Oral lipid-based formulations

Nutraceutically-enhanced oral delivery of vitamin D3 via Bio-SNEDDS: Demonstrating in vivo superiority over pediatric formulations

BACKGROUND

Vitamin D3 (VD3) deficiency among children in Saudi Arabia remains a pressing concern due to its poor bioavailability and the limitations of current pediatric formulations. To address this challenge, we developed a groundbreaking pediatric self-nanoemulsifying drug delivery system (Bio-SNEDDS) for VD3, fortified with black seed oil and moringa seed oil for dual therapeutic benefits. Through meticulous formulation optimization using ternary phase diagrams and comprehensive testing, our Bio-SNEDDS demonstrated exceptional performance.

METHODS

Bio-SNEDDS were manufactured by incorporating Black seed oil and moringa seed oil as bioactive nutraceutical excipients along with various cosurfactant and surfactants. Bio-SNEDDS were systematically optimized through ternary phase diagrams, visual tests, droplet size analysis, drug solubilization studies, dispersion assessments, and pharmacokinetic testing in rats compared to Vi-De 3®.

RESULTS

Pseudoternary phase diagrams identified oil blends producing large nanoemulsion regions optimal for SNEDDS formation. The optimized F1 Bio-SNEDDS showed a mean droplet diameter of 33.7 nm, solubilized 154.46 mg/g VD3 with no metabolite formation, and maintained >88% VD3 in solution during 24 h dispersion testing. Notably, in vivo pharmacokinetic evaluation at a high VD3 dose demonstrated an approximately two-fold greater relative bioavailability over Vi-De 3®, validating the superb oral delivery performance of Bio-SNEDDS even under challenging high-dose conditions.

CONCLUSIONS

The Bio-SNEDDS provides an effective VD3 delivery strategy with established in vivo superiority over marketed products, along with offering additional health benefits from the natural oils.

Enhanced Stability and Improved Oral Absorption of Enzalutamide with Self-Nanoemulsifying Drug Delivery System

The purpose of this study is to develop and evaluate a self-nanoemulsifying drug delivery system (SNEDDS) to improve the oral absorption of poorly water-soluble enzalutamide (ENZ). Considering the rapid recrystallization of the drug, based on solubility and crystallization tests in various oils, surfactants and co-surfactants, Labrafac PG 10%, Solutol HS15 80%, and Transcutol P 10%, which showed the most stable particle size and polydispersity index (PDI) without drug precipitation, were selected as the optimal SNEDDS formulation. The optimized SNEDDS formulation showed excellent dissolution profiles for all the drugs released at 10 min of dissolution due to the increased surface area with a small particle size of approximately 16 nm. Additionally, it was confirmed to be stable without significant differences in physical and chemical properties for 6 months under accelerated conditions (40 ± 2 °C, 75 ± 5% RH) and stressed conditions (60 ± 2 °C). Associated with the high dissolutions of ENZ, pharmacokinetic parameters were also greatly improved. Specifically, the AUC was 1.9 times higher and the Cmax was 1.8 times higher than those of commercial products (Xtandi® soft capsule), resulting in improved oral absorption. Taken together with the results mentioned above, the SNEDDS could be an effective tool as a formulation for ENZ and other similar drugs.

Unveiling polyamorphism and polyamorphic interconversions in pharmaceuticals: the peculiar case of hydrochlorothiazide

Polyamorphism has been a controversial and highly debated solid-state phenomenon in both material and pharmaceutical communities. Although some evidence of this fascinating phenomenon has been reported for several inorganic systems, and more recently also for a few organic compounds, the occurrence of polyamorphism is poorly understood and the molecular-level organization of polyamorphic forms is still unknown. Here we have investigated the occurrence of polyamorphism and polyamorphic interconversions in hydrochlorothiazide (HCT), using both experimental and computational methods. Three distinct HCT polyamorphs, presenting distinct physical and thermal stabilities as well as distinct relaxation properties, were systematically prepared using spray-drying (SD), quench-cooling (QC) and ball milling (BM) methods. HCT polyamorph II (obtained by QC) was found to be more physically stable than polyamorphs I and III (obtained by SD and BM, respectively). Furthermore, polyamorphs I and III could be converted into polyamorph II after QC, while polyamorph II did not convert to any other polyamorph after SD or BM. Molecular dynamics simulations show that HCT dihedral angle distributions are significantly different for polyamorphs I and II, which is postulated as a possible explanation for their different physicochemical properties.

Evaluating human milk as a drug delivery vehicle for clofazimine to premature infants

Human milk is proposed as a drug delivery vehicle suitable for use in neonatal patients. Clofazimine, traditionally used for the treatment of leprosy and tuberculosis, is emerging as a treatment for cryptosporidiosis in infants, however its poor aqueous solubility has led to its commercial formulation as a waxy lipid formulation in a capsule, a format that is not suitable for infants. In this study, the evaluation of pasteurised human milk for the delivery of clofazimine was investigated using an in vitro lipolysis model to simulate gastric and intestinal digestion. The total lipid composition of the human milk was characterised alongside the liberated fatty acid species following digestion for comparison to alternative lipid-based delivery systems. Small-angle X-ray scattering was used to measure the presence of crystalline clofazimine during digestion and hence the extent of drug solubilisation. High-performance liquid chromatography was used to quantify the mass of clofazimine solubilised per gram of human milk fat (drug-to-fat ratio) in digested and undigested human milk. The digestion process was essential for the solubilisation of clofazimine, with digested human milk solubilising a sufficient dose of clofazimine for treatment of a premature infant. Human milk solubilised the clofazimine to a greater extent than bovine milk and infant formula during digestion, most likely as a result of differing lipid composition and increased long-chain fatty acid concentrations. These findings show that human milk enhances the solubility of clofazimine as a model drug and may be a suitable drug delivery vehicle for infant populations requiring therapeutic treatment.

Wet granulation of co-amorphous indomethacin systems

The feasibility of co-amorphous systems to be wet granulated together with microcrystalline cellulose (MCC) was investigated. Solid state and molecular interactions were analysed for various co-amorphous drug-amino acid formulations of indomethacin with tryptophan and arginine, respectively, via XRPD, DSC and FTIR. The co-amorphous binary systems were produced by ball-milling for 90 min at different molar ratios followed by wet granulation with MCC and water in a miniaturised scale. Tryptophan containing systems showed crystalline reflections in their XRPD diffractograms and endothermal events in their DSC analyses, and were therefore excluded from upscaling attempts. The systems containing arginine were found to be remain amorphous for at least ten months and were upscaled for production in a high-shear blender under application of two different parameter settings. Under the harsher instrument settings, a composition with a low MCC ratio experienced recrystallisation during wet granulation, while all other compositions could be successfully processed via wet granulation and stayed stable for a storage period of at least twelve weeks, indicating that wet granulation of co-amorphous systems can be feasible.

