Development and oral bioavailability assessment of a supersaturated self-microemulsifying drug delivery system (SMEDDS) of albendazole

Assembly of nanostructured lipid carriers loaded gefitinib and simvastatin as hybrid therapy for metastatic breast cancer: Codelivery and repurposing approach

Breast cancer represents a life-threatening problem globally. The major challenge in the clinical setting is the management of cancer resistance and metastasis. Hybrid therapy can affect several cellular targets involved in carcinogenesis with a lessening of adverse effects. Therefore, the current study aims to assemble, and optimize a hybrid of gefitinib (GFT) and simvastatin (SIM)-loaded nanostructured lipid carrier (GFT/SIM-NLC) to combat metastatic and drug-resistant breast cancer. GFT/SIM-NLC cargos were prepared using design of experiments to investigate the impact of poloxamer-188 and fatty acids concentrations on the physicochemical and pharmaceutical behavior properties of NLC. Additionally, the biosafety of the prepared GFT/SIM-NLC was studied using a fresh blood sample. Afterward, the optimized formulation was subjected to an MTT assay to study the cytotoxic activity of GFT/SIM-NLC compared to free GFT/SIM using an MCF-7 cell line as a surrogate model for breast cancer. The present results revealed that the particle size of the prepared NLC ranged from (209 to 410 nm) with a negative zeta potential value ranging from (-17.2 to -23.9 mV). Moreover, the optimized GFT/SIM-NLC formulation showed favorable physicochemical properties and promising lymphatic delivery cargos. A biosafety study indicates that the prepared NLC has a gentle effect on erythrocyte hemolysis. Cytotoxicity studies revealed that GFT/SIM-NLC enhanced the killing of the MCF-7 cell line compared to free GFT/SIM. This study concluded that the hybrid therapy of GFT/SIM-NLC is a potential approach to combat metastatic and drug-resistant breast cancer.

Micro-Injection Moulding of PEO/PCL Blend–Based Matrices for Extended Oral Delivery of Fenbendazole

Fenbendazole (FBZ) is a broad-spectrum anthelmintic administered orally to ruminants; nevertheless, its poor water solubility has been the main limitation to reaching satisfactory and sustained levels at the site of the target parasites. Hence, the exploitation of hot-melt extrusion (HME) and micro-injection moulding (µIM) for the manufacturing of extended-release tablets of plasticised solid dispersions of poly(ethylene oxide) (PEO)/polycaprolactone (PCL) and FBZ was investigated due to their unique suitability for semi-continuous manufacturing of pharmaceutical oral solid dosage forms. High-performance liquid chromatography (HPLC) analysis demonstrated a consistent and uniform drug content in the tablets. Thermal analysis using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) suggested the amorphous state of the active ingredient, which was endorsed by powder X-ray diffraction spectroscopy (pXRD). Fourier transform infrared spectroscopy (FTIR) analysis did not display any new peak indicative of either a chemical interaction or degradation. Scanning electron microscopy (SEM) images showed smoother surfaces and broader pores as we increased the PCL content. Electron-dispersive X-ray spectroscopy (EDX) revealed that the drug was homogeneously distributed within the polymeric matrices. Drug release studies attested that all moulded tablets of amorphous solid dispersions improved the drug solubility, with the PEO/PCL blend–based matrices showing drug release by Korsmeyer–Peppas kinetics. Thus, HME coupled with µIM proved to be a promising approach towards a continuous automated manufacturing process for the production of oral solid dispersions of benzimidazole anthelmintics to grazing cattle.

The Development and Optimization of Lipid-Based Self-Nanoemulsifying Drug Delivery Systems for the Intravenous Delivery of Propofol

PURPOSE

Propofol is a relatively short-acting potent anesthetic lipophilic drug used during short surgical procedures. Despite the success of propofol intravenous emulsions, drawbacks to such formulations include inherent emulsion instability, the lack of a safe vehicle to prevent sepsis, and concern regarding hyperlipidemia-related side effects. The aim of the current investigation was to develop a novel, lipid-based self-nanoemulsifying drug delivery system (SNEDDS) for propofol with improved stability and anesthetic activity for human use.

METHODS

A series of SNEDDS formulations were developed using naturally obtained medium-chain/long-chain mono-, di-, and triglycerides, glyceryl monocaprylate, and water-soluble cosolvents with hydrogenated castor oil constructing ternary phase diagrams for propofol. The developed SNEDDS formulations were characterized using visual observation, particle size analysis, zeta potential, transmission electron microscopy, equilibrium solubility, in vitro dynamic dispersion and stability, and in vivo sleeping disorder studies in rats. The in vivo bioavailability of the SNEDDSs in rats was also studied to compare the representative formulations with the marketed product Diprivan^®.

RESULTS

Medium-chain triglycerides (M810) with mono-diglycerides (CMCM) as an oil blend and hydrogenated castor oil (KHS15) as a surfactant were selected as key ingredients in ternary phase diagram studies. The nanoemulsifying regions were identified from the studies and a number of SNEDDSs were formulated. Results from the characterization studies demonstrated the formation of efficient nanosized particles (28-45 nm globule size, 0.10-0.20 PDI) in the optimized SNEDDS with a drug loading of 50 mg/g, which is almost 500-fold higher than free propofol. TEM analysis showed the formation of spherical and homogeneous nanoparticles of less than 50 nm. The dissolution rate of the representative SNEDDS was faster than raw propofol and able to maintain 99% propofol in aqueous solution for around 24 h. The optimized liquid SNEDDS formulation was found to be thermodynamically stable. The intravenous administration of the SNEDDS in male Wistar rats induced a sleeping time of 73-88 min. The mean plasma concentrations after the IV administration of propofol nano-formulations PF2-SNEDDS and PF8-SNEDDS were 1348.07 ± 27.31 and 1138.66 ± 44.97 µg/mL, as compared to 891.44 ± 26.05 µg/mL (p = 0.05) observed after the IV administration of raw propofol.

