The development and characterisation of triglyceride-based ‘spontaneous’ multiple emulsions

Novel radioiodinated desvenlafaxine-loaded lipid nanocapsule for brain delivery

Lipid nanocapsules (LNCs) are lipid nanocarriers developed for drug delivery enhancement. The antidepressant drug desvenlafaxine (DSV) was entrapped in LNC to improve its brain delivery. Different DSV-loaded LNCs formulae using different oils and surfactants were studied to obtain the optimum formula for further studies. In vivo biodistribution studies were done using Swiss albino mice by intravenous injection of DSV-loaded LNCs by radioiodination technique. The optimum DSV-loaded LNC formula was obtained by using Labrafil® M1944CS as the oil and Solutol® HS15 as the surfactant in the ratio of 1:1, with a particle size of 34.28 ± 0.41 nm, a polydispersity index of 0.032 ± 0.05, a zeta potential of -25.77 ± 1.41, and good stability for up to 6 months. The in vivo biodistribution and pharmacokinetics data ensure the bioavailability improvement for DSV brain delivery as Cmax and AUC(1-t) increased more than double for intravenously DSV-loaded LNCs compared with the DSV solution. In conclusion, the results obtained from this study give an insight into the great potential of using DSV-loaded LNC for the enhancement of brain delivery.

The optimization of technological processes, stability and microbiological evaluation of innovative natural ingredients-based multiple emulsion

For the last couple of decades, multiple emulsions were prepared either by the re-emulsification of primary emulsion or they were produced by an emulsion inversion and their technological peculiarities were widely investigated. The aim of our study was to investigate and determine the optimal technological parameters of innovative multiple emulsion, prepared directly-by addition of ethanolic rosemary extract in the presence of polymeric emulsifier-and evaluate its stability by experimental surface response design approach. The results revealed that simplified W/O/W emulsification process is stirring time and stirring speed sensitive: the change of stirring time from 5 to 15 min at 600 rpm resulted in increased viscosity (from 1705.6 ± 62.2 to 3364.1 ± 112.5 mPA/s) and smaller oil droplet size (from 33.09 ± 1.51 to 17.81 ± 0.78 μm), though the conductivity increased from 800 ± 2 to 882 ± 2 μS/cm (p < .05). The second mixing stage (1000 rpm) had a negative effect on the conductivity of W/O/W emulsion because of the inner aqueous phase encapsulation efficiency. Ethanolic rosemary extract was used as multifunctional agent: not only to form multiple emulsion but also to preserve it; microbiological assay confirmed its effectiveness. A stable W/O/W type drug delivery system was successfully created without additional technological stages, phase inversion or surfactants.

Formulation and cytotoxicity evaluation of new self-emulsifying multiple W/O/W nanoemulsions

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 (IC₅₀) was determined using the alamarBlue^® test, giving after 24 hours of incubation, IC₅₀ = 10.2 mg/mL for the Labrasol formulation and IC₅₀ = 11.8 mg/mL for the Cremophor EL formulation. Corresponding calculated IC₅₀ 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.

Influence of phase inversion on the formation and stability of one-step multiple emulsions

A novel method of preparation of water-in-oil-in-micelle-containing water (W/O/W(m)) multiple emulsions using the one-step emulsification method is reported. These multiple emulsions were normal (not temporary) and stable over a 60 day test period. Previously, reported multiple emulsion by the one-step method were abnormal systems that formed at the inversion point of simple emulsion (where there is an incompatibility in the Ostwald and Bancroft theories, and typically these are O/W/O systems). Pseudoternary phase diagrams and bidimensional process-composition (phase inversion) maps were constructed to assist in process and composition optimization. The surfactants used were PEG40 hydrogenated castor oil and sorbitan oleate, and mineral and vegetables oils were investigated. Physicochemical characterization studies showed experimentally, for the first time, the significance of the ultralow surface tension point on multiple emulsion formation by one-step via phase inversion processes. Although the significance of ultralow surface tension has been speculated previously, to the best of our knowledge, this is the first experimental confirmation. The multiple emulsion system reported here was dependent not only upon the emulsification temperature, but also upon the component ratios, therefore both the emulsion phase inversion and the phase inversion temperature were considered to fully explain their formation. Accordingly, it is hypothesized that the formation of these normal multiple emulsions is not a result of a temporary incompatibility (at the inversion point) during simple emulsion preparation, as previously reported. Rather, these normal W/O/W(m) emulsions are a result of the simultaneous occurrence of catastrophic and transitional phase inversion processes. The formation of the primary emulsions (W/O) is in accordance with the Ostwald theory ,and the formation of the multiple emulsions (W/O/W(m)) is in agreement with the Bancroft theory.

Approaches for the development of solid and semi-solid lipid-based formulations

Interest in Lipid Based Drug Delivery (LBDD) has developed over the past decade fuelled by a better understanding of the multiple roles lipids may play in enhancing oral bioavailability. Moreover, the emergence of novel excipients with acceptable regulatory and safety profiles coupled with advances in formulation technologies have greatly improved the potential for successful lipid based formulations. With the growing interest in this field, there is an increasing need for guidelines in excipient selection and characterization; material handling, formulation design, and processing techniques to obtain effective and patient-compliant dosage forms. The aim of this review is to present the recent approaches in selecting the most appropriate lipid system(s); methods for characterization of their behavior in vitro and in vivo; and the current formulation and processing techniques to obtain various solid dosage forms.

Enhancing effect of Labrafac Lipophile WL 1349 on oral bioavailability of hydroxysafflor yellow A in rats

The objective of the present investigation was to clarify the mechanism by which Labrafac Lipophile WL 1349 (WL 1349) enhanced the oral bioavailability (BA) of hydroxysafflor yellow A (HSYA), the representative low permeable hydrophilic (biopharmaceutic classification system (BCS) Class III) drug. HSYA-phospholipid complex was prepared, and dissolved into WL 1349 with a certain surfactant to form a stable oil solution. Oral administration of HSYA aqueous solution at a dosage of 4.5mg/kg resulted a low plasma HSYA concentration with C(max) and AUC(0-8h) values of 0.105 microg/ml and 10.29 microg min/ml, respectively. HSYA-phospholipid complex oil solution with the same administration and dosage increased the plasma HSYA concentration significantly with C(max) and AUC(0-8h) values of 2.063 microg/ml and 381.145 microg min/ml, respectively. The results showed that WL 1349 could improve oral absorption of HSYA remarkably. Bioavailability investigations were performed to show WL 1349 dosage independent from HSYA absorption within the dosage from 1 ml/kg to 9 ml/kg. The test of bile duct ligation in rats showed that the oil solution containing WL 1349 did not result in detectable plasma HSYA concentration, but HSYA aqueous solution had the same AUC(0-8h) as the bile duct was not ligated. The in vitro lipolysis experiments of WL 1349 showed that WL 1349 was emulsified by deoxycholate, and then was hydrolyzed to fatty acids and monoglycerides by pancreatic lipase rapidly. The lipolysis products of WL 1349, caprylic acid, capric acid and caprylic and capric acid monoglycerides all improved the BA of HSYA in vivo. The results above indicated the emulsifying by bile, and hydrolysis to fatty acids and monoglycerides by pancreatic lipase was one of the enhancing mechanisms of HSYA-phospholipid complex oil solution absorption.