Dissolution changes in drug-amino acid/biotin co-amorphous systems: Decreased/increased dissolution during storage without recrystallization

Co-amorphous systems have been proven to be a promising strategy to address the poor water solubility of poorly water-soluble drugs. Generally, the initial dissolution behaviors after co-amorphous system preparation and the potential recrystallization during storage are used to evaluate the performance of co-amorphous systems. However, this study reveals that decreased dissolution and unexpected increased dissolution were observed during storage though the co-amorphous systems maintained amorphous form. Three drugs (valsartan, tadalafil, mebendazole) and three co-formers (arginine, tryptophan, biotin) were used to prepare co-amorphous systems and the samples were stored for different times. After stored for 80 d, most of the co-amorphous systems maintained amorphous form, however, decreased and increased intrinsic dissolution rates (IDRs) were both observed in these non-recrystallized co-amorphous systems. The moisture changes of the systems during storage and the possible drug-co-former molecular interactions showed no effect on the dissolution changes, while phase separation might play a role in it. In conclusion, more attention should be paid to the dissolution changes of co-amorphous systems during storage. Focusing on the initial dissolution behaviors after sample preparation and the physical recrystallization during storage is not enough for the development of co-amorphous systems in future.

Optimization of a Self-microemulsifying Drug Delivery System for Oral Administration of the Lipophilic Drug, Resveratrol: Enhanced Intestinal Permeability in Rat

Purpose

This study aimed to formulate Resveratrol, a practically water-insoluble antioxidant in a self-microemulsifying drug delivery system (SMEDDS) to improve the solubility, release rate, and intestinal permeability of the drug.

Methods

The suitable oil, surfactant, and co-surfactant were chosen according to the drug solubility study. Utilizing the design of experiment (DoE) method, the pseudo-ternary phase diagram was plotted based on the droplet size. In vitro dissolution study and the single-pass intestinal perfusion were performed for the investigation of in vitro and in-situ permeability for drugs formulated as SMEDDS in rat intestine using High-Performance Liquid Chromatography.

Results

Castor oil, Cremophor® RH60, and PEG 1500 were selected as oil, surfactant, and co-surfactant. According to the pseudo-ternary phase diagram, nine formulations developed microemulsions with sizes ranging between 145-967 nm. Formulations passed the centrifuge and freeze-thaw stability tests. The optimum formulation possessed an almost 2.5-fold higher cumulative percentage of in vitro released resveratrol, in comparison to resveratrol aqueous suspension within 120 minutes. The results of the in-situ permeability study suggested a 2.6-fold higher intestinal permeability for optimum formulation than that of the resveratrol suspension.

Conclusion

SMEDDS can be considered suitable for the oral delivery of resveratrol according to the observed increased intestinal permeability, which could consequently enhance the bioavailability and therapeutic efficacy of the drug.

Study of kaempferol in the treatment of COVID-19 combined with Chikungunya co-infection by network pharmacology and molecular docking technology

Chikungunya (CHIK) patients may be vulnerable to coronavirus disease (COVID-19). However, presently there are no anti-COVID-19/CHIK therapeutic alternatives available. The purpose of this research was to determine the pharmacological mechanism through which kaempferol functions in the treatment of COVID-19-associated CHIK co-infection. We have used a series of network pharmacology and computational analysis-based techniques to decipher and define the binding capacity, biological functions, pharmacological targets, and treatment processes in COVID-19-mediated CHIK co-infection. We identified key therapeutic targets for COVID-19/CHIK, including TP53, MAPK1, MAPK3, MAPK8, TNF, IL6 and NFKB1. Gene ontology, molecular and upstream pathway analysis of kaempferol against COVID-19 and CHIK showed that DEGs were confined mainly to the cytokine-mediated signalling pathway, MAP kinase activity, negative regulation of the apoptotic process, lipid and atherosclerosis, TNF signalling pathway, hepatitis B, toll-like receptor signaling, IL-17 and IL-18 signaling pathways. The study of the gene regulatory network revealed several significant TFs including KLF16, GATA2, YY1 and FOXC1 and miRNAs such as let-7b-5p, mir-16-5p, mir-34a-5p, and mir-155-5p that target differential-expressed genes (DEG). According to the molecular coupling results, kaempferol exhibited a high affinity for 5 receptor proteins (TP53, MAPK1, MAPK3, MAPK8, and TNF) compared to control inhibitors. In combination, our results identified significant targets and pharmacological mechanisms of kaempferol in the treatment of COVID-19/CHIK and recommended that core targets be used as potential biomarkers against COVID-19/CHIK viruses. Before conducting clinical studies for the intervention of COVID-19 and CHIK, kaempferol might be evaluated in wet lab tests at the molecular level.

Oral lipid-based formulations alter delivery of cannabidiol to different anatomical regions in the brain

Delivery to the brain is a challenging task due to its protection by the blood-brain barrier (BBB). Lipids and fatty acids are reported to affect the permeability of the BBB, although this has not been reported following oral administration. Cannabidiol (CBD) has high therapeutic potential in the brain, therefore, this work investigated CBD delivery to anatomical brain regions following oral administration in lipid-based and lipid-free vehicles. All formulations resulted in a short brain T_max (1 h) and brain-plasma ratios ≥ 3.5, with retention up to 18 h post administration. The highest CBD delivery was observed in the olfactory bulb and striatum, and the medulla pons and cerebellum the lowest. The lipid-free vehicle led to the highest levels of CBD in the whole brain. However, when each anatomical region was assessed individually, the long chain triglyceride-rich rapeseed oil formulation commonly showed optimal performance. The medium chain triglyceride-rich coconut oil formulation did not result in the highest CBD concentration in any brain region. Overall, differences in CBD delivery to the whole brain and various brain regions were observed following administration in different formulations, indicating that the oral formulation selection may be important for optimal delivery to specific regions of the brain.

Poly (amino acid)s as new co-formers in amorphous solid dispersion

The drug-amino acid co-amorphous systems and amorphous solid dispersions (ASDs) are promising methods to address the poor water solubility of poorly water-soluble drugs. However, some amino acids might not be perfect co-formers for co-amorphous systems, and the relatively low drug-loading of many ASDs is one of the main disadvantages of ASDs. Thus, poly-l-lysine and polyglutamic acid were selected as the co-formers, ball milled with basic mebendazole, neutral tadalafil and acidic valsartan at different weight ratios (from 3:1 to 1:3) to prepare poly (amino acid)-based ASDs, aiming to combine the advantages of co-amorphous systems (high drug-loading) and ASDs (relatively high T_g and high physical stability). All the mixtures were converted into amorphous after milling. The powder dissolution studies showed that drug-poly (amino acid) ASDs improved the dissolution rate of the drug in different ways and to different degrees. Moreover, the two poly (amino acid)s enhanced the physical stability of amorphous drugs. It is worthy to mention that the salt formation between the drug and the poly (amino acid) does not necessarily mean better performance compared to non-salt forming systems, and salt formation is also not a prerequisite for the formation of promising drug-poly (amino acid) ASDs.

