

PROteolysis TArgeting Chimeras (PROTACs) offer new opportunities in modern medicine by targeting proteins that are intractable to classic inhibitors. Heterobifunctional in nature, PROTACs are small molecules that offer a unique mechanism of protein degradation by hijacking the ubiquitin-mediated protein degradation pathway, known as the ubiquitin-proteasome system. Herein, we present an analysis on the structural characteristics of this novel chemical modality. Furthermore, we review and discuss the formulation opportunities to overcome the oral delivery challenges of PROTACs in drug discovery.

Evaluating physiochemical properties of FDA-approved orally administered drugs

INTRODUCTION

Analyses of orally administered FDA-approved drugs from 1990 to 1993 enabled the identification of a set of physiochemical properties known as Lipinski's Rule of Five (Ro5). The original Ro5 and extended versions still remain the reference criteria for drug development programs. Since many bioactive compounds do not conform to the Ro5, we validated the relevance of and adherence to these rulesets in a contemporary cohort of FDA-approved drugs.

AREAS COVERED

The authors noted that a significant proportion of FDA-approved orally administered parent compounds from 2011 to 2022 deviate from the original Ro5 criteria (~38%) or the Ro5 with extensions (~53%). They then evaluated if a contemporary Ro5 criteria (cRo5) could be devised to better predict oral bioavailability. Furthermore, they discuss many case studies showcasing the need for and benefit of increasing the size of certain compounds and cover several evolving strategies for improving oral bioavailability.

EXPERT OPINION

Despite many revisions to the Ro5, the authors find that no single proposed physiochemical rule has universal concordance with absolute oral bioavailability. Innovations in drug delivery and formulation have dramatically expanded the range of physicochemical properties and the chemical diversity for oral administration.

Polyenylphosphatidylcholine as bioactive excipient in tablets for the treatment of liver fibrosis

Liver fibrosis is a condition characterized by the accumulation of extracellular matrix (ECM) arising from the myofibroblastic transdifferentiation of hepatic stellate cells (HSCs) occurring as the natural response to liver damage. To date, no pharmacological treatments have been specifically approved for liver fibrosis. We recently reported a beneficial effect of polyenylphosphatidylcholines (PPCs)-rich formulations in reverting fibrogenic features of HSCs. However, unsaturated phospholipids' properties pose a constant challenge to the development of tablets as preferred patient-centric dosage form. Profiting from the advantageous physical properties of the PPCs-rich Soluthin® S 80 M, we developed a tablet formulation incorporating 70% w/w of this bioactive lipid. Tablets were characterized via X-ray powder diffraction, thermogravimetry, and Raman confocal imaging, and passed the major compendial requirements. To mimic physiological absorption after oral intake, phospholipids extracted from tablets were reconstituted as protein-free chylomicron (PFC)-like emulsions and tested on the fibrogenic human HSC line LX-2 and on primary cirrhotic rat hepatic stellate cells (PRHSC). Lipids extracted from tablets and reconstituted in buffer or as PFC-like emulsions exerted the same antifibrotic effect on both activated LX-2 and PRHSCs as observed with plain S 80 M liposomes, showing that the manufacturing process did not interfere with the bioactivity of PPCs.

Improvement and characterization of oral absorption behavior of clofazimine by SNEDDS: Quantitative evaluation of extensive lymphatic transport

Clofazimine, an anti-leprosy drug, has been anticipated for a candidate to treat tuberculosis, cryptosporidiosis, and coronavirus infection, but its low oral bioavailability is considered a reason for its limited activity. In the current study, we have tried to improve the oral bioavailability of clofazimine by several SNEDDS formulations and characterized the absorption behavior from various aspects. Among four SNEDDS formulations prepared, SNEDDS A, prepared with castor oil as an oil component, provided the highest bioavailability (around 61%) and SNEDDS D, prepared with Capryol 90, gave the second highest bioavailability. SNEDDS A formed the finest nanoparticles, which were maintained under gastric and intestinal luminal conditions. The comparison in oral bioavailability between the SNEDDS formulation and its corresponding preformed nanoemulsion suggested that SNEDDS A would efficiently form nanoemulsion in the gastrointestinal tract after oral administration. AUC of mesenteric lymph node concentration was the highest for SNEDDS A, which would be one of the reasons for SNEDDS A to reveal the highest oral bioavailability. A cycloheximide-treated oral absorption study and single-pass perfusion study by utilizing a vascular-luminal perfused small intestine-liver preparation clearly indicated that over 90% of clofazimine absorbed to systemic circulation should be derived from lymphatic transport for both SNEDDS A and D. Furthermore, the fraction of dose absorbed was around 65% for SNEDDS D, but SNEDDS A achieved around 94%, indicating the excellent performance of SNEDDS A.

Formulation and evaluation of the antimalarial N-89 as a transdermal drug candidate

The discovery of new effective and safe antimalarial drugs is mandatory. In this report, we formulate and evaluate transdermal (td) 1,2,6,7-tetraoxaspiro[7.11]nonadecane (N-89) using the Plasmodium berghei rodent malaria parasite in vivo model. The selected solvent for the ointment type of td N-89 was polyethylene glycol (PEG) [PEG400:PEG 4000 = 8:1 (v/w)]. We tested different application areas of 4, 6, and 8 cm² on the shaved backs of mice. Pharmacokinetic (PK) analysis of N-89 parameters after a single 4 cm² transdermal application revealed that the T_max was 2 h, the T_1/2 was 1.9 h, and the AUC was 1951.1 ng^.h/mL. More than 10 ng/mL of plasma concentration was maintained for 12 h. The ED₅₀ values for the 4, 6, and 8 cm² application areas in a 4-day suppressive test were 18.9, 25.1, and 26.8 mg/kg, respectively. We additionally tested the cure effect of td N-89 in mice at a dose of 60 mg/kg, twice daily for 4 days at 0.2% parasitemia. Parasites disappeared following day 7 post-treatment in all td N-89 treated groups. Mice were cured without any parasite recurrence or dermal irritation. In conclusion, this study determined for the first time the PK parameters and effect of a new ointment type of td N-89. This suggests that transdermal treatment with N-89 is an effective and safe alternative route for the treatment of malaria, especially in children.