CONCLUSION

Propofol-loaded SNEDDS formulations could be a potential pharmaceutical product with improved stability, bioavailability, and anesthetic activity.

Optimization of Gefitinib-Loaded Nanostructured Lipid Carrier as a Biomedical Tool in the Treatment of Metastatic Lung Cancer

Gefitinib (GEF) is utilized in clinical settings for the treatment of metastatic lung cancer. However, premature drug release from nanoparticles in vivo increases the exposure of systemic organs to GEF. Herein, nanostructured lipid carriers (NLC) were utilized not only to avoid premature drug release but also due to their inherent lymphatic tropism. Therefore, the present study aimed to develop a GEF-NLC as a lymphatic drug delivery system with low drug release. Design of experiments was utilized to develop a stable GEF-NLC as a lymphatic drug delivery system for the treatment of metastatic lung cancer. The in vitro drug release of GEF from the prepared GEF-NLC formulations was studied to select the optimum formulation. MTT assay was utilized to study the cytotoxic activity of GEF-NLC compared to free GEF. The optimized GEF-NLC formulation showed favorable physicochemical properties: <300 nm PS, <0.2 PDI, <−20 ZP values with >90% entrapment efficiency. Interestingly, the prepared formulation was able to retain GEF with only ≈57% drug release within 24 h. Furthermore, GEF-NLC reduced the sudden exposure of cultured cells to GEF and produced the required cytotoxic effect after 48 and 72 h incubation time. Consequently, optimized formulation offers a promising approach to improve GEF’s therapeutic outcomes with reduced systemic toxicity in treating metastatic lung cancer.

Combined Ramipril and Black Seed Oil Dosage Forms Using Bioactive Self-Nanoemulsifying Drug Delivery Systems (BIO-SNEDDSs)

Purpose: Ramipril (RMP)—an angiotensin-converting enzyme (ACE) inhibitor—and thymoquinone (THQ) suffer from poor oral bioavailability. Developing a combined liquid SNEDDS that comprises RMP and black seed oil (as a natural source of THQ) could lead to several formulations and therapeutic benefits. Methods: The present study involved comprehensive optimization of RMP/THQ liquid SNEDDS using self-emulsification assessment, equilibrium solubility studies, droplet size analysis, and experimentally designed phase diagrams. In addition, the optimized RMP/THQ SNEDDS was evaluated against pure RMP, pure THQ, and the combined pure RMP + RMP-free SNEDDS (capsule-in-capsule) dosage form via in vitro dissolution studies. Results: The phase diagram study revealed that black seed oil (BSO) showed enhanced self-emulsification efficiency with the cosolvent (Transcutol P) and hydrogenated castor oil. The phase diagram studies also revealed that the optimized formulation BSO/TCP/HCO-30 (32.25/27.75/40 % w/w) showed high apparent solubility of RMP (25.5 mg/g), good THQ content (2.7 mg/g), and nanometric (51 nm) droplet size. The in-vitro dissolution studies revealed that the optimized drug-loaded SNEDDS showed good release of RMP and THQ (up to 86% and 89%, respectively). Similarly, the isolation between RMP and SNEDDS (pure RMP + RMP-free SNEDDS) using capsule-in-capsule technology showed >84% RMP release and >82% THQ release. Conclusions: The combined pure RMP + RMP-free SNEDDS (containing black seed oil) could be a potential dosage form combining the solubilization benefits of SNEDDSs, enhancing the release of RMP/THQ along with enhancing RMP stability through its isolation from lipid-based excipients during storage.

Status and prospect of novel treatment options toward alveolar and cystic echinococcosis

Cystic echinococcosis (CE) and alveolar echinococcosis (AE) are the two most important global parasitic infectious diseases caused by species of Echinococcus granulosus and E. multilocularis, respectively. Although numerous trials have been performed in search of novel therapeutic options to curb the neglected zoonosis, no other nonsurgical options are currently available to replace the licensed anti echinococcal drugs albendazole (ABZ) and mebendazole (MBZ). A safer and more effective treatment plan for echinococcosis is therefore urgently needed to compensate for this therapeutic shortfall. Here, we present a review of the literature for state-of-the-art valuable anti-parasitic compounds and novel strategies that have proved effective against CE and AE, which includes details about the pharmaceutical type, practical approach, experimental plan, model application and protoscolecidal effects in vivo and in vitro. The content includes the current application of traditional clinical chemicals, the preparation of new compounds with various drug loadings, repurposing findings, combined programs, the prospects for Chinese herbal medicines, non-drug administrations and the exploration of target inhibitors based on open-source information for parasitic genes. Next the conventional experimental projects and pharmacodynamic evaluation methods are systematically summarized and evaluated. The demands to optimize the construction of the echinococcosis model and improve the dynamic monitoring method in vivo are also discussed given the shortcomings of in vivo models and monitoring methods.

Explicating the molecular level drug-polymer interactions at the interface of supersaturated solution of the model drug: Albendazole

Supersaturation as a formulation principle relates to the aqueous solubility of poorly soluble drugs in solution . However, supersaturation state of drugs tends to crystallize because of its thermodynamic instability thereby compromising the solubility and biopharmaceutical performance of drugs. The present study aims to investigate the supersaturation potential of albendazole (ABZ) and its precipitation via nucleation and crystal growth. We hypothesized the use of polymers will avoid ABZ precipitation by interacting with drug molecules. The drug polymer interactions are characterized using conventional methods of Fourier transform infrared (FTIR), Nuclear magnetic resonance (NMR) and Polarized light microscopy (PLM). We have used a novel approach of sum frequency generation (SFG) vibrational spectroscopic in exploring the drug polymer interactions at air-water interface. Recently we have reported the SFG for e rifaximin-polymer interactions (Singh et al., 2021). The supersaturation assay, saturation solubility studies and nucleation induction time analysis revealed polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP K30) as effective precipitation inhibitors thereby enhancing the ABZ equilibrium solubility and in vitro supersaturation maintenance of ABZ. Further, modification in the solid state of ABZ has confirmed the influence of polymers on its precipitation behaviour. We conclude that PVA and PVP K30 act as nucleation and crystal growth inhibitor, respectively for the precipitation inhibition of ABZ.

