Stratum corneum lipids liposomes for the topical delivery of 5-aminolevulinic acid in photodynamic therapy of skin cancer: preparation and in vitro permeation study

BACKGROUND: Photodynamic therapy (PDT) using 5-aminolevulinic acid (5-ALA) is a skin cancer therapy that still has limitations due to the low penetration of this drug into the skin. We have proposed in this work a delivery system for 5-ALA based on liposomes having lipid composition similar to the mammalian stratum corneum (SCLLs) in order to optimize its skin delivery in Photodynamic Therapy (PDT) of skin cancers. METHODS: SCLLs were obtained by reverse phase evaporation technique and size distribution of the vesicles was determinated by photon correlation spectroscopy. In vitro permeation profile was characterized using hairless mouse skin mounted in modified Franz diffusion cell. RESULTS: Size exclusion chromatography on gel filtration confirmed vesicle formation. SCLLs obtained by presented a degree of encapsulation of 5-ALA around 5.7%. A distribution of vesicle size centering at around 500 nm and 400 nm respectively for SCLLs and SCLLs containing 5-ALA was found. In vitro 5-ALA permeation study showed that SCLLs preparations presented higher skin retention significantly (p < 0.05) on the epidermis without SC + dermis, with a decreasing of skin permeation compared to aqueous solution. CONCLUSIONS: The in vitro delivery performance provided by SCLLs lead to consider this systems adequate for the 5-ALA-PDT of skin cancer, since SCLLs have delivered 5-ALA to the target skin layers (viable epidermis + dermis) to be treated by topical PDT of skin cancer

Method of simultaneous analysis of liposome components using HPTLC/FID.

Liposomes are composed of different kind of lipids or lipophilic substances and are used as carriers of bioactive molecules. The characterization of the prepared liposomes consists of the calculation of the drug to lipid molar ratio by measuring the lipids and the encapsulated molecule.The present work describes an analytical methodology on simultaneous determination of all the lipid ingredients of the liposome formulation, using Thin Layer Chromatography coupled with a Flame Ionization Detector (TLC/FID), using the least possible sample quantity. The method consists of a chromatographic separation of the liposomal ingredients on silica gel scintillated on quartz rods and subsequent detection of the ingredients by scanning the rods by a hydrogen flame. The produced ions are detected by a Flame Ionization Detector and the signal is converted to a chromatogram.This method may be applied on every step of the liposome preparation for examining the quality of the raw materials, tracking possible errors of the preparation procedure and finally analyzing the content of the final liposomal composition

Qualitative and quantitative one-step analysis of lipids and encapsulated bioactive molecules in liposome preparations by HPTLC/FID (IATROSCAN)

Liposomes are widely used vehicles for the delivery of bioactive molecules. They are composed mainly from acyl-phosphatidylcholines, cholesterol, and charged lipids (e.g., stearylamine, dipalmitoylphosphatidylglycerol (DPPG), phosphatidylethanolamine).The incorporation efficiencies of the bioactive molecule and the drug to lipid molar ratio are important factors for the assessment of the liposomal formulation. In order to successfully characterize a liposomal formulation, it is necessary to be able to accurately measure the lipids and the encapsulated molecule, using the smallest possible sample.The present work describes an analytical methodology on qualitative and quantitative determination of all the lipid ingredients that are involved in the liposome formulation, as well as the drug incorporation and the drug-lipid ratio, by a simultaneous measurement of all the liposomal ingredients using thin-layer chromatography coupled with a flame ionization detector (HPTLC/FID).The procedure requires only one measurement per sample, and it can be applied even in very small or much diluted samples.The proposed analytical method can be applied in general on all steps of the development of liposomal formulations. The purity and stability of the raw materials can also be easily evaluated. In addition the preparation procedure can be tracked in order to locate possible losses of raw material and errors of the preparation method resulting in the amelioration of the method. Copyright © Informa Healthcare

Lipid analysis of Greek walnut oil (Juglans regia L.)

