Comparison across Three Hybrid Lipid-Based Drug Delivery Systems for Improving the Oral Absorption of the Poorly Water-Soluble Weak Base Cinnarizine

Supersaturating lipid-based solid dispersion of atazanavir provides enhanced solubilization and supersaturation in the digestive aqueous phase

Understanding and controlling the drug solubilization in digestive environment is of great importance in the design of lipid based solid dispersion (LBSD) for oral delivery of poorly aqueous soluble drugs. In the current study we determined the extent of drug solubilization and supersaturation of supersaturating lipid based solid dispersion which is governed by formulation variables like drug payload, lipid composition, solid carrier properties and lipid to solid carrier ratio. Initially, the impact of lipid chain length and drug payload on drug solubilization in lipid preconcentrate and dispersibility were evaluated to design liquid LbF of the model antiretroviral drug, atazanavir. The temperature induced supersaturation method enhanced the drug payload in medium chain triglyceride formulation at 60 °C. Further, the selected liquid supersaturated LbF was transformed into solid state LbF by employing different solid carriers including silica (Neusilin® US2 and Aerosil® 200), clay (Montmorillonite and Bentonite) and polymer (HPMC-AS and Kollidon® CL-M). The fabricated LBSDs were evaluated for solid state characterization to identify the physical nature of drug. In vitro digestion studies were conducted using pH-stat lipolysis method to assess the supersaturation propensity in aqueous digestive phase. Results revealed that LBSDs with silica and polymer carriers showed maximum drug solubilization throughout experiment compared to liquid LbF. The ionic interaction between drug-clay particles significantly reduced the ATZ partitioning from clay based LBSDs. LBSDs with dual purpose solid carrier like HPMC-AS and Neusilin® US2 offers the potential to improve drug solubilization of ATZ for physiologically relevant time. Lastly, we conclude that evaluation of formulation variables is crucial to achieve optimal performance of supersaturating LBSD.

Cubosomes as an emerging platform for drug delivery: a state-of-the-art review

Lipid-based drug delivery nanoparticles, including non-lamellar type, mesophasic nanostructured materials of lyotropic liquid crystals (LLCs), have been a topic of interest for researchers for their applications in encapsulation of drugs...

Bioadhesive polymer/lipid hybrid nanoparticles as oral delivery system of raloxifene with enhancive intestinal retention and bioavailability

Raloxifene (RLX) is a second-generation selective estrogen receptor modulator used to treat osteoporosis in postmenopausal women. RLX fails to be developed into injectable dosage forms due to poor solubility. Although oral formulations are clinically available, the lower bioavailability (<2%) embarrasses the pharmaceutists. This work reported a bioadhesive nanosystem intended for oral delivery of RLX to enhance its oral bioavailability and address the formulation challenge. The bioadhesive nanosystem refers to polymer-lipid hybrid nanoparticles made up of Carbopol 940, glyceryl distearate, and TGPS. RLX was solidly encapsulated into bioadhesive nanoparticles (bNPs) through a nanoprecipitation technique along with synchronous desalting of RLX·HCl. The resultant RLX-loaded bNPs (RLX-bNPs) were characterized by particle size, ζ potential, morphology, and entrapment efficiency. The in vitro release and in vivo oral bioavailability of RLX-bNPs in rats were comparatively investigated with RLX-loaded common lipid nanoparticles (RLX-cNPs). The preferred formulation possesses a particle size of 150 nm around with a polydispersity index (PDI) of 0.282. RLX-bNPs exhibited slower drug release than RLX-cNPs owing to the presence of an adhesive layer. After oral administration, RLX-bNPs resulted in significant enhancement in the bioavailability of RLX, up to 556.9% relative to RLX suspensions, while it was merely 244.7% for RLX-cNPs. Cellular testing and ex vivo transport imaging demonstrated that bNPs were endowed with excellent intestinal epithelial affinity and absorbability. Our study affords an alternative option for designing a suitable oral delivery system specific to amphiphobic drugs like RLX·HCl.

Recent Advances in Mesoporous Silica Nanoparticles for Targeted Drug Delivery applications

Nanotechnology provides the means to design and fabricate delivery vehicles capable of overcoming physiologically imposed obstacles and undesirable side effects of systemic drug delivery. This protocol allows maximal targeting effectiveness and therefore enhances therapeutic efficiency. In recent years, mesoporous silica nanoparticles (MSNPs) have sparked interest in the nanomedicine research community, particularly for their promising applications in cancer treatment. The intrinsic physio-chemical stability, facile functionalization, high surface area, low toxicity, and great loading capacity for a wide range of chemotherapeutic agents make MSNPs very appealing candidates for controllable drug delivery systems. Importantly, the peculiar nanostructures of MSNPs enabled them to serve as an effective drug, gene, protein, and antigen delivery vehicle for a variety of therapeutic regimens. For these reasons, in this review article, we underscore the recent progress in the design and synthesis of MSNPs and the parameters influencing their characteristic features and activities. In addition, the process of absorption, dissemination, and secretion by injection or oral management of MSNPs are also discussed, as they are key directions for the potential utilization of MSNPs. Factors influencing the in vivo fate of MSNPs will also be highlighted, with the main focus on particle size, morphology, porosity, surface functionality, and oxidation. Given that combining other functional materials with MSNPs may increase their biological compatibility, monitor drug discharge, or improve absorption by tumor cells coated MSNPs; these aspects are also covered and discussed herein.