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.

Docusate-Based Ionic Liquids of Anthelmintic Benzimidazoles Show Improved Pharmaceutical Processability, Lipid Solubility, and in Vitro Activity against Cryptococcus neoformans

As the existing therapeutic modalities for the treatment of cryptococcal meningitis (CM) have suboptimal efficacy, repurposing existing drugs for the treatment of CM is of great interest. The FDA-approved anthelmintic benzimidazoles, albendazole, mebendazole, and flubendazole, have demonstrated potent but variable in vitro activity against Cryptococcus neoformans, the predominant fungal species responsible for CM. We performed molecular docking studies to ascertain the interaction of albendazole, mebendazole, and flubendazole with a C. neoformans β-tubulin structure, which revealed differential binding interactions and explained the different in vitro efficacies reported previously and observed in this investigation. Despite their promising in vitro efficacy, the repurposing of anthelmintic benzimidazoles for oral CM therapy is significantly hampered due to their high crystallinity, poor pharmaceutical processability, low and pH-dependent solubility, and drug precipitation upon entering the intestine, all of which result in low and variable oral bioavailability. Here, we demonstrate that the anthelmintic benzimidazoles can be transformed into partially amorphous low-melting ionic liquids (ILs) with a simple metathesis reaction using amphiphilic sodium docusate as a counterion. In vitro efficacy studies on a laboratory reference and a clinical isolate of C. neoformans showed 2- to 4-fold lower IC₉₀ values for docusate-based ILs compared to the pure anthelmintic benzimidazoles. Furthermore, using a C. neoformans strain with green fluorescent protein (GFP)-tagged β-tubulin and albendazole and its docusate IL as model candidates, we showed that the benzimidazoles and their ILs reduce the viability of C. neoformans by interfering with its microtubule assembly. Unlike pure anthelmintic benzimidazoles, the docusate-based ILs showed excellent solubility in organic solvents and >30-fold higher solubility in bioavailability-enhancing lipid vehicles. Finally, the docusate ILs were successfully incorporated into SoluPlus, a self-assembling biodegradable polymer, which upon dilution with water formed polymeric micelles with a size of <100 nm. Thus, the development of docusate-based ILs represents an effective approach to improve the physicochemical properties and potency of anthelmintic benzimidazoles to facilitate their repurposing and preclinical development for CM therapy.

Supersaturable self-microemulsifying delivery systems: an approach to enhance oral bioavailability of benzimidazole anticancer drugs

This study explored the design of supersaturable self-microemulsifying drug delivery systems (S-SMEDDS) to address poor solubility and oral bioavailability of a novel benzimidazole derivative anticancer drug (BI). Firstly, self-microemulsifying drug delivery systems SMEDDS made of Miglyol® 812, Kolliphor® RH40, Transcutol® HP, and ethanol were prepared and loaded with the BI drug. Upon dispersion, the systems formed neutrally charged droplets of around 20 nm. However, drug precipitation was observed following incubation with simulated gastric fluid (pH 1.2). Aiming at reducing this precipitation and enhancing drug payload, supersaturable systems were then prepared by adding 1% hydroxypropyl cellulose as precipitation inhibitor. Supersaturable systems maintained a higher amount of drug in a supersaturated state in gastric medium compared with conventional formulations and were stable in simulated intestinal medium (pH 6.8). In vitro cell studies using Caco-2 cell line showed that these formulations reduced in a transient manner the transepithelial electrical resistance of the monolayers without toxicity. Accordingly, confocal images revealed that the systems accumulated at tight junctions after a 2 h exposure. In vivo pharmacokinetic studies carried out following oral administration of BI-loaded S-SMEDDS, SMEDDS, and free drug to healthy mice showed that supersaturable systems promoted drug absorption compared with the other formulations. Overall, these data highlight the potential of using the supersaturable approach as an alternative to conventional SMEDDS for improving oral systemic absorption of lipophilic drugs.

Self-Nano-Emulsifying Drug-Delivery Systems: From the Development to the Current Applications and Challenges in Oral Drug Delivery

Approximately one third of newly discovered drug molecules show insufficient water solubility and therefore low oral bio-availability. Self-nano-emulsifying drug-delivery systems (SNEDDSs) are one of the emerging strategies developed to tackle the issues associated with their oral delivery. SNEDDSs are composed of an oil phase, surfactant, and cosurfactant or cosolvent. SNEDDSs characteristics, their ability to dissolve a drug, and in vivo considerations are determinant factors in the choice of SNEDDSs excipients. A SNEDDS formulation can be optimized through phase diagram approach or statistical design of experiments. The characterization of SNEDDSs includes multiple orthogonal methods required to fully control SNEDDS manufacture, stability, and biological fate. Encapsulating a drug in SNEDDSs can lead to increased solubilization, stability in the gastro-intestinal tract, and absorption, resulting in enhanced bio-availability. The transformation of liquid SNEDDSs into solid dosage forms has been shown to increase the stability and patient compliance. Supersaturated, mucus-permeating, and targeted SNEDDSs can be developed to increase efficacy and patient compliance. Self-emulsification approach has been successful in oral drug delivery. The present review gives an insight of SNEDDSs for the oral administration of both lipophilic and hydrophilic compounds from the experimental bench to marketed products.