Characterizing the Impact of Chitosan on the Nucleation and Crystal Growth of Ritonavir from Supersaturated Solutions

The addition of polymeric materials is often used to delay nucleation or crystal growth and maintain the high supersaturation of amorphous drugs. Therefore, this study aimed to investigate the impact of chitosan on the supersaturation behavior of drugs with a low recrystallization tendency and elucidate the mechanism of its crystallization inhibition in an aqueous solution. It was carried out using ritonavir (RTV) as a model of poorly water-soluble drugs categorized as class III of Taylor's classification, while chitosan was used as a polymer, and hypromellose (HPMC) was used for comparison. The inhibition of the nucleation and crystal growth of RTV by chitosan was examined by measuring the induction time. The interactions of RTV with chitosan and HPMC were evaluated by NMR measurements, FT-IR, and an in silico analysis. The results showed that the solubilities of amorphous RTV with and without HPMC were quite similar, while the amorphous solubility was significantly increased by the chitosan addition due to the solubilization effect. In the absence of the polymer, RTV started to precipitate after 30 min, indicating that it is a slow crystallizer. Chitosan and HPMC effectively inhibited the nucleation of RTV, as reflected by a 48-64-fold enhancement in the induction time. Furthermore, NMR, FT-IR, and in silico analysis demonstrated that the hydrogen bond interaction between the amine group of RTV and a proton of chitosan, as well as the carbonyl group of RTV and a proton of HPMC, was observed. This indicated that the hydrogen bond interaction between RTV and chitosan as well as HPMC can contribute to the crystallization inhibition and maintenance of RTV in a supersaturated state. Therefore, the addition of chitosan can delay nucleation, which is crucial for stabilizing supersaturated drug solutions, specifically for a drug with a low crystallization tendency.

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.

Co-Crystallization Approach to Enhance the Stability of Moisture-Sensitive Drugs

Stability is an essential quality attribute of any pharmaceutical formulation. Poor stability can change the color and physical appearance of a drug, directly impacting the patient's perception. Unstable drug products may also face loss of active pharmaceutical ingredients (APIs) and degradation, making the medicine ineffective and toxic. Moisture content is known to be the leading cause of the degradation of nearly 50% of medicinal products, leading to impurities in solid dose formulations. The polarity of the atoms in an API and the surface chemistry of API particles majorly influence the affinity towards water molecules. Moisture induces chemical reactions, including free water that has also been identified as an important factor in determining drug product stability. Among the various approaches, crystal engineering and specifically co-crystals, have a proven ability to increase the stability of moisture-sensitive APIs. Other approaches, such as changing the salt form, can lead to solubility issues, thus making the co-crystal approach more suited to enhancing hygroscopic stability. There are many reported studies where co-crystals have exhibited reduced hygroscopicity compared to pure API, thereby improving the product's stability. In this review, the authors focus on recent updates and trends in these studies related to improving the hygroscopic stability of compounds, discuss the reasons behind the enhanced stability, and briefly discuss the screening of co-formers for moisture-sensitive drugs.

Gliclazide in Binary and Ternary Systems Improves Physicochemical Properties, Bioactivity, and Antioxidant Activity

The poor solubility of the antidiabetic drug gliclazide (Glc) is due to its hydrophobic nature. This research is aimed at improving Glc's solubility and drug release profile, as well as at investigating additional benefits such as bioactivity and antioxidant activity, by forming binary complexes with HPβCD at different w/w ratios (1 : 1, 1 : 2.5, 1 : 4, and 1 : 9) and ternary complexes with HPβCD and Tryp at 1 : 1 : 1, 1 : 1 : 0.27, 1 : 2.5 : 0.27, 1 : 3.6 : 3.6, 1 : 4 : 1, and 1 : 9 : 1, respectively. Complexes were prepared by the physical mixing (PM) and solvent evaporation (SE) methods. The prepared inclusion complexes were meticulously characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectra. To verify our findings, the inclusion complexes were evaluated by equilibrium solubility, in vitro drug release profile, kinetic models, and antidiabetic and antioxidant activities in animal models. Our results demonstrated that the solubility and drug release profile were found to be enhanced through binary as well as ternary complexes. Notably, ternary complexes with a ratio of 1 : 9 : 1 showed the highest solubility and drug release profile compared to all other preparations. Data on antioxidant activity indicated that the ternary complex had the higher total antioxidant status (TAS), superoxide dismutase (SOD), and catalase (CAT) activity than the binary complex and Glc alone, in contrast to the diabetic group. In vivo antidiabetic activity data revealed a high percentage reduction in the blood glucose level by ternary complexes (49-52%) compared to the binary complexes (45-46%; p ≤ 0.05). HPβCD and Tryp provide a new platform for overcoming the challenges associated with poorly soluble Glc by providing greater complexing and solubilizing capabilities and imparting ancillary benefits to improve the drug's antidiabetic and antioxidant activities.

The Impact of Water-Soluble Chitosan on the Inhibition of Crystal Nucleation of Alpha-Mangostin from Supersaturated Solutions

The use of an amorphous drugs system to generate supersaturated solutions is generally developed to improve the solubility and dissolution of poorly soluble drugs. This is because the drug in the supersaturation system has a high energy state with a tendency to precipitate. In the amorphous solid dispersion (ASD) formulation, it was discovered that polymer plays a critical role in inhibiting nucleation or crystal growth of the drugs. Therefore, this study aimed to evaluate the crystallization inhibition of water-soluble chitosan (WSC) on nucleation as well as crystal growth from alpha-mangostin (AM) and elucidate its inhibition mechanism in the supersaturated solutions. During the experiment, WSC was used as a polymer to evaluate its ability to inhibit AM nucleation. The interaction between WSC and AM was also estimated using FT-IR, NMR, and in silico study. The result showed that in the absence of polymer, the concentration of AM rapidly decreased due to the precipitation in one minute. Meanwhile, the addition of WSC effectively inhibited AM crystallization and maintained a supersaturated state for the long term. FT-IR measurement also revealed that the shift in the amine primer of WSC occurred because of the interaction between WSC and AM. In the 1H NMR spectra, the proton peaks of WSC showed an upfield shift with the presence of AM, indicating the intermolecular interactions between AM and WSC. Moreover, in silico study revealed the hydrogen bond interaction between the carbonyl group of AM with hydrocarbon groups of WSC. This indicated that WSC interacted with AM in the supersaturated solution and suppressed their molecular mobility, thereby inhibiting the formation of the crystal nucleus. Based on these results, it can be concluded that the interaction between drug polymers contributed to the maintenance of the drug supersaturation by inhibiting both nucleation and growth.