Solid microemulsion preconcentrates on pH responsive metal-organic framework for tableting

Poorly water-soluble drugs are frequently formulated with lipid-based formulations including microemulsions and their preconcentrates. We detailed the solidification of drug-loaded microemulsion preconcentrates with the acid-sensitive metal-organic framework ZIF-8 by X-ray powder diffraction and solid-state nuclear magnetic resonance spectroscopy. Adsorption and desorption dynamics were analyzed by fluorescence measurement, high-performance liquid chromatography, dynamic light scattering and ¹H-DOSY experiments using the model compounds Nile Red, Vitamin K₁, and Lumefantrine. Preconcentrates and drugs were successfully loaded onto ZIF-8 while preserving its crystal structure. The solid powder was pressable to tablets or 3D-printed into oral dosage forms. At low pH, colloidal solutions readily formed, solubilizing the poorly water-soluble compounds. The use of stimuli-responsive metal organic frameworks as carriers for the oral delivery of lipid-based formulations points towards solid dosage forms readily forming colloidal microemulsions.

Enhanced Intestinal Permeability of Cefixime by Self-Emulsifying Drug Delivery System: In-Vitro and Ex-Vivo Characterization

BACKGROUND

Cefixime (CFX) belongs to a group of third-generation cephalosporin antibiotics with low water solubility and low intestinal permeability, which ultimately leads to significantly low bioavailability.

AIM

This study aimed to increase solubility, improve drug release, and intestinal permeability of CFX by loading into SEDDS.

METHODS

Suitable excipients were selected based on drug solubility, percent transmittance, and emulsification efficiency. Pseudo-ternary phase diagram was fabricated for the identification of effective self-emulsification region. The best probably optimized formulations were further assessed for encumbered drug contents, emulsification time, cloud point measurement, robustness to dilution, mean droplet size, zeta potential, polydispersity index (PDI), and thermodynamic and chemical stability. Moreover, in vitro drug release studies and ex vivo permeation studies were carried out and apparent drug permeability P_app of different formulations was compared with the marketed brands of CFX.

RESULTS

Amongst the four tested SEDDS formulations, F-2 formulation exhibited the highest drug loading of 96.32%, emulsification time of 40.37 ± 3 s, mean droplet size of 19.01 ± 1.12 nm, and demonstrated improved long-term thermodynamic and chemical stability when stored at 4 °C. Release studies revealed a drug release of 97.32 ± 4.82% within 60 min in simulated gastric fluid. Similarly, 97.12 ± 5.02% release of CFX was observed in simulated intestinal fluid within 120 min; however, 85.13 ± 3.23% release of CFX was observed from the marketed product. Ex vivo permeation studies displayed a 2.7-fold increase apparent permeability compared to the marketed product in 5 h.

CONCLUSION

Owing to the significantly improved drug solubility, in vitro release and better antibacterial activity, it can be assumed that CFX-loaded SEDDS might lead to an increased bioavailability and antibacterial activity, possibly leading to improved therapeutic effectiveness.

Influence of Hydrophobic and Hydrophilic Chain Length of CiEj Surfactants on the Solubilization of Active Pharmaceutical Ingredients

Up to 90% of all newly developed active pharmaceutical ingredients (APIs) are poorly water soluble, most likely also showing a low oral bioavailability. In order to increase the aqueous solubility of these APIs, surfactants are promising excipients to increase both solubility and consequently bioavailability (e.g., in lipid- and surfactant-based drug delivery systems). In this work, we investigated the influence of hydrophobic and hydrophilic chain lengths of C_iE_j surfactants (C₈E₆, C₁₀E₆, and C₁₀E₈) toward the solubilization of fenofibrate, naproxen, and lidocaine. Furthermore, we investigated the partitioning of these APIs between the surfactant aggregates and the surrounding aqueous bulk phase. For all APIs considered, we determined the locus of API solubilization as well as the individual aggregation numbers (N_agg) of surfactants and API molecules in an API/surfactant aggregate. We further determined the hydrodynamic radius (R_h) of the API/surfactant aggregates in the absence and presence of the APIs. The size of the API/surfactant aggregates (N_agg, R_h) passes through a minimum upon lidocaine solubilization; it gradually increases upon naproxen solubilization and is almost constant upon fenofibrate solubilization. The results give valuable insights into the solubilization mechanisms of APIs in the C_iE_j surfactant aggregates. Our results reveal that fenofibrate is solely solubilized in the hydrophobic core of the C_iE_j surfactant aggregates, as only the hydrophobic chain length of the surfactant influences its solubilization. Naproxen is solubilized in the palisade layer of the surfactant aggregates, as both the hydrophobic and hydrophilic chain lengths are decisive for its solubilization. Lidocaine is mainly solubilized in the rather hydrophilic corona region of the surfactant aggregates, as the hydrophilic chain length of the surfactant governs its solubilization. The results further reveal that the hydrophilic/lipophilic balance is not an appropriate measure to estimate the solubilization capacity of surfactant aggregates.

