Pharmacokinetics and tissue distribution of etoposide delivered in long circulating parenteral emulsion

Pharmacokinetics of inhaled nanotherapeutics for pulmonary delivery

Pulmonary delivery of lipid-based nanotherapeutics by inhalation presents an advantageous alternative to oral and intravenous routes of administration that avoids enzymatic degradation in gastrointestinal tract and hepatic first pass metabolism and also limits off-target adverse side effects upon heathy tissues. For lung-related indications, inhalation provides localized delivery in order to enhance therapeutic efficacy at the site of action. Optimization of physicochemical properties, selected drug and inhalation format can greatly influence the pharmacokinetic behavior of inhaled nanoparticle systems and their payloads. The present review analyzes a wide range of nanoparticle systems, their formulations and consequent effect on pharmacokinetic distribution of delivered active components after inhalation.

A new pleuromutilin candidate with potent antibacterial activity against Pasteurella multocida

This study assessed the antimicrobial activity of 14-O-[(4,6-Diaminopyrimidine-2-yl) thioacetyl] mutilin (DPTM), a novel pleuromutilin candidate with a substituted pyrimidine moiety, against Pasteurella multocida. Minimum Inhibitory Concentration (MIC), Oxford Cup assay, and time-kill experiments were used to measure the activity of DPTM against P. multocida serotype A in vitro. We observed that DPTM was potent against Pasteurella multocida serotype A with the MIC value of 0.781 μg/mL. The mean inhibition-zone diameters of DPTM (50, 25, and 12.5 μg/mL) were 29.4, 24.2 and 20.1 mm, respectively. Time-kill experiments showed that the drug caused a rapid decline in the number of bacteria compared with the initial inoculum at 4 h and killed 94.6% of the bacteria during 24 h. Furthermore, DPTM activity was also assessed in a lung infection model challenged with 4.0 × 109 CFU/mL P. multocida serotype A. The results showed that DPTM significantly reduced mortality rate and bacterial load, and alleviated the pathological changes of lung. The antibacterial effect of DPTM found in this study suggested that it was useful in the prevention or control of pneumonia caused by P. multocida.

Cytotoxicity Enhancement of Paclitaxel by Loading on Stearate-g-dextran Micelles on Breast Cancer Cell Line MCF-7

Objective:

Paclitaxel (PTX) is a chemotherapeutic agent used for treating breast cancer. The study aimed to prepare PTX loaded dextran stearate (Dex-SA) and evaluate its efficacy against human breast cancer cell line MCF-7.

Methods:

Dex-SA/PTX micelles were prepared by dialysis method. The micelles size, zeta potential and particle size distribution were measured by dynamic laser light scattering method. Amount of loaded PTX on the polymer measured by HPLC. Release profiles of the drug from the micelles were obtained in buffer (phosphate pH=7.4). Then the cytotoxicity of blank micelles, Dex-SA/PTX micelles and free PTX were evaluated in the MCF-7 cells by MTT method.

Result:

Loading efficiency of PTX on the Dex-SA was measured about 84.24±9.07%. The smallest particles size was about 193.9±7.1 nm but the other formulation with larger particle size had better zeta potential (-33.5±6.74 mV). The drug release from the micelles was slowly and reached steady state after about 12 hours. The cytotoxicity experiment showed that Dex-SA/PTX micelles have more cytotoxicity compared to free PTX against MCF7 cell lines.

Conclusions:

Dex-SA polymeric micelle is a suitable carrier for hydrophobic cytotoxic drugs such as PTX.

Uptake of etoposide in CT-26 cells of colorectal cancer using folate targeted dextran stearate polymeric micelles

Targeted drug delivery using folate receptors is one of the most interesting chemotherapeutic research areas over the past few years. A novel folate targeted copolymer was synthesized using dextran stearate coupled to folic acid. FT-IR and NMR spectroscopy were used to confirm successful conjugation. Micelles prepared using this copolymer were characterized for their particle size, zeta potential, critical micelle concentration (CMC), drug loading capacity, and release efficiency. Cytotoxicity and cellular uptake of the micelles were estimated using CT-26 colorectal carcinoma cell line. FT-IR and NMR spectroscopy confirmed production of folate grafted dextran stearate copolymer. Low CMC value indicates that the copolymers are suitable for preparation of stable micelles useful in parenteral dosage forms. Particle size and zeta potential of the targeted nanoparticles were 105.5 ± 2.0 nm and −21.2 mV, respectively. IC₅₀ of etoposide loaded in folate grafted dextran stearate enhanced about 20-fold compared to the pure drug (0.49 ± 0.11 μg/mL versus 9.41 ± 0.52 μg/mL). It seems that etoposide loaded in micelles of folate grafted dextran stearate copolymer is promising in reducing drug resistance of colorectal cancer by boosting etoposide cellular uptake.

