Pharmaceutical characterization of commercially available intravenous fat emulsions: estimation of average particle size, size distribution and surface potential using photon correlation spectroscopy

Towards Effective Antiviral Oral Therapy: Development of a Novel Self-Double Emulsifying Drug Delivery System for Improved Zanamivir Intestinal Permeability

Self-double emulsifying drug delivery systems have the potential to enhance the intestinal permeability of drugs classified under the Biopharmaceutics Classification System (BCS) class III. One such example is the antiviral agent zanamivir, exhibiting suboptimal oral absorption (with a bioavailability range of 1-5%). To address this challenge, we have developed an innovative oral formulation for zanamivir: a self-double nanoemulsifying Winsor delivery system (SDNE-WDS) consisting of the microemulsion, which subsequently yields final double nanoemulsion (W1/O/W2) upon interaction with water. Two distinct formulations were prepared: SDNE-WDS1, classified as a W/O microemulsion, and SDNE-WDS2, discovered to be a bicontinuous microemulsion. The inner microemulsions displayed a consistent radius of gyration, with an average size of 35.1 ± 2.1 nm. Following self-emulsification, the resultant zanamivir-loaded nanoemulsion droplets for zSDNE-WDS1 and zSDNE-WDS2 measured 542.1 ± 36.1 and 174.4 ± 3.4 nm, respectively. Both types of emulsions demonstrated the ability to enhance the transport of zanamivir across a parallel artificial membrane. Additionally, in situ rat intestinal perfusion studies involving drug-loaded SDNE-WDSs revealed a significantly increased permeability of zanamivir through the small intestinal wall. Notably, both SDNE-WDS formulations exhibited effective permeability (Peff) values that were 3.5-5.5-fold higher than those of the low/high permeability boundary marker metoprolol. This research emphasizes the success of SDNE-WDSs in overcoming intestinal permeability barriers and enabling the effective oral administration of zanamivir. These findings hold promise for advancing the development of efficacious oral administration of BCS class III drugs.

Lipid emulsions in clinical nutrition: Enteral and parenteral nutrition

Clinical nutrition emulsions are important products that can be life-saving for many patients suffering from gastrointestinal tract disorders, swallowing impairment, cancer, liver diseases, and many other clinical conditions. The transfer of lipids to the human body can be either intravenously (Parenteral Nutrition, PN) or through the gastrointestinal tract (Enteral Nutrition, EN). PN emulsions are considered pharmaceuticals and thus regulated accordingly. On the other hand, EN emulsions are classified as Food for Specific Medical Purposes (FSMP) and do not follow pharmaceutical regulations. Regarding product design, PN emulsions must follow theoretical emulsion formulation and production aspects, but special requirements regarding droplet size distribution must be followed to comply with national pharmacopeia monographs. Furthermore, a full clinical program on clinical evidence to prove safety and efficacy must be provided for marketing approval. On the contrary, EN emulsions require limited clinical evidence to substantiate health or clinical benefits. A short introduction to clinical nutrition with a focus on lipid emulsions is presented in this chapter. Furthermore, a general overview of the composition and main ingredients of clinical nutrition lipid emulsions is reviewed. Main clinical aspects are also mentioned here, highlighting the difficulties of clinically proving the efficacy of these products. The manufacturing and control of clinical nutrition emulsions are also reviewed, focusing on PN products and the main regulatory requirements related to the safety of these intravenous emulsions. Finally, stability and physicochemical properties are reviewed, and examples of commercially available products are used to illustrate these properties linked to the stability of these products. Lipids in clinical nutrition is a moving field and we do hope this chapter may remain a valuable source to understand newly emerging research on this topic.

Enhanced bioaccessibility and stability of iron through W/O/W double emulsion-based solid lipid nanoparticles and coating with water-soluble chitosan

W/O/W double emulsion-based iron-solid lipid nanoparticles (Fe-SLNs) and water-soluble chitosan-coated Fe-SLNs (WSC-Fe-SLNs) were developed to increase the bioaccessibility and stability of iron. Fe-SLNs exhibited a small diameter (158.17 ± 0.72 nm) and adequate zeta potential (-34.31 ± 0.41 mV) to maintain stable dispersion. The coating with WSC resulted in an increase in particle diameter (up to 226.13 ± 1.97 nm) and change of zeta potential to positive value (+47.83 ± 1.24 mV) because of the amine groups of chitosan. The lipid peroxidation of the Fe-SLNs and WSC-Fe-SLNs was substantially lower than that of pure iron. Both Fe-SLNs and WSC-Fe-SLNs were also able to protect the encapsulated iron in simulated gastric fluid, while effectively releasing almost 80% of the iron in simulated intestinal fluid. The Fe-SLNs and WSC-Fe-SLNs showed a great potential as functional materials to apply to various food industries through enhancement of physical stability and bioaccessibility of the encapsulated iron.

