Liposomes as a topical delivery system: the role of size on transport studied by the EPR imaging method

• Published in: Journal of controlled release Vol. 59; no. 1; pp. 87 - 97
• Main Authors: Šentjurc, M, Vrhovnik, K, Kristl, J
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.05.1999; Elsevier
• Subjects: 1,2-Dipalmitoylphosphatidylcholine - chemistry; Administration, Topical; Animals; Biological and medical sciences; Biological Transport; Chemical Phenomena; Chemistry, Physical; Drug Delivery Systems; Electron paramagnetic resonance imaging; Electron Spin Resonance Spectroscopy - methods; General pharmacology; Liposome; Liposomes - chemistry; Medical sciences; Particle Size; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Phosphatidylcholines - chemistry; Size; Skin; Skin - metabolism; Skin Absorption; Spin Labels; Swine; Transport; Liposome; Skin; Transport; Size; Electron paramagnetic resonance imaging; Encapsulation; Particle size; Pharmaceutical technology; Biological transport; Lipids; Drug carrier; In vitro; Pig; Vertebrata; Mammalia; Animal; Dosage form; Artiodactyla; Electron paramagnetic resonance; Ungulata
• ISSN: 0168-3659; 1873-4995
• DOI: 10.1016/S0168-3659(98)00181-3

The relative contribution of the liposome size, lamellarity, composition and charge to the transport into the skin of drug, which was applied entrapped in liposomes is a subject of some controversy. In this study the influence of liposome size on the transport of hydrophilic substance was investigated. For this purpose liposomes composed of dipalmitoylphosphatidylcholine (DPPC), or non-hydrogenated soya lecithin (NSL) or hydrogenated soya lecithin (HSL), all in combination with 30% cholesterol, as well as of two types of niosomes: from glyceryl distearate or PEG stearate in combination with 45% of cholesterol and 10% of lipoaminosalt were prepared and their physical characteristics (size, polydispersity index, zeta potential, entrapped volume) were determined. Their size was varied by extrusion and by sonication. The transport of the entrapped spin labeled hydrophilic compounds into the skin was measured by electron paramagnetic resonance imaging methods. No significant transport into the deeper skin layers (more than 100 μm deep) was observed for NSL liposomes, irrespective of vesicle size. For all other vesicular systems some transport into the deeper skin layers was observed, which did not depend on vesicle size, significantly until the vesicle diameter of approximately 200 nm was reached. However, for small vesicles (with diameter less than 200 nm) the transport is significantly decreased. We have proven that small vesicles are not stable and disintegrate immediately in contact with other surfaces. As a consequence, they lose an important influence on the topical delivery of the entrapped hydrophilic substances.