Enhanced intestinal lymphatic absorption of saquinavir through supersaturated self-microemulsifying drug delivery systems

The therapeutic potential of saquinavir, a specific inhibitor of human immunodeficiency virus (HIV)-1 and HIV-2 protease enzymes, has been largely limited because of a low solubility and consequnt low bioavailability. Thus, we aimed to design a supersaturated self-microemulsifying drug delivery system (S-SMEDDS) that can maintain a high concentration of saquinavir in gastro-intestinal fluid thorugh inhibiting the drug precipitation to enhance the lymphatic transport of saquinavir and to increase the bioavailability of saquinavir considerably. Solubilizing capacity of different oils, surfactants, and cosurfactants for saquinavir was evaluated to select optimal ingredients for preparation of SMEDDS. Through the construction of pseudo-ternary phase diagram, SMEDDS formulations were established. A polymer as a precipitation inhibitor was selected based on its viscosity and drug precipitation inhibiting capacity. The S-SMEDDS and SMEDDS designed were administered at an equal dose to rats. At predetermined time points, levels of saquinavir in lymph collected from the rats were assessed. SMEDDS prepared presented a proper self-microemulsification efficiency and dispersion stability. The S-SMEDDS fabricated using the SMEDDS and hydroxypropyl methyl cellulose 2910 as a precipitation inhibitor exhibited a signficantly enhanced solubilizing capacity for saquinavir. The drug concentration in a simulated intestinal fluid evaluated with the S-SMEDDS was also maintained at higher levels for prolonged time than that examined with the SMEDDS. The S-SMEDDS showed a considerably enhanced lymphatic absoprtion of saquinavir in rats compared to the SMEDDS. Therefore, the S-SMEDDS would be usefully exploited to enhance the lymphatic absorption of hydrophobic drugs that need to be targeted to the lymphatic system.

Current Status of Supersaturable Self-Emulsifying Drug Delivery Systems

Self-emulsifying drug delivery systems (SEDDSs) are a vital strategy to enhance the bioavailability (BA) of formulations of poorly water-soluble compounds. However, these formulations have certain limitations, including in vivo drug precipitation, poor in vitro in vivo correlation due to a lack of predictive in vitro tests, issues in handling of liquid formulation, and physico-chemical instability of drug and/or vehicle components. To overcome these limitations, which restrict the potential usage of such systems, the supersaturable SEDDSs (su-SEDDSs) have gained attention based on the fact that the inclusion of precipitation inhibitors (PIs) within SEDDSs helps maintain drug supersaturation after dispersion and digestion in the gastrointestinal tract. This improves the BA of drugs and reduces the variability of exposure. In addition, the formulation of solid su-SEDDSs has helped to overcome disadvantages of liquid or capsule dosage form. This review article discusses, in detail, the current status of su-SEDDSs that overcome the limitations of conventional SEDDSs. It discusses the definition and range of su-SEDDSs, the principle mechanisms underlying precipitation inhibition and enhanced in vivo absorption, drug application cases, biorelevance in vitro digestion models, and the development of liquid su-SEDDSs to solid dosage forms. This review also describes the effects of various physiological factors and the potential interactions between PIs and lipid, lipase or lipid digested products on the in vivo performance of su-SEDDSs. In particular, several considerations relating to the properties of PIs are discussed from various perspectives.

Chitosan coated nanostructured lipid carriers for enhanced in vivo efficacy of albendazole against Trichinella spiralis

The study investigated chitosan coated nanostructured lipid carriers (NLCs) for oral delivery of albendazole in treatment of trichinellosis. NLCs comprised precirol and oleic acid with Tween and Span 80. Dicetylphosphate was used as charging agent to allow chitosan coating. Trichinella spiralis infected mice were used and albendazole suspension, coated or uncoated NLCs were orally administered at different stages of infection. NLCs were spherical with size of 188 and 200 nm for coated and uncoated NLC, respectively. Treatment during intestinal phase reduced worm count with NLCs showing better rank. This was reflected further by reduced larvae count and improved histopathological features. Starting treatment in the migrating phase reduced larval count by 62.9, 99.6 and 89.5 % after administration of suspension, coated and uncoated NLCs, respectively. The same rank was recorded for the encysted phase. NLCs enhanced the efficacy of albendazole against Trichinella spiralis compared with suspension with chitosan coated NLCs being superior.

Self-microemulsifying Drug Delivery System for Improved Oral Delivery of Limonene: Preparation, Characterization, in vitro and in vivo Evaluation

The current investigation aimed at formulating self-microemulsifying drug delivery system (SMEDDS) to ameliorate oral bioavailability of a hydrophobic functional ingredient, limonene. Solubility test, compatibility test, and pseudo-ternary phase diagrams (PTPD) were adopted to screen the optimal compositions of limonene-SMEDDS (L-SMEDDS). The characteristics of this system assessed in vitro, mainly included determination of particle size distribution, observation of morphology via transmission electron microscopy (TEM), testing of drug release in different dissolution media, and evaluation of stability. The oral bioavailability study in vivo of the formulated limonene was performed in rats with the free limonene as the reference. Compared with the free limonene, the distribution study of L-SMEDDS was conducted in Kunming mice after oral administration. The optimized SMEDDS (ethyl oleate, 14.2%; Cremophor EL, 28.6%; isopropanol, 28.6%; and loaded limonene, 28.6%) under the TEM (about 100 nm) was spherical with no significant variations in size/appearance for 30 days at 4, 25, and 60°C. In comparison with free limonene, higher than 89.0% of limonene was released from SMEDDS within 10 min in different dissolution media. An in vivo study showed a 3.71-fold improved oral bioavailability of the formulated limonene compared to the free limonene. The tissue distribution results showed that limonene predominantly accumulated in the various tissues for the L-SMEDDS compared with the free limonene. Hence, L-SMEDDS could remarkably improve the concentration of limonene in the various organs. These findings hinted that the oral bioavailability of limonene could be improved via an effectual delivery system like SMEDDS.

