Gelled non-toxic microemulsions: phase behavior & rheology

Area of Science:

• Colloid and Surface Science
• Materials Science
• Pharmaceutical Sciences

Background:

• Bicontinuous microemulsions offer potential for transdermal drug delivery due to their mechanical stability.
• Existing systems often lack non-toxic and economical components, hindering practical application.
• A suitable formulation for efficient transdermal delivery remains unaddressed.

Purpose of the Study:

• To formulate and characterize a non-toxic, gelled bicontinuous microemulsion for transdermal drug delivery.
• To replace expensive and potentially toxic components of a known system with economical and safe alternatives.
• To evaluate the gelation capability of different low molecular weight gelators and confirm the system's suitability.

Main Methods:

• Modification of a scouting system (H2O-n-octane-n-octyl β-d-glucopyranoside-1-octanol) using non-toxic components and cost-effective surfactants (Plantacare® series).
• Screening of three low molecular weight gelators: 12-hydroxyoctadecanoic acid (12-HOA), 1,3:2,4-dibenzylidene-d-sorbitol (DBS), and N,N'-dibenzoyl-l-cystine (DBC).
• Characterization of the optimized gelled system (H2O-IPM-Plantacare 1200 UP-1,2-octanediol with DBS) using oscillatory shear rheometry and small-angle neutron scattering (SANS).

Main Results:

• Only 1,3:2,4-dibenzylidene-d-sorbitol (DBS) effectively gelled the non-toxic microemulsion.
• The gelled system confirmed its gel state through rheological measurements.
• Small-angle neutron scattering (SANS) verified that the gel network did not alter the microemulsion's microstructure.

Conclusions:

• A cost-effective, non-toxic, gelled bicontinuous microemulsion suitable for transdermal drug delivery has been successfully formulated.
• 1,3:2,4-dibenzylidene-d-sorbitol is an effective gelator for this specific non-toxic microemulsion system.
• The developed system maintains its structural integrity, supporting its potential as a transdermal carrier.