A stable and practical etoposide-containing intravenous long-/medium-chain triglycerides-based lipid emulsion formulation: pharmacokinetics, biodistribution, toxicity, and antitumor efficacy

OBJECTIVES

This work aimed to evaluate pharmacokinetics, biodistribution, toxicity, and antitumor activities of a highly stable long-/medium-chain triglycerides (LCT/MCT)-based etoposide parenteral emulsion (EPE) in comparison to etoposide parenteral solution (EPS).

METHODS

Using high-pressure homogenization method, EPE was prepared and sterilized at 121°C for 10 min by autoclaving. The biological samples were analyzed using the UPLC-ESI-MS/MS method.

RESULTS

Superior stability of EPE was verified with no significant changes in physicochemical properties in the accelerating and long-term stability tests. Similar pharmacokinetic behavior in beagle dogs was obtained and the AUC 0 - 12h values were 1196.73 ± 320.85 and 1505.56 ± 617.93 µg.h/L for EPE and EPS (p > 0.5), respectively. Likewise, no remarkable difference in biodistribution profiles in mice was found for both formulations. Safety assessment studies including hemolysis test, rabbit ear vein test and injection anaphylaxis were undertaken and the EPE was proven to be safe for intravenous administration. Specifically, after consecutive 12 weeks administration in rats, systematic and local toxicity induced by EPE were alleviated relative to that of EPS. Furthermore, significant and comparable antitumor activities to EPS were also demonstrated by EPE with tumor suppression rate (TSR) of 66.63, 55.94, and 60.16% against H460, Hep G2, and BCAP-37 human cancer cell lines in nude mice at the dose of 15 mg/kg, respectively.

CONCLUSION

These results suggest that this LCT/MCT-based lipid emulsion is a promising alternative intravenous carrier for etoposide with high stability, improved convenience, alleviated toxicity, and noncompromised antitumor efficacy.

In-vivo pharmacokinetics, tissue distribution and anti-tumour effect of hydroxycamptothecin delivered in oil-in-water submicron emulsions

Objectives

The aim of this study was to investigate the pharmacokinetics, tissue distribution and anti-tumour effect of hydroxycamptothecin submicron emulsions (HCPT-SEs).

Methods

HCPT-SEs or HCPT injection (HCPT-I) was administered intravenously into the tail vein of rats or S180 tumour-bearing mice.

Key findings

HCPT-SEs increased the plasma concentration of HCPT compared with HCPT-I at all time points. The AUC0-∞, elimination half-life and mean residence time of anionic submicron emulsions containing HCPT (HCPT-ASEs) and cationic submicron emulsions containing HCPT (HCPT-CSEs) were significantly greater than those of HCPT-I (P < 0.01). Especially, a prolonged elimination half-life was found for HCPT-CSEs. HCPT-CSEs and HCPT-ASEs resulted in a 7.9-fold and 3.1-fold increase in AUC0-6h of tumour compared with HCPT-I, respectively. The targeting efficiency (Te) of HCPT-ASEs and HCPT-CSEs indicated their selectivity to tumour and the Te of HCPT-CSEs was significantly higher than that of HCPT-ASEs (P < 0.01). The anti-tumour effect studies showed that HCPT-SEs improved the therapeutic efficiency of HCPT compared with HCPT-I. The percentage of tumour growth suppression rate of mice treated with HCPT-CSEs (2.0 mg HCPT eq./kg) increased 2.1 fold compared with that of HCPT-I.

Conclusions

Submicron emulsions can alter the pharmacokinetic characteristics and tissue distribution of HCPT, and enhance tumour targeting and anti-tumour activity.

Nanoemulsion formulation of fisetin improves bioavailability and antitumour activity in mice

The natural flavonoid fisetin (3,3',4',7-tetrahydroxyflavone) has shown antitumour activity but its administration is complicated by its low water solubility. Our aim was to incorporate fisetin into a nanoemulsion to improve its pharmacokinetics and therapeutic efficacy. Solubility and emulsification tests allowed to develop an optimal nanoemulsion composed of Miglyol 812N/Labrasol/Tween 80/Lipoid E80/water (10%/10%/2.5%/1.2%/76.3%). The nanoemulsion had an oil droplet diameter of 153 ± 2 nm, a negative zeta potential (-28.4 ± 0.6 mV) and a polydispersity index of 0.129. The nanoemulsion was stable at 4 °C for 30 days, but phase separation occurred at 20 °C. Pharmacokinetic studies in mice revealed that the fisetin nanoemulsion injected intravenously (13 mg/kg) showed no significant difference in systemic exposure compared to free fisetin. However, when the fisetin nanoemulsion was administered intraperitoneally, a 24-fold increase in fisetin relative bioavailability was noted, compared to free fisetin. Additionally, the antitumour activity of the fisetin nanoemulsion in Lewis lung carcinoma bearing mice occurred at lower doses (36.6 mg/kg) compared to free fisetin (223 mg/kg). In conclusion, we have developed a stable nanoemulsion of fisetin and have shown that it could improve its relative bioavailability and antitumour activity.