Nutritional Composition and Bioactive Compounds of Native Brazilian Fruits of the Arecaceae Family and Its Potential Applications for Health Promotion

The fruits from the Arecaceae family, although being rich in bioactive compounds with potential benefits to health, have been underexplored. Studies on their composition, bioactive compounds, and effects of their consumption on health are also scarce. This review presents the composition of macro- and micronutrients, and bioactive compounds of fruits of the Arecaceae family such as bacaba, patawa, juçara, açaí, buriti, buritirana, and butiá. The potential use and reported effects of its consumption on health are also presented. The knowledge of these underutilized fruits is important to encourage production, commercialization, processing, and consumption. It can also stimulate their full use and improve the economy and social condition of the population where these fruits are found. Furthermore, it may help in future research on the composition, health effects, and new product development. Arecaceae fruits presented in this review are currently used as raw materials for producing beverages, candies, jams, popsicles, ice creams, energy drinks, and edible oils. The reported studies show that they are rich in phenolic compounds, carotenoids, anthocyanins, tocopherols, minerals, vitamins, amino acids, and fatty acids. Moreover, the consumption of these compounds has been associated with anti-inflammatory, antiproliferative, antiobesity, and cardioprotective effects. These fruits have potential to be used in food, pharmaceutical, and cosmetic industries. Despite their potential, some of them, such as buritirana and butiá, have been little explored and limited research has been conducted on their composition, biological effects, and applications. Therefore, more detailed investigations on the composition and mechanism of action based on in vitro and/or in vivo studies are needed for fruits from the Arecaceae family.

Self-Emulsifying Formulations to Increase the Oral Bioavailability of 4,6,4′-Trimethylangelicin as a Possible Treatment for Cystic Fibrosis

4,6,4′-trimethylangelicin (TMA) is a promising pharmacological option for the treatment of cystic fibrosis (CF) due to its triple-acting behavior toward the function of the CF transmembrane conductance regulator. It is a poorly water-soluble drug, and thus it is a candidate for developing a self-emulsifying formulation (SEDDS). This study aimed to develop a SEDDS to improve the oral bioavailability of TMA. Excipients were selected on the basis of solubility studies. Polyoxyl-35 castor oil (Cremophor® EL) was proposed as surfactant, diethylene glycol-monoethyl ether (Transcutol® HP) as cosolvent, and a mixture of long-chainmono-,di-, and triglycerides (Maisine® CC) or medium-chain triglycerides (LabrafacTM lipophile) as oil phases. Different mixtures were prepared and characterized by measuring the emulsification time, drop size, and polydispersity index to identify the most promising formulation. Two formulations containing 50% surfactant (w/w), 40% cosolvent (w/w), and 10% oil (w/w) (Maisine® CC or LabrafacTM lipophile) were selected. The results showed that both formulations were able to self-emulsify, producing nanoemulsions with a drop size range of 20–25 nm, and in vivo pharmacokinetic studies demonstrated that they were able to significantly increase the oral bioavailability of TMA. In conclusion, SEEDS are useful tools to ameliorate the pharmacokinetic profile of TMA and could represent a strategy to improve the therapeutic management of CF.

β-Artemether and Lumefantrine Dual Drug Loaded Lipid Nanoparticles: Physicochemical Characterization, Pharmacokinetic Evaluation and Biodistribution Study

BACKGROUND

β-artemether (BAT) and lumefantrine (LFT) combination therapies are well recognized for the treatment of malaria. However, the current conventional formulations have several drawbacks.

OBJECTIVE

The study aims to develop novel lipid nanoparticles (LNP) for efficient delivery of BAT and LFT.

METHODS

The LNP were prepared by solvent injection method and optimized by the Box-Behnken experimental design to achieve the desired particle size, maximum entrapment efficiency (EE), and percentage drug release. BAT and LFT in rat plasma were estimated by liquid chromatographytandem mass spectrometry (LC-MS/MS).

RESULTS

Freeze-dried LNP comprised of 78.74% (w/w) lipid, 15.74% (w/w) surfactant, 3.93% (w/w) co-surfactant and 1.57% mannitol with respect to the total inactive components. Mean particle size and zeta potential were found to be 140.22 ± 1.36 nm and -35.23 mv, respectively. EE was 80.60 ± 3.85% for BAT and 69.64 ± 2.63% for LFT. The optimized formulation exhibited a biphasic release profile in phosphate buffer (pH 7.2). In vivo study revealed an increased bioavailability of BAT and LFT from dual drug loaded LNP compared to the pure drug solution. Moreover, the tissue distribution study confirmed the high uptake of both the drugs in the liver and spleen.

CONCLUSION

The study demonstrated the potential use of the developed formulation for oral administration in the treatment of malaria.

Mesoporous silica nanocarriers as drug delivery systems for anti-tubercular agents: a review

The treatment and management of tuberculosis using conventional drug delivery systems remain challenging due to the setbacks involved. The lengthy and costly treatment regime and patients' non-compliance have led to drug-resistant tuberculosis, which is more difficult to treat. Also, anti-tubercular drugs currently used are poor water-soluble drugs with low bioavailability and poor therapeutic efficiency except at higher doses which causes drug-related toxicity. Novel drug delivery carrier systems such as mesoporous silica nanoparticles (MSNs) have been identified as nanomedicines capable of addressing the challenges mentioned due to their biocompatibility. The review discusses the sol-gel synthesis and chemistry of MSNs as porous drug nanocarriers, surface functionalization techniques and the influence of their physico-chemical properties on drug solubility, loading and release kinetics. It outlines the physico-chemical characteristics of MSNs encapsulated with anti-tubercular drugs.

A fluorescent, chirality-responsive, and water-soluble cage as a multifunctional molecular container for drug delivery

In recent years, the rational design and construction of drug delivery systems (DDSs) via a supramolecular approach for improving chemical therapeutics have gained significant attention. Here, we report a host-guest DDS formed from a fluorescent, chirality-responsive, and water-soluble tetraphenylethene-based octacationic cage as a fluorescent/chiral probe, solubilizer, and molecular cargo, which can recognize chiral nucleoside drugs, enhance the solubility of insoluble drugs, and protect drugs from the outside environment by forming host-guest complexes in aqueous solution. Given the fluorescence properties and dynamically rotational conformation of tetraphenylethene (TPE) units, this fluorescent and chirality-responsive cage exhibits different responses including turn-on/turn-off fluorescence and negative/positive circular dichroism (CD) when binding with different chiral nucleoside drugs in water, resulting in multiple-responsive photophysical behaviors for these chiral drugs. Furthermore, this water-soluble cationic cage with a hydrophobic cavity can improve the water solubility of insoluble drugs (e.g., CPT) by forming host-guest complexes in water. More importantly, this multifunctional cage exhibits a low toxicity to both human colon and breast cancer cell lines in vitro, and drugs encapsulated by the cage are more effective in killing cancer cells than drugs alone. Finally, the on-off-on fluorescence responses in the formation and dissociation processes of the cage⊃drug complexes have been successfully used to monitor drug release and track drug delivery by fluorescence microscopy in vitro. Therefore, this fluorescent, chirality-responsive, and water-soluble cage as a multifunctional molecular container can be used to construct a smart drug delivery system with several functions of fluorescence and CD detection, water solubilization, real-time monitoring, and chemotherapy.

