Articles Accepted

Pharmaceutical co-crystals improve the solubility and dissolution of poorly soluble drugs, but quantitative analysis becomes difficult when the co-former shows overlapping UV absorbance. This study developed and validated a dual-wavelength UV spectrophotometric method for estimating acyclovir in its L-tryptophan co-crystal and applied it to intrinsic dissolution studies. The method employed wavelength pairs at which the co-former exhibited zero absorbance difference, while acyclovir showed a significant absorbance difference. Among the screened pairs, 267 and 283 nm were selected based on excellent linearity. Validation as per ICH Q2(R2) demonstrated good linearity over 5–35 µg/mL (R² = 0.9993) with acceptable precision, accuracy, specificity, and ruggedness (%RSD 2%). The validated method successfully quantified acyclovir during dissolution studies, where the co-crystal demonstrated enhanced dissolution performance and higher IDR than pure acyclovir, confirming the method as a simple and reliable analytical tool.