Nanoencapsulation as a Promising Platform for the Delivery of the Morin-Cu(II) Complex: Antibacterial and Anticancer Potential

Nanoencapsulation has emerged as a promising approach for the effective delivery of poorly aqueous soluble compounds. The current study focuses on the preparation of human serum albumin (HSA)-based nanoparticles (NPs) and poly lactic-co-glycolic acid (PLGA)-based nanoparticles for effective delivery of the morin-Cu(II) complex. The NPs were analyzed based on different parameters such as particle size, surface charge, morphology, encapsulation efficiency, and in vitro release properties. The average particle sizes were found to be 214 ± 6 nm for Mor-Cu-HSA-NPs and 185 ± 7.5 nm for Mor-Cu-PLGA-NPs. The release of the morin-Cu(II) complex from both the NPs (Mor-Cu-HSA-NPs and Mor-Cu-PLGA-NPs) followed a biphasic behavior, which comprises an early burst release followed by a sustained and controlled release. The resulting NPs also exhibit free radical scavenging activity confirmed by a standard antioxidant assay. The antibacterial activities of the NPs were investigated using a disk diffusion technique, and it was observed that both the NPs showed better antibacterial activity than morin and the morin-Cu(II) complex. The anticancer activities of the prepared NPs were examined on MDA-MB-468 breast cancer cell lines using a cytotoxicity assay, and the mode of cell death was visualized using fluorescence microscopy. Our results revealed that NPs kill the cancer cells with greater efficiency than free morin and the morin-Cu(II) complex. Thus, both HSA-based NPs and PLGA-based NPs can act as promising delivery systems for the morin-Cu(II) complex and can be utilized for further biomedical applications.

CONTINUOUS PRODUCTION OF RALOXIFENE HYDROCHLORIDE LOADED NANOSTRUCTURED LIPID CARRIERS USING HOT-MELT EXTRUSION TECHNOLOGY

The aim of this study was to utilize a continuous process for the production of orally administered raloxifene hydrochloride (RX-HCl) loaded nanostructured lipid carrier (NLC) formulations for extended drug release using hot-melt extrusion (HME) technology coupled with probe sonication, and also to evaluate the in vitro characteristics of the prepared NLCs. Preparation of the NLCs using HME technology involved two main steps, first formation of a pre-emulsion after extrusion and then size reduction of the pre-emulsion using probe sonication to obtain the NLCs. A screw speed of 100 rpm and a barrel temperature of 85 °C, were used in the extrusion process. NLCs prepared by HME technology showed a lower particle size compared to those prepared by the conventional probe sonication method. The prepared NLCs had high entrapment efficiency values (>90 %). In vitro drug release was evaluated using dialysis bag diffusion technique and USP apparatus I. Overall, the RX-HCl loaded NLCs had a higher rate of drug release than the pure drug. The release profile for the F4-3 NLC formulations and pure drug at the beginning and end of the stability study were comparable. The particle size of the prepared NLCs remained stable over the storage period and all PDI and zeta potential values were ≤ 0.5 and in the range of -15 to -30 mV, respectively, indicating good physical stability of the formulations. In summary, HME technology and probe sonication were successfully used to prepare RX-HCl loaded NLC formulations with shorter processing times as compared to the conventional probe sonication method, which makes this technique a uniquely more industry-friendly method.

Curcumin-loaded Pluronic® F-127 Micelles as a Drug Delivery System for Curcumin-mediated Photodynamic Therapy for Oral Application

Antimicrobial photodynamic therapy (aPDT) is promising for oral decontamination. Curcumin has been used as photosensitizer; however, the hydrophobic properties can negatively affect aPDT. This study evaluated the aPDT efficacy using Cur-loaded Pluronic^® F-127 micelles against Streptococcus mutans and Candida albicans biofilms. Micelles characterization was performed by zeta potential, dynamic light scattering, transmission electron microscopy, absorption and fluorescence spectroscopy. Cur concentrations, cell viability by CFU mL^-1 and confocal microscopy were determined. Data were analyzed by parametric and nonparametric tests under 5%. Cur-loaded Pluronic^® F-127 exhibited spherical shape, suitable particle size (≤100 nm), adequate polydispersity index, best stability, lower photodegradation and autoaggregation compared to unloaded-Cur. Both microorganisms were sensitive to Cur-loaded Pluronic^® F-127 micelles aPDT, with minimum inhibitory concentration (MIC) of 270 μm and 2.1093 μm for S. mutans and C. albicans suspended culture, respectively. Cur-loaded Pluronic^® F-127 aPDT exhibited antibacterial/antifungal effect against the biofilms (~3 log₁₀ reduction; P ≤ 0.05); however, similar to unloaded (P ≥ 0.05). Confocal images confirmed these results. Cur-loaded Pluronic^® F-127 micelles exhibited good photo-chemical properties and may be a viable alternative to deliver Cur and to improve aPDT effect during the treatment of dental caries. Moreover, Pluronic^® micelles can enhance the solubility, stability, permeability and control the release of Cur.

Optimization of nanostructured lipid carriers for Zidovudine delivery using a microwave-assisted production method

An adapted methodology for obtaining lipid nanoparticles that only uses the microwave reactor in the synthesis process was developed. The method has the following features: one-pot, one-step, fast, practical, economical, safe, readiness of scaling-up, lack of organic solvents and production of nanoparticles with low polydispersity index (PDI) (below 0.3). This new method was applied for the development of nanostructured lipid carriers (NLC) loaded with a hydrophilic drug, the antiretroviral agent zidovudine (AZT). The aim of the present work was to develop, evaluate and compare optimized NLC formulations produced by two different methods - hot ultrasonication and microwave-assisted method. The development and optimization of the NLC formulations were supported by a Quality by Design (QbD) approach. All formulations were physicochemically characterized by the same parameters. The optimized formulations presented a suitable profile for oral administration (particle size between 100 and 300 nm, PDI < 0.3 and negative zeta potential >-20 mV). Furthermore, the morphologies assessed by TEM showed spherical shape and confirmed the results obtained by DLS. Both AZT loaded formulations were physically stable for at least 45 days and non-toxic on Jurkat T cells. Drug release studies showed a controlled release of AZT under gastric and plasma-simulated conditions.

