Zanco Journal of Medical Sciences (Aug 2024)
Formulation and evaluation of salicylic acid hydrogel based on hydrotropic solubility enhancement technique
Abstract
Background and objective: Salicylic acid (SA) has keratolytic activities and it is used topically to treat dandruff and seborrheic dermatitis. The hydrotropic phenomenon in pharmaceutical preparations is utilized to enhance the solubility of water-insoluble drug molecules that promoted to prepare the salicylic acid as a hair gel for local effect and it can extend its keratolytic action for a longer period compared to the salicylic acid solution. Methods: Preformulation study was performed to exclude any unwanted chemical interaction between SA and excipients using Fourier-transform infrared spectroscopy (FTIR). The solubility of SA was determined separately in sodium acetate and sodium citrate solutions at a concentration of 1, 3, and 5 %w/v, using distilled water as a solvent. An optimum gel formulation was developed and it was used to prepare the SA gel formulation. Characterizations were performed in terms of physical appearance, viscosity, pH, and spreadability, in-vitro studies were performed in physiological pH, and ex-vivo diffusion studies were performed utilizing rats’ skin. Results: FTIR did not show any chemical interaction between the drug and sodium citrate. The hydrotropic solution of sodium citrate with a concentration of 5% w/v increased the solubility of SA by 28 folds, while the sodium acetate solutions with a concentration of 5% w/v increased the solubility of SA by 19 folds. The optimum gel formula (F1) with a drug content of 97% showed a slow dissolution rate and minimum diffusion through the skin. Conclusion: The hydrotropic solubilization technique significantly influenced the solubilization of salicylic acid in the water and the highest solubility rate was achieved from 5% w/v sodium citrate solution. The formulated hydrogels using carbopol 971P as gelling agent decreased the diffusion rate of SA.
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