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

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

Bio-enabling strategies to mitigate the pharmaceutical food effect: a mini review

The concomitant administration of oral drugs with food can result in significant changes in bioavailability, leading to variable pharmacokinetics and considerable clinical implications, such as over- or under-dosing. Consequently, there is increasing demand for bio-enabling formulation strategies to reduce variability in exposure between the fasted and fed state and/or mitigate the pharmaceutical food effect. The current review critically evaluates technologies that have been implemented to overcome the positive food effects of pharmaceutical drugs, including, lipid-based formulations, nanosized drug preparations, cyclodextrins, amorphisation and solid dispersions, prodrugs and salts. Additionally, improved insight into preclinical models for predicting the food effect is provided. Despite the wealth of research, this review demonstrates that application of optimal formulation strategies to mitigate the positive food effects and the evaluation in preclinical models is not a universal approach, and improved standardisation of models to predict the food effects would be desirable. Ultimately, the successful reformulation of specific drugs to eliminate the food effect provides a panoply of advantages for patients with regard to clinical efficacy and compliance.

Pharmaceutical cocrystals of nomegestrol acetate with superior dissolution

The improvement of solubility and dissolution properties are the focus of research on poorly water-soluble APIs.

Nanostructured Lipid Carriers Can Enhance Oral Absorption of Khellin, a Natural Pleiotropic Molecule

A novel formulation based on nanostructured lipid carriers (NLCs) was developed to increase solubility and intestinal absorption of khellin. K-NLCs were prepared with stearic acid, hempseed oil, Brij S20, and Labrafil M 1944 CS, using the emulsification-ultrasonication method. Developed nanoparticles were chemically and physically characterized by liquid chromatography, light scattering techniques, and electron microscopy. The size, about 200 nm, was optimal for oral delivery, and the polydispersity index (around 0.26), indicated high sample homogeneity. Additionally, K-NLCs showed a spherical morphology without aggregation by microscopic analysis. The encapsulation efficiency of khellin was about 55%. In vitro release studies were carried out in media with different pH to mimic physiological conditions. K-NLCs were found to be physically stable in the simulated gastric and intestinal fluids, and they preserved about 70% of khellin after 6 h incubation. K-NLCs were also successfully lyophilized testing different lyoprotectants, and obtained freeze-dried K-NLCs demonstrated good shelf life over a month. Lastly, permeability studies on Caco-2 cells were performed to predict khellin passive diffusion across the intestinal epithelium, demonstrating that nanoparticles increased khellin permeability by more than two orders of magnitude. Accordingly, developed NLCs loaded with khellin represent a versatile formulation with good biopharmaceutical properties for oral administration, possibly enhancing khellin's bioavailability and therapeutic effects.

HLD-NAC design and evaluation of a fully dilutable lecithin-linker SMEDDS for ibuprofen

Lecithin-linker microemulsions have been previously proposed as a platform for designing a fully dilutable self-microemulsifying drug delivery system (SMEDDS). This SMEDDS formulation, composed of ethyl caprate (oil), lecithin (Le), glycerol monooleate (lipophilic linker, LL) and polyglycerol caprylate (hydrophilic linker, HL), produced a ternary phase diagram (TPD) that had a fully dilutable path suitable for oral drug delivery. However, introducing ibuprofen as an active pharmaceutical ingredient (API) resulted in TPD phase boundaries that eliminated the fully dilutable path. The purpose of this work was to understand the origin of the changes in the TPD, use that understanding to restore the fully dilutable path with an ibuprofen-loaded SMEDDS, and finally to evaluate the absorption of ibuprofen in vivo. The effect of ibuprofen on the HLD (hydrophilic-lipophilic difference, interpreted as normalized net interfacial curvature) of the system was evaluated via a polar oil model, showing that ibuprofen played a surfactant-like role, having a characteristic curvature (Cc) value of +5 (highly hydrophobic). The net-average curvature (NAC) framework used the HLD calculated with Le, LL, HL and ibuprofen Cc to generate TPDs in ibuprofen lecithin-linker systems. The HLD-NAC simulations show that restoring full dilutability required a highly hydrophilic linker (HL^-) with a Cc of -5 or more negative. The fully dilutable path was restored after introducing a hexaglycerol caprylate as HL- (Cc = -6). Plasma concentration profiles obtained with this ibuprofen-loaded SMEDDS showed a more than three-fold increase in the area under the curve (AUC) of rat plasma concentration profiles compared to the same 25 mg/kg ibuprofen dose in suspension.

Variable-Temperature NMR Analysis of the Thermodynamics of Polymer Partitioning between Aqueous and Drug-Rich Phases and Its Significance for Amorphous Formulations

We previously reported that the polymers used in amorphous solid dispersion (ASD) formulations, such as polyvinylpyrrolidone (PVP), polyvinylpyrrolidone/vinyl acetate (PVP-VA), and hypromellose (HPMC), distribute into the drug-rich phase of ibuprofen (IBP) formed by liquid-liquid phase separation, resulting in a reduction in the maximum drug supersaturation in the aqueous phase. Herein, the mechanism underlying the partitioning of the polymer into the drug-rich phase was investigated from a thermodynamic perspective. The dissolved IBP concentration in the aqueous phase and the amount of polymer distributed into the IBP-rich phase were quantitatively analyzed in IBP-supersaturated solutions containing different polymers using variable-temperature solution-state nuclear magnetic resonance (NMR) spectroscopy. The polymer weight ratio in the IBP-rich phase increased at higher temperatures, leading to a more notable reduction of IBP amorphous solubility. Among the polymers, the amorphous solubility reduction was the greatest for the PVP-VA solution at lower temperatures, while HPMC reduced the amorphous solubility to the greatest extent at higher temperatures. The change in the order of polymer impact on the amorphous solubility resulted from the differences in the temperature dependency of polymer partitioning. The van't Hoff plot of the polymer partition coefficient revealed that both enthalpy and entropy changes for polymer transfer into the IBP-rich phase from the aqueous phase (ΔH_{aqueous→IBP-rich} and ΔS_{aqueous→IBP-rich}) gave positive values for most of the measured temperature range, indicating that polymer partitioning into the IBP-rich phase was an endothermic but entropically favorable process. The polymer transfer into the IBP-rich phase was more endothermic for HPMC than for PVP and PVP-VA. The solid-state NMR analysis of the IBP/polymer ASD implied that the newly formed IBP/polymer interactions in the IBP-rich phase upon polymer incorporation were weaker for HPMC, providing a rationale for the larger positive transfer enthalpy for HPMC. The change in Gibbs free energy for polymer transfer (ΔG_{aqueous→IBP-rich}) showed negative values across the experimental temperature range, decreasing with an increase in temperature, indicating that the distribution of the polymer into the IBP-rich phase is favored at higher temperatures. Moreover, ΔG_{aqueous→IBP-rich} for HPMC showed the greatest decrease with the temperature, likely reflecting the temperature-induced dehydration of HPMC in the aqueous phase. This study contributes fundamental insights into the phenomenon of polymer partitioning into drug-rich phases, furthering the understanding of achievable supersaturation levels and ultimately providing information on polymer selection for ASD formulations.