Increased therapeutic efficacy of a newly synthesized tyrosinase inhibitor by solid lipid nanoparticles in the topical treatment of hyperpigmentation

Hyperpigmentation caused by melanin overproduction is a major skin disorder in humans. Inhibition of tyrosinase, a key regulator of melanin production, has been used as an effective strategy to treat hyperpigmentation. In this study, we investigated the use of solid lipid nanoparticles (SLNs) as a highly effective and nontoxic means to deliver a newly synthesized potent tyrosinase inhibitor, MHY498, and to target melanocytes through the skin. MHY498-loaded SLNs (MHY-SLNs) were prepared by an oil-in-water emulsion solvent-evaporation method, and their morphological and physicochemical properties were characterized. MHY-SLNs showed a prolonged drug-release profile and higher skin permeation than that of MHY solution. In an in vivo evaluation of antimelanogenic activity, MHY-SLNs showed a prominent inhibitory effect against ultraviolet B-induced melanogenesis, resulting in no change in the skin color of C57BL/6 mouse, compared with that observed in an MHY solution-treated group and an untreated control group. The antimelanogenic effect of MHY-SLNs was further confirmed through Fontana-Masson staining. Importantly, MHY-SLNs did not induce any toxic effects in the L929 cell line. Overall, these data indicate that MHY-SLNs show promise in the topical treatment of hyperpigmentation.

Improvement of oral bioavailability of lovastatin by using nanostructured lipid carriers

Nanostructured lipid carriers (NLCs) have been one of the systems of choice for improving the oral bioavailability of drugs with poor water solubility. In the present study, lovastatin (LVT)-loaded NLCs (LVT-NLCs) were successfully prepared by hot high-pressure homogenization method with high entrapment efficiency, drug loading, and satisfactory particle size distribution. The particles had almost spherical and uniform shapes and were well dispersed with a particle size of <50 nm (23.5 ± 1.6 nm) and a low polydispersity index (0.17 ± 0.05 mV). The result of stability showed that the LVT-NLCs dispersion maintained excellent stability without exhibiting any aggregation, precipitation, or phase separation at 4 °C for 6 months of storage. The LVT release data from all developed solid lipid nanoparticles (SLNs) and NLCs were best fitted to a Ritger-Peppas kinetic model (0.9832 and 0.9783 for NLCs and SLNs, respectively). This indicated that the release of LVT from the SLNs and NLCs was due to a combination of drug diffusion and erosion from the lipid matrix. The pharmacokinetic and pharmacodynamic results show that LVT-NLCs were better compared to free drug, which could be attributed to an increase in bioavailability.

Lipid effects on expulsion rate of amphotericin B from solid lipid nanoparticles

We aimed to investigate the effects that natural lipids, theobroma oil (TO) and beeswax (BW), might have on the physical properties of formulated nanoparticles and also the degree of expulsion of encapsulated amphotericin B (AmB) from the nanoparticles during storage. Lecithin and sodium cholate were used as emulsifiers whilst oleic acid (OA) was used to study the influence of the state of orderliness/disorderliness within the matrices of the nanoparticles on the degree of AmB expulsion during storage. BW was found to effect larger z-average diameter compared with TO. Lecithin was found to augment the stability of the nanoparticles imparted by BW and TO during storage. An encapsulation efficiency (%EE) of 59% was recorded when TO was the sole lipid as against 42% from BW. In combination however, the %EE dropped to 39%. When used as sole lipid, TO or BW formed nanoparticles with comparatively higher enthalpies, 21.1 and 23.3 J/g respectively, which subsequently caused significantly higher degree of AmB expulsion, 81 and 83% respectively, whilst only 11.8% was expelled from a binary TO/BW mixture. A tertiary TO/BW/OA mixture registered the lowest enthalpy at 8.07 J/g and expelled 12.6% of AmB but encapsulated only 22% of AmB. In conclusion, nanoparticles made from equal concentrations of TO and BW produced the most desirable properties and worthy of further investigations.

A novel nanoscale-dispersed eye ointment for the treatment of dry eye disease

A novel nanoscale-dispersed eye ointment (NDEO) for the treatment of severe evaporative dry eye has been successfully developed. The excipients used as semisolid lipids were petrolatum and lanolin, as used in conventional eye ointment, which were coupled with medium-chain triglycerides (MCT) as a liquid lipid; both phases were then dispersed in polyvinyl pyrrolidone solution to form a nanodispersion. Single-factor experiments were conducted to optimize the formulations. A transmission electron micrograph showed that the ointment matrix was entrapped in the nanoemulsion of MCT, with a mean particle size of about 100 nm. The optimized formulation of NDEO was stable when stored for six months at 4 °C, and demonstrated no cytotoxicity to human corneal epithelial cells when compared with commercial polymer-based artificial tears (Tears Natural Forte). The therapeutic effects of NDEO were evaluated on a mouse model with 'dry eye'. Both the tear break-up time and fluorescein staining demonstrated therapeutic improvement, displaying a trend of positive correlation with higher concentrations of ointment matrix in the NDEO formulations compared to a marketed product. Histological evaluation demonstrated that the NDEO restored the normal corneal and conjunctival morphology and is safe for ophthalmic application.