The Influence of Blonanserin Supersaturation in Liquid and Silica Stabilised Self-Nanoemulsifying Drug Delivery Systems on In Vitro Solubilisation

Reformulating poorly water-soluble drugs as supersaturated lipid-based formulations achieves higher drug loading and potentially improves solubilisation and bioavailability. However, for the weak base blonanserin, silica solidified supersaturated lipid-based formulations have demonstrated reduced in vitro solubilisation compared to their liquid-state counterparts. Therefore, this study aimed to understand the influence of supersaturated drug load on blonanserin solubilisation from liquid and silica solidified supersaturated self-nanoemulsifying drug delivery systems (super-SNEDDS) during in vitro lipolysis. Stable liquid super-SNEDDS with varying drug loads (90-300% of the equilibrium solubility) were solidified by imbibition into porous silica microparticles (1:1 lipid: silica ratio). In vitro lipolysis revealed greater blonanserin solubilisation from liquid super-SNEDDS compared to solid at equivalent drug saturation levels, owing to strong silica-BLON/lipid interactions, evidenced by a significant decrease in blonanserin solubilisation upon addition of silica to a digesting liquid super-SNEDDS. An increase in solid super-SNEDDS drug loading led to increased solubilisation, owing to the increased drug:silica and drug:lipid ratios. Solidifying SNEDDS with silica enables the fabrication of powdered formulations with higher blonanserin loading and greater stability than liquid super-SNEDDS, however at the expense of drug solubilisation. These competing parameters need careful consideration in designing optimal super-SNEDDS for pre-clinical and clinical application.

Oral drug delivery strategies for development of poorly water soluble drugs in paediatric patient population

Selecting the appropriate formulation and solubility-enabling technology for poorly water soluble drugs is an essential element in the development of formulations for paediatric patients. Different methodologies and structured strategies are available to select a suitable approach and guide formulation scientists for development of adult formulations. However, there is paucity of available literature for selection of technology and overcoming the challenges in paediatric formulation development. The need for flexible dosing, and the limited knowledge of the safety of many formulation excipients in paediatric subjects, impose significant constraints and in some instances require adaptation of the approaches taken to formulating these drugs for the adult population. Selection of the best drug delivery system for paediatrics requires an efficient, systematic approach that considers a drug's physical and chemical properties and the targeted patient population's requirements. This review is a step towards development of a strategy for the design of solubility enhancing paediatric formulations of highly insoluble drugs. The aim of this review is to provide an overview of different approaches and strategies to consider in order to assist development of paediatric formulation for poorly water-soluble drugs with the provision of examples of some marketed products. In addition, it provides recommendations to overcome the range of challenges posed by these strategies and adaptations of the adult approach/product presentation required to enable paediatric drug development and administration.

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.

Central Composite Optimization of Glycerosomes for the Enhanced Oral Bioavailability and Brain Delivery of Quetiapine Fumarate

This study aimed to formulate and statistically optimize glycerosomal formulations of Quetiapine fumarate (QTF) to increase its oral bioavailability and enhance its brain delivery. The study was designed using a Central composite rotatable design using Design-Expert^® software. The independent variables in the study were glycerol % w/v and cholesterol % w/v, while the dependent variables were vesicle size (VS), zeta potential (ZP), and entrapment efficiency percent (EE%). The numerical optimization process resulted in an optimum formula composed of 29.645 (w/v%) glycerol, 0.8 (w/v%) cholesterol, and 5 (w/v%) lecithin. It showed a vesicle size of 290.4 nm, zeta potential of −34.58, and entrapment efficiency of 80.85%. The optimum formula was further characterized for DSC, XRD, TEM, in-vitro release, the effect of aging, and pharmacokinetic study. DSC thermogram confirmed the compatibility of the drug with the ingredients. XRD revealed the encapsulation of the drug in the glycerosomal nanovesicles. TEM image revealed spherical vesicles with no aggregates. Additionally, it showed enhanced drug release when compared to a drug suspension and also exhibited good stability for one month. Moreover, it showed higher brain C_max, AUC_0–24, and AUC_0–∞ and plasma AUC_0–24 and AUC_0–∞ in comparison to drug suspension. It showed brain and plasma bioavailability enhancement of 153.15 and 179.85%, respectively, compared to the drug suspension. So, the optimum glycerosomal formula may be regarded as a promising carrier to enhance the oral bioavailability and brain delivery of Quetiapine fumarate.

Formulation and Evaluation of SNEDDS Loaded with Original Lipophenol for the Oral Route to Prevent Dry AMD and Stragardt’s Disease

Dry age-related macular degeneration (Dry AMD) and Stargardt’s disease (STGD1) are common eye diseases, characterized by oxidative and carbonyl stress (COS)-inducing photoreceptor degeneration and vision loss. Previous studies have demonstrated the protective effect of photoreceptors after the intravenous administration of a new lipophenol drug, phloroglucinol-isopropyl-DHA (IP-DHA). In this study, we developed an oral formulation of IP-DHA (BCS Class IV) relying on a self-nanoemulsifying drug delivery system (SNEDDS). SNEDDS, composed of Phosal® 53 MCT, Labrasol®, and Transcutol HP® at a ratio of 25/60/15 (w/w/w), led to a homogeneous nanoemulsion (NE) with a mean size of 53.5 ± 4.5 nm. The loading of IP-DHA in SNEDDS (SNEDDS-IP-DHA) was successful, with a percentage of IP-DHA of 99.7% in nanoemulsions. The in vivo study of the therapeutic potency of SNEDDS-IP-DHA after oral administration on mice demonstrated photoreceptor protection after the induction of retinal degeneration with acute light stress (73–80%) or chronic light stress (52–69%). Thus, SNEDDS formulation proved to increase the solubility of IP-DHA, improving its stability in intestinal media and allowing its passage through the intestinal barrier after oral force-fed administration, while maintaining its biological activity. Therefore, SNEDDS-IP-DHA is a promising future preventive treatment for dry AMD and STGD1.

