Development and validation of a visible spectrophotometric method for the determination of tretinoin in bulk and pharmaceutical formulations

Background: Tretinoin is a widely used dermatological agent, and its accurate quantification is essential for quality control in pharmaceutical formulations. Existing UV-spectrophotometric methods often lack the sensitivity and simplicity required for routine analysis. Methodology: A simple, rapid, and cost-effective visible spectrophotometric method was developed for the determination of tretinoin in bulk and 0.05% cream formulations. The method is based on the formation of a stable ion-pair complex between tretinoin and methylene blue in an alkaline medium (pH 9.8). The resulting complex exhibits maximum absorbance at 650 nm. Method validation was carried out in accordance with ICH Q2(R1) guidelines. Results and Discussion: The method showed linearity in the concentration range of 2–10 µg/mL, with a correlation coefficient (r²) of 0.999. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.0434 µg/mL and 0.1316 µg/mL, respectively. Precision and accuracy results were within acceptable limits. Recovery ranges for 0.05% tretinoin cream formulations are 98.7% to 101.1%, confirming the method’s suitability for real-sample analysis. Compared to existing UV methods, this approach offers enhanced sensitivity and operational simplicity. Conclusion: The proposed spectrophotometric method is a reliable and sensitive alternative for the routine quantification of tretinoin in pharmaceutical formulations. Its simplicity, cost-effectiveness, and compliance with regulatory validation standards make it well-suited for quality control laboratories.