Application of spray granulation for conversion of mixed phospholipid-bile salt micelles to dry powder form: influence of drug hydrophobicity on nanoparticle reagglomeration

The aim of this study was to investigate the feasibility of using spray granulation as a drying method to convert phospholipid (PL)-sodium deoxycholate (SDC)-mixed micelles (MMs) containing a water-insoluble drug to a solid dosage form and to evaluate how drugs with significantly different physicochemical properties affect the spray granulation process and subsequent in vitro and in vivo processes. Cucurbitacin B (Cu B) and glycyrrhizin (GL) were used as the model drugs. After spray granulation, the dried Cu B-PL/SDC-MM powder was completely redispersible within 15 minutes in vitro. Meanwhile, the area under the curve during 24 hours (AUC_0–24) and peak serum concentration from the dried powder were significantly (P<0.05) lower than the values from Cu B-PL/SDC-MMs in vivo. However, a better result was obtained for GL, ie, the drug was redispersed completely within 5 minutes in vitro. Further, absorption from the dried GL-PL/SDC-MM powder was increased to the same level as that for GL-PL/SDC-MMs in vivo compared with the control group. The difference in these results can be found in Cu B and GL. Cu B nanoparticles reagglomerated when released, resulting in slower redispersibility and less absorption compared with the original PL-SDC-MMs. However, no agglomeration or delay was observed for GL. A possible explanation is the difference in surface hydrophobicity between Cu B and GL. The results of this study not only show that spray granulation is an effective drying technique that can complement spray-drying and freeze-drying, but also confirm that the physicochemical properties of a drug have a significant influence on the in vitro and in vivo performance of the dried powder obtained after spray granulation.

Solid lipid nanoparticles of a water soluble drug, ciprofloxacin hydrochloride

The aim of this study was to understand and investigate the relationship between experimental factors and their responses in the preparation of ciprofloxacin hydrochloride based solid lipid nanoparticles. A quadratic relationship was studied by developing central composite rotatable design. Amount of lipid and drug, stirring speed and stirring time were selected as experimental factors while particle size, zeta potential and drug entrapment were used as responses. Prior to the experimental design, a qualitative prescreening study was performed to check the effect of various solid lipids and their combinations. Results showed that changing the amount of lipid, stirring speed and stirring time had a noticeable influence on the entrapment efficiencies and particle size of the prepared solid lipid nanoparticles. The particle size of a solid lipid nanoparticle was in the range of 159-246 nm and drug encapsulation efficiencies were marginally improved by choosing a binary mixture of physically incompatible solid lipids. Release of ciprofloxacin hydrochloride from solid lipid nanoparticle was considerably slow, and it shows Higuchi matrix model as the best fitted model. Study of solid lipid nanoparticle suggested that the lipid based carrier system could potentially be exploited as a delivery system with improved drug entrapment efficiency and controlled drug release for water soluble actives.

Novel resveratrol nanodelivery systems based on lipid nanoparticles to enhance its oral bioavailability

INTRODUCTION

Resveratrol is a polyphenol found in grapes and red wines. Interest in this polyphenol has increased due to its pharmacological cardio- and neuroprotective, chemopreventive, and antiaging effects, among others. Nevertheless, its pharmacokinetic properties are less favorable, since the compound has poor bioavailability, low water solubility, and is chemically unstable. To overcome these problems, we developed two novel resveratrol nanodelivery systems based on lipid nanoparticles to enhance resveratrol's oral bioavailability for further use in medicines, supplements, and nutraceuticals.

METHODS AND MATERIALS

Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) loaded with resveratrol were successfully produced by a modified hot homogenization technique. These were completely characterized to evaluate the quality of the developed resveratrol-loaded nanoparticles.

RESULTS

Cryo-scanning electron microscopy morphology studies showed spherical and uniform nanoparticles with a smooth surface. An average resveratrol entrapment efficiency of ~70% was obtained for both SLNs and NLCs. Dynamic light scattering measurements gave a Z-average of 150-250 nm, polydispersity index of ~0.2, and a highly negative zeta potential of around -30 mV with no statistically significant differences in the presence of resveratrol. These characteristics remained unchanged for at least 2 months, suggesting good stability. Differential scanning calorimetry studies confirmed the solid state of the SLNs and NLCs at both room and body temperatures. The NLCs had a less ordered crystalline structure conferred by the inclusion of the liquid lipid, since they had lower values for phase transition temperature, melting enthalpy, and the recrystallization index. The presence of resveratrol induced a disorder in the crystal structure of the nanoparticles, suggesting a favoring of its entrapment. The in vitro release studies on conditions of storage showed a negligible resveratrol release over several hours for both nanosystems and the in vitro simulation of gastrointestinal transit showed that the resveratrol remained mostly associated with the lipid nanoparticles after their incubation in digestive fluids.

CONCLUSION

Both nanodelivery systems can be considered suitable carriers for oral administration, conferring protection to the incorporated resveratrol and allowing a controlled release after uptake.

Formulation optimization and topical delivery of quercetin from solid lipid based nanosystems

The presence of large amounts of reactive oxygen species (ROS) leads to oxidative stress that can damage cell membranes, lead to DNA breakage and cause inactivation of free radical scavenger enzymes, eventually resulting in skin damage. Quercetin is a natural flavonoid that has been shown to have the highest anti-radical activity, along with the ability to act as a scavenger of free radicals and an inhibitor of lipid peroxidation. In this research work, a solvent-free solid lipid based nanosystem has been developed and evaluated for topical delivery of quercetin. Systematic screening of the formulation and process parameters led to the development of a solid lipid (glyceryl dibehenate) based nanosystem using a probe ultrasonication method. The selected variant demonstrated good physical stability for up to 8 weeks at 2-8 °C. Transmission electron microscopy (TEM) images showed spherical particles in the nanometer range. In vitro release studies showed biphasic release of quercetin from the SLN formulation, with an initial burst release followed by prolonged release for up to 24h. In vitro permeation studies using full thickness human skin showed higher amounts of quercetin to be localized within the skin compared to a control formulation with particles in the micrometer range. Such accumulation of quercetin in the skin is highly desirable since the efficacy of quercetin in delaying ultra-violet radiation mediated cell damage and eventual necrosis mainly occurs in the epidermis.

