Formulation and evaluation of novel solid lipid microparticles as a sustained release system for the delivery of metformin hydrochloride

Overview of Nanocosmetics with Emphasis on those Incorporating Natural Extracts

The cosmetic industry is rapidly rising worldwide. To overcome certain deficiencies of conventional cosmetics, nanomaterials have been introduced to formulations of nails, lips, hair, and skin for treating/alleviating hyperpigmentation, hair loss, acne, dandruff, wrinkles, photoaging, etc. Innovative nanocarrier materials applied in the cosmetic sector for carrying the active ingredients include niosomes, fullerenes, liposomes, carbon nanotubes, and nanoemulsions. These exhibit several advantages, such as elevated stability, augmented skin penetration, specific site targeting, and sustained release of active contents. Nevertheless, continuous exposure to nanomaterials in cosmetics may pose some health hazards. This review features the different new nanocarriers applied for delivering cosmetics, their positive impacts and shortcomings, currently marketed nanocosmetic formulations, and their possible toxic effects. The role of natural ingredients, including vegetable oils, seed oils, essential oils, fats, and plant extracts, in the formulation of nanocosmetics is also reviewed. This review also discusses the current trend of green cosmetics and cosmetic regulations in selected countries.

Freeze-drying of bupivacaine lipospheres: preparation, characterization, and evaluation of anti-microbial properties

PURPOSE

To prepare freeze-dried bupivacaine lipospheres intended for topical application in burn injuries. The aim was improving the storage stability and developing a prolonged release pattern to tackle the adverse reactions resulting from the frequent administration of bupivacaine.

METHODS

The lipospheres were prepared by hot-melt dispersion method employing bupivacaine base at 1.5 and 3%w/w, tristearin 6% w/w as the core while dipalmitoyl phosphatidylcholine (DPPC) and soy phosphatidylcholine (SPC) as the coat at 0.75, 1.5 and 3% w/w. The lotion was then freeze-dried and cryoprotected by sucrose 3% w/w. Evaluation was carried out through loading and release analysis, storage study, particle characterization including morphology, zeta potential and particle size as well as anti-microbial assessment.

RESULTS

The highest loading, (87.6 ± 0.1%), was achieved using bupivacaine 3% and SPC 0.75%. After 6 months of storage at 4 ͦC, the loading in the lotion and the freeze-dried samples were 17.4 ± 0.2 and 87.2 ± 0.3%, respectively. In vitro dissolution test demonstrated 94.5% and 95% of bupivacaine release from lotion and freeze-dried samples, after 24 h. The respective zeta potential of -1.30 and 26 mV was recorded for lotion and solid-state bupivacaine. Micromeritic evaluation of freeze-dried powder exhibited particle size of 35.23 ± 2.02 μm and highly-wrinkled-irregular morphology without detectable needle structures related to drug free crystals. The powder had rapid reconstitution property and antibacterial activity.

CONCLUSION

Freeze- drying holds a promising potential to improve the storage stability of bupivacaine lipospheres with well- preserved release pattern and particle properties for further topical application.

Metformin HCl-loaded transethosomal gel; development, characterization, and antidiabetic potential evaluation in the diabetes-induced rat model

Herein we designed, optimized, and characterized the Metformin Hydrochloride Transethosomes (MTF-TES) and incorporate them into Chitosan gel to develop Metformin Hydrochloride loaded Transethosomal gel (MTF-TES gel) that provides a sustained release, improved transdermal flux and improved antidiabetic response of MTF. Design Expert® software (Ver. 12, Stat-Ease, USA) was applied for the statistical optimization of MTF-TES. The formulation with Mean Particle Size Distribution (MPSD) of 165.4 ± 2.3 nm, Zeta Potential (ZP) of -21.2 ± 1.9 mV, Polydispersity Index (PDI) of 0.169 ± 0.033, and MTF percent Entrapment Efficiency (%EE) of 89.76 ± 4.12 was considered to be optimized. To check the chemical incompatibility among the MTF and other formulation components, Fourier Transform Infrared (FTIR) spectroscopy was performed and demonstrated with no chemical interaction. Surface morphology, uniformity, and segregation were evaluated through Transmission Electron Microscopy (TEM). It was revealed that the nanoparticles were spherical and round in form with intact borders. The fabricated MTF-TES has shown sustained release followed by a more pronounced effect in MTF-TES gel as compared to the plain MTF solution (MTFS) at a pH of 7.4. The MTF-TES has shown enhanced permeation followed by MTF-TES gel as compared to the MTFS at a pH of 7.4. In vivo antidiabetic assay was performed and results have shown improved antidiabetic potential of the MTF-TES gel, in contrast to MTF-gel. Conclusively, MTF-TES is a promising anti-diabetic candidate for transdermal drug delivery that can provide sustained MTF release and enhanced antidiabetic effect.

