Development of Better-Quality Assay Method for the Citric Acid and Sodium Citrate in Ophthalmic/Oral Solutions and Their Application to Deformulation Studies

There were several techniques determined for the analysis of citrate and citric acid mixtures in the pharmaceutical dosage forms. Titration methods, photometric and ion chromatographic methods were used for their determination. These methods will restrict too many factors where the accurate quantification of citrate and citric acid is extremely challenging. Citric acid is the natural flavor used as a preservative for many pharmaceutical applications. Deformulation techniques used for the manufacturing of generic drugs require authentic data for their regulatory submissions. Simple accurate and reproducible validated method developed for the determination of citric acid and sodium citrate by titration followed by HPLC analysis. Free citric acid was determined by the titration method and total citric acid was determined by HPLC analysis. After subtracting the free citric acid from total citric acid content, citric acid present in the sodium citrate content was determined. Sodium citrate content was determined by applying sodium correction factor to the subtracted value of the citric acid. The results met all the validation parameters and the method was successfully measured the amount of citric acid and sodium citrate in the marketed ophthalmic/oral solutions.