Low-Surfactant Microemulsions for Enhanced Topical Delivery of Poorly Soluble Drugs

Abstract

Purpose: To develop and characterize low-surfactant microemulsion (ME) gels to enhance topical delivery of poorly soluble drugs. Method: Five low surfactant ME formulations were manufactured following the construction of pseudo-ternary phase diagrams. The MEs were screened for their ability to dissolve a poorly soluble new chemical entity (Model Drug X). Various viscosity imparting agents like Carbopol 934, Colloidal Silica, HPMC K100M, Lubrajel NP, and Xanthan Gum were evaluated for the manufacture of these ME gels. Each ME gel was then further evaluated for physical stability, including assessing rheological profiles. In vitro release profiles were also determined and compared to a conventional ointment. Results: Three of the five low surfactant MEs developed (ME1, ME4 and ME5) were capable of dissolving Model Drug X up to 14 fold higher than the conventional ointment formulation. ME1 and ME4 gels comprising Xanthan gum or Carbopol 934 were physically stable, while ME5 gel was stable only with Colloidal Silica. The ME5 gel with Colloidal Silica showed an irreversible increase in its elastic modulus when exposed to high temperature, indicating that the formulation would be less suitable for commercial use. The Xanthan Gum and Colloidal Silica gels yielded significantly higher release rates (8 - 10 fold) compared to a conventional ointment and formulations containing Carbopol 934. The significant difference in drug release rates between Xanthan Gum and Carbopol 934 indicated that choice of viscosity imparting agent played an important role in governing drug release from ME gels. Conclusion: ME gels were developed with low surfactant concentrations and improved formulation characteristics, which increased the solubility and subsequent release of a poorly soluble drug. 
 
 This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.

Evaluation of the UVB‐screening capacity and restorative effects exerted by farnesol gel on UVB‐caused sunburn

“…It can be used in small amounts to produce an inexpensive formulation and naturally preserve the products so that a cost‐effective result can be obtained. XG with colloidal silica gels has been found to significantly increase release rates (by 8–10 fold) compared with a conventional ointment and formulations, demonstrating that XG is essential for the manipulation of drug release from low‐surfactant microemulsion gels …”

Spectroscopic Evaluation of Activated Charcoal as a Poison Antidote for Gliclazide Drug

“…The enhancement of the solubility of insoluble or poorly soluble drugs in the water now become a major challenge for researchers [24]. Different techniques have been developed for this purpose, of which is the low-surfactant microemulsion gels [25], Liquisolid technique [26], and micronization through pH change [27].…”

Analytical Approaches in Unveiling the Compatibility of Collagenase With Additives in View of Its Colloidal Delivery

“…Further, the enzyme was added with increasingly larger amounts of solvents using vortex mixer (Fisher Scientific, UK) for one minute. The solutions were further sonicated to reduce air bubbles and examined visually for any signs of crystallization or precipitation if any at 20 th minutes, 24 h, 48 h, and 72 h. Solubility (mg/ml) was determined by dividing of the enzyme weight (mg) with weight of solvent (ml) required to obtain a clear solution after 72 h [7,8].…”