Lipid-based nanoparticles for treatment of cancer

Investigators were continuously creating novel nanotechnologies to address unmet requirements throughout the administration of therapeutic medicines & imaging agents for cancer treatment & diagnostics, appropriately. LNPs(Lipid nanoparticles) are legitimate particulates (approx. 100 nm in size) gathered from various lipid as well as other biochemical compounds which overall functionality to resolve biological barriers (biobarriers), allowing LNPs to selectively collect somewhere outside of disease-target cells again for responsive therapeutics. Most pharmaceutically important compounds were insoluble throughout water solutions, were chemical & physiologically unstable, or have toxicities. Among the most potential drug carrier for bioactive organic compounds is LBNPs (Lipid based nanoparticles) technologies. Its present use in chemotherapy have transformed treatment for cancer by increasing the antitumor effect of a number of chemotherapeutics. Because they may be created using naturally occurring sources, LBNPs have great temporal and thermal stability, maximum load potential, simplicity of preparations, cheap manufacturing costs, & big manufacturing output. Furthermore, combining chemotherapeutic drugs with LNPs reduces active therapeutic dosage and toxicities, lowers treatment resistance, & raises drug concentration in tumour cells while reducing concentrations in normal tissue. LBNPs were widely studied in cancer treatment, both in vitro and in vivo, with encouraging outcomes in certain clinical trials. This study provides an overview of the many types of LBNPs which have been created in latest years and their applications and contributions in different types of cancers.

Introducing Lipophilicity to (Polyhydroxyalkyl)thiazolidine Carboxylic Acids Via Acylation

The therapeutic efficacy of bioactive compounds is related to their bioavailability. In turn, the bioavailability depends on the equilibrium between the hydrophilicity and the lipophilicity. 2(R,S)-(Polyhydroxyalkyl)thiazolidine-4(R) carboxylic acids (TCAs), obtained from the condensation of l-cysteine and an aldose, have been recognized as nontoxic precursors of glutathione with important preventive and therapeutic effects. The bioavailability of these compounds can be improved by enhancing their lipophilicity. This can be achieved by the introduction of some acyl groups derived from fatty acids via esterification of the aldose hydroxyl groups. With this purpose four new compounds were synthesized through a selective palmitoyl acylation of d-(-)-ribose and d-(+)-glucose and subsequent condensation with l-cysteine. In addition, the log P of the new compounds was calculated as a measure of the lipophilicity, and in vitro 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) tests were performed as a measure of the antioxidant capability.

Charge-reversal nanoemulsions: A systematic investigation of phosphorylated PEG-based surfactants

Surfactants bearing monophosphate esters with PEG of increasing chain length and different lipophilic tail structures were investigated to improve the effectiveness of enzyme triggered charge-converting nanoemulsions. The surfactants PEG-8-stearate, PEG-22-tocopheryl succinate (TPGS), PEG-3-oleate, PEG-9-oleate and PEG-9-lauryl ether were phosphorylated and incorporated in a self-emulsifying drug delivery system (SEDDS) exhibiting a defined PEG corona. To provide a positive zeta potential increasing amounts of the cationic surfactant benzalkonium chloride (BA) were incorporated. The effect of these PEG monophosphate esters (P-PEG-surfactants) was evaluated based on enzyme induced phosphate release and change in zeta potential. Significant enzyme induced charge conversion was observed for all P-PEG-surfactants, showing shifts from Δ3 mV to Δ31 mV. Surfactants comprising the shortest and longest PEG chain showed similar amplitudes (P-PEG-3-oleate: Δ11.9 mV; P-PEG-22-TPGS Δ10.2 mV), whereas P-PEG-8-stearate, P-PEG-9-oleate and P-PEG-9-lauryl ether bearing similarly long PEG chains but different lipophilic tail structures resulted in pronounced differences in amplitudes of Δ10.3 mV, Δ14.5 mV and Δ18.1 mV, respectively. Furthermore, an indirect correlation between the lipophilicity of P-PEG-surfactants and the obtained charge-reversing effect was observed. With the exception of P-PEG-lauryl ether, this charge-reversal effect decreased with increasing BA concentrations. In conclusion, the enzyme induced amplitude of charge conversion of P-PEG-surfactants depends to a high extent on their lipophilic tail structure. Based on this knowledge potent charge-reversal nanoemulsions can be designed.

Assessment of the Anti-Malarial Properties of Dihydroartemisinin- Piperaquine Phosphate Solid Lipid-Based Tablets

BACKGROUND

Artemisininbased combination therapies (ACTs) typified by dihydroartemisinin- piperaquine phosphate are first-line drugs used in the treatment of Plasmodium falciparum malaria. However, the emergence of drug resistance to ACTs shows the necessity to develop novel sustained release treatments in order to ensure maximum bioavailability.

OBJECTIVES

To formulate dihydroartemisinin (DHA)-piperaquine phosphate (PQ) sustained release tablets based on solidified reverse micellar solutions (SRMS).

METHODS

The SRMS was prepared by fusion using varying ratios of Phospholipon® 90H and Softisan® 154 and characterised. The tablets were prepared by using an in-house made and validated mould. The formulations were tested for uniformity of weight, hardness, friability, softening time, erosion time and in vitro-in vivo dissolution rate. Antimalarial properties were studied using modified Peter's 4-days suppressive test in mice. One-way analysis of variance (ANOVA) was used in the analysis of results.

RESULTS

Smooth caplets, with average weight of 1300 ± 0.06 mg to 1312 ± 0.11 mg, drug content of 61 mg for DHA and t 450 mg for PQ. Tablet hardness ranged from 7.1 to 9.0 Kgf and softening time of 29.50 ± 1.90 min. Erosion time of 62.00 ± 2.58 to 152.00 ± 1.89 min were obtained for tablets formulated with Poloxamer 188 (Batches R2, S2 and T2) which significantly reduced the softening and erosion time (p < 0.05). In vitro release showed that the optimized formulations had a maximum release at 12 h. Formulations exhibited significantly higher parasitaemia clearance and in vivo absorption compared to marketed formulations at day 7 (p < 0.05).

CONCLUSION

DHA-PQ tablets based on SRMS were much easier and relatively cheaper to produce than compressed tablets. They also showed exceptionally better treatment of malaria owing to their sustained release properties and improved bioavailability and are recommended to Pharmaceutical companies for further studies.