Formulation and evaluation of carnosic acid nanoparticulate system for upregulation of neurotrophins in the brain upon intranasal administration

To develop formulations of carnosic acid nanoparticles and to assess their in vivo efficacy to enhance the expression of neurotrophins in rat model. Carnosic acid loaded chitosan nanoparticles were prepared by ionotropic gelation technique using central composite design. Response surface methodology was used to assess the effect of three factors namely chitosan concentration (0.1-1% w/v), tri-poly phosphate concentration (0.1-1% w/v) and sonication time (2-10 min) on the response variables such as particle size, zeta potential, drug encapsulation efficiency and drug release. The neurotrophins level in the rat brain upon intranasal administration of optimized batch of carnosic acid nanoparticles was determined. The experimental values for the formulation were in good agreement with those predicted by the mathematical models. A single intranasal administration of the optimized formulation of carnosic acid nanoparticles was sufficient to result in comparable levels of endogenous neurotrophins level in the brain that was almost on par with four, once a day intranasal administration of solution in rats. The results clearly demonstrated the fact that nanoparticulate drug delivery system for intranasal administration of carnosic acid would require less number of administrations to elicit the required pharmacological activity owing to its ability to localize on the olfactory mucosal region and provide controlled delivery of carnosic acid for prolonged time periods.

Preparation and characterization of a lovastatin-loaded protein-free nanostructured lipid carrier resembling high-density lipoprotein and evaluation of its targeting to foam cells

This study was designed to investigate whether a non-protein nanostructured lipid carrier (NLC) resembling high-density lipoprotein (HDL) could deliver a hydrophobic anti-atherogenic drug, lovastatin, to foam cells. Lovastatin-loaded NLC (LT-NLC) was prepared by a nanoprecipitation/solvent diffusion method. The LT-NLC-apoprotein (LT-NLC-apo) was prepared by incubating LT-NLC with native HDL. The physicochemical parameters of LT-NLC were characterized in terms of particle size, zeta potential, morphology, entrapment efficiency, and crystallization behavior. Targeting behavior and mechanism were demonstrated by the incubation of LT-NLC-apo with a RAW 264.7 macrophage-derived foam cell model in the presence or absence of very-low-density lipoprotein (VLDL) and lipase. The results showed that LT-NLC was solid spherical or oval in shape with an average diameter of 13.8 ± 2.2 nm, zeta potential of −29.3 ± 0.2 mV and entrapment efficiency of 96.2 ± 1.3%. Phagocytosis studies showed that uptake of LT-NLC-apo by macrophages was significantly lower than LT-NLC (p < 0.01), suggesting that LT-NLC-apo could possibly escape recognition from macrophages in vivo. The uptake was increased twofold when LT-NLC-apo was incubated with transfected foam cells containing VLDL and lipase. These results indicated that non-protein NLC resembling HDL could be a useful tool to deliver lipophilic anti-atherogenic drugs to foam cells, and that uptake could be enhanced by the VLDL receptor pathway.

Preparation and evaluation of zolmitriptan submicron emulsion for rapid and effective nasal absorption in beagle dogs

Submicron emulsion was prepared for rapid and effective nasal absorption of zolmitriptan (ZT). The different charge inducers and pH values of the formulations were evaluated to optimize the formulations. Submicron emulsion prepared by using stearylamine as positive charge inducer with pH of 5.0 was stable and most of ZT was freely dispersed in the aqueous phase of the preparation. In vitro release study demonstrated that ZT from the submicron emulsion preparation could be released as fast as that from the solution preparation. The pharmacokinetics was studied after intranasal administration of the submicron emulsion and solution preparation of ZT to beagle dogs. ZT from the submicron emulsion was absorbed much more rapidly and the absolute availability of the submicron emulsion preparation was significantly higher compared with the solution preparation. The nasal ciliotoxicity of the preparations was evaluated by using in situ toad palate model, which indicated that the submicron emulsion of ZT did not exhibit any obvious nasal ciliotoxicity. These results demonstrated that the submicron emulsion preparation of ZT was a relatively safe dosage form for rapid and effective intranasal delivery of ZT.

Mixed micelles loaded with silybin-polyene phosphatidylcholine complex improve drug solubility

AIM

To prepare a novel formulation of phosphatidylcholine (PC)-bile salts (BS)-mixed micelles (MMs) loaded with silybin (SLB)-PC complex for parenteral applications.

METHODS

SLB-PC-BS-MMs were prepared using the co-precipitation method. Differential scanning calorimetry (DSC) analysis was used to confirm the formation of the complex and several parameters were optimized to obtain a high quality formulation. The water-solubility, drug loading, particle size, zeta potential, morphology and in vivo properties of the SLB-PC-BS-MMs were determined.

RESULTS

The solubility of SLB in water was increased from 40.83 ± 1.18 μg/mL to 10.14 ± 0.36 mg/mL with a high drug loading (DL) of 14.43% ± 0.44% under optimized conditions. The SLB-PC-BS-MMs were observed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) and showed spherical shapes. The particle size and zeta potential, as measured by photon correlation spectroscopy (PCS), were about 30 ± 4.8 nm and -39 ± 5.0 mV, respectively. In vivo studies showed that incorporation of the SLB-PC complex into PC-BS-MMs led to a prolonged circulation time of the drug.

