ABSTRACT
PURPOSE: The objective was to develop, characterize and assess the potentiality of W1/O/W2 self-emulsifying multiple nanoemulsions to enhance signal/noise ratio for Magnetic Resonance Imaging (MRI). METHODS: For this purpose, a new formulation, was designed for encapsulation efficiency and stability. Various methods were used to characterize encapsulation efficiency ,in particular calorimetric methods (Differential Scanning Calorimetry (DSC), thermogravimetry analysis) and ultrafiltration. MRI in vitro relaxivities were assessed on loaded DTPA-Gd multiple nanoemulsions. RESULTS: Characterization of the formulation, in particular of encapsulation efficiency was a challenge due to interactions found with ultrafiltration method. Thanks to the specifically developed DSC protocol, we were able to confirm the formation of multiple nanoemulsions, differentiate loaded from unloaded nanoemulsions and measure the encapsulation efficiency which was found to be quite high with a 68% of drug loaded. Relaxivity studies showed that the self-emulsifying W/O/W nanoemulsions were positive contrast agents, exhibiting higher relaxivities than those of the DTPA-Gd solution taken as a reference. CONCLUSION: New self-emulsifying multiple nanoemulsions that were able to load satisfactory amounts of contrasting agent were successfully developed as potential MRI contrasting agents. A specific DSC protocol was needed to be developed to characterize these complex systems as it would be useful to develop these self-formation formulations.
Subject(s)
Chelating Agents/chemistry , Contrast Media/chemistry , Emulsions/chemistry , Gadolinium DTPA/chemistry , Gadolinium/chemistry , Nanoparticles/chemistry , Chemistry, Pharmaceutical/methods , Magnetic Resonance Imaging/methodsABSTRACT
Three multiple water-in-oil-in-water (W/O/W) nanoemulsions have been designed for potential inclusion of either lipophilic or hydrophilic drugs using a two-step emulsification process exclusively based on low-energy self-emulsification. The W/O primary emulsion was constituted by a blend of oil (medium chain triglyceride), a mixture (7:3) of two surfactants, and a 10% water phase. The surfactants were a mixture of Polysorbate-85/Labrasol(®), Polysorbate-85/Cremophor(®) EL or glycerol/Polysorbate-85. The final W/O/W nanoemulsions were obtained by the addition of water, with a weight ratio nanoemulsion/water of 1:2. The multiple emulsion stability was found to increase from 24 hours to 2 and 6 months with Labrasol, glycerol, and Cremophor, respectively. Cytotoxicity was found for formulations including Labrasol and Cremophor EL. The concentration of emulsion inhibiting 50% cell viability (IC(50)) was determined using the alamarBlue(®) test, giving after 24 hours of incubation, IC(50) = 10.2 mg/mL for the Labrasol formulation and IC(50) = 11.8 mg/mL for the Cremophor EL formulation. Corresponding calculated IC(50) values for surfactants were 0.51 mg/mL for Labrasol and 0.59 mg/mL for Cremophor EL. In both cases, cytotoxicity was due to an apoptotic mechanism, evidenced by chromatin condensation and P2X7 cell death receptor activation. The formulation including glycerol, investigated between 1 and 100 mg/mL concentration of nanoemulsion, did not affect cell viability. Moreover, neither chromatin condensation nor P2X7 activation was found between the 10 and 30 mg/mL final concentration of the emulsion. This last formulation would therefore be of major interest for further developments.
Subject(s)
Nanoparticles/chemistry , Pharmaceutical Vehicles/chemistry , Analysis of Variance , Apoptosis/drug effects , Cell Line , Cell Survival/drug effects , Drug Stability , Emulsions/administration & dosage , Emulsions/chemistry , Emulsions/toxicity , Epithelial Cells/cytology , Epithelial Cells/drug effects , Epithelium, Corneal/cytology , Epithelium, Corneal/drug effects , Glycerides , Glycerol/administration & dosage , Glycerol/analogs & derivatives , Glycerol/chemistry , Humans , Nanoparticles/administration & dosage , Nanoparticles/toxicity , Organic Chemicals/administration & dosage , Organic Chemicals/chemistry , Pharmaceutical Vehicles/administration & dosage , Pharmaceutical Vehicles/toxicity , Polysorbates/administration & dosage , Polysorbates/chemistry , Surface-Active Agents/administration & dosage , Surface-Active Agents/chemistry , Surface-Active Agents/toxicity , Water/chemistryABSTRACT
PURPOSE: Aseptic technique of pharmacy operators was assessed using simulated media-fill tests challenged with microorganisms. METHODS: Simulation of the process was done in accordance with multiple transfer steps using tryptone soya broth. All stoppers of broth medium vials were deliberately contaminated with a challenge micro-organism (Enterococcus faecalis). Each final preparation (vials, syringes, and minibags), including the culture medium, was incubated for 14 days at 32 °C. Vials, syringes, and bags were held in front of light daily for 14 days to detect any visual turbidity. At the end of the 14-day period, all clear culture media were filtered via a 0.45-µm sterile filter, which was then incubated at 32 °C on a tryptone soya agar plate. Bags and vials not subjected to manipulation were incubated simultaneously and served as controls. Visual observation by a pharmacist was conducted during the media-fill test, and finger dabs were taken at the end of the media-fill test to test for contamination. RESULTS: Ten operators previously trained in aseptic technique were assessed. The overall operator failure rate was 40%, and 2.3% of the 300 preparations were contaminated. Similarly, 10 of 60 finger dabs were found to be contaminated with E. faecalis, the challenge microorganism. There was no association between operators' years of experience and media-fill test results. CONCLUSION: Optimized media-fill tests allowed for the detection of minor deviances from standard protocol and helped to provide evidence of improper aseptic technique used by pharmacy operators.