Computational and Experimental Models of Type III Lipid-Based Formulations of Loratadine Containing Complex Nonionic Surfactants

Type III lipid-based formulations (LBFs) combine poorly water-soluble drugs with oils, surfactants, and cosolvents to deliver the drugs into the systemic circulation. However, the solubility of the drug can be influenced by the colloidal phases formed in the gastrointestinal tract as the formulation is dispersed and makes contact with bile and other materials present within the GI tract. Thus, an understanding of the phase behavior of LBFs in the gut is critical for designing efficient LBFs. Molecular dynamics (MD) simulation is a powerful tool for the study of colloidal systems. In this study, we modeled the internal structures of five type III LBFs of loratadine containing poly(ethylene oxide) nonionic surfactants polysorbate 80 and polyoxyl hydrogenated castor oil (Kolliphor RH40) using long-timescale MD simulations (0.4-1.7 μs). We also conducted experimental investigations (dilution of formulations with water) including commercial Claritin liquid softgel capsules. The simulations show that LBFs form continuous phase, water-swollen reverse micelles, and bicontinuous and phase-separated systems at different dilutions, which correlate with the experimental observations. This study supports the use of MD simulation as a predictive tool to determine the fate of LBFs composed of medium-chain lipids, polyethylene oxide surfactants, and polymers.

Study and Computational Modeling of Fatty Acid Effects on Drug Solubility in Lipid-Based Systems

Lipid-based systems have many advantages in formulation of poorly water-soluble drugs but issues of a limited solvent capacity are often encountered in development. One of the possible solubilization approaches of especially basic drugs could be the addition of fatty acids to oils but currently, a systematic study is lacking. Therefore, the present work investigated apparently neutral and basic drugs in medium chain triglycerides (MCT) alone and with added either caproic acid (C6), caprylic acid (C8), capric acid (C10) or oleic acid (C18:1) at different levels (5 - 20%, w/w). A miniaturized solubility assay was used together with X-ray diffraction to analyze the residual solid and finally, solubility data were modeled using the conductor-like screening model for real solvents (COSMO-RS). Some drug bases had an MCT solubility of only a few mg/ml or less but addition of fatty acids provided in some formulations exceptional drug loading of up to about 20% (w/w). The solubility changes were in general more pronounced the shorter the chain length was and the longest oleic acid even displayed a negative effect in mixtures of celecoxib and fenofibrate. The COSMO-RS prediction accuracy was highly specific for the given compounds with root mean square errors (RMSE) ranging from an excellent 0.07 to a highest value of 1.12. The latter was obtained with the strongest model base pimozide for which a new solid form was found in some samples. In conclusion, targeting specific molecular interactions with the solute combined with mechanistic modeling provides new tools to advance lipid-based drug delivery.

In Vitro Evaluation of a Solid Supersaturated Self Nanoemulsifying Drug Delivery System (Super-SNEDDS) of Aprepitant for Enhanced Solubility

Aprepitant (APR) belongs to Class II of the Biopharmaceutical Classification System (BCS) because of its low aqueous solubility. The objective of the current work is to develop self-nanoemulsifying drug delivery systems (SNEDDS) of APR to enhance its aqueous solubility. Preformulation studies involving screening of excipients for solubility and emulsification efficiency were carried out. Pseudo ternary phase diagrams were constructed with blends of oil (Imwitor^® 988), cosolvent (Transcutol^® P), and various surfactants (Kolliphor^® RH40, Kolliphor^® ELP, Kolliphor^® HS15). The prepared SNEDDS were characterized for droplet size and nanoemulsion stability after dilution. Supersaturated SNEDDS (super-SNEDDS) were prepared to increase the quantity of loaded APR into the formulations. HPMC, PVP, PVP/VA, and Soluplus^® were used as polymeric precipitation inhibitors (PPI). PPIs were added to the formulations at 5% and 10% by weight. The influence of the PPIs on drug precipitation was investigated. In vitro lipolysis test was carried out to simulate digestion of formulations in the gastrointestinal tract. Optimized super-SNEDDS were formulated into free-flowing granules by adsorption on the porous carriers such as Neusilin^® US2. In vitro dissolution studies of solid super-SNEDDS formulation revealed an increased dissolution rate of the drug due to enhanced solubility. Consequently, a formulation to improve the solubility and potentially bioavailability of the drug was developed.

Effects of Formulation and Manufacturing Process on Drug Release from Solid Self-emulsifying Drug Delivery Systems Prepared by High Shear Mixing

This study sought to investigate the influence of formulation and process factors of the high shear mixing (HSM) on the properties of solid self-emulsifying drug delivery systems (S-SEDDS) containing the model drug carvedilol (CAR). Firstly, liquid SEDDS (L-SEDDS) were prepared by mixing castor oil with different proportions of surfactant (Solutol or Kolliphor RH40) and cosolvent (Transcutol or PEG400). A miscible L-SEDDS with high drug solubility (124.3 mg/g) was selected and gave rise to 10% (m/m) CAR loaded-emulsion with reduced particle size. Then, a factorial experimental design involving five component's concentration and two process factors was used to study the solidification of the selected L-SEDDS by HSM. CAR content, diffractometric profile, and in vitro dissolution were determined. Morphological and flow analyses were also performed. Porous and spherical particles with mean sizes ranging from 160 to 210 µm were obtained. Particle size was not affected by any formulation factor studied. Powder flowability, in turn, was influenced by L-SEDDS and crospovidone concentration. CAR in vitro dissolution from S-SEDDS was significantly increased compared to the drug as supplied and was equal (pH 1.2) or lower (pH 6.8) than that determined for L-SEDDS. Colloidal silicon dioxide decreased drug dissolution, whereas an increase in water-soluble diluent lactose and L-SEDDS concentration increased CAR dissolution. The proper selection of liquid and solid constituents proved to be crucial to developing an S-SEDDS by HSM. Indeed, the results obtained here using experimental design contribute to the production of S-SEDDS using an industrially viable process.