CONCLUSION

This novel formulation appears to be a good candidate for drug substances that exhibit poor solubility for parenteral administration.

Formulation, preparation and evaluation of flunarizine-loaded lipid microspheres

The aim of this study was to investigate the feasibility of preparing flunarizine-loaded lipid microspheres. Lipid microspheres (LMs) are excellent drug carriers for drug delivery systems (DDS) and are relatively stable and easily mass-produced. They have no particular adverse effects. LMs have been widely studied as drug carriers for water-soluble drugs, lipid-soluble drugs and inadequately soluble (in water or in lipid) drugs, in that they have a lipid layer, a water layer and an emulsifier layer. Flunarizine (FZ), a poorly water-soluble drug, was incorporated in lipid microspheres to reduce side effects by avoiding the use of supplementary agents, compared with solution injection. After investigation, the final formulation was as follows: 10% oil phase (long-chain triglyceride (LCT); medium-chain fatty acid (MCT) = 50:50); 1.2% egg lecithin; 0.2% Tween-80; 2.5% glycerin; 0.3% dl-α-tocopherol; 0.02% EDTA; 0.03% sodium oleate; 0.1% FZ and double-distilled water to give a total volume of 100 mL. Homogenization was the main method of preparation and the best conditions were a temperature of 40°C, a pressure of 700–800 bar and a suitable cycle frequency of about 10. The particle size distribution, zeta-potential and entrapment efficacy were found to be 198.7 ± 54.0 nm, −26.4mV and 96.2%, respectively. Its concentration in the preparation was 1.0mg mL−1. The lipid microspheres were stable during storage at 4°C, 25°C and 37°C for 3 months. Pharmacokinetic studies were performed in rats using a dose of 1.0 mg kg−1. The pharmacokinetic parameters were as follows: AUC0-t 6.13 μg h mL−1, t½ 5.32 h and Ke 0.16 Lh−1. The preparation data fitted a two-compartment model estimated by using 3p87 analysis software. From the observed data, FZ encapsulated in LMs did not significantly alter the pharmacokinetic characteristic compared with the FZ solution injection and did not produce a delayed release effect, when it was released in-vivo in rats. However, the availability of the drug was increased. These results suggested that this LM system is a promising option for the preparation of the liquid form of FZ for intravenous administration.

Preparation of ergoloid mesylate submicron emulsions for enhancing nasal absorption and reducing nasal ciliotoxicity

The aim of this investigation was to prepare ergoloid mesylate submicron emulsions (EMSEs) for enhancing nasal absorption of drug and reducing nasal ciliotoxicity. Following intranasal administrations of EMSE and ergoloid mesylate solution (EMS) and intravenous administration of EMS to rats separately at the dose of 2 mg kg(-1), the levels of EM in blood and the cerebrospinal fluid (CSF) were evaluated by microdialysis method. The nasal ciliotoxicity was evaluated by using in situ toad palate model. The absolute bioavailability and the AUC in the CSF following intranasal administration of EMSE (56.3 +/- 5.3%, AUC(CSF) 28,594 +/- 5680 ng ml(-1) min) were statistically higher than those after intranasal administration of EMS (47.4 +/- 3.5%, AUC(CSF) 19,870 +/- 2247 ng ml(-1) min). No significant difference was found for the value of the brain drug direct transport percentage (DTP%) or the drug targeting efficiency (DTE) between the group receiving EMSE and the group receiving EMS. In conclusion, EMSE exhibited higher nasal absorption of EM in rats and significantly lower nasal ciliotoxicity whereas no greater brain-targeting efficiency in comparison with EMS.

Influence of incorporation methods on partitioning behavior of lipophilic drugs into various phases of a parenteral lipid emulsion

The purpose of this study was to investigate the effect of drug incorporation methods on the partitioning behavior of lipophilic drugs in parenteral lipid emulsions. Four lipophilic benzodiazepines, alprazolam, clonazepam, diazepam, and lorazepam, were used as model drugs. Two methods were used to incorporate drugs into an emulsion: dissolving the compound in the oil phase prior to emulsification (de novo emulsification), and directly adding a concentrated solution of drug in a solubilizer to the emulsion base (extemporaneous addition). Based on the molecular structures and determination of the oil and aqueous solubilities and the partition coefficients of the drugs, the lipophilicity was ranked as diazepam > clonazepam > lorazepam > alprazolam. Ultracentrifugation was used to separate the emulsion into four phases, the oil phase, the phospholipid-rich phase, the aqueous phase and the mesophase, and the drug content in each phase was determined. Partitioning of diazepam, which has the highest lipophilicity and oil solubility among the four drugs, was unaffected by the drug incorporation method, with both methods giving a high proportion of drug in the inner oil phase and the phospholipid-rich phase, compared to the aqueous phase and mesophase. Partitioning of the less lipophilic drugs (alprazolam, clonazepam, and lorazepam) in the phases of the emulsion system was dependent on the method of incorporation and the drug solubility properties. Emulsions of the three drugs prepared by de novo emulsification exhibited higher drug localization in the phospholipid-rich phase compared to those made by extemporaneous addition. With the latter method, the drugs tended to localize in the outer aqueous phase and mesophase, with less deposition in the phospholipid-rich phase and no partitioning into the inner oil phase.