Formulation Development of Albendazole-Loaded Self-Microemulsifying Chewable Tablets to Enhance Dissolution and Bioavailability

Albendazole is an anthelmintic agent with poor solubility and absorption. We developed a chewable tablet (200 mg drug equivalent), containing a self-microemulsifying drug delivery system (SMEDDS), with oral disintegrating properties. The emulsion was developed using sesame and soybean oils along with surfactant/co-surfactants, and the tablets were prepared by wet granulation using superdisintegrants and adsorbents. Infra-red (IR) spectral studies revealed no interaction between the drug and excipients, and all physical and chemical parameters were within acceptable limits. Stability studies for the formulation indicated no significant change over time. An in vitro release study indicated 100% drug release within 30 min, and in vivo plasma concentrations indicated that the area under the curve (AUC) of albendazole in rats administered SMEDDS chewable tablets was significantly higher than in those administered commercial tablets or powder (p-value < 0.05). The systemic bioavailability of albendazole achieved through the SMEDDS tablets was 1.3 times higher than that achieved by the administration of comparable quantities of albendazole commercial tablets. This was due to the higher dissolution of albendazole SMEDDS in the chewable tablets. We conclude that the SMEDDS chewable formulation can be used to improve the dissolution and systemic availability of poorly water-soluble drugs.

Albendazole-lipid nanocapsules: Optimization, characterization and chemoprophylactic efficacy in mice infected with Echinococcus granulosus

Cystic echinococcosis (CE), which is caused during the metacestode larval stage of Echinococcus granulosus, is a life-threatening disease and is very difficult to treat. At present, the FDA-approved antihelmintic drugs are mebendazole (MBZ), albendazole (ABZ) and its principal metabolite ABZ sulfoxide (ABZSO), but as these have a therapeutic efficacy over 50%, underlining the need for new drug delivery systems. The aim of this work was the optimization and characterization of previously developed ABZ lipid nanocapsules (ABZ-LNCs) and evaluate their efficacy in mice infected with E. granulosus. LNCs were prepared by the phase inversion technique and characterized in terms of size, surface charge, drug loading, and in vitro stability followed by an in vivo proof-of-concept using a murine model infected with E. granulosus. Stable particle dispersions with a narrow size distribution and high efficiency of encapsulation (≥90%) were obtained. ABZ-LNCs showed a greater chemoprophylactic efficacy than ABZ suspension administered by the oral route as 4 out of the 10 ABZ-LNCs treated mice did not develop any cysts, whereas the infection progressed in all mice from the ABZ suspension group. Regarding the ultrastructural studies of cysts, mice treated with ABZ-LNCs or ABZ suspension revealed changes in the germinal layer. However, the extent of the damage appeared to be greater after ABZ-LNC administration compared to the suspension treatment. These results suggest that ABZ-LNCs could be a promising novel candidate for ABZ delivery to treat CE.

Stabilizing supersaturated drug-delivery system through mechanism of nucleation and crystal growth inhibition of drugs

A supersaturated drug-delivery system is capable of enhancing oral bioavailability of hydrophobic drugs. Maintenance of the supersaturated system both in vitro and in vivo is one of the most challenging parts, for that it is required to keenly understand the nucleation and crystal growth behavior. Polymers are widely used to stabilize supersaturated solutions; screening of polymers is done on the basis of their interaction with drug. Nucleation and crystal growth inhibition and drug–polymer interactions can be investigated by using various spectroscopic methods. Various formulations are prepared as supersaturated systems using different drug-delivery systems utilizing different polymers, which illustrates that supersaturation is worthwhile to increase the solubility and hence oral bioavailability of poorly soluble drugs.

Application of a Refined Developability Classification System

In 2010, the Developability Classification System was proposed as an extension of the Biopharmaceutics Classification System to align the classification system with the need for early evaluation of drug candidates according to their developability as oral formulations. Recent work on the Developability Classification System has resulted in the refined developability classification system (rDCS), consisting of standard investigations to estimate drug candidate solubility and permeability and offering customized investigations that are triggered when there is a potential for supersaturation/precipitation (e.g., salts of acids, weak bases) or to investigate permeation versus dissolution-limited absorption. In the present study, the rDCS concept was successfully applied to 6 marketed compounds (aciclovir, albendazole, danazol, dantrolene, dipyridamole, and piroxicam), for which there is a rich database of information. Furthermore, the rDCS was applied to 20 pipeline compounds from past and current research projects at Bayer AG. The rDCS was able to predict the results in humans correctly in 80% of cases. Overall, the results suggest that the rDCS is a highly useful tool for estimating the in vivo behavior of new drug candidates.

Oral Bioavailability and Lymphatic Transport of Pueraria Flavone-Loaded Self-Emulsifying Drug-Delivery Systems Containing Sodium Taurocholate in Rats

We developed self-microemulsifying drug-delivery systems (SMEDDS), including bile salts, to improve the oral bioavailability of pueraria flavones (PFs). The physical properties of the SMEDDS using Cremophor RH 40, and bile salts as mixed surfactants at weight ratios of 10:0⁻0:10 were determined. The particle sizes of PFs-SMEDDS_NR containing sodium taurocholate (NaTC) and Cremophor RH 40, and PFs-SMEDDS_R containing Cremophor RH 40 were measured upon dilution with deionized water and other aqueous media. Dilution volume presented no remarkable effects on particle size, whereas dilution media slightly influenced particle size. PFs-SMEDDS_NR and PFs-SMEDDS_R provided similar release rates in pH-1.2 hydrochloride solution. However, the release rate of PFs-SMEDDS_NR was faster than that of PFs-SMEDDS_R in pH-6.8 phosphate buffer containing 20 mM NaTC and 500 U/mL porcine pancreas lipase. The pharmacokinetics and bioavailability were measured in rats. The oral bioavailability of PFs-SMEDDS_NR was 2.57- and 2.28-fold that of a suspension of PFs (PFs-suspension) before and after the blockade of the lymphatic transport route by cycloheximide, respectively. These results suggested PFs-SMEDDS_NR could significantly improve the oral relative absorption of PFs via the lymphatic uptake pathway. SMEDDS containing NaTC may provide an effective approach for enhancing the oral bioavailability of PFs.