Harnessing the potential of nanostructured formulations to mimic the food effect of lurasidone

Lurasidone is an important antipsychotic drug indicated for the treatment of schizophrenia and bipolar disorder, with an oral bioavailability of 9-19% owing to its poor aqueous solubility. Additionally, lurasidone exhibits a 2-fold positive food effect, such that patients must administer their medication with a meal, leading to significant non-compliance. The aim of this research was to evaluate the in vitro and in vivo performance of lurasidone when engineered as nanostructured systems. Specifically, a nanosuspension, nano-emulsion and silica-lipid hybrid (SLH) microparticles were formulated and the influence of composition and nanostructure on the mechanism of solubilisation was compared. Formulations were shown to enhance fasted state solubilisation levels in vitro by up to 5.9-fold, compared to pure drug. Fed- and fasted-state solubilisation profiles revealed that in contrast to the nanosuspension and nano-emulsion, lurasidone SLH mitigated the positive pharmaceutical effect of lurasidone. In vivo pharmacokinetic evaluations revealed that the nanosuspension, nano-emulsion and SLH enhanced the bioavailability of lurasidone by 3-fold, 2.4-fold and 8.8-fold, respectively, compared to pure drug after oral administration. For lurasidone, the combination of lipid-based nanostructure and porous silica nanostructure (SLH) led to optimal fasted state bioavailability which can ultimately result in enhanced treatment efficacy, easier dosing regimens and improved patient outcomes.

Primaquine Loaded Solid Lipid Nanoparticles (SLN), Nanostructured Lipid Carriers (NLC), and Nanoemulsion (NE): Effect of Lipid Matrix and Surfactant on Drug Entrapment, in vitro Release, and ex vivo Hemolysis

Primaquine (PQ), an 8-aminoquinoline antimalarial drug, has been widely used for the eradication of hypnozoites from the liver and, therefore, recognized as the radical cure of malaria. However, the clinical applications of PQ are restricted to patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency due to severe dose-related hemolytic side effects. Nanoparticle carriers have shown great potential in achieving higher PQ concentrations in the target site, thereby reducing dose-related systemic toxicity caused by non-specific exposure. This work aims to develop, compare, and evaluate three PQ-loaded lipid-based drug carriers including solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC), and nano-emulsions (NE). The optimized PQ-SLN, PQ-NLC, and PQ-NE had a particle size of 250 nm, a PDI range of 0.1 to 0.3, a zeta potential of - 30 mV, and entrapment efficiency of ~ 90%. All lipid formulations showed sustained release in both simulated gastric and intestinal fluids over 6 h. Four empirical models - including zero-order, Higuchi, Korsmeyer-Peppas, and Hixson-Crowell models - were tested to understand the drug release mechanisms of PQ-SLN, PQ-NLC, and PQ-NE. The model fitness was found to be the highest in the Korsmeyer-Peppas model for all the PQ-loaded lipid formulations (R²: 0.88-0.94). No significant changes were observed in the entrapment efficiency, particle size, and PDI of lipid formulations throughout 1 month of storage at 4 °C and 25 °C. PQ-SLN and PQ-NLC can be further lyophilized with cryoprotectants to improve long-term stability. Finally, the treatment of erythrocytes with PQ-SLN, PQ-NLC, and PQ-NE reduced erythrocyte hemolysis by approximately 4.5-fold compared to the free drug solution.

Exploration on the drug solubility enhancement in aqueous medium with the help of endo-functionalized molecular tubes: a computational approach

One major problem in the pharmaceutical industry is the aqueous solubility of newly developed orally administered drug candidates. More than 50% of newly developed drug molecules suffer from low aqueous solubility. The therapeutic effects of drug molecules are majorly dependent on the bioavailability and, in essence, on the solubility of the used drug molecules. Thus, enhancement of drug solubility of sparingly soluble drug molecules is a need of modern times. Considering the high importance of drug solubility, we have computationally shown the enhancement of drug solubility for seven class II (poorly water-soluble) drug molecules in a water medium. The uses of supramolecular macrocycles have immense importance in the same field. Thus, we have used two synthetic supramolecular receptors named host-1a and host-1b to enhance the water solubility of fluorouracil, albendazole, camptothecin, clopidogrel, indomethacin, melphalan, and tolfenamic acid drug molecules. Biomedical engagements of a supramolecular receptor commence with the formation of stable host-drug complexes. These complexations enhance the water solubility of drug molecules and sustain the release rate and bioavailability of drug molecules. Thus, in this work, we focus on the formation of stable host-drug complexes in water medium. Molecular dynamics simulation is applied to analyze the structural features and the energetics involved in the host-drug complexation process. The information obtained at the atomistic level helps us gain better insights into the key interactions that operate to produce such highly stable complexes. Thus, we can propose that these two supramolecular receptors may be used as drug solubilizing agents, and patients will benefit from this theragnostic application shortly.

Sensing technologies and experimental platforms for the characterization of advanced oral drug delivery systems

Complex and miniaturized oral drug delivery systems are being developed rapidly for targeted, controlled drug release and improved bioavailability. Standard analytical techniques are widely used to characterize i) drug carrier and active pharmaceutical ingredients before loading into a delivery device (to ensure the solid form), and ii) the entire drug delivery system during the development process. However, in light of the complexity and the size of some of these systems, standard techniques as well as novel sensing technologies and experimental platforms need to be used in tandem. These technologies and platforms are discussed in this review, with a special focus on passive delivery systems in size range from a few 100 µm to a few mm. Challenges associated with characterizing these systems and evaluating their effect on oral drug delivery in the preclinical phase are also discussed.

