Design, Optimization, and Evaluation of Lincomycin Hydrochloride Transdermal Patches for Sustained Drug Release and Improved Antimicrobial Efficacy

Background: Antimicrobial Resistance (AMR) presents a major global health concern, necessitating the development of novel antimicrobial agents and effective drug delivery systems. Lincomycin hydrochloride, a lincosamide antibiotic active against Gram-positive bacteria, exhibits poor oral bioavailability and causes systemic side effects, limiting its therapeutic potential. Objectives: This study aimed to formulate and evaluate lincomycin hydrochloride-loaded transdermal patches to enhance localized antimicrobial efficacy, improve patient compliance, and minimize systemic toxicity. Materials and Methods: Transdermal patches were prepared by the solvent casting method using Hydroxypropyl Methylcellulose (HPMC) K100M and Polyvinyl Alcohol (PVA) as film-forming polymers, propylene glycol as a permeation enhancer, and glycerine as a plasticizer. A 2² full factorial design was employed to optimize polymer concentrations for maximum drug release. The prepared patches were evaluated for physicochemical characteristics, in vitro drug release, and antimicrobial activity against Staphylococcus aureus. FTIR analysis was conducted to assess drug-excipient compatibility. Results: The patches exhibited uniform thickness, flexibility, suitable surface pH, and stable drug content, confirming formulation stability and skin compatibility. In vitro release studies showed that higher polymer concentrations decreased drug release. The optimized formulation containing 1032 mg HPMC K100M and 663 mg PVA achieved 75.87% cumulative drug release over 6 hr. Antimicrobial studies revealed significant inhibition zones, demonstrating superior antibacterial activity compared to pure drug discs. FTIR spectra confirmed no significant drug-excipient interactions. Conclusion: Lincomycin hydrochloride transdermal patches demonstrated promising physicochemical stability, controlled release, and potent antibacterial activity. The optimized formulation provides an effective, patient-friendly approach for localized treatment of bacterial infections and may serve as a potential strategy to mitigate antimicrobial resistance.