Comparison of the In Vitro Drug Release Methods for the Selection of Test Conditions to Characterize Solid Lipid Microparticles

The release profiles of active substances from microspheres are one of the most important features in solid lipid microparticles (SLM) characterization. Unfortunately, the results of the dissolution tests are largely dependent on the chosen method and test conditions, which in relation to novel dosage forms, such as dispersions of lipid microspheres, are not clearly defined in international compendiums and guidelines. This makes it impossible to compare the results of different studies. The aim of the research was to identify the factors most influencing the variability of the obtained results. An attempt was also made to select the most appropriate method for testing drug substance release from SLM. Various dissolution methods were employed (method I: without a membrane, method II: in a dialysis bag, and method III: in a Side-Bi-Side chamber), and the obtained release profiles of cyclosporine and indomethacin from SLM dispersions were compared. In addition to the effect of membranes, the types of acceptor fluids were also investigated. Significant differences were observed when testing the SLM formulations under various test conditions. The results were significantly influenced by the selected membrane, the acceptor fluid, or the difference in the concentrations of active substance between the donor and acceptor compartments. The burst effect observed in some experimental methods was not noticed in other conditions. At this stage, the method with a dialysis bag has been selected as the most suitable, while the methods without the membrane can only play a complementary role.

Protective effect of l-carnitine-loaded solid lipid nanoparticles against H2O2-induced genotoxicity and apoptosis

L-carnitine (LC) is a highly water-soluble compound involved in the β-oxidation of lipids and transportation of long-chain fatty acids across the membrane of mitochondria. However, the higher hydrophilicity of LC limits its free diffusion across the bilayer lipid membrane of intestinal epithelium in oral administration, decreasing oral bioavailability. Drug delivery with nanoparticles enhances cargo bioavailability and cellular uptake and improves therapeutic outcomes while decreasing unwanted side effects. Here, we proposed solid lipid nanoparticles (SLNs) as a hydrophobic carrier for LC delivery, aiming at increasing LC bioavailability and its protective role against intracellular oxidative stress damages. The LC-SLNs were prepared using the hot homogenization technique, and different physicochemical properties were investigated. The inhibition of H₂O₂-induced ROS generation in human umbilical vein endothelial cells (HUVECs) with plain LC and LC-SLNs was investigated. Moreover, various in vitro experiments were performed to assess whether LC-SLNs can protect HUVECs from H₂O₂-induced genotoxicity and apoptosis. The monodispersed and spherical blank SLNs and LC-SLNs were 104 ± 1.8 and 128 ± 1.5 nm, respectively with a drug loading (DL) of 11.49 ± 0.78 mg/mL and acceptable encapsulation efficiency (EE%) (69.09 ± 1.12) of LC-SLNs. The formulation process did not affect the antioxidant properties of LC. MTT assay and comet assay demonstrated that the LC-SLNs decreased cytotoxicity and genotoxicity of H₂O₂, respectively on HUVECs. Besides, LC-SLNs more inhibited ROS generation, along with apoptotic events in H₂O₂-treated HUVECs compared to the plain LC. Altogether, our findings affirmed the protective effects of LC-SLNs against H₂O₂-induced genotoxicity and apoptosis in HUVECs. In conclusion, LC-SLN formulation is a promising drug delivery system to overcome the bioavailability issue of hydrophilic LC, enhancing the antioxidant and biological properties of the plain LC.