Nanostructured lipid carriers (NLCs) as drug delivery platform: Advances in formulation and delivery strategies

NLCs have provoked the incessant impulsion for the development of safe and valuable drug delivery systems owing to their exceptional physicochemical and then biocompatible characteristics. Throughout the earlier period, a lot of studies recounting NLCs based formulations have been noticeably increased. They are binary system which contains both solid and liquid lipids aiming to produce less ordered lipidic core. Their constituents particularly influence the physicochemical properties and effectiveness of the final product. NLCs can be fabricated by different techniques which are classified according to consumed energy. More utilization NLCs is essential due to overcome barriers surrounded by the technological procedure of lipid-based nanocarriers' formulation and increased information of the core mechanisms of their transport via various routes of administration. They can be used in different applications and by different routes such as oral, cutaneous, ocular and pulmonary. This review article seeks to present an overview on the existing situation of the art of NLCs for future clinics through exposition of their applications which shall foster their lucid use. The reported records evidently demonstrate the promise of NLCs for innovate therapeutic applications in the future.

Inclusion of Medium-Chain Triglyceride in Lipid-Based Formulation of Cannabidiol Facilitates Micellar Solubilization In Vitro, but In Vivo Performance Remains Superior with Pure Sesame Oil Vehicle

Oral sesame oil-based formulation facilitates the delivery of poorly water-soluble drug cannabidiol (CBD) to the lymphatic system and blood circulation. However, this natural oil-based formulation also leads to considerable variability in absorption of CBD. In this work, the performance of lipid-based formulations with the addition of medium-chain triglyceride (MCT) or surfactants to the sesame oil vehicle has been tested in vitro and in vivo using CBD as a model drug. The in vitro lipolysis has shown that addition of the MCT leads to a higher distribution of CBD into the micellar phase. Further addition of surfactants to MCT-containing formulations did not improve distribution of the drug into the micellar phase. In vivo, formulations containing MCT led to lower or similar concentrations of CBD in serum, lymph and MLNs, but with reduced variability. MCT improves the emulsification and micellar solubilization of CBD, but surfactants did not facilitate further the rate and extent of lipolysis. Even though addition of MCT reduces the variability, the in vivo performance for the extent of both lymphatic transport and systemic bioavailability remains superior with a pure natural oil vehicle.

Oral delivery of proteins and peptides: Challenges, status quo and future perspectives

Proteins and peptides (PPs) have gradually become more attractive therapeutic molecules than small molecular drugs due to their high selectivity and efficacy, but fewer side effects. Owing to the poor stability and limited permeability through gastrointestinal (GI) tract and epithelia, the therapeutic PPs are usually administered by parenteral route. Given the big demand for oral administration in clinical use, a variety of researches focused on developing new technologies to overcome GI barriers of PPs, such as enteric coating, enzyme inhibitors, permeation enhancers, nanoparticles, as well as intestinal microdevices. Some new technologies have been developed under clinical trials and even on the market. This review summarizes the history, the physiological barriers and the overcoming approaches, current clinical and preclinical technologies, and future prospects of oral delivery of PPs.

Amorphous Drug Solubility and Maximum Free Drug Concentrations in Cyclodextrin Solutions: A Quantitative Study Using NMR Diffusometry

Cyclodextrin (CD) has been widely used as a solubilizing agent for poorly water-soluble drugs. In the present study, the effect of CD on the amorphous drug solubility and the maximum thermodynamic activity of the drug in the aqueous phase when the drug concentration exceeded the liquid-liquid phase separation (LLPS) concentration was investigated using three chemically diverse CDs, β-cyclodextrin (β-CD), dimethyl-β-CD (DM-β-CD), and hydroxypropyl-β-CD (HP-β-CD). The amorphous solubility of ibuprofen (IBP) increased substantially linearly with the increase in the CD concentration due to IBP/CD complex formation. Surprisingly, although the crystalline solubility of IBP in the β-CD solution reached a plateau at β-CD concentrations above 3 mM (B_S-type solubility diagram) because of the limited crystalline solubility of the IBP/β-CD complex, the amorphous solubility of IBP increased linearly even when the β-CD concentration was higher than 3 mM. The amorphous solubility of IBP in CD solutions was influenced primarily by the phase separation of the IBP-supersaturated solution to the aqueous phase and the other phase mainly composed of IBP, namely, the IBP-rich phase, via LLPS. NMR spectroscopy revealed that DM-β-CD was distributed into the IBP-rich phase when the IBP concentration exceeded its amorphous solubility, while β-CD and HP-β-CD showed minimal mixing with the IBP-rich phase. NMR diffusometry showed that the maximum free IBP concentration was reduced in the DM-β-CD solution compared to that in the buffer. The mixing of DM-β-CD with the IBP-rich phase reduced the chemical potential of IBP in the IBP-rich phase, which in turn reduced the maximum thermodynamic activity of IBP in the aqueous phase. In contrast, the maximum free IBP concentration was unchanged when β-CD or HP-β-CD was present. The hydrophobic nature of the DM-β-CD substituent may contribute to its partitioning into the IBP-rich phase. The present study highlights the impact of CD on the maximum thermodynamic activity of drugs as well as the apparent amorphous solubility of the drug. This aspect should be considered for improving the effective absorption of poorly water-soluble drugs.

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

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

Challenges in Oral Drug Delivery and Applications of Lipid Nanoparticles as Potent Oral Drug Carriers for Managing Cardiovascular Risk Factors

BACKGROUND

The oral application of drugs is the most popular route through which the systemic effect can be achieved. Nevertheless, oral administration is limited by difficulties related to the physicochemical properties of the drug molecule, including low aqueous solubility, instability, low permeability, and rapid metabolism, all of which result in low and irregular oral bioavailability.

OBJECTIVE

The enhancement of oral bioavailability of drug molecules with such properties could lead to extreme complications in drug preparations. Oral lipid-based nanoparticles seem to possess extensive advantages due to their ability to increase the solubility, simplifying intestinal absorption and decrease or eradicate the effect of food on the absorption of low soluble, lipophilic drugs and therefore improving the oral bioavailability.

METHODS

The present review provides a summary of the general theory of lipid-based nanoparticles, their preparation methods, as well as their oral applications. Moreover, oral drug delivery challenges are discussed.

RESULTS

According to this review, the most frequent types of lipid-based nanoparticle, the solid lipid nanoparticles and nanostructured lipid carriers are potent oral carriers due to their ability to penetrate the oral drug adsorption barriers. Moreover, such lipid nanoparticles can be beneficial drug carriers against cardiovascular risk disorders as diabetes, hypertension, etc. Conclusion: In this review, the most current and promising studies involving Solid Lipid Nanoparticles and Nanostructured Lipid Carriers as oral drug carriers are reported aiming to assist researchers who focus their research on lipid-based nanoparticles.

