Development And In Vitro Characterization of Submicron Emulsion Gel of Tretinoin

The present study aimed to develop and evaluate a tretinoin-loaded submicron emulsion gel for topical drug delivery. Tretinoin is a lipophilic drug used in the treatment of acne and other skin conditions. A submicron emulsion-based gel system was developed to improve drug incorporation and provide a suitable topical formulation. Preformulation studies included organoleptic evaluation, melting point determination, solubility studies, partition coefficient determination, UV spectrophotometric calibration, and Fourier-transform infrared (FTIR) analysis. Submicron emulsions were prepared using soybean oil as the oil phase, lecithin as the emulsifier, and poloxamer 188 (F68) as a co-emulsifier, followed by high-speed stirring and probe sonication. The optimized emulsion was subsequently incorporated into a Carbopol gel base at different polymer concentrations and evaluated for appearance, pH, drug content, viscosity, and in vitro drug release.Among the prepared emulsions, formulation X6 exhibited the highest drug content of 87.10 ± 0.41%, with a mean globule size of 148.52 nm, a polydispersity index (PDI) of 0.124, and a zeta potential of −28.75 mV. The optimized gel formulation, X6G2, containing 1.5% Carbopol 980, demonstrated a drug content of 99.42 ± 0.36% and a viscosity of 2396.62 ± 1.09 cP. In the in vitro drug release study, X6G2 released 99.35 ± 0.89% of the drug within 24 hours, compared with 42.10 ± 0.56% from the control gel. These findings indicate that the developed submicron emulsion gel showed promising in vitro characteristics and enhanced drug release compared with the control formulation. Further studies are required to establish its stability, skin permeation, and clinical performance.