Design and Evaluation of Tenofovir Alafenamide-Loaded Solid Lipid Nanoparticles Gel for Enhanced Transdermal Delivery

This research essentially examines the design and evaluation of a gelling agent for transdermal delivery enhancement of Tenofovir Alafenamide (TAF)-loaded solid lipid nanoparticles (SLNs). Pre-formulation screening proved the drug is pure with a λ max 260 nm and a calibration curve (R² = 0.9999) for quantifying it. TAF-loaded SLNs showed a particle size distribution between 125.8 ± 2.0 nm to 274 ± 2.5 nm, with a PDI of 0.192 ± 0.04 to 0.214 ± 0.06 and zeta potential of -18.2 ± 4.1 mV to - 26.6 ± 3.2 mV, denoting ideal characteristics for stability and drug delivery. Formulation optimization of SLN was carried out with 96.42% entrapment efficiency. The TAF-loaded SLN-gel is characterized by a homogeneous texture, adequate smoothness, and has pH values in the range of 6.02 to 6.15; during the ex-vivo permeation study, it was found that the cumulative TAF permeation over 24 h was 45.2 µg/cm². In vitro drug release data showed sustained release for 12 hours and a cumulative drug release at 71.4%. The gel showed good spreadability (7.2 cm) and extrudability (4.8-5.5 N) and minor variability over a period of 3 months. Acute dermal toxicity and skin irritation assessments were carried out and exhibited no significant side effects. The Primary Irritation Index (PII) of 0.44 classified it as a mild irritant. Therefore, it can be legitimately stated from the studies that the TAF-loaded SLN gel can be developed into a potential transdermal drug delivery system with sustained release characteristics, excellent entrapment efficiency, and good safety profiles.