Multi-Layer Self-Nanoemulsifying Pellets: an Innovative Drug Delivery System for the Poorly Water-Soluble Drug Cinnarizine

Beside their solubility limitations, some poorly water-soluble drugs undergo extensive degradation in aqueous and/or lipid-based formulations. Multi-layer self-nanoemulsifying pellets (ML-SNEP) introduce an innovative delivery system based on isolating the drug from the self-nanoemulsifying layer to enhance drug aqueous solubility and minimize degradation. In the current study, various batches of cinnarizine (CN) ML-SNEP were prepared using fluid bed coating and involved a drug-free self-nanoemulsifying layer, protective layer, drug layer, moisture-sealing layer, and/or an anti-adherent layer. Each layer was optimized based on coating outcomes such as coating recovery and mono-pellets%. The optimized ML-SNEP were characterized using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), in vitro dissolution, and stability studies. The optimized ML-SNEP were free-flowing, well separated with high coating recovery. SEM showed multiple well-defined coating layers. The acidic polyvinylpyrrolidone:CN (4:1) solution presented excellent drug-layering outcomes. DSC and XRD confirmed CN transformation into amorphous state within the drug layer. The isolation between CN and self-nanoemulsifying layer did not adversely affect drug dissolution. CN was able to spontaneously migrate into the micelles arising from the drug-free self-nanoemulsifying layer. ML-SNEP showed superior dissolution compared to Stugeron® tablets at pH 1.2 and 6.8. Particularly, on shifting to pH 6.8, ML-SNEP maintained > 84% CN in solution while Stugeron® tablets showed significant CN precipitation leaving only 7% CN in solution. Furthermore, ML-SNEP (comprising Kollicoat® Smartseal 30D) showed robust stability and maintained > 97% intact CN within the accelerated storage conditions. Accordingly, ML-SNEP offer a novel delivery system that combines both enhanced solubilization and stabilization of unstable poorly soluble drugs.

Solid Lipid Nanoparticles of Albendazole for Enhancing Cellular Uptake and Cytotoxicity against U-87 MG Glioma Cell Lines

Albendazole (ABZ) is an antihelminthic drug used for the treatment of several parasitic infestations. In addition to this, there are reports on the anticancer activity of ABZ against a wide range of cancer types. However, its effect on glioma has not yet been reported. In the present study, cytotoxicity of ABZ and ABZ loaded solid lipid nanoparticles (ASLNs) was tested in human glioma/astrocytoma cell line (U-87 MG). Using glyceryl trimyristate as lipid carrier and tween 80 as surfactant spherical ASLNs with an average size of 218.4 ± 5.1 nm were prepared by a combination of high shear homogenization and probe sonication methods. A biphasic in vitro release pattern of ABZ from ASLNs was observed, where 82% of ABZ was released in 24 h. In vitro cell line studies have shown that ABZ in the form of ASLNs was more cytotoxic (IC50 = 4.90 µg/mL) to U-87 MG cells compared to ABZ in the free form (IC₅₀ = 13.30 µg/mL) due to the efficient uptake of the former by these cells.

Nanoemulsion formulations for anti-cancer agent piplartine--Characterization, toxicological, pharmacokinetics and efficacy studies

Piplartine (PL) is an alkaloid found in black-pepper and known for its anticancer activity, however, due to poor solubility and lack of proper formulation, its use for oral administration is a challenge. The objective of this study was to formulate PL into nanoemulsion drug delivery system for oral delivery and thereafter evaluate toxicity, pharmacokinetics and therapeutic efficacy. Optimized nanoemulsions were formulated by self-emulsification as well as by homogenization-sonication method. Two nanoemulsions enhanced the solubility of PL with low polydispersity index and high stability. Both PL loaded nanoemulsions exhibited enhanced dissolution, cellular permeability and cytotoxic effects as compared to pure PL. Formulation of PL into nanoemulsions did not obstruct its cellular uptake in cancer cells. Blank or PL loaded nanoemulsions did not exhibited toxicity in mice upon daily oral administration for 60 days. Pharmacokinetics of PL followed a two-compartment model after intravenous administration. PL loaded nanoemulsions showed 1.5-fold increase in oral bioavailability as compared to free PL. Finally, PL loaded nanoemulsions showed marked anti-tumor activity at a dose of 10mg/kg in melanoma tumor bearing mice. In conclusion, for the first time we have developed a stable nanoemulsion delivery system for oral administration of PL, which enhanced its solubility, oral bioavailability and anti-tumor efficacy.

Cystic echinococcosis therapy: Albendazole-loaded lipid nanocapsules enhance the oral bioavailability and efficacy in experimentally infected mice

Therapeutic failures attributed to medical management of cystic echinococcosis (CE) with albendazole (ABZ) have been primarily linked to the poor drug absorption rate resulting in low drug level in plasma and hydatid cysts. Lipid nanocapsules (LNCs) represent nanocarriers designed to encapsulate lipophilic drugs, such as ABZ. The goals of the current work were: (i) to characterize the plasma and cyst drug exposure after the administration of ABZ as ABZ-LNCs or ABZ suspension (ABZ-SUSP) in mice infected with Echinococcus granulosus, and ii) to compare the clinical efficacies of both ABZ formulations. Enhanced ABZ sulphoxide (ABZ-SO) concentration profiles were obtained in plasma and cysts from ABZ-LNC treated animals. ABZSO exposure (AUC0-LOQ) was significantly higher in plasma and cyst after the ABZ-LNC treatments, both orally and subcutaneously, compared to that observed after oral administration of ABZ-SUSP. Additionally, ABZSO concentrations measured in cysts from ABZ-LNC treated mice were 1.7-fold higher than those detected in plasma. This enhanced drug availability correlated with an increased efficacy against secondary CE in mice observed for the ABZ-LNCs, while ABZ-SUSP did not reach differences with the untreated control group. This new pharmacotechnically-based strategy could be a potential alternative to improve the treatment of human CE.