Potential enhancement of metformin hydrochloride in solidified reverse micellar solution-based PEGylated lipid nanoparticles targeting therapeutic efficacy in diabetes treatment

Metformin hydrochloride (MH) is a widely used oral biguanide antihyperglycemic (antidiabetic) drug with poor bioavailability which necessitates the development of novel drug delivery systems such as PEGylated solid lipid nanoparticles for improving its therapeutic activity. The aim of this study was to formulate, characterize and evaluate in vitro and in vivo pharmacodynamic properties of metformin-loaded PEGylated solid lipid nanoparticles (PEG-SLN) for improved delivery of MH. The lipid matrices (non-PEGylated lipid matrix and PEGylated lipid matrices) used in the formulation of both non-PEGylated (J0) and PEGylated SLNs (J10, J20, J40) were prepared by fusion using beeswax and Phospholipon ® 90H at 7:3 ratio with or without polyethylene glycol (PEG) 4000 (0, 10, 20 and 40% w/w), respectively. Representative lipid matrices (LM and PEG-LM) were loaded with MH by fusion and then characterized by differential scanning calorimetry (DSC) and Fourier transform infrared (FT-IR) spectroscopy. The PEG-SLNs were prepared by high shear hot homogenization using the lipid matrices (5% w/w), drug (MH) (1.0% w/w), sorbitol (4% w/w) (cryoprotectant), Tween ® 80 (2% w/w) (surfactant) and distilled water (q.s to 100% w/w) (vehicle). The non-PEGylated and PEGylated SLNs (J0, J10, J20, J40)) were characterized with respect to encapsulation efficiency (EE%), loading capacity (LC), morphology by scanning electron microscopy (SEM), mean particle size (Zav) and polydispersity indices (PDI) by photon correlation spectroscopy (PCS), compatibility by FT-IR spectroscopy and in vitro drug release in biorelevant medium. Thereafter, in vivo antidiabetic study was carried out in alloxanized rats' model and compared with controls (pure sample of MH and commercial MH- Glucophage®)). Solid state characterizations indicated the amorphous nature of MH in the drug loaded-lipid matrices. The PEG-SLNs were mostly smooth and spherical nanoformulations with Zav and PDI of 350.00 nm and 0.54, respectively, for non-PEGylated SLNs, and in the range of 386.80-783.10 nm and 0.592 to 0.752, respectively, for PEGylated SLNs. The highest EE% and LC were noted in batch J20 and were 99.28% and 16.57, respectively. There was no strong chemical interaction between the drug and excipients used in the preparation of the formulations. The PEGylated SLN (batch J40) exhibited the highest percentage drug released (60%) at 8 h. The PEGylated SLNs showed greater hyperglycemic control than the marketed formulation (Glucophage ®) after 24 h. This study has shown that metformin-loaded PEGylated solid lipid nanoparticles could be employed as a potential approach to improve the delivery of MH in oral diabetic management, thus encouraging further development of the formulations.

Enhanced circulation longevity and pharmacodynamics of metformin from surface-modified nanostructured lipid carriers based on solidified reverse micellar solutions

Metformin hydrochloride (MTH) has been associated with poor/incomplete absorption (50–60%), low bioavailability, short half-life (0.4–0.5 h), high dosage and dose-related side effects. To overcome these barriers and improve oral bioavailability and efficacy of MTH, surface-modified nanostructured lipid carriers (NLCs) were developed. Lipid matrices composed of rational blends of beeswax and Phospholipon® 90H (as solid lipids) and Capryol-PGE 860 (as liquid lipid) were prepared by fusion, and the resultant lipid matrices were PEGylated to give 10, 20 and 40% PEGylated lipid matrices. MTH-loaded non-PEGylated and PEGylated NLCs were prepared via high-shear hot homogenization and characterized regarding particle properties and physicochemical performance. The encapsulation efficiencies (EE%) and loading capacities (LC) of the MTH-loaded NLCs were determined while the in vitro drug release was evaluated in phosphate buffered saline (PBS, pH 7.4). Antidiabetic and pharmacokinetics properties of the NLCs were ascertained in an alloxan-induced diabetic rats model after oral administration. The MTH-loaded NLCs were nanomeric (particle size: 184.8–882.50 nm) with low polydispersity index (0.368–0.687) and zeta potential (26.5–34.2 mV), irregular shape, amorphous nature with reduced crystallinity. The EE% and LC were >90 % and 16%, respectively. The formulations showed >65 % release over 12 h in a greater sustained manner than marketed MTH formulation (Glucophage®) as well as enhanced pharmacokinetics properties and sustained blood glucose lowering effect, even at reduced doses with PEGylated NLCs than Glucophage®. Thus, PEGylated NLC is a promising approach for improved delivery and oral bioavailability of MTH thus encouraging further development of the formulation.

