Particle size analysis of concentrated phospholipid microemulsions: II. Photon correlation spectroscopy

Journal Title: The AAPS Journal - Year 2000, Vol 2, Issue 3

Abstract

The solvated droplet size of concentrated water-in-oil (w/o) microemulsions prepared frome egg and soy lecithin/water/isopropyl myristate and containing short-chain alcohol cosurfactants has been determined using photon correlation spectroscopy (PCS). The effect of increasing the water volume fraction (from 0.04 to 0.26) on the solvated size of the w/o droplets at 298 K has been investigated at 4 different surfactant/cosurfactant weight ratios (Km of 1∶1, 1.5∶1, 1.77∶1, and 1.94∶1); in all cases the total surfactant/cosurfactant concentration was kept constant at 25% w/w. In the case of the microemulsions prepared from egg lecthin, the diffusion coefficients obtained from PCS measurements were corrected for interparticulate interactions using a hard-sphere model that necessitated estimation of the droplet volume fractions, which in the present study were obtained from earlier total intensity light-scattering (TILS) studies performed on the same systems. Once corrected for hard-sphere interactions, the diffusion coefficients were converted to solvated radii using the Stokes-Einstein equation assuming spherical microemulsion droplets. For both egg and soy lecithin systems, no microemulsion droplets were detected at water concentrations less than 9 wt% regardless of the alcohol and Km used, suggesting that at low concentrations of added water, cosolvent systems were formed. At higher water concentrations, however, microemulsion droplets were observed. The changes in droplet size followed the expected trend in that for a fixed Km the size of the microemulsion droplets increased with increasing volume fraction of water. At constant water concentration, droplet size decreased slightly upon increasing Km. Interestingly, only small differences in size were seen upon changing the type of alcohol used. The application of the hard-sphere model to account for interparticulate interactions for the egg lecithin systems indicated that the uncorrected diffusion coefficients underestimated particle size by a factor of slightly less than 2. Reassuringly, the corrected droplet sizes agreed very well with those obtained from our earlier TILS study.

Authors and Affiliations

Reza Aboofazeli, David J. Barlow, M. Jayne Lawrence

Keywords

Related Articles

Regulatory Pathways for ATP-binding Cassette Transport Proteins in Kidney Proximal Tubules

The ATP-binding cassette transport proteins (ABC transporters) represent important determinants of drug excretion. Protective or excretory tissues where these transporters mediate substrate efflux include the kidney prox...

Practical Anticipation of Human Efficacious Doses and Pharmacokinetics Using In Vitro and Preclinical In Vivo Data

Accurate predictions of human pharmacokinetic and pharmacodynamic (PK/PD) profiles are critical in early drug development, as safe, efficacious, and “developable” dosing regimens of promising compounds ha...

Transfection efficiency and toxicity of polyethylenimine in differentiated Calu-3 and nondifferentiated COS-1 cell cultures

In the present study, we evaluated polyethylenimine (PEI) of different molecular weights (MWs) as a DNA complexing agent for its efficiency in transfecting nondifferentiated COS-1 (green monkey fibroblasts) and well-diff...

Pharmacokinetic Evaluation of Intranasally Administered Vinyl Polymer-Coated Lorazepam Microparticles in Rabbits

The intranasal (IN) administration of lorazepam is desirable in order to maximize speed of onset and minimise carry-over sedation; however, this benzodiazepine is prone to chemical hydrolysis and poor airway retention, a...

Paracellular Tightness and Claudin-5 Expression is Increased in the BCEC/Astrocyte Blood–Brain Barrier Model by Increasing Media Buffer Capacity During Growth

Most attempts to develop in vitro models of the blood–brain barrier (BBB) have resulted in models with low transendothelial electrical resistances (TEER), as compared to the native endothelium. The aim of the pre...

Download PDF file
  • EP ID EP682092
  • DOI  10.1208/ps020319
  • Views 94
  • Downloads 0

How To Cite

Reza Aboofazeli, David J. Barlow, M. Jayne Lawrence (2000). Particle size analysis of concentrated phospholipid microemulsions: II. Photon correlation spectroscopy. The AAPS Journal, 2(3), -. https://www.europub.co.uk/articles/-A-682092