Facile synthesis of PEI-based crystalline templated mesoporous silica with molecular chirality for improved oral delivery of the poorly water-soluble drug

The aim of this study was to build up a novel chiral mesoporous silica called PEIs@TA-CMS through a facile biomimetic strategy and to explore its potential to serve as a drug carrier for improving the delivery efficiency of poorly water-soluble drug. PEIs@TA-CMS was synthesized by using a chiral crystalline complex associated of tartaric acid and polyethyleneimine (PEIs) as templates, scaffolds and catalysts. The structural features including morphology, size, pore structure and texture properties were systematacially studied. The results showed that PEIs@TA-CMS was monodispersed spherical nanoparticles in a uniformed diameter of 120–130 nm with well-developed pore structure (S_BET: 1009.94 m²/g, pore size <2.21 nm). Then PEIs@TA-CMS was employed as nimodipine (NMP) carrier and compared with the drug carry ability of MCM41. After drug loading, NMP was effectively transformed from the crystalline state to an amorphous state due to the space confinement in mesopores. As expected, PEIs@TA-CMS had superiority in both drug loading and drug release compared to MCM41. It could incorporate NMP with high efficiency, and the dissolution-promoting effect of PEIs@TA-CMS was more obvious because of the unique interconnected curved pore channels. Meanwhile, PEIs@TA-CMS could significantly improve the oral adsorption of NMP to a satisfactory level, which showed approximately 3.26-fold higher in bioavailability, and could effectively prolong the survival time of mice on cerebral anoxia from 10.98 to 17.33 min.

Developing pH-Modulated Spray Dried Amorphous Solid Dispersion of Candesartan Cilexetil with Enhanced In Vitro and In Vivo Performance

Candesartan cilexetil (CC), a prodrug and highly effective antihypertensive agent, is a poorly soluble (BCS Class II) drug with limited bioavailability. Here, we attempted to improve CC's bioavailability by formulating several CC-loaded amorphous solid dispersions with a hydrophilic carrier (PVPK30) and pH modifier (sodium carbonate) using the spray drying technique. Solubility, in vitro dissolution, and moisture content tests were used for screening the optimized formulation. We identified an optimized formulation of CC/PVPK30/SC, which at the ratio of 1:0.5:1 (w/w/w) exhibited a 30,000-fold increase in solubility and a more than 9-fold enhancement in dissolution compared to pure CC. Solid-state characterization revealed that in pH-modulated CC amorphous solid dispersion (CCSDpM), CC's crystallinity was altered to an amorphous state with the absence of undesirable interactions. Stability studies also showed that the optimized formulation was stable with good drug content and drug release under accelerated conditions of up to 4 weeks and real-time stability conditions of up to 12 weeks. Furthermore, pharmacokinetic parameters, such as AUC and Cmax of candesartan, had a 4.45-fold and 7.42-fold improvement, respectively, in CCSDpM-treated rats compared to those in the CC-treated rats. Thus, these results suggest that CCSDpM is highly effective for increasing oral absorption. The application of these techniques can be a viable strategy to improve a drug's bioavailability.

Indomethacin co-amorphous drug-drug systems with improved solubility, supersaturation, dissolution rate and physical stability

In this study, new co-amorphous drug systems were designed using a pharmacologically relevant combination to improve the solubility and dissolution of indomethacin. Combinations of indomethacin-paracetamol (IND-PAR) as an anti-inflammatory/pain killer, and indomethacin-nicotinamide (IND-NCT) for prevention of gastric ulcers caused by IND, were developed for co-amorphization. The effect of PAR and NCT on the solubility, supersaturation, and dissolution of the poorly soluble counterpart, IND, was investigated. PAR and NCT were found to enhance the solubility and supersaturation of IND in biorelevant medium (FaSSIF) and in FaSSIF blank. Differential scanning calorimetry (DSC) showed capability of IND-PAR and IND-NCT binary mixtures to form eutectic mixture. Powder X-ray diffraction and DSC indicated the formation of a homogenous co-amorphous system with single T_g value. Hydrogen bonding between IND and each of PAR and NCT were found to stabilize the co-amorphous systems as supported by FTIR studies. The intrinsic dissolution rate under sink conditions was improved over that of plain amorphous IND both in FaSSIF and FaSSIF blank. IND-PAR 2:1 and IND-NCT 1:1 were extremely stable and remained amorphous for 7 months at 25 °C, while all co-amorphous formulations were stable at least up to one month at 40 °C under dry condition. The present work demonstrates an improved approach to combine IND-PAR and IND-NCT as promising co-amorphous systems for potential therapeutical applications.

Advances in Oral Drug Delivery

The oral route is the most common route for drug administration. It is the most preferred route, due to its advantages, such as non-invasiveness, patient compliance and convenience of drug administration. Various factors govern oral drug absorption including drug solubility, mucosal permeability, and stability in the gastrointestinal tract environment. Attempts to overcome these factors have focused on understanding the physicochemical, biochemical, metabolic and biological barriers which limit the overall drug bioavailability. Different pharmaceutical technologies and drug delivery systems including nanocarriers, micelles, cyclodextrins and lipid-based carriers have been explored to enhance oral drug absorption. To this end, this review will discuss the physiological, and pharmaceutical barriers influencing drug bioavailability for the oral route of administration, as well as the conventional and novel drug delivery strategies. The challenges and development aspects of pediatric formulations will also be addressed.

Effect of Polymer Species on Maximum Aqueous Phase Supersaturation Revealed by Quantitative Nuclear Magnetic Resonance Spectroscopy

The polymer used in an amorphous solid dispersion (ASD) formulation impacts the maximum achievable drug supersaturation. Herein, the effect of dissolved polymer on drug concentration in the aqueous phase when a drug-rich phase was generated by liquid-liquid phase separation (LLPS) was investigated for different polymers at various concentrations of drug and polymer. Solution nuclear magnetic resonance (NMR) spectroscopy revealed that polyvinylpyrrolidone (PVP), polyvinylpyrrolidone/vinyl acetate (PVP-VA), and hypromellose (HPMC) distributed into the ibuprofen (IBP)-rich phase formed by LLPS when the amorphous solubility of IBP was exceeded. The amount of polymer in the drug-rich phase increased for higher-molecular-weight grades of PVP and HPMC. Moreover, PVP-VA showed a greater extent of distribution into the IBP-rich phase compared to PVP, and this is attributed to its reduced hydrophilicity resulting from the incorporation of vinyl acetate monomers. Direct quantification by NMR measurements indicated that the IBP concentration in the aqueous phase decreased as the amount of polymer in the IBP-rich phase increased. This can be attributed to a reduction of the chemical potential of IBP in the IBP-rich phase. The reduction in dissolved IBP concentration was greater for the IBP/PVP-VA system compared to the IBP/HPMC system, as a result of more extensive drug-polymer interactions in the former system. The present study highlights the impact of polymer selection on the attainable supersaturation of the drug and the factors that need to be considered in the formulation of ASDs to obtain optimized in vivo performance.