Comparative Study of Anti-Acne Gel Formulations with Thymus vulgaris, Tretinoin, and Their Combined Therapeutic Effect
Abstract
Acne vulgaris is a chronic inflammatory skin disorder affecting more than 85% of adolescents and 20–40% of adults. Its pathogenesis involves sebum overproduction, follicular hyperkeratinisation, Cutibacterium acnes proliferation, and inflammatory mediators such as IL-1β and TNF-α. Conventional therapies like tretinoin and antibiotics are effective but limited by irritation, poor compliance, and emerging resistance. In the present study, carbopol-based gel formulations containing Thymus vulgaris (thyme) methanol extract, tretinoin (0.025-0.05% w/w), and their combination were developed and evaluated. Thyme extract is rich in thymol, carvacrol, flavonoids, and polyphenols, exhibiting antimicrobial, anti-inflammatory, and antioxidant activities against C. acnes. The formulations showed acceptable physicochemical properties, including pH (5.7–6.5), viscosity (15,030–15,660 cps), spreadability (29–32 g·cm/s), and drug content (98–102%). Antimicrobial studies demonstrated zone of inhibition of 10 mm (thyme), 15 mm (tretinoin), and 20 mm (combination), indicating synergistic activity. No dermal irritation was observed (PII = 0), and accelerated stability studies confirmed less than 5% variation over 90 days under ICH conditions. Preliminary evaluation indicated superior efficacy of the combination gel with approximately 70–72% reduction in acne lesions and improved tolerability compared to individual treatments. Overall, the thyme–tretinoin gel represents a stable, effective, and synergistic topical formulation for acne management, particularly suitable for humid climatic conditions.
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