Development and optimization of a self-microemulsifying drug delivery system for atorvastatin calcium by using D-optimal mixture design

In this study, we developed and optimized a self-microemulsifying drug delivery system (SMEDDS) formulation for improving the dissolution and oral absorption of atorvastatin calcium (ATV), a poorly water-soluble drug. Solubility and emulsification tests were performed to select a suitable combination of oil, surfactant, and cosurfactant. A D-optimal mixture design was used to optimize the concentration of components used in the SMEDDS formulation for achieving excellent physicochemical characteristics, such as small droplet size and high dissolution. The optimized ATV-loaded SMEDDS formulation containing 7.16% Capmul MCM (oil), 48.25% Tween 20 (surfactant), and 44.59% Tetraglycol (cosurfactant) significantly enhanced the dissolution rate of ATV in different types of medium, including simulated intestinal fluid, simulated gastric fluid, and distilled water, compared with ATV suspension. Good agreement was observed between predicted and experimental values for mean droplet size and percentage of the drug released in 15 minutes. Further, pharmacokinetic studies in rats showed that the optimized SMEDDS formulation considerably enhanced the oral absorption of ATV, with 3.4-fold and 4.3-fold increases in the area under the concentration-time curve and time taken to reach peak plasma concentration, respectively, when compared with the ATV suspension. Thus, we successfully developed an optimized ATV-loaded SMEDDS formulation by using the D-optimal mixture design, that could potentially be used for improving the oral absorption of poorly water-soluble drugs.

Exploring the Preparation of Albendazole-Loaded Chitosan-Tripolyphosphate Nanoparticles

The objective of this study was to improve the solubility of albendazole and optimize the preparation of an oral nanoparticle formulation, using β-cyclodextrin (βCD) and chitosan-tripolyphosphate (TPP) nanoparticles. The solubility of albendazole in buffers, surfactants, and various concentrations of acetic acid solution was investigated. To determine drug loading, the cytotoxic effects of the albendazole concentration in human hepatocellular carcinoma cells (HepG2) were investigated. The formulations were prepared by mixing the drug solution in Tween 20 with the chitosan solution. TPP solution was added dropwise with sonication to produce a nanoparticle through ionic crosslinking. Then the particle size, polydispersity index, and zeta potential of the nanoparticles were investigated to obtain an optimal composition. The solubility of albendazole was greater in pH 2 buffer, Tween 20, and βCD depending on the concentration of acetic acid. Drug loading was determined as 100 µg/mL based on the results of cell viability. The optimized ratio of Tween 20, chitosan/hydroxypropyl βCD, and TPP was 2:5:1, which resulted in smaller particle size and proper zeta positive values of the zeta potential. The chitosan-TPP nanoparticles increased the drug solubility and had a small particle size with homogeneity in formulating albendazole as a potential anticancer agent.

Preparation and characterisation of Kolliphor® P 188 and P 237 solid dispersion oral tablets containing the poorly water soluble drug disulfiram

The oral route of administration is the most common and preferred route of drug delivery due to its ease of administration, cost-effectiveness and flexibility in design. However, limited aqueous solubility of the active pharmaceutical ingredient can result in poor bioavailability, which is a major issue for the pharmaceutical industry. Increasing numbers of new drugs are falling into class II of the Biopharmaceutical Classification System (BCS), where they have a low solubility and high tissue permeability, meaning that bioavailability is solubility dependent. Here we demonstrate the development and characterisation of solid dispersion oral tablets, containing the poorly water-soluble drug disulfiram, prepared using both the hot melt and solvent evaporation methods and manufactured from two different polymers, Kolliphor(®) P 188 and P 237, specifically designed for the manufacture of solid dispersions. This paper demonstrates that the disulfiram solid dispersions tablets have an enhanced release rate of disulfiram compared to the control tablets. The Kolliphor(®) P 188 polymer control tablets released approximately 48.8% of their disulfiram content over 8h, with the solvent evaporated tablets releasing approximately 65.8%, while the 60 and 80 °C hot melt tablets released approximately 73.2 and 100% of their disulfiram content respectively. A similar trend was seen with Kolliphor(®) P 237 as the control tablets released approximately 50.5% of their disulfiram content over 8h, while the solvent evaporated tablets released approximately 79.5% and the 60 and 80 °C hot melt tablets released 100.2 and 100.3% respectively. Depending on what method and polymer is used to manufacture the solid dispersions the disulfiram is either maintained completely or partially in its amorphous state and it is this which enhances its solubility and release rate from the tablets. The disulfiram in the Kolliphor(®) P 188 solvent evaporated and 60 °C hot melt tablets retained 50.5 and 44.1% of its crystallinity, while the disulfiram in the 80 °C hot melt tablets was completely amorphous. Whereas the disulfiram in the Kolliphor(®) P 237 solvent evaporated tablets retained 45.2% crystallinity, while the disulfiram in both of the hot melt tablets was completely in its amorphous form.

A new strategy for enhancing the oral bioavailability of drugs with poor water-solubility and low liposolubility based on phospholipid complex and supersaturated SEDDS

A novel supersaturated self-emulsifying drug delivery system (Super-SEDDS) loaded with scutellarin-phospholipid complex (SPC) was developed. The system aimed to address the limitations presented by conventional SEDDS as delivery carriers for drugs with poor water-solubility, low liposolubility and high dose. As an intermediate, SPC was first prepared based on the response surface design. The presence of amorphous scutellarin was demonstrated through differential scanning calorimetry (DSC) and X-ray diffraction (XRD), while enhanced liposolubility was confirmed through comparison with scutellarin powder via an octanol/water distribution test. On the basis of the solubility study and ternary phase diagram, Super-SEDDS containing SPC of up to 200% equilibrium solubility (S_eq) was designed, which composed of ethyl oleate, Cremophor RH40 and Transcutol HP with a ratio of 60∶25∶15 (w/w%). The subsequent in vitro lipolysis study and ex vivo intestinal absorption test indicated that Super-SEDDS enhanced the cumulative dissolution from 70% to 100% and improved the intestinal absorption from 0.04 to 0.12 µg/cm² compared with scutellarin powder. Furthermore, an in vivo study demonstrated that Super-SEDDS achieved the AUC_0-t of scutellarin up to approximate 1.7-fold as scutellarin powder. It was also proved superior to SPC and the conventional SEDDS. Super-SEDDS showed great potential for expanding the usage of SEDDS and could act as an alternative to conventional SEDDS.