Distribution of Drug Substances in Solid Lipid Microparticles (SLM)—Methods of Analysis and Interpretation

The incorporation of drug substances into the matrix of solid lipid microparticles (SLM) is critical to providing effects such as prolonged release, taste masking, and protection of the labile API. Currently, a commonly used method of characterizing multi-compartment lipid systems, such as SLM, is to determine entrapment efficiency (EE) and drug loading (DL) parameters, but this is not sufficient for understanding the localization of API either in the core or on the surface of the microspheres. The main objective of the research was to study the distribution of API in an aqueous dispersion of SLM in order to distinguish between the API incorporated in the lipid matrix and localized in the superficial region (interphase) and to refer the obtained results to the EE and DL parameters. SLM dispersions (10–30% of the lipid) with four model drug substances, i.e., cyclosporine, clotrimazole, diclofenac sodium and hydrocortisone, were prepared and investigated. In the first stage, the experiments were designed to optimize the method of extracting the API fraction localized on the SLM surface by shaking the dispersions with methanol. The fraction dissolved in the aqueous phase was obtained by ultrafiltration of SLM dispersions. Total drug content and the concentration in the separated phases were determined by the HPLC method. The obtained results were compared with the EE and DL parameters. Selected SLM dispersions were tested both before and after thermal sterilization. Short-term shaking of SLM dispersion with methanol does not damage the lipid matrix and allows the API fraction localized on the SLM surface to be extracted, the result of which was the determination of API distribution between lipid matrix, interphase and aqueous phase. It was found that the majority of API represented by EE value was localized on the surface of SLM. Only for cyclosporine was the incorporation of drug molecules in the lipid core very effective (up to 48%), while for other drug substances only 1–21% was found in the lipid core of SLM. A clear influence of the sterilization process on the distribution of API within the microparticles was found. The presented studies showed that the characterization of multi-compartment SLM dispersions solely on the basis of EE and DL values, is insufficient. The proposed new distribution test method enables the localization of API to be demonstrated within the microspheres, with the quantitative characteristics of the drug fraction incorporated in the lipid matrix and the fraction associated with the surface of the lipid matrix. The proposed new method allows the influence of the sterilization process on the changes in the API distribution within the lipospheres to be evaluated. Such characteristics provide new opportunities for the development and use of this dosage form as a carrier providing prolonged release and other aforementioned advantages.

Formulation, Optimization, In Vitro and In Vivo Evaluation of Saxagliptin-Loaded Lipospheres for an Improved Pharmacokinetic Behavior

The development and optimization of controlled release lipospheres (LS) from safe biocompatible behenic acid (BA) was performed for not only enhancing patient's compliance against highly prevailed chronic diabetes but also to vanquish the insufficiencies of traditional methods of drug delivery. The Box-Bhenken design (BBD) was utilized to statistically investigate the impact of formulation variables on percentage yield (Y ₁), entrapment efficiency (Y ₂), and SG-release (Y ₃) from saxagliptin- (SG-) loaded LS, and the chosen optimized LS were subjected to a comparative in vivo pharmacokinetic analysis against commercially available SG brand. The compatibility analysis performed by DSC and FTIR established a complete lack of interaction of formulation components with SG, while p-XRD suggested a mild transformation of crystalline drug to its amorphous form during encapsulation process. The spherical, free flowing smooth surface LS having zeta potential of -32 mV and size range of 11-20 μm were conveniently formulated. The obtained data for Y ₁ (30-80%), Y ₂ (30-70%), and Y ₃ (40-90%) showed a best fit with quadratic model. The pharmacokinetics analysis of LS showed a significantly decreased C _max of SG (75.63 ± 3.85) with a sufficiently elevated T _max (10.53 h) as compared to commercial brand of SG (99.66 ± 2.97 ng/mL and 3.55 ± 2.18 h). The achievement of greater bioavailability of SG was most probably attributed to higher level of half-life, mean residence time (MRT), and AUC_0-24 for SG released from LS. Conclusively, the novel approach of SG-loaded LS had successfully sustained the plasma SG level for a prolonged time without increasing C _max which would ultimately bring an effective management of chronic diabetes.

