An intravenous clarithromycin lipid emulsion with a high drug loading, H-bonding and a hydrogen-bonded ion pair complex exhibiting excellent antibacterial activity

Clarithromycin-Loaded Submicron-Sized Carriers: Pharmacokinetics and Pharmacodynamic Evaluation

The current study aims to improve clarithromycin bioavailability and effectiveness in complicated intra-abdominal infection management. Therefore, clarithromycin-loaded submicron dual lipid carriers (CLA-DLCs) were developed via hot high shear homogenization technique and evaluated for colloidal parameters, release behavior, stability study, and in-vitro antibiofilm activity. Bioavailability and therapeutic efficacy of optimized formulation on hampering cytokines storm induction was determined in E. coli-induced peritonitis. The developed CLA-DLCs (particle size 326.19 ± 24.14 nm, zeta potential -31.34 ± 2.81 mV, and entrapment efficiency 85.78 ± 4.01%) exhibited smooth spherical shapes and sustained in vitro release profiles. Long-term stability study of optimized CLA-DLCs ensured maintenance of colloidal parameters for 1 year at room temperature. In vitro antimicrobial studies revealed 3.43-fold higher anti-biofilm activity of CLA-DLCs compared with clarithromycin. In addition, the relative bioavailability of CLA-DLCs was enhanced 5.89-fold compared to pure drug in rats. The remarkable decrease in microbial burden in blood as well as tissues, along with oxidative stress markers (lipid peroxidation, myeloperoxidase activity, and carbonylated protein level) and immunological markers (total leukocyte count, neutrophil migration, NO, TNF-, and IL-6) on treatment with CLA-DLCs enhanced the survival in a rat model of peritonitis compared with the pure drug and untreated groups. In conclusion, CLA-DLCs hold promising potential in management of intra-abdominal infections and prevention of associated complications.

Formulation, Characterization, and the Diuretic Effects of a New Intravenous Metolazone Emulsion

OBJECTIVE

Acute decompensated heart failure is often treated with a combination of loop and thiazide-like diuretics. Of these thiazide-like diuretics, two common choices are intravenous chlorothiazide or oral metolazone. Metolazone is more potent and has a longer duration of action, but since it is an oral formulation, it has a longer on-set time as compared to chlorothiazide. In addition, metolazone is poorly water-soluble, thereby rendering intravenous formulation more challenging. To address these issues, we proposed the formulation of a solvent-free metolazone emulsion for intravenous administration.

METHODS

An oil-in-water emulsion containing 1 mg/mL of metolazone was formulated by homogenizing soybean oil and l-lecithin in water in the presence of optimized concentrations of glycerin with tween 80 or poloxamer 188 as surfactant. The emulsion was characterized on the basis of particle size, zeta potential, morphology and metolazone release kinetics. The diuretic effect of the metolazone emulsion was evaluated in rats.

RESULTS

The 1 mg/mL metolazone emulsion prepared with 5% tween 80 displayed the best physical stability. The emulsion exhibited a hydrodynamic diameter of 157.13±1.52 nm. About 93% of metolazone was released from the formulation within 2 h. The 2 mg/kg and 4 mg/kg dose of the metolazone emulsion increased urine output in the rats by 68.9 and 134%, respectively, as compared to control rats. Furthermore, the 4 mg/kg dose exhibited a 168.8%, 25.8%, and 150.9% increase in sodium, potassium, and chloride, respectively.

CONCLUSION

This metolazone emulsion was capable of increasing urine volume output and demonstrated both natriuretic and kaliuretic properties.

Antibiotic-loaded lipid-based nanocarrier: a promising strategy to overcome bacterial infection

According to the World Health Organization (WHO) and Centers for Disease Control and Prevention (CDC), bacterial infections are one of the greatest threats to global health, food production, and life expectancy. In this sense, the development of innovative formulations aiming at greater therapeutic efficacy, safety, and shorter treatment duration compared to conventional products is urgently needed. Lipid-based nanocarriers (LBNs) have demonstrated the potential to enhance the effectiveness of available antibiotics. Among them, liposome, nanoemulsion, solid lipid nanoparticle (SLN), and nanostructured lipid carrier (NLC) are the most promising due to their solid technical background for laboratory and industrial production. This review describes recent advances in developing antibiotic-loaded LBNs against susceptible and resistant bacterial strains and biofilm. LBNs revealed to be a promising alternative to deliver antibiotics due to their superior characteristics compared to conventional preparations, including their modified drug release, improved bioavailability, drug protection against chemical or enzymatic degradation, greater drug loading capacity, and biocompatibility. Antibiotic-loaded LBNs can improve current clinical drug therapy, bring innovative products and rescue discarded antibiotics. Thus, antibiotic-loaded LBNs have potential to open a window of opportunities to continue saving millions of lives and prevent the devastating impact of bacterial infection.

