Mathematical modeling of surface-active and non-surface-active drug transport in emulsion systems

Abstract

Mathematical models were developed for the prediction of surface-active and non surfaceactive drug transport in triphasic (oil, water, and micellar) emulsion systems as a function of micellar concentration. These models were evaluated by comparing experimental and simulated data. Fick's first law of diffusion with association of the surfaceactive or complexation nature of the drug with the surfactant was used to derive a transport model for surface-active drugs. This transport model assumes that the oil/water (O/W) partitioning process was fast compared with membrane transport and therefore drug transport was limited by the membrane. Consecutive rate equations were used to model transport of non surface-active drugs in emulsion systems assuming that the O/W interface acts as a barrier to drug transport. Phenobarbital (PB) and barbital (B) were selected as surface-active model drugs. Phenylazoaniline (PAA) and benzocaine (BZ) were selected as non surface-active model drugs. Transport studies at pH 7.0 were conducted using side-by-side diffusion cells and bulk equilibrium reverse dialysis bag techniques. According to the surface-active drug model, an increase in micellar concentration is expected to decrease drug-transport rates. Using the Microsoft EXCEL program, the non surface-active drug model was fitted to the experimental data for the cumulative amount of the model drug that disappeared from the donor chamber. The oil/continuous phase partitioning rates (k 1 ) and the membrane transport rates (k 2 ) were estimated. The predicted data were consistent with the experimental data for both the surface-active and non surface-active models.

The partitioning of emulsifiers in o/w emulsions: A comparative study of SANS, ultrafiltration and dialysis

“…Chidambaram and Burgess [43] reported the formation of CTAB micelles in an emulsified system as starting at about 27 mM. However, the droplet diameters of their samples were smaller by a factor of 10, with the result that the total interfacial areas of their emulsions were markedly larger than the ones in the present study [43]. This discrepancy reflects the fact that the exact cmc in a dispersed system is dependent on the total interfacial area of the respective emulsion.…”

“…For SDS, this value agrees well with the findings of Staples et al [12] with respect to measurements of hexadecane/water emulsions. Chidambaram and Burgess [43] reported the formation of CTAB micelles in an emulsified system as starting at about 27 mM. However, the droplet diameters of their samples were smaller by a factor of 10, with the result that the total interfacial areas of their emulsions were markedly larger than the ones in the present study [43].…”

“…Considering pharmaceutical applications, the release of active compounds can depend on their partitioning. It has been demonstrated that drugs can be transported by excess ionic and non-ionic emulsifiers [43,56].…”

Drug Absorption Principles

“…The passive diffusion of the molecules is governed by Fick's first law (Lennernas, 1998;Yoon and Burgess, 1998;Chidambaram and Burgess, 2000).…”

Hot homogenization process optimization for fragrance encapsulation in solid lipid nanoparticles

“…[56] The objective was to develop macroscopically stable and homogeneous preparation (without aggregated particles). Nonionic surfactants classically used for this type of emulsion were tested, polyoxyethylene 20 sorbitan ester, sorbitan ester, [54] polyoxyethylene glycol alkyl ethers [57] and polyoxyethylenepropylene oxide blocks copolymer, [56] and two non-conventional surfactants with an HLB close to HLBr for petrolatum i.e. 12 ± 1 [43] ( Table 2).…”