The walnut oil (Juglans regia L.) total lipids (TL) were extracted by the Bligh-Dyer method and the lipid classes have been isolated by chromatographic techniques and they were analyzed by high performance thin layer chromatography (HPTLC) /FID and GC-MS. The oil was found to be rich in neutral lipids (96.9% of total lipids) and low in polar lipids (3.1% of total lipids). The neutral lipid fraction consisted mainly of triacylglycerides whereas the polar lipids mainly consisted of sphingolipids. GC-MS data showed that the main fatty acid was linoleic acid. Unsaturated fatty acids were found as high as 85%, while the percentage of the saturated fatty acids was found 15%. Two types of liposomes were prepared from the isolated walnut oil phospholipids and characterized as new formulations. These formulations may have future applications for encapsulation and delivery of drugs and cosmetic active ingredients

Assessment of the physicochemical stability of all-in-one parenteral emulsions for neonates according to USP specifications

Background: The purpose of this study was to describe the methodology to assess the stability of all-in-one (AIO) parenteral nutrition admixtures, containing glucose, proteins, and lipids, to the standards of U.S. Pharmacopoeia (USP &lt;729&gt;). The influence of calcium and commercially available lipid emulsions and amino acid solutions were also examined. Methods: Four batches of 5 AIO admixtures containing calcium were compounded with commercially available lipid emulsions and amino acid solutions. Two of them contained calcium. Their stability was tested under conditions simulating clinical use. All the admixtures were assessed for criteria set by the USP &lt;729&gt;: (1) mean droplet diameter (MDD) and (2) percentage of volume weighted particles with diameter &gt; 5 μm (PFAT5). Results: All admixtures were within the specifications set by the USP with respect to the MDD at 0, 24, and 48 hours, but only those batches lacking calcium met the benchmarks set by the pharmacopoeia, with respect to PFAT5, on the day of preparation. Conclusions: The presence of calcium destabilized the admixtures, while the use of different commercial ingredients altered the admixtures&apos; characteristics. Only 1 batch of the AIO admixtures studied was found to be compliant with USP &lt;729&gt; standards. © 2013 American Society for Parenteral and Enteral Nutrition

Effect of a bioactive curcumin derivative on DPPC membrane: A DSC and Raman spectroscopy study

Interactions of dimethoxycurcumin (1) a lipophilic bioactive curcumin derivative with dipalmitoyl phosphatidylcholine (DPPC) were investigated. The thermodynamic changes caused by (1) and its location into DPPC lipid bilayers were monitored by differential scanning calorimetry and Raman spectroscopy. The results reveal that (1) influences the thermotropic properties of DPPC lipid membrane causing abolition of the pretransition and broadening of the phase-transition profile and slightly decreases the Tm at increasing concentrations. The Raman height intensity ratios of the peaks I2935/2880, I2844/2880 and I1090/1130 are representative of the interaction of (1) with the alkyl chains and furnish information about the ratio between disorder and order that exists in the conformation of the alkyl chain. The intensity changes of the peak at 715 cm-1 indicates interaction between the choline head group and (1). The Raman spectroscopy results are in agreement with the thermal analysis results. Biologically active lipophilic molecules such as (1) should be studied in terms of their interaction with lipid bilayers prior to the development of advanced lipid carrier systems such as liposomes. The results of these studies provide information on the membrane integrity and physicochemical properties that are essential for the rational design lipidic drug delivery systems. © 2006 Elsevier B.V. All rights reserved

Lipid analysis of Greek broad bean oil: Preparation of liposomes and physicochemical characterization

Liposomes were prepared from the isolated phospholipids of mature broad bean [Vicia faba L. (syn. Fabae calabaricae)] oil and their physical properties were studied. The method of preparation was the hydration of the thin lipid film, while the probe sonication methodology was used for reducing the size of the vesicles. The seeds of the broad bean were collected in two different periods of maturity and extracted by the Bligh-Dyer method, and the lipid classes were studied by HPTLC/FID. The oils were found to be rich in polar lipids (63.1% and 60.2% of total lipids) and low in neutral lipids (36.9% and 39.8% of total lipids) for the immature and mature seed oils, respectively. The neutral lipid fraction consisted mainly of triacylglycerides (34.2% and 32.3%) whereas the polar lipids mainly consisted of phospholipids (60.2% and 54.2%) for the mature and immature seed oils, respectively. Sphingolipids (8.9%) were identified only in the immature seed oil. The overall goal of this study was the preparation of a new liposomal formulation with physicochemical properties such as unique lipid composition, size and ζ-potential, which are important factors influencing drug delivery to the target tissues. © 2005 Wiley-VCH Verlag GmbH &amp; Co. KGaA