Objectives: The present study aimed to develop and validate a discriminative dissolution method for tetrahydrocurcumin (THC), a Biopharmaceutical Classification System class II drug, by a simple ultraviolet (UV) spectrophotometric analysis. The final dissolution medium composition was selected based on the solubility and stability criteria of the drug.
Materials and methods: As a prerequisite for this, the solubility of the drug was assessed in media of different pH (1.2-7.4), and surfactant concentrations of 0.5-1.5% (w/v) sodium lauryl sulfate (SLS) in water, and pH 7.4 phosphate buffer. The dissolved drug concentration in each medium was quantified by UV analysis at 280 nm wavelength.
Results: The drug solubility was found to be high at a pH of 1.2 and 7.4. The media with surfactant enhanced solubility of the drug by approximately 17-fold and exhibited better sink conditions. The discriminative power of the developed dissolution medium (i.e., 1% w/v SLS in pH 7.4) was determined by performing in vitro dissolution studies of the prepared THC tablets and comparing their release profiles using fit factors (f1 and f2). The results of the fit factor comparisons made between the dissolution profiles of THC tablets proved the discriminative ability of the medium. The validation of the developed dissolution method was performed by international guidelines and the method showed specificity, linearity, accuracy, and precision within the acceptable range.
Conclusion: The proposed dissolution method was found to be adequate for the routine quality control analysis of THC, as there is no specified dissolution method for the drug in the pharmacopoeia.
Keywords: Tetrahydrocurcumin; dissolution comparison; dissolution medium; fit factors; sodium lauryl sulfate; solubility.