Development and characterisation of a self-microemulsifying drug delivery systems (SMEDDSs) for the vaginal administration of the antiretroviral UC-781

UC-781 is highly selective and potent against HIV-1. However, its hydrophobic nature (logP 5.1) and lack of aqueous solubility have limited its development as a HIV microbicide. Self-microemulsifying drug delivery systems (SMEDDSs) have been developed to enhance the water solubility and bioavailability of hydrophobic drugs, such as UC781. In this study, we show the development of UC781-loaded SMEDDS and their enhanced release of UC781 from hard gelatine capsules, when compared to UC781 powder only. The majority of antiretrovirals being evaluated as potential HIV microbicides are hydrophobic. Therefore, a SMEDDS formulation offers an alternative approach to enhancing the vaginal absorption of these microbicidal candidates.

Formulation and in vitro evaluation of self-emulsifying formulations of Cinnarizine

The main objectives of this study were to improve the aqueous solubility and to modify in vitro dissolution profile of hydrophobic drug using self-emulsifying drug delivery systems (SEDDS). SEDDS were formulated using Capmul PG-12, Cremophor RH 40 and Tween 20 at different weight ratios and incorporated with Cinnarizine. The drug incorporation into pre-concentrate and drug solubility in phosphate buffer (pH 7.2) were investigated. In addition, the mean droplet size and drug release profile of the SEDDS were also determined. The drug incorporation was over 120 mg per 0.5 g pre-concentrate regardless of the composition of the formulations. The solubility of Cinnarizine in phosphate buffer (pH 7.2) was at least 1500 μM in the SEDDS. Formulations with only 10% w/w Capmul PG-12 were less than 20 nm in mean diameter while those produced with at least 20% w/w Capmul PG-12 were more than 100 nm regardless of the ratios of Cremophor RH 40 to Tween 20. SEDDS showed a significant increase of the mean percentage drug release than pure drug (p < 0.0001). In general, the SEDDS with 30% w/w of Capmul PG-12 provided the greatest enhancement in drug solubility in phosphate buffer as well as rapid drug release despite forming larger droplets upon emulsification. The combination of Capmul PG-12, Tween 20 and Cremophor RH 40 can produce SEDDS which can be used as an alternative dosage form for poorly water soluble drug.

Preparation and evaluation of Cremophor-free paclitaxel solid dispersion by a supercritical antisolvent process

OBJECTIVES

To avoid the major adverse effects induced by Cremophor EL formulated in the commercial paclitaxel products of Taxol.

METHODS

An injectable paclitaxel solid dispersion free of Cremophor was prepared by a supercritical antisolvent process and then was fully characterized and investigated with regard to its short-term and long-term stability. Pharmacokinetics in rats was also evaluated compared with the commercial product.

KEY FINDINGS

The solid dispersion system at a 1/20/40 weight ratio of paclitaxel/HP-β-CD/HCO-40 had a paclitaxel solubility of about 10 mg/ml, an almost 10 000-fold increase over its aqueous solubility. This system was physically stable for at least six months or four weeks in accelerated conditions (40 ± 2°C; RH: 75 ± 5%) and stress conditions (60°C), respectively. The precipitation time of paclitaxel solid dispersion in 0.9% sodium chloride injection at a concentration of 1000 µg/ml was above 70 h at room temperature. Intravenous administration of paclitaxel solid dispersion at a dose of 6 mg/kg revealed no significant differences when compared with the commercial product. However, our results obtained at a dose of 12 mg/kg showed a striking non-linear increase in the plasma Cmax and AUCall with increased dose. In addition, the concentrations of paclitaxel in various organs in the solid dispersion group were found to be higher than those of Taxol at 6 mg/kg, and the paclitaxel levels in these organs increased proportionately with increasing dose.

CONCLUSIONS

Nano-scale paclitaxel solid dispersion without Cremophor EL provided advantageous results over Taxol with respect to the physicochemical properties, safety, clinic convenience and pharmacokinetic behaviour in rats.

Positively-charged microemulsion for improving the oral bioavailability of alendronate: in-vitro and in-vivo assessment

Objectives

Alendronate is a poorly absorbed bisphosphonate with an oral bioavailability of 0.7%. In this study, a positively-charged microemulsion was prepared with the aim of improving the bioavailability of alendronate.

Methods

The positively-charged microemulsion was evaluated for physical stability, cellular uptake and permeability enhancement on Caco-2 monolayers. The bioavailability of alendronate from the microemulsion was compared with the commercially available tablet (Fosmax) for beagle dogs.

Key findings

The 2.0, 0.4 and 0.2% positively-charged microemulsion, stable for 4 h after preparation, promoted alendronate transport across the Caco-2 cells by a factor of 194, 146,and 45.1, respectively, compared with the alendronate solution, though no significant cellular uptake enhancement of alendronate was observed. The permeability enhancement was parallel to the reduction in transendothelial electrical resistance, which indicated the microemulsion modulated the tight junctions and widened the paracellular pathway. In-vivo results showed that the microemulsion gave the highest alendronate plasma concentration at 502 ng/ml (Cmax) after 0.563 h (Tmax), while tablets gave a Cmax of 152 ng/ml after 0.750 h (Tmax). Furthermore, the AUC0-∞ of alendronate from the microemulsion increased by 2.82-fold when compared with the tablets.

Conclusions

Based on the results, the oral bioavailability of alendronate could be significantly improved by the positively-charged microemulsion, which opened the tight junctions and thus increased absorption through the paracellular route.