Formulation and Evaluation of Spray Gel Dosage Form of Shrimp Head Extract (Litopenaeus vannamei) with Propyleneglycol Variations

Background: Vannamei shrimp (Litopenaeus vannamei) head waste can serve as a chitosan source for topical formulations. Objective: This study aimed to formulate and evaluate the physical properties of chitosan spray gels with varying propylene glycol concentrations. Methods: A laboratory experiment was conducted from March to June 2026. F1, F2, and F3 contained 0.10%, 0.50%, and 1.50% chitosan and 5%, 10%, and 15% propylene glycol, respectively. Evaluations included appearance, homogeneity, pH, viscosity, spray pattern, drying time, skin retention, and six cycling-test cycles at 4 °C and 40 °C. Results: All formulations are homogeneous before and after cycling. According to the results tables, initial pH values are 6.63 ± 0.09, 6.15 ± 0.02, and 5.59 ± 0.01, and viscosities are 7,033.33 ± 25.17, 9,832.00 ± 8.00, and 19,542.00 ± 10.00 mPa•s for F1–F3, respectively. Spray diameters are 4.50 ± 0.10, 2.20 ± 0.10, and 1.95 ± 0.07 cm. Following cycling, pH increases and viscosity decreases significantly according to the reported paired t-tests. Conclusion: F1 has the widest spray pattern and lowest viscosity and is a candidate for further optimization. Simultaneous variation of chitosan and propylene glycol limits attribution to either ingredient. Analgesic efficacy and dermal safety remain undetermined.