Injectable lipid emulsions-advancements, opportunities and challenges

Injectable lipid emulsions, for decades, have been clinically used as an energy source for hospitalized patients by providing essential fatty acids and vitamins. Recent interest in utilizing lipid emulsions for delivering lipid soluble therapeutic agents, intravenously, has been continuously growing due to the biocompatible nature of the lipid-based delivery systems. Advancements in the area of novel lipids (olive oil and fish oil) have opened a new area for future clinical application of lipid-based injectable delivery systems that may provide a better safety profile over traditionally used long- and medium-chain triglycerides to critically ill patients. Formulation components and process parameters play critical role in the success of lipid injectable emulsions as drug delivery vehicles and hence need to be well integrated in the formulation development strategies. Physico-chemical properties of active therapeutic agents significantly impact pharmacokinetics and tissue disposition following intravenous administration of drug-containing lipid emulsion and hence need special attention while selecting such delivery vehicles. In summary, this review provides a broad overview of recent advancements in the field of novel lipids, opportunities for intravenous drug delivery, and challenges associated with injectable lipid emulsions.

Pharmacokinetics and pharmacodynamics of chlorambucil delivered in long-circulating nanoemulsion

Chlorambucil was incorporated into a nanoemulsion modified with poly(ethylene glycol) to improve its pharmacokinetics and tissue distribution, and thus enhance its therapeutic efficacy. A long-circulating nanoemulsion (LNE) was prepared using soybean oil, egg lecithin, cholesterol and PEG(2000)DSPE. The LNE had an oil droplet size <200 nm with a surface charge of -32.2 to -35.6 mV. Approximately, 97% of the chlorambucil was encapsulated in the LNE. Intravenous (i.v.) administration of the chlorambucil LNE to C57 B/6 mice showed improved pharmacokinetic parameters with 1.4-fold higher area under the plasma concentration-time curve (AUC) and 1.3-fold longer half-life compared to a non-PEG-modified nanoemulsion, and 2.7-fold higher AUC and 7.6-fold longer half-life compared to chlorambucil solution. Tissue distribution studies after i.v. administration with LNE showed a considerable decrease in drug uptake in the reticulo-endothelial system containing organs compared to non-PEG-modified nanoemulsion. Additionally, the chlorambucil delivered in LNE significantly enhanced therapeutic efficacy in the subcutaneous colon-38 adenocarcinoma tumor mouse model with no apparent increase in toxicity. This study suggests that LNE could produce remarkably improved pharmacokinetic profile and therapeutic efficacy of chlorambucil compared to non-PEG-modified nanoemulsion and solution.

Formulation, characterization and pulmonary deposition of nebulized celecoxib encapsulated nanostructured lipid carriers

The aim of the current study was to encapsulate celecoxib (Cxb) in the nanostructured lipid carrier (Cxb-NLC) nanoparticles and evaluate the lung disposition of nanoparticles following nebulization in Balb/c mice. Cxb-NLC nanoparticles were prepared with Cxb, Compritol, Miglyol and sodium taurocholate using high-pressure homogenization. Cxb-NLC nanoparticles were characterized for physical and aerosol properties. In-vitro cytotoxicity studies were performed with A549 cells. The lung deposition and pharmacokinetic parameters of Cxb-NLC and Cxb solution (Cxb-Soln) formulations were determined using the Inexpose system and Pari LC star jet nebulizer. The particle size and entrapment efficiency of the Cxb-NLC formulation were 217+/-20nm and >90%, respectively. The Cxb-NLC released the drug in controlled fashion, and in-vitro aerosolization of Cxb-NLC formulation showed an FPF of 75.6+/-4.6%, MMAD of 1.6+/-0.13microm and a GSD of 1.2+/-0.21. Cxb-NLC showed dose and time dependent cytotoxicity against A549 cells. Nebulization of Cxb-NLC demonstrated 4 fold higher AUC(t)/D in lung tissues compared to the Cxb-Soln. The systemic clearance of Cxb-NLC was slower (0.93l/h) compared to the Cxb-Soln (20.03l/h). Cxb encapsulated NLC were found to be stable and aerodynamic properties were within the respirable limits. Aerosolization of Cxb-NLC improved the Cxb pulmonary bioavailability compared to solution formulation which will potentially lead to better patient compliance with minimal dosing intervals.