Article

Influence of membrane-solvent-solute interactions on solute permeation in model membranes

Department of Pharmaceutics, School of Pharmacy, University of London, 29-39 Brunswick Square, London WC1N 1AX, UK.
International Journal of Pharmaceutics (Impact Factor: 3.79). 06/2007; 336(1):108-14. DOI: 10.1016/j.ijpharm.2006.11.054
Source: PubMed

ABSTRACT The interaction of the components of topical formulations with the skin is an important consideration for effective drug delivery and efficacy. The relative importance of solubility parameters and other solvent properties on membrane diffusion processes has not been fully elucidated in the literature. In this paper, the effect of different vehicles on the permeation of caffeine, salicylic acid and benzoic acid through silicone membranes was evaluated. Polydimethylsiloxane membranes were used as model membranes for comparing the release characteristics of saturated solutions of model permeants because of their homogeneity and uniformity. Log P (octanol-water partition coefficient) and solubility parameter values were calculated for the compounds under study. In vitro diffusion studies indicated that the permeation profiles of all solutes showed a similar pattern. The permeation rates of benzoic acid and salicylic acid through silicone membrane from saturated solutions were higher than those for caffeine reflecting the more lipophilic nature of these compounds in comparison with caffeine. Solvent uptake studies confirmed that the vehicles that were highly sorbed by the membrane altered its properties and hence the flux. Vehicles that were not sorbed by the membrane showed similar steady-state fluxes for the model drugs. This suggests that the diffusion process is mainly influenced by the interactions between the vehicles and the membrane. Solubility parameter alone cannot explain the interactions between the membrane and the vehicles in all cases. Rather, it is likely that membrane flux reflects a combination of different solvent and solute characteristics, such as size, shape and charge distribution.

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    • "However, this explanation only considered the interaction between drug and vehicle. Actually, the behaviour of drug permeation across a membrane was controlled by the interplay of drug–vehicle–membrane multiple interactions (Dias et al., 2007a,b). This could produce a nonideal behaviour of the membrane and the physicochemical properties of the membrane would change accordingly (Twist and Zatz, 1988). "
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    ABSTRACT: The purpose of this work was to investigate the effect of solute-membrane interaction under supersaturated conditions on the transport of model solute (salicylic acid) across poly(dimethylsiloxane) (PDMS) membrane. Supersaturated systems with a degree of saturation (DS) up to 8 were prepared using a molecular form technique with water as the vehicle to minimize the vehicle-membrane interaction. The spectroscopic and thermal analysis revealed the presence of both hydrogen bonding and nonpolar interaction between the solute and PDMS. Upon treatment by supersaturated solutions the degree of solute-membrane interaction increased with increasing DS. This enhanced the barrier property of PDMS and thus led to the flux attenuation compared to that calculated by Higuchi equation. This work highlighted the importance of solute-membrane interaction under supersaturation in the flux reduction, which should be considered when designing, and optimising supersaturated topical and transdermal drug delivery systems.
    International Journal of Pharmaceutics 11/2012; 441(1-2). DOI:10.1016/j.ijpharm.2012.11.016 · 3.79 Impact Factor
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    ABSTRACT: The relative importance of solubility parameters and other solvent properties on membrane diffusion processes has not been fully elucidated in the literature. Previously, we have studied the effect of different vehicles on the permeation of caffeine, benzoic acid (BA) and salicylic acid (SA) through silicone membranes. The present paper investigates diffusion of the selected permeants from different saturated solutions through human epidermis. The permeation of caffeine was strongly affected by the vehicle chosen and the maximum enhancement observed for the permeation of caffeine was 288-fold. A maximum of 12-fold enhancement in the flux was observed for the permeation of SA and a maximum of 10-fold enhancement was observed for the permeation of BA. The diffusion profiles obtained for SA in the different solvents were very similar when compared with those obtained for BA but the permeation rates were higher for BA than for SA. This similarity results from the similar chemical structure and lipophilicity.
    International Journal of Pharmaceutics 09/2007; 340(1-2):65-70. DOI:10.1016/j.ijpharm.2007.03.030 · 3.79 Impact Factor
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