Lipid-based emulsion drug delivery systems - a comprehensive review

Lipid-based emulsion system - a subcategory of emulsion technology, has emerged as an enticing option to improve the solubility of the steadily rising water-insoluble candidates. Along with enhancing solubility, additional advantages such as improvement in permeability, protection against pre-systemic metabolism, ease of manufacturing, and easy to scale-up have made lipid-based emulsion technology very popular among academicians and manufacturers. The present article provides a comprehensive review regarding various critical properties of lipid-based emulsion systems, such as microemulsion, nanoemulsion, SMEDDS (self microemulsifying drug delivery system), and SNEDDS (self nanoemulsifying drug delivery system). The present article also explains in detail the similarities and differences between them, the stabilization mechanism, methods of preparation, excipients used to prepare them, and evaluation techniques. Subtle differences between nearly related terminologies such as microemulsion and nanoemulsion, SMEDDS, and SNEDDS are also explained in detail to clarify the basic differences. The present article also gives in-depth information regarding the chemical structure of various lipidic excipients, various possible chemical modifications to modify their inherent properties, and their regulatory status for rational selection.

Lipid-Based Drug Delivery Systems in Regenerative Medicine

The most important goal of regenerative medicine is to repair, restore, and regenerate tissues and organs that have been damaged as a result of an injury, congenital defect or disease, as well as reversing the aging process of the body by utilizing its natural healing potential. Regenerative medicine utilizes products of cell therapy, as well as biomedical or tissue engineering, and is a huge field for development. In regenerative medicine, stem cells and growth factor are mainly used; thus, innovative drug delivery technologies are being studied for improved delivery. Drug delivery systems offer the protection of therapeutic proteins and peptides against proteolytic degradation where controlled delivery is achievable. Similarly, the delivery systems in combination with stem cells offer improvement of cell survival, differentiation, and engraftment. The present review summarizes the significance of biomaterials in tissue engineering and the importance of colloidal drug delivery systems in providing cells with a local environment that enables them to proliferate and differentiate efficiently, resulting in successful tissue regeneration.

Lipophilic Salts and Lipid-Based Formulations for Bridging the Food Effect Gap of Venetoclax

Lipid based formulations (LBF) have shown to overcome food dependent bioavailability for some poorly water-soluble drugs. However, the utility of LBFs can be limited by low dose loading due to a low drug solubility in LBF vehicles. This study investigated the solubility and drug loading increases in LBFs using lipophilic counterions to form lipophilic salts of venetoclax. Venetoclax docusate was formed from venetoclax free base and verified by ¹H NMR. Formation of stable venetoclax-fatty acid associations with either oleic acid or decanoic acid were attempted, however, the molecular associations were less consistent based on ¹H NMR. Venetoclax docusate displayed a up to 6.2-fold higher solubility in self-emulsifying drug delivery systems (SEDDS) when compared to the venetoclax free base solubility resulting in a higher dose loading. A subsequent bioavailability study in landrace pigs demonstrated a 2.5-fold higher bioavailability for the lipophilic salt containing long chain SEDDS compared to the commercially available solid dispersion Venclyxto® in the fasted state. The bioavailability of all lipophilic salt SEDDS in the fasted state was similar to Venclyxto® in the fed state. This study confirmed that lipophilic drug salts increase the dose loading in LBFs and showed that lipophilic salt-SEDDS combinations may be able to overcome bioavailability limitations of drugs with low inherent dose loading in lipid vehicles. Furthermore, the present study demonstrated the utility of a LBF approach, in combination with lipophilic salts, to overcome food dependent variable oral bioavailability of drugs.

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.

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

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

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.

Predicting the API partitioning between lipid-based drug delivery systems and water

Partitioning tests in water are early-stage standard experiments during the development of pharmaceutical formulations, e.g. of lipid-based drug delivery system (LBDDS). The partitioning behavior of the active pharmaceutical ingredient (API) between the fatty phase and the aqueous phase is a key property, which is supposed to be determined by those tests. In this work, we investigated the API partitioning between LBDDS and water by in-silico predictions applying the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) and validated these predictions experimentally. The API partitioning was investigated for LBDDS comprising up to four components (cinnarizine or ibuprofen with tricaprylin, caprylic acid, and ethanol). The influence of LBDDS/water mixing ratios from 1/1 up to 1/200 (w/w) as well as the influence of excipients on the API partitioning was studied. Moreover, possible API crystallization upon mixing the LBDDS with water was predicted. This work showed that PC-SAFT is a strong tool for predicting the API partitioning behavior during in-vitro tests. Thus, it allows rapidly assessing whether or not a specific LBDDS might be a promising candidate for further in-vitro tests and identifying the API load up to which API crystallization can be avoided.

Improvement of lipid solubility and oral bioavailability of a poorly water- and poorly lipid-soluble drug, rebamipide, by utilizing its counter ion and SNEDDS preparation

Among drugs in development and/or in market, there are poorly water-soluble and poorly lipid-soluble compounds. Rebamipide, classified into BCS class IV, is one of those drugs which provide very low bioavailability and/or the difficulty of formulation for oral administration. Because of its low solubility in available lipoidal excipients, it was impossible to prepare an adequate SNEDDS formulation of rebamipide. Then, we tried to increase the solubility of rebamipide in lipoidal excipients for preparing a more practical SNEDDS formulation by making the complex with its counter ion, tetrabutylphosphonium hydroxide (TBPOH) or NaOH. Rebamipide concentration in ethanol was proportionally increased with the increment of TBPOH or NaOH added, indicating that the formation of complex with a counter ion should contribute to the solubilization of rebamipide in ethanol. Both Rebamipide-TBPOH complex (Reb-TBPOH) and Rebamipide-NaOH complex (Reb-NaOH) obtained by lyophilization showed no endothermic peak in DSC and no diffraction peak in XRPD, suggesting that the solid state of both complexes should be amorphous. Reb-TBPOH maintained the dissolution of rebamipide in SNEDDS vehicle (Capryol 90:Cremophor EL:Transcutol P = 4:3:3) at 20 mg/g at least for 28 days, while Reb-NaOH did it at 10 mg/g. In vitro dissolution study showed that Reb-TBPOH SNEDDS and Reb-NaOH SNEDDS containing rebamipide at 10 mg/g maintained the complete dissolution of rebamipide in FaSSIF (intestinal luminal condition). In the gastric luminal condition (pH3.9 acetate buffer), the high concentration, close to the complete dissolution, was transiently observed and quickly decreased to one-sixth of the maximum, but it was still around 70 times higher than that of the crystalline powder. The additional utilization of Eudragit EPO for SNEDDS preparations of both complexes successfully maintained the high concentrations of rebamipide in the gastric luminal condition. In vivo oral absorption studies clearly indicated that SNEDDS preparations utilizing Reb-counter ion complex successfully improved rebamipide absorption.

