Development and validation of UV–Vis spectrophotometric method for determination of rivastigmine in PBS and biological matrices: Application to ex vivo permeation profiles