Preclinical evaluations of Norcantharidin liposome and emulsion hybrid delivery system with improved encapsulation efficiency and enhanced antitumor activity

BACKGROUND

Norcantharidin (NCTD) has a certain degree of hydrophilicity and poor lipophilicity, and has some side-effects, including short t_1/2, vascular irritation, cardiotoxicity and nephrotoxicity, which bring difficulties for formulation research. In this study, we aim to develop a novel nanocarrier to improve encapsulation efficiency, increase sterilization stability and enhance antitumor activity.

METHODS

Phospholipid complexes methods were used for increasing the lipophilicity of norcantharidin (NCTD), then NCTD phospholipid complexes were not only loaded in the oil phase and oil-water interface surface, but also encapsulated in phospholipid bilayers to obtain NCTD liposome-emulsion hybrid (NLEH) delivery system. The in vitro cytotoxicity and apoptosis, in vivo tissue distribution, tumor penetration, heterotopic and orthotopic antitumor studies were conducted to evaluate therapeutic effect.

RESULTS

NLEH exhibited an improved encapsulation efficiency (89.3%) and a better sterilization stability, compared to NCTD liposomes and NCTD emulsions. NLEH can achieve a better antitumor activity by promoting absorption (1.93-fold), prolonging blood circulation (2.08-fold), enhancing tumor-targeting accumulation (1.19 times), improving tumor penetration, and increasing antitumor immunity.

CONCLUSIONS

The liposome-emulsion hybrid (LEH) delivery system was potential carrier for NCTD delivery, and LEH could open opportunities for delivery of poorly soluble anticancer drugs, especially drugs that are more hydrophilicity than lipophilicity.

Aprepitant Intravenous Emulsion Based on Ion Pairing/Phospholipid Complex for Improving Physical and Chemical Stability During Thermal Sterilization

An aprepitant (APT) cholesteryl hemisuccinate (CHEMS) ion pair complex emulsion (AIPE) with high lecithin content was prepared to improve sterilization stability through the film dispersion homogenization method; therefore, it could be a promising delivery system of APT. Medium-chain triglycerides (MCT) was selected as the oil phase to improve the solubility and stability of APT in oil phase. DSC, XRD, FT-IR, and ¹H-NMR spectroscopies confirmed that the APT-CHEMS ion pair (AIP) was formed between CHEMS and APT. The formation of AIP significantly increased the hydrophobicity of APT, allowing it to be completely embedded in the oil phase core to improve chemical stability and decrease hydrolysis of APT in the water phase. Also, CHEMS had a strong affinity with lecithin and could stabilize lipid membranes, forming a stronger and thicker interface membrane to increase the physical stability of AIPE. As a result, AIPE could withstand autoclaving at 120°C for 8 min without any change of particle size or content. Furthermore, AIPE with a potential of - 53.4 mV remained stable through spatial repulsion during sterilization. The encapsulation efficiency of AIPE was over 90% and the particle size was 106.8 ± 65.62 nm(0.286). Pharmacokinetic study in rats was comparable with that of CINVANTI which yielded a relative bioavailability of 114.31% indicating that the AIPE had similar pharmacokinetic processes in vivo with the analog of CINVANTI®. The AUC0-t of the AIPE was 4.31-fold that of the APT solution.