In-Silico Screening of Lipid-Based Drug Delivery Systems

PURPOSE

This work proposes an in-silico screening method for identifying promising formulation candidates in complex lipid-based drug delivery systems (LBDDS).

METHOD

The approach is based on a minimum amount of experimental data for API solubilites in single excipients. Intermolecular interactions between APIs and excipients as well as between different excipients were accounted for by the Perturbed-Chain Statistical Associating Fluid Theory. The approach was applied to the in-silico screening of lipid-based formulations for ten model APIs (fenofibrate, ibuprofen, praziquantel, carbamazepine, cinnarizine, felodipine, naproxen, indomethacin, griseofulvin and glibenclamide) in mixtures of up to three out of nine excipients (tricaprylin, Capmul MCM, caprylic acid, Capryol™ 90, Lauroglycol™ FCC, Kolliphor TPGS, polyethylene glycol, carbitol and ethanol).

RESULTS

For eight out of the ten investigated model APIs, the solubilities in the final formulations could be enhanced by up to 100 times compared to the solubility in pure tricaprylin. Fenofibrate, ibuprofen, praziquantel, carbamazepine are recommended as type I formulations, whereas cinnarizine and felodipine showed a distinctive solubility gain in type II formulations. Increased solubility was found for naproxen and indomethacin in type IIIb and type IV formulations. The solubility of griseofulvin and glibenclamide could be slightly enhanced in type IIIb formulations. The experimental validation agreed very well with the screening results.

CONCLUSION

The API solubility individually depends on the choice of excipients. The proposed in-silico-screening approach allows formulators to quickly determine most-appropriate types of lipid-based formulations for a given API with low experimental effort. Graphical abstract.

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

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

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

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

Dual Formulation and Interaction Strategies to Enhance the Oral Bioavailability of Paclitaxel

A self-microemulsifying drug delivery system (SMEDDS) was developed to enhance Paclitaxel (PTX) solubility and membrane permeability, thus improve its bioavailability. Pre-formulation studies were performed to optimize PTX-SMEDDS formulation. Then, in vitro characteristics of the formulation were determined and PTX oral absorption was investigated in rabbits. The optimized PTX-SMEDDS showed emulsification time of 31 ± 4 s, droplet size of 19.4 ± 0.5 nm, poly-dispersibility index of 0.35 ± 0.08, percentage transmittance after dilution of 99 ± 0.02%, zeta potential of 36.82 ± 1.8 mv, cloud point of 78 ± 0.5 °C and infinite dilution capability. The formulation maintained its physical and chemical stability during storage at 4 °C for three months. Oral administration of 10 mg/kg of 1.5% w/w PTX-loaded SMEDDS to rabbits increased PTX bioavailability by 4.5 fold in comparison to untreated PTX suspension. While when the rabbits received 1.5% w/w PTX-loaded SMEDDS after pretreated with 1 dose and 2 doses of cyclosporine A, PTX bioavailability increased by 4.4 and 7.8 fold, respectively. This indicates that the combined effect of the SMEDDS formulation in addition to pretreatment with P-gp and CYP3A4 inhibitor, can improve the oral bioavailability of poorly soluble and poorly permeable drugs such as PTX in rabbits.

Supersaturated Lipid-Based Formulations to Enhance the Oral Bioavailability of Venetoclax

Increasing numbers of beyond Rule-of-Five drugs are emerging from discovery pipelines, generating a need for bio-enabling formulation approaches, such as lipid-based formulations (LBF), to ensure maximal in vivo exposure. However, many drug candidates display insufficient lipid solubility, leading to dose-loading limitations in LBFs. The aim of this study was to explore the potential of supersaturated LBFs (sLBF) for the beyond Rule-of-Five drug venetoclax. Temperature-induced sLBFs of venetoclax were obtained in olive oil, Captex^® 1000, Peceol^® and Capmul MCM^®, respectively. A Peceol^®-based sLBF displayed the highest drug loading and was therefore evaluated further. In vitro lipolysis demonstrated that the Peceol^®-based sLBF was able to generate higher venetoclax concentrations in the aqueous phase compared to a Peceol^®-based suspension and an aqueous suspension. A subsequent bioavailability study in pigs demonstrated for sLBF a 3.8-fold and 2.1-fold higher bioavailability compared to the drug powder and Peceol^®-based suspension, respectively. In conclusion, sLBF is a promising bio-enabling formulation approach to enhance in vivo exposure of beyond Rule-of-Five drugs, such as venetoclax. The in vitro lipolysis results correctly predicted a higher exposure of the sLBF in vivo. The findings of this study are of particular relevance to pre-clinical drug development, where maximum exposure is required.