Formulation, characterization and statistical optimization of enalapril-loaded lipospheres

Lipid-based polymers have been proved efficient drug carriers for overcoming the insufficiencies of conventional formulations. Ceresin wax was employed to improve permeability, oral bioavailability and patient compliance by preparing enalapril (EP)-loaded lipospheres with a simple solvent evaporation method. A Box–Behnken design with the proposed polynomial equations and quadratic model was applied to investigate and statistically validate the collective influence of formulation variables on lipospheres. Spherical smooth-surfaced lipospheres with an average size of 55 μm with excellent micromeritic properties were produced. Differential scanning calorimetry, X-ray diffraction and Fourier transmission infrared spectroscopy findings proved the lack of any possible interaction between formulation components. The zeta potential ranged from −5 to −20 mV, suggesting the significant stability of lipospheres. Responses such as percentage yield (29–68%), entrapment efficiency (21–53%) and drug release (42–93%) were found to be affected greatly by the concentrations of lipids and the surfactant, and the stirring speed. Reduced and sustained EP release from lipospheres may lower treatment cost and enhance hypertensive patients’ compliance.

Lipospheres for Simultaneous Controlled Release and Improved Pharmacokinetic Profiles of Saxagliptin-Enalapril: Formulation, Optimization, and Comparative In Vitro-In Vivo Evaluation

The current study aims at formulating and optimizing lipospheres (LS) by the Box-Behnken design (BBD) from safe biodegradable carnauba wax (CW) to co-administer saxagliptin (SG) and enalapril (EP) for co-existing chronic hypertensive diabetes in order to overcome inadequacies of conventional modes of drug administration. Optimized liposphere formulation (OLF) was selected by a numerical optimization procedure and a comparative in vivo pharmacokinetic study of OLF and commercial brands was also performed. Discrete, free-flowing, spherical, smooth-surface LS having a size range of 5-10 μm and zeta potential of - 20 to - 30 mV were successfully formulated. Compatibility studies by FTIR and DSC proved the lack of interaction of components while XRD suggested the transformation of crystalline drugs to amorphous form. Outcomes of dependent optimizing variables like percentage yield (30-90%), EP-release (32-92%), and SG-release (28-95%) followed a polynomial quadratic model. Pharmacokinetics studies indicated a significantly lower C_max of EP (125.22 ± 6.32) and SG (75.63 ± 3.85) and higher mean T_max values (9.4 h for EP and 10.73 h for SG) from OLF in comparison with reference brands of EP (257.54 ± 8.23 ng/mL) and SG (393.66 ± 2.97 ng/mL). Additionally, a potential rise in half-life and MRT of SG and EP was achieved reaching approximately 2- to 3-fold higher than noted for reference brands. Importantly, the enhanced T_max and AUC_0-24 specified the achievement of enhanced bioavailability of both drugs from LS. Consequently, such an innovative approach could not only control drug release in both in vitro and in vivo analyses but also maintain plasma drug concentration for a longer time without maximizing C_max leading towards effective management of chronic illnesses.

