Abstract
Introduction: Acyclovir (ACV) is an antiviral medication primarily used to treat herpes simplex virus (HSV) infections. The methyl thiazolyl tetrazolium (MTT) assay is a reliable quantitative method for assessing cell viability.
Objectives: The study aimed to develop and evaluate the cytotoxic effects of an ACV-based organo-gel lipstick.
Materials and Methods: In this in-vitro and experimental study, formulations of an ACV-based organo-gel lipstick were created using varying amounts of 12-hydroxystearic acid (12HSA), beeswax, vitamin E, and oleic acid, resulting in a total of 34 formulations, of which 20 successfully gelled into lipsticks. To evaluate these formulations, a series of tests were conducted, including tabletop rheology to assess flow properties, pH measurement to ensure skin compatibility, spreadability testing to determine ease of application, and melting and breaking point analysis to evaluate thermal stability. Additionally, optical microscopy was employed to observe microstructural characteristics, in vitro release studies measured drug release profiles, skin irritation tests assessed biocompatibility using mice, permeation studies evaluated drug absorption through skin models, oscillatory rheology analyzed viscoelastic properties, and MTT cytotoxicity assays assessed cell viability in the presence of ACV.
Results: The results revealed diverse characteristics among the formulations, with gel-sol temperatures exceeding 34 °C and pH values ranging from 4 to 7, indicating their stability for topical applications. Spreadability testing showed poor performance for formulations F1 and F5, while other formulations demonstrated adequate spreadability. Notably, formulations F24 and F34 exhibited melting points above 50 °C, reflecting good thermal stability and the breaking point was highest in beeswax lipsticks across both solvents tested. Microscopic analysis indicated that oleic acid-based organogels formed spherulites, whereas vitamin E formulations displayed fibrillar networks. ACV release was significantly higher in beeswax formulations with oleic acid compared to those containing vitamin E in 12HSA organogels. Skin irritation tests on mice showed no signs of irritation, with formulation F34 demonstrating higher permeation through external lower and inner mucus bovine lips than formulation F21. Oscillatory rheology tests indicated that selected organogels exhibited strength, showing comparable storage modulus (G’) values, linear viscoelastic region (LVER), flow points, and frequency independence, except formulation F21. Additionally, the MTT assay results indicated that the F34 lipstick formulation significantly increased rhabdomyosarcoma cell viability against the HSV.
Conclusion: In conclusion, formulation F34, utilizing gelators in oleic acid, has shown significant promise as an effective delivery system for ACV. Its high melting point and excellent elastic properties further support its suitability for use in a lipstick-based organo-gel format. Additionally, the formulation’s ability to enhance the inhibition of viral toxicity to rhabdomyosarcoma cells underscores its potential therapeutic efficacy against HSV, distinguishing it from other formulations that hinder ACV release.