Quality by Design Approach for the Development of Self-Emulsifying Systems for Oral Delivery of Febuxostat: Pharmacokinetic and Pharmacodynamic Evaluation

The goal of the present investigation is to formulate febuxostat (FXT) self-nanoemulsifying delivery systems (liquid SNEDDS, solid SNEDDS, and pellet) to ameliorate the solubility and bioavailability. To determine the self-nanoemulsifying region, ternary plot was constructed utilizing Capmul MCM C8 NF® as an oil phase, Labrasol® as principal surfactant, and Transcutol HP® being the co-surfactant. Liquid SNEDDS (L-SNEDDS) were characterized by evaluating droplet size, zeta potential, % transmission, and for thermodynamic stability. In vitro dissolution study of FXT loaded L-SNEDDS (batch F7) showed increased dissolution (about 48.54 ± 0.43% in 0.1 N HCl while 86.44 ± 0.16% in phosphate buffer pH 7.4 within 30 min) compared to plain drug (19.65 ± 2.95% in 0.1 N HCl while about 17.61 ± 2.63% in phosphate buffer pH 7.4 within 30 min). Single pass intestinal permeability studies revealed fourfold increase in the intestinal permeability of F7 compared to plain drug. So, for commercial aspects, F7 was further transformed into solid SNEDDS (S-SNEDDS) as readily nanoemulsifying powder form (SNEP) as well as pellets prepared by application of extruder spheronizer. The developed formulation was found superior to pure FXT with enhanced oral bioavailability and anti-gout activity (with reduced uric acid levels), signifying a lipidic system being an efficacious substitute for gout treatment.

Application of SRMS 154 as Sustained Release Matrix for the Delivery of Stavudine: In vitro and in vivo Evaluation and Effect of Poloxamer 188 on the Properties of the Tablets

BACKGROUND

Stavudine is an antiretroviral therapy with so many side effects and has a short half-life of 1.5 h. It degrades to thymine under hydrolytic, oxidative and photolytic conditions hence has major formulation challenges.

OBJECTIVES

To formulate sustained release lipid based stavudine and to study the properties of the formulations by in vitro and in vivo methods.

METHODS

Stavudine tablets were formulated by moulding using validated tablets moulds. The carrier used were solidified reverse micellar solution (SRMS) made up of varying ratios of hydrogenated palm oil and Phospholipid admixtures. Evaluation tests were carried out on the tablets using both Pharmacopoeial and non Pharmacopoeial test. Drug release was studied in both simulated gastric fluid (SGF, pH 1.2) and simulated intestinal fluid (SIF, pH 7.2). In vivo release was studied using Wistar rats.

RESULTS

The results showed that stavudine tablets exhibited weight range of 372 ± 0.14 to 386 ± 0.52 mg, friability ranged from 0.00 to 0.13 % and hardness ranged from 4.27 ± 0.25 to 5.30 ± 0.21 Kgf. Tablets formulated with SRMS 1:2 had erosion time range of 60.80 ± 1.23 to 87.90 ± 2.33 min and was affected significantly by the presence of Poloxamer 188 (p < 0.05). The formulations exhibited T100 % at 10 to13 h in SIF. Stavudine tablets showed the area under the curve (AUC) of 854.0 μg/h/ml, significantly higher than the AUC of the reference (p < 0.05).

CONCLUSION

Stavudine SRMS-based tablets had good stability and sustained release properties. Formulations containing 1 % Poloxamer 188 exhibited enhanced in vivo absorption and hence could be used once daily in order to enhance the bioavailability of this drug.

Drug supersaturation during formulation digestion, including real-time analytical approaches

Self-emulsifying and other lipid-based drug delivery systems have drawn considerable interest from pharmaceutical scientists for managing oral delivery of poorly water-soluble compounds. Following administration, self-emulsifying systems exhibit complex aqueous dispersion and digestion in the gastro-intestinal tract. These processes generally result in drug supersaturation, which leads to enhanced absorption or the high drug concentrations may cause precipitation with erratic and variable oral bioavailability. This review briefly outlines drug supersaturation obtained from self-emulsifying and other lipid-based formulations; recent advancements of in vitro lipolysis testing are also discussed. Further, a main focus is mechanisms by which supersaturation is triggered from gastro-intestinal processes, as well as analytical techniques that are promising from a research and development perspective. Comparatively simple approaches are presented together with more sophisticated process analytics to enable direct examination of kinetic changes. The analytical methods together with their sensor probes are discussed in detail to clarify opportunities as well as technical limitations. Some of the more sophisticated methods, including those based on synchrotron radiation, are primarily research oriented despite interesting experimental findings from an industrial viewpoint. The availability of kinetic data further opens the door to mathematical modeling of supersaturation and precipitation versus permeation, which lays the groundwork for better in vitro to in vivo correlations as well as for physiologically-based modeling of lipid-based systems.

New Insights into Using Lipid Based Suspensions for 'Brick Dust' Molecules: Case Study of Nilotinib

PURPOSE

Lipid suspensions have been shown to be a suitable bio-enabling formulation approach for highly lipophilic or 'grease ball' drug molecules, but studies on 'brick dust' drugs are lacking. This study explored the utility of lipid suspensions for enhancing oral bioavailability of the rather hydrophobic drug nilotinib in vivo in rats.

METHODS

Four lipid suspensions were developed containing long chain triglycerides, medium chain triglyceride, long chain monoglycerides and medium chain monoglycerides and in vivo bioavailability was compared to an aqueous suspension. Additionally, in vitro lipolysis and wettability tests were conducted.

RESULTS

Nilotinib lipid suspensions did not show a bioavailability increase compared to an aqueous suspension. The bioavailability was lower for triglyceride suspensions, relative to both monoglyceride and an aqueous suspension. The long chain monoglyceride displayed a significantly higher bioavailability relative to triglycerides. In vitro lipolysis results suggested entrapment of nilotinib crystals within poorly dispersible triglycerides, leading to slower nilotinib release and absorption. This was further supported by higher wettability of nilotinib by lipids.

CONCLUSION

Monoglycerides improved oral bioavailability of nilotinib in rats, relative to triglycerides. For 'brick dust' drugs formulated as lipid suspensions, poorly dispersible formulations may delay the release of drug crystals from the formulation leading to reduced absorption. Graphical Abstract An aqueous and four lipid suspensions have been evaluated in in vitro and in vivo to gain insights into the potential benefits and limitations of lipid suspensions.