Anhydrous reverse micelle nanoparticles: new strategy to overcome sedimentation instability of peptide-containing pressurized metered-dose inhalers

The objective of this study was to develop a novel anhydrous reverse micelle nanoparticles (ARM-NPs) system to overcome the sedimentation instability of peptide-containing pressurized metered-dose inhalers (pMDIs). A bottom-up method was utilized to fabricate ARM-NPs. Tertiary butyl alcohol (TBA)/water system, freeze-drying and lipid inversion method were successively used to produce the ARM-NPs for pMDI. Various characteristics of ARM-NPs were investigated including particle size, morphology, secondary structure of the peptide drug, aerosolization properties and storage stability. As revealed by the results, ARM-NPs with spherical shape possessed 147.7 ± 2.0 nm of particle size with 0.152 ± 0.021 PdI. The ARM-NPs for pMDI had satisfactory fine particle fraction (FPF) value of 46.99 ± 1.33%, while the secondary structure of the peptide drug was unchanged. Stability tests showed no pronounced sedimentation instability for over 12 weeks at 4–6 °C. Furthermore, a hypothesis was raised to explain the formation mechanism of ARM-NPs, which was verified by the differential scanning calorimetry analysis. The lecithin employed in the reverse micelle vesicles could serve as a steric barrier between peptide drugs and bulk propellant, which prevented the instability of peptide drugs in hydrophobic environment. Homogenous particle size could avoid Ostwald ripening phenomenon of particles in pMDIs. It was concluded that the ARM-NPs for pMDI could successfully overcome sedimentation instability by the steric barrier effect and homogeneous particle size.

Investigation of novel solid lipid microparticles based on homolipids from Bos indicus for the delivery of gentamicin

Background:

The aim of this study was to formulate solidified reverse micellar solution (SRMS)-based solid lipid microparticles (SLMs) using homolipids from tallow fat (Bos indicus) and evaluate its potential for enhanced delivery of gentamicin.

Materials and Methods:

SLMs were formulated by melt-emulsification using SRMS (15% w/w Phospholipon^® 90G in 35% w/w Bos indicus), polyethylene glycol 4000 (PEG) and gentamicin (1.0, 2.0, 3.0% w/w), and characterized with respect to size, morphology, encapsulation efficiency % and pH-dependent stability. The in vitro release of gentamicin from the SLMs was performed in phosphate buffer (pH 7.4) while bioevaluation was carried out using clinical isolates of Staphylococcus aureus and Escherichia coli.

Results:

Results showed that the lipid matrix accommodated gentamicin in a concentration-dependent manner, and that stable and spherical SLMs with size range of 18.62 ± 1.24-20.59 ± 1.36 μm and 21.35 ± 1.57-50.62 ± 2.37 μm respectively for unloaded and drug-loaded formulations were obtained. The in vitro drug release studies revealed that SRMS-based SLMs could better be used to control the release of gentamicin than gentamicin injection. Results of sensitivity test revealed that the SLMs time-dependently and capacity-limitedly produced greater inhibition zone diameters (IZDs) than the standards, an indication of improved bioactivity against the test organisms, with greater IZDs against S. aureus than E. coli. Overall, SLMs containing 2% w/w SRMS, 3% w/w gentamicin and PEG 4000 entrapped the highest amount of drug, achieved complete drug release and gave highest IZD against the organisms within 420 min, while plain gentamicin gave the least.

Conclusion:

This research has shown that SLMs based on Bos indicus and P90G is a potential carrier system for dissolution and bioactivity enhancement of gentamicin.

Microparticulate and nanoparticulate drug delivery systems for metformin hydrochloride

CONTEXT

Metformin hydrochloride is a biguanide derivative widely used for the treatment of type 2 diabetes, prescribed nearly to 120 million people worldwide. Metformin has a relatively low oral bioavailability (about 50-60%). Although the major effect of metformin is to decrease hepatic glucose output as an antihyperglycemic agent, its inhibitory effects on the proliferation of some cancer cells (e.g. prostate, breast, glioma cells) have been demonstrated in the cell culture studies. Development of novel formulation (e.g. microparticles, nanoparticles) strategies for metformin might be useful to improve its bioavailability, to reduce the dosing frequency, to decrease gastrointestinal side effects and toxicity and to be helpful for effective use of metformin in cancer treatment.

OBJECTIVE

The main aim of this review is to summarize metformin HCl-loaded micro- and nanoparticulate drug delivery systems.

METHOD

The literature was rewieved with regard to the physicochemical, pharmacological properties of metformin, and also its mechanism of action in type 2 diabetes and cancer. In addition, micro- and nanoparticulate drug delivery systems developed for metformin were gathered from the literature and the results were discussed.