Characterization and body distribution of beta-elemene solid lipid nanoparticles (SLN)

Solid lipid nanoparticles (SLN) containing beta-elemene, a volatile oil used for the treatment of cancer, were prepared by the method combining probe sonication and membrane extrusion. Effects of the formulations and procedures on the characteristics of SLN were investigated. Body distribution of beta-elemene SLN in rats after intravenous administration was compared with that of the commercial emulsion. The results showed that dispersing the surfactant in the melted lipid matrix could obtain smaller particles than that dispersing in the water phase. Increasing the ratio of monostearin in the lipid matrix or the concentration of surfactant reduced the mean volume size of the SLN. Optimized formulation was composed of monostearin and precirol ATO 5 at a mass ratio of 3:7, which was quite stable for 8 months at room temperature. In vitro release of beta-elemene from the SLN was slow and stable without obvious burst release and was found to follow the Higuich equation. After intravenous administration, the beta-elemene levels after 5 min injection of SLN formulation were 1.5, 2.9, and 1.4 times higher than those of beta-elemene emulsion in liver, spleen, and kidney, respectively, while the concentrations of beta-elemene were decreased 30% in heart and lung. Therefore, the SLN containing beta-elemene might be an attractive candidate for the treatment of liver cancer.

A less irritant norcantharidin lipid microspheres: formulation and drug distribution

Lipid microspheres (LM) have recently been used as intravenous (i.v.) carriers for drugs, which are sufficiently soluble in oil. However, in the case of norcantharidin (NCTD), which is poorly soluble in both the water and oil phases, this approach is not feasible. In this study, NCTD-loaded LM was prepared by transferring the drug to the interfacial surface of the oil and aqueous phases to produce a less irritating i.v. formulation of NCTD. A probe type sonicator was used to disperse NCTD into the oil phase together with lecithin and Tween 80. A high-pressure homogenization process was used to prepare the lipid microspheres and localize the drug at the surfactant layer. The LM loaded with NCTD consisted of 0.02% drug. Characterization of LMs and short-term stability was performed by photon correlation spectroscopy (PCS) and a centrifugation test was also carried out. The results showed that NCTD-loaded LM (2 mg/ml) with over 80% NCTD loaded in the interfacial surface were stable for a period of 2 months, and were suitable for i.v. injection in terms of size and stability, whether be diluted or not. Such formulations produced less pain and irritation in animal studies.

Preparation and characterization of stearic acid nanostructured lipid carriers by solvent diffusion method in an aqueous system

Nanostuctured lipid carriers (NLC) based on mixture of solid lipids with spatially incompatible liquid lipids are a new type of lipid nanoparticles, which offer the advantage of improved drug loading capacity and release properties. In present study, stearic acid (SA) nanostuctured lipid carriers with various oleic acid (OA) content were successfully prepared by solvent diffusion method in an aqueous system. The size and surface morphology of nanoparticles were significantly influenced by OA content. As OA content increased up to 30wt%, the obtained particles showed pronounced smaller size and more regular morphology in spherical shape with smooth surface. Compared with solid lipid nanoparticles (SLN), NLC exhibited improved drug loading capacity, and the drug loading capacity increased with increasing OA content. These results were explained by differential scanning calorimetry (DSC) investigations. The addition of OA to nanoparticles formulation resulted in massive crystal order disturbance and less ordered matrix of NLC, and hence, increased the drug loading capacity. The drug in vitro release behavior from NLC displayed biphasic drug release pattern with burst release at the initial stage and prolonged release afterwards, and the successful control of release rate at the initial stage can be achieved by controlling OA content.

Evaluation of the physical stability of SLN and NLC before and after incorporation into hydrogel formulations

Aqueous dispersions of lipid nanoparticles are being investigated as drug delivery systems for different therapeutic purposes. One of their interesting features is the possibility of topical use, for which these systems have to be incorporated into commonly used dermal carriers, such as creams or hydrogels, in order to have a proper semisolid consistency. For the present investigation four different gel-forming agents (xanthan gum, hydroxyethylcellulose 4000, Carbopol943 and chitosan) were selected for hydrogel preparation. Aqueous dispersions of lipid nanoparticles--solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC)--made from tripalmitin were prepared by hot high pressure homogenization and then incorporated into the freshly prepared hydrogels. NLC differ from SLN due to the presence of a liquid lipid (Miglyol812) in the lipid matrix. Lipid nanoparticles were physically characterized before and after their incorporation into hydrogels. By means of rheological investigations it could be demonstrated that physical properties of the dispersed lipid phase have a great impact on the rheological properties of the prepared semisolid formulations. By employing an oscillation frequency sweep test, significant differences in elastic response of SLN and NLC aqueous dispersions could be observed.

Preparation of solid lipid nanoparticles with clobetasol propionate by a novel solvent diffusion method in aqueous system and physicochemical characterization

Solid lipid nanoparticles (SLN) are a colloidal carrier system for controlled drug delivery. Monostearin SLN were prepared by a novel solvent diffusion method in an acidic aqueous system in order to improve the recovery of the method. The lipophilic model drug clobetasol propionate was incorporated to study the recovery of nanoparticles, entrapment efficacy, zeta potential (charge) and drug delivery characterization. The drug and monostearin were dissolved in acetone and ethanol at 50 degrees C in water bath, the resultant organic solution was poured into an acidic aqueous (pH 1.10) containing 1% polyvinyl alcohol (PVA) under mechanical agitation at room temperature. The drug loaded SLN was quickly produced with an aggregation state and easily separated by centrifugation. The recovery of nanoparticles was markedly increased compared to using a usual aqueous (pH 5.73) containing the same concentration of PVA. After burst drug release at the first 3 h, a distinctly prolonged release over a monitored period of 4 days was observed and nearly 6% drug was released in each day. Further, a novel preparation method and the optimized separation parameters in the present research for SLN were established. These results also demonstrate the principle suitability of SLN as a prolonged release formulation for lipophilic drugs.