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

OBJECTIVE

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

SIGNIFICANCE

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

METHODS AND RESULTS

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

CONCLUSIONS

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

Enhancement of abiraterone acetate oral bioavailability by supersaturated-silica lipid hybrids

Abiraterone acetate (AbA) has an oral bioavailability of <10% due to its poor water solubility. Here we investigate the performance of silica-lipid hybrids (SLH) and supersaturated SLH (super-SLH) in improving oral bioavailability of AbA. Specifically, we investigate the influence of lipid type and AbA saturation level of the equilibrium solubility in the lipid (S_eq), and explore in vitro-in vivo correlation (IVIVC). An oral pharmacokinetic study was conducted in fasted Sprague-Dawley rats. Suspensions of the formulations were administered via oral gavage at an AbA dose of 25 mg/kg. Plasma samples were collected and analyzed for drug content. SLH with a saturation level of 90% S_eq enhanced the oral bioavailability of unformulated AbA by 31-fold, and super-SLH with saturation levels of 150, 200 and 250% S_eq, enhanced the bioavailability by 11, 10 and 7-fold, respectively. In comparison with the commercial product Zytiga, SLH (90% S_eq) increased the oral bioavailability 1.43-fold whereas super-SLH showed no improvement. A reasonable IVIVC existed between the performance of unformulated AbA, SLH and super-SLH, in the in vitro lipolysis and in vivo oral pharmacokinetic studies. SLH and super-SLH significantly enhanced the oral bioavailability of AbA. Additionally, supersaturation of SLH improved drug loading but did not correlate with enhanced AbA bioavailability.

Microporosity, Pore Size, and Diffusional Path Length Modulate Lipolysis Kinetics of Triglycerides Adsorbed onto SBA-15 Mesoporous Silica Particles

Understanding lipase-mediated hydrolysis mechanisms within solid-state nanocarriers is fundamental for the rational design of lipid-based formulations. In this study, SBA-15 ordered mesoporous silica (MPS) particles were engineered with well-controlled nanostructural properties to systematically elucidate the role of intrawall microporosity, mesopore size, and particle structure on lipase activity. The microporosity and diffusional path length were shown to be key modulators for lipase-provoked hydrolysis of medium chain triglycerides confined within MPS, with small changes in the pore size, between 9 and 13 nm, showing now a clear correlation to lipase activity. Lipid speciation within MPS after lipolysis, obtained through ¹H NMR, indicated that free fatty acids preferentially adsorbed to rod-shaped MPS (RodMPS) particles with high microporosity. MPS that formed aggregated spindle-like structures (AggMPS) had intrinsically reduced microporosity, which was hypothesized to limit lipase/lipid diffusion to and from the MPS pores and thus retard lipolysis kinetics. A linear correlation between the microporosity and the extent of lipase-provoked hydrolysis was observed within both AggMPS and RodMPS, ultimately indicating that the intricate interplay between the microporosity and lipid/lipase diffusion can be harnessed to optimize lipolysis kinetics for silica-lipid hybrid carriers. The new insights derived in this study are integral to the future development of solid-state lipid-based nanocarriers that control the lipase activity for improving the absorption of poorly soluble bio-active compounds.

An update on polymer-lipid hybrid systems for improving oral drug delivery

INTRODUCTION

A promising approach that has recently emerged to overcome the complex biobarriers and interrelated challenges associated with oral drug absorption is to combine the benefits of polymeric and lipid-based nanocarriers within one hybrid system. This multifaceted formulation strategy has given rise to a plethora of polymer-lipid hybrid (PLH) systems with varying nanostructures and biological activities, all of which have demonstrated the ability to improve the biopharmaceutical performance of a wide range of challenging therapeutics.

AREAS COVERED

The multitude of polymers that can be combined with lipids to exert a synergistic effect for oral drug delivery have been identified, reviewed and critically evaluated. Specific focus is attributed to preclinical studies performed within the past 5 years that have elucidated the role and mechanism of the polymer phase in altering the oral absorption of encapsulated therapeutics.

EXPERT OPINION

The potential of PLH systems has been clearly identified; however, improved understanding of the structure-activity relationship between PLH systems and oral absorption is fundamental for translating this promising delivery approach into a clinically relevant formulation. Advancing research within this field to identify optimal polymer, lipid combinations and engineering conditions for specific therapeutics are therefore encouraged.