CONCLUSION

Metformin is an oral antihyperglycemic agent and also has potential antitumorigenic effects. The repeated applications of high doses of metformin (as immediate release formulations) are needed for an effective treatment due to its low oral bioavailability and short biological half-life. Drug delivery systems are very useful systems to overcome the difficulties associated with conventional dosage forms of metformin and also for its effective use in cancer treatment.

Characterization and evaluation of metformin-loaded solid lipid nanoparticles for celluar and mitochondrial uptake

Considered a popular drug for diabetes in recent years, metformin was determined to have a moderate anti-tumor effect, particularly in breast cancer. In this study, the anticancer mechanism of metformin was verified by preparing solid lipid nanoparticles (SLNs) and chitosan-modified solid lipid nanoparticles (CSLNs) containing metformin and then estimating the potential of these SLNs for uptake in cells and mitochondria. Metformin-SLNs were prepared using an emulsification and low-temperature solidification method. The mean particle size, zeta potential, entrapment efficiency, and loading efficiency of metformin-SLNs and metformin chitosan-modified SLNs were 102.3 ± 4.16 and 200.1 ± 17.69 nm, -21.25 ± 4.89 and 50.6 ± 4.09 mv, 26.25 ± 2.59% and 33.6 ± 2.21%, and 1.74 ± 0.16% and 1.46 ± 0.10%, respectively. TEM images showed that both the nanoparticles had spherical morphologies with no aggregation. Results of cellular and mitochondrial uptake showed that the metformin-SLNs were easier to uptake in cells and mitochondria than the pure drug group (that was the control group without SLN structure modification). The findings of this research provide a basis for conducting further studies on the anticancer mechanism of metformin.

Formulation in vitro and in vivo evaluation of SRMS-based heterolipid-templated homolipid delivery system for diclofenac sodium

The sole objective of this work was to design successful dosage oral forms of diclofenac sodium (DiNa)-loaded solid lipid microparticles (SLM) based on solidified reverse micellar solution (SRMS). Hot homogenization technique was employed to prepare DicNa SLM using a mixture goat fat and Phospholipon® 90 G as lipid matrix and Tween®-80 as mobile surfactant. Characterization based on percentage yield, morphology, particle size, zeta potential, percentage encapsulation, pH and stability of SLMs were investigated. Anti-inflammatory, gastrointestinal tract (GIT) sparing effect and pharmacokinetics were carried out in rat model after oral administration. Results showed that the SLMs were spherical and smooth. The optimized formulation (SLM-4) had particle size of 79.40 ± 0.31 µm, polydispersity index of 0.633 ± 0.190, zeta potential of -63.20 ± 0.12 mV and encapsulation efficiency of 91.2 ± 0.1% with good stability after 8 months of storage. The DicNa SLM had sustained release effect with good anti-inflammatory activity. Higher and prolonged plasma DicNa concentration was shown by the SLM-4 compared to pure drug and a conventional sample. These studies demonstrate that DicNa-loaded SLM based on SRMS could be a promising oral formulation for enhanced bioavailability, pharmacologic activity and gastrointestinal sparing effect of the NSAID, DicNa.

Perspective and potential of oral lipid-based delivery to optimize pharmacological therapies against cardiovascular diseases

Cardiovascular diseases (CVDs) remain the major cause of morbidity and mortality globally. Despite the large number of cardiovascular drugs available for pharmacological therapies, factors limiting the efficient oral use are identified, including low water solubility, pre-systemic metabolism, food intake effects and short half-life. Numerous in vivo proof-of-concepts studies are presented to highlight the viability of lipid-based delivery to optimize the oral delivery of cardiovascular drugs. In particular, the key performance enhancement roles of oral lipid-based drug delivery systems (LBDDSs) are identified, which include i) improving the oral bioavailability, ii) sustaining/controlling drug release, iii) improving drug stability, iv) reducing food intake effect, v) targeting to injured sites, and vi) potential for combination therapy. Mechanisms involved in achieving these features, range of applicability, and limits of available systems are detailed. Future research and development efforts to address these issues are discussed, which is of significant value in directing future research work in fostering translation of lipid-based formulations into clinical applications to reduce the prevalence of CVDs.