Application of dynamic laser scattering to the quality control of injectable drugs: polymer formation in ampicillin solution

OBJECTIVE

To assess the usefulness of dynamic laser scattering for monitoring the stability of ampicillin after reconstitution from commercially available vials with respect to the polymer formation and potency.

METHODS

Polymer formation and the remaining potency of the reconstituted ampicillin solution were estimated using dynamic laser scattering and high-performance liquid chromatography.

RESULTS

The laser light-scattering submicron particle analyser was sufficiently sensitive for detecting both monomer and polymer aggregates with the average diameter of 1.1 +/- 0.2 and 7.3 +/- 1.7 nm, respectively, in the ampicillin solution. Polymer formation was dependent on both the storage temperature and the storage period, but it was detected, even when no precipitates were visible and when loss of potency was less than 10% of the initial value following storage at 4 or -15 degrees C.

CONCLUSION

Submicron particle analysis using scanning electron microscopy, when used in combination with high-performance liquid chromatography, provides a useful method for studying polymer formation in antibiotic solutions and for the quality control of antibiotic injections during storage.

Modification of ceftibuten transport by the addition of non-ionic surfactants

The effects of non-ionic surfactants on the carrier-mediated transport of ceftibuten by rat intestinal brush-border membrane vesicles (BBMVs) were investigated. Ceftibuten uptake by BBMVs was measured by a rapid filtration technique. The concentration of surfactants for the uptake experiments was determined by a decrease in the turbidity of BBMV suspension and by the release of an impermeable probe, 2',7'-bis(carboxyethyl)-4(5)-carboxyfluorescein, from the vesicle inside. In fact, the surfactant concentration of 0. 03% (w/v) was selected to maintain the stability of BBMVs. The extent of ceftibuten uptake by BBMVs with various surfactants was correlated with their physicochemical properties, i.e. hydrophile-lipophile balance (HLB), critical micelle concentration (c.m.c.), average diameter of micelle colloid, and polydispersity determined by particle size distribution. The surfactants used were divided into two groups on the basis of polydispersity index (d(w)/d(n)), i.e. low polydispersity (d(w)/d(n) congruent with1) and high polydispersity d(w)/d(n)2). The ceftibuten uptake due to the addition of surfactants with low polydispersity increased with a decrease in the HLB number. These results indicate that the ceftibuten transport is modulated by the size distribution and hydrophobicity of surfactants. In addition, the effects of surfactants on the membrane lipid fluidity monitored by diphenylhexatriene (DPH) and trimethylammonium diphenylhexatriene (TMA-DPH) were investigated. There was significant correlation between ceftibuten uptake and the fluorescence anisotropy of TMA-DPH-labeled membranes due to the addition of surfactants with low polydispersity (r=-0.81, P<0.0001). These results suggest that surfactants with low polydispersity, in part, increase or decrease the outer membrane leaflet, thereby enhancing or suppressing the ceftibuten transport by BBMVs, and that ceftibuten transport caused by surfactants with low polydispersity may be strongly dependent on the hydrophobic interaction.

Preparation of fine emulsified fat particles without glycerol for intravenous nutrition

A method of preparing fine emulsified fat particles without glycerol for intravenous nutrition was investigated. The factors assessed were the oil phase ratio, the glucose level of the aqueous phase and the temperature of high-pressure homogenization. The particle size decreased with an increase in the oil phase ratio and it went below 250 nm only in the emulsion with a 50% oil phase ratio. The weight-weighted particle size (dw)/number-weighted particle size (dn) value reflected the particle size distribution. The emulsion with a 50% oil phase ratio had a very narrow distribution of particle sizes and the dw/dn value was below 1.1. With the use of glucose solutions for the aqueous phase, smaller particle sizes and narrower distributions were obtained with increasing glucose concentrations. The controlled temperature of 50 degrees C was appropriate for high-pressure homogenization, producing particles below 160 nm. The rate of the layer separation was a function of particle size. The particle sizes below 180 nm can be expected to suppress the separation of the formulation which consisted of 10.0% soybean oil, 1.2% phospholipids and 5.0% glucose. The stability studies were conducted at 40 degrees C for 3 months and the fat emulsion was stable during storage. These investigations contribute to the preparation of a new caloric source for peripheral parenteral nutrition.

Suppressive effects of salts on droplet coalescence in a commercially available fat emulsion during freezing for storage

To assess possible improvements in the practical use of long-term freezing storage for commercially available fat emulsions, the effects of salts on coalescence (fusion) of emulsions during freeze-thawing cycles were studied. For this purpose, apparent size changes were measured by dynamic light scattering, and the dispersed droplets were directly observed by freeze-fracture electron microscopy before and after the freeze-thawing processes. Intravenous high-calorie nutrient fluid, based on soybean oil in water (2.2 wt% glycerin) and emulsified by egg phosphatides, was selected as a representative commercially available fat emulsion. Possible mechanisms of the suppressive effects of various salts (Li, Na, K, Rb, and Cs chlorides) on coalescence during repeated freezing with liquid nitrogen and subsequent thawing were examined in terms of the zeta-potential of the emulsion droplets and differential scanning calorimetry heating curves of the water-salt-glycerin ternary solution. The suppressive effects of salts on the coalescence of the emulsion droplets during freeze-thaw cycles could be ascribed to the suppression of ice crystal formation and the condensation of the droplets in unfrozen aqueous channels between the ice crystals during the freezing cycle.