Solidification to improve the biopharmaceutical performance of SEDDS: Opportunities and challenges

Self-emulsifying drug delivery systems (SEDDS) offer potential for overcoming the inherent slow dissolution and poor oral absorption of hydrophobic drugs by retaining them in a solubilised state during gastrointestinal transit. However, the promising biopharmaceutical benefits of liquid lipid formulations has not translated into widespread commercial success, due to their susceptibility to long term storage and in vivo precipitation issues. One strategy that has emerged to overcome such limitations, is to combine the solubilisation and dissolution enhancing properties of lipids with the stabilising effects of solid carrier materials. The development of intelligent hybrid drug formulations has presented new opportunities to harness the potential of emulsified lipids in optimising oral bioavailability for lipophilic therapeutics. Specific emphasis of this review is placed on the impact of solidification approaches and excipients on the biopharmaceutical performance of self-emulsifying lipids, with findings highlighting the key design considerations that should be implemented when developing hybrid lipid-based formulations.

Mesoporous silica nanoparticles for therapeutic/diagnostic applications

Based on unique intrinsic properties of mesoporous silica nanoparticles (MSNs) such as high surface area, large pore size, good biocompatibility and biodegradability, stable aqueous dispersion, they have received much attention in the recent decades for their applications as a promising platform in the biomedicine field. These porous structures possess a pore size ranging from 2 to 50 nm which make them excellent candidates for various biomedical applications. Herein, at first we described the common approaches of cargo loading and release processes from MSNs. Then, the intracellular uptake, safety and cytotoxicity aspects of MSNs are discussed as well. This review also highlights the most recent advances in the biomedical applications of MSNs, including 1) MSNs-based carriers, 2) MSNs as bioimaging agents, 3) MSNs-based biosensors, 4) MSNs as therapeutic agents (photodynamic therapy), 5) MSN based quantum dots, 6) MSNs as platforms for upconverting nanoparticles, and 6) MSNs in tissue engineering.

Engineering intelligent particle-lipid composites that control lipase-mediated digestion

Nanostructured particle-lipid composites have emerged as state-of-the-art carrier systems for poorly water-soluble bioactive molecules due to their ability to control and enhance the lipase-mediated hydrolysis of encapsulated triglycerides, leading to a subsequent improvement in the solubilisation and absorption of encapsulated species. The first generation of particle-lipid composites (i.e. silica-lipid hybrid (SLH) microparticles) were designed and fabricated by spray drying a silica nanoparticle-stabilised Pickering emulsion, to create a novel three-dimensional architecture, whereby lipid droplets were encapsulated within a porous matrix support. The development of SLH microparticles has acted as a solid foundation for the synthesis of several next generation particle-lipid composites, including polymer-lipid hybrid (PLH) and clay-lipid hybrid systems (CLH), which present lipase with unique lipid microenvironments for optimised lipolysis. This review details the methods utilised to engineer lipid hybrid particles and the strategic investigations that have been performed to determine the influence of key material characteristics on digestion enzyme activity. In doing so, this provides insight into manipulating the mechanism of lipase action through the intelligent design of lipid-based biomaterials for their use in drug delivery formulations and novel functional foods.

Praziquantel-lipid nanocapsules: an oral nanotherapeutic with potential Schistosoma mansoni tegumental targeting

Purpose

Lipid nanocapsules (LNCs) have shown potential to increase the bioavailability and efficacy of orally administered drugs. However, their intestinal translocation to distal target sites and their implication in pharmacokinetic (PK)–pharmacodynamic (PD) relationships are yet to be elucidated. In this study, the effect of LNCs on the PD activity and pharmacokinetics of praziquantel (PZQ), the mainstay of schistosomiasis chemotherapy, was investigated.

Materials and methods

The composition of LNCs was modified to increase PZQ payload and to enhance membrane permeability. PZQ–LNCs were characterized in vitro for colloidal properties, entrapment efficiency (EE%), and drug release. PD activity of the test formulations was assessed in Schistosoma mansoni-infected mice 7 days post-oral administration of a single 250 mg/kg oral dose. Pharmacokinetics of the test formulations and their stability in simulated gastrointestinal (GI) fluids were investigated to substantiate in vivo data.

Results

PZQ–LNCs exhibited good pharmaceutical attributes in terms of size (46–62 nm), polydispersity index (0.01–0.08), EE% (>95%), and sustained release profiles. Results indicated significant efficacy enhancement by reduction in worm burden, amelioration of liver pathology, and extensive damage to the fluke suckers and tegument. This was partly explained by PK data determined in rats. In addition, oral targeting of the worms was supported by the stability of PZQ–LNCs in simulated GI fluids and scanning electron microscopy (SEM) visualization of nanostructures on the tegument of worms recovered from mesenteric/hepatic veins. Cytotoxicity data indicated tolerability of PZQ–LNCs.

Conclusion

Data obtained provide evidence for the ability of oral LNCs to target distal post-absorption sites, leading to enhanced drug efficacy. From a practical standpoint, PZQ–LNCs could be suggested as a potential tolerable single lower dose oral nanomedicine for more effective PZQ mass chemotherapy.