Clarithromycin-Loaded Poly (Lactic-co-glycolic Acid) (PLGA) Nanoparticles for Oral Administration: Effect of Polymer Molecular Weight and Surface Modification with Chitosan on Formulation, Nanoparticle Characterization and Antibacterial Effects

Clarithromycin (CLR) is a member of the macrolide antibiotic group. CLR has low systemic oral bioavailability and is a drug of class II of the Biopharmaceutical Classification System. In many studies, using nanoparticles (NPs) as a drug delivery system has been shown to increase the effectiveness and bioavailability of active drug substances. This study describes the development and evaluation of poly (lactic-co-glycolic acid) (PLGA) NPs and chitosan (CS)-coated PLGA NPs for oral delivery of CLR. NPs were obtained by nanoprecipitation technique and characterized in detail, and the effect of three molecular weights (Mw1: 7.000-17.000, Mw2: 38.000-54.000, Mw3: 50.000-190.000) of PLGA and CS coating on particle size (PS), zeta potential (ZP), entrapment efficiency (EE%), and release properties etc. were elucidated. Gastrointestinal stability and cryoprotectant effect tests were performed on the NPs. The PS of the prepared NPs were in the range of 178 to 578 nm and they were affected by the Mw and CS coating. In surface-modified formulations with CS, the ZP of the NPs increased significantly to positive values. EE% varied from 62% to 85%, depending upon the Mw and CS coating. In vitro release studies of CLR-loaded NPs showed an extended release up to 144 h. Peppas-Sahlin and Weibull kinetic model was found to fit best for CLR release from NPs. By the broth microdilution test method, the antibacterial activity of the formulations was determined on Staphylococcus aureus (ATCC 25923), Listeria monocytogenes (ATCC 1911), and Klebsiella pneumoniae (ATCC 700603). The structures of the formulations were clarified by thermal (DSC), FT-IR, and 1H-NMR analysis. The results showed that PS, ZP, EE%, and dissolution rates of NPs were directly related to the Mw of PLGA and CS coating.

The modulation of drug-loading stability within lipid membranes via medium chain triglycerides incorporation

The current research aimed to explore medium chain triglycerides (MCT) incorporation in liposomes to overcome stability challenges when drugs with high molecular weight and payload are loaded within lipid membranes. A model drug clarithromycin was loaded in lipid dispersions with various MCT/phospholipids ratios (R_M/P = 0, 0.5, 1.75 and 7.5 w/w). TEM images demonstrated a liposome-to-emulsion structural transformation by MCT incorporation to cause increased particle size (104.3-167.7 nm) but decreased zeta potential (-63.6 to -44.4 mV) of lipid particles. MCT incorporation produced biphasic release in PBS and accelerated released in plasma. The tolerance of liposomes for thermal sterilization, high temperature test and freeze-thaw cycles were significantly improved by MCT incorporation. However, MCT incorporation produced adverse effects on colloidal stability in plasma and pharmacokinetics behavior in vivo to some extent. MCT stabilizing mechanism attributes to the modulation of drug loading area and stability improvement of lipid carriers. MCT incorporated liposomes achieved 2-3 fold cellular uptake level than traditional liposomes without significant cytotoxicity. These results indicated that MCT incorporation could be a promising strategy to apply in liposome production to achieve stable drug loading.

A new alternative for intravenous lipid emulsion 20% w/w from superolein oil and its effect on lipid and liver profiles in an animal model

PURPOSE

Intravenous lipid emulsion (IVLE) was first used to prevent essential fatty acids deficiency. IVLE with α-tocopherol was reported to provide protection against parenteral nutrition-associated liver disease. This study aims to determine the optimal parameters and conditions in developing a physically stable IVLE from superolein palm oil (SoLE 20%) and its effect on lipid and liver profiles in an animal model.

METHODS

SoLE 20% was prepared using superolein oil and MCT oil (1:1), stabilized with egg lecithin and homogenized using a high pressure homogenizer. Mean droplet size was used as the response variable and was measured using laser diffraction and dynamic light scattering method. Physical stability at 4 °C, 25 °C and 40 °C storage temperatures were determined based on particle size and distribution, polydispersity index, zeta potential, viscosity, vitamin E contents and pH. Sterility and pyrogenicity were also investigated. Rabbits were administered with 1.0 g/kg SoLE 20% for 5 h and repeated daily for 3 days to investigate its effect on blood lipid and liver enzymes profile.

RESULTS

SoLE 20% was succesfully prepared using the optimized parameters of 800 psi, 7 cycles and 1.2 g lecithin. The IVLE prepared had a particle size of 252.60 ± 4.88 nm and was physically stable for 4 weeks at different storage temperatures. SoLE 20% had a high content of natural vitamin E, remained sterile and pyrogen free. It was also safe for intravenous administration and did not alter the blood lipid (p > 0.05) and liver enzymes profiles (p > 0.05) of the rabbits.

CONCLUSION

The optimal parameters to develop a stable superolein based IVLE are 800 psi homogenization pressure, 7 homogenization cycles and using 1.2 g lecithin as the emulsifier. SoLE 20% is safe for intravenous administration and does not significantly alter lipid and liver enzymes profiles of the rabbits.

PEGylated lipid microspheres loaded with cabazitaxel for intravenous administration: stability, bioavailability, antitumor efficacy, and toxicity

This paper aimed to develop a novel lipid microsphere delivering cabazitaxel (CTX) using phosphatidylcholine combined with DSPE-PEG2000 as emulsifier, and evaluate its stability, pharmacokinetics, antitumor efficacy, and toxicity. The pegylated cabazitaxel-loaded lipid microspheres (CTX-PLMs) were prepared by high-pressure homogenization methods; the biological samples were analyzed by the UPLC-MS/MS method. CTX-PLMs had a drug concentration of 1.2 mg/ml and a mean particle size of 180.0 ± 51.119 nm. CTX-PLMs showed a superior physical stability as it could remain nearly intact after 1-year storage. The AUC_0-t of the CTX-PLMs was 1562.6 ± 520.1 μg h L^-1 compared with the CTX-solution of 860.734 ± 312.4 μg h L^-1. CTX-PLMs exhibited a strong antitumor efficacy against NCI-N87 and DU145 tumor models with tumor growth inhibition rates of 93.5 and 88.5%, respectively. The LD50 of CTX-PLMs in rats was 20.89 mg/kg. As for the long-term toxicity, the thymus, mesenteric lymph nodes, and bone marrow were the main toxic target organs and systemic toxicity induced by CTX-PLMs was alleviated relative to that of the CTX-solution. Safety assessment studies including hemolysis test, dermal sensitization test, systemic anaphylaxis, and vascular stimulation test indicated that CTX-PLMs is safe enough for intravenous administration. In a word, CTX-PLMs are a promising carrier for intravenous administration with satisfactory stability, stronger tumor inhibition, and superior safety profile.

Vincristine-loaded liposomes prepared by ion-paring techniques: Effect of lipid, pH and antioxidant on chemical stability

In the present study, vincristine (VCR)-loaded liposomes were designed by ion-pairing techniques and the model could be applied to investigate the effect of lipids on the degradation of vinca alkaloids, and how to weaken their influence by adjusting pH and adding antioxidants. It was found that there was a positive correlation between degree of degradation and the unsaturation extent of the phospholipids. In the phospholipid with the lowest oxidation index, only 6% of VCR was degraded in 6days at 37°C, whereas for the phospholipids with highest oxidation index, the degradation reached above 95% over the same time. At pH6.8 and 7.4, the degradation rate of VCR in the lipid membrane was significantly faster than that in aqueous solution, instead, at pH5.0. After the addition of butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), tocopherol, ascorbate and tocopherol with ascorbate, the residual content of VCR after 6days was 79.9%, 78.1%, 7.1%, 89.6% and 94.6% respectively. It was speculated that VCR could be oxidized by hydrated peroxyl radicals, which formed from lipid peroxidation as well as nucleophilic substitution with peroxyl radicals in the dry state. Also, the antioxidants were shown to have different eliminating capacity on the peroxyl radicals whether hydrated or not, and the phenoxyl radicals generated from fat-soluble antioxidants may be potentially destabilizing to VCR. Therefore, for these two crucial reasons, the degradation of VCR was quite different when used with a combination of water and fat-soluble antioxidants, and thus provides the best protection for VCR.

Essential oil micro- and nanoemulsions: promising roles in antimicrobial therapy targeting human pathogens

Antimicrobial resistance is a major health concern worldwide. A narrowing of the antibiotic development pipeline and a resurgence in public opinion towards 'natural' therapies have renewed the interest in using essential oils as antimicrobial agents. The drawbacks of bulk dosing of essential oils can be mitigated by formulating them as micro- and nanoemulsions. These emulsions have an added advantage as they are in the nanometre size range whose thermodynamic properties enable them to be used as an effective drug delivery system. This review describes the current work on the antimicrobial activities of essential oil micro- and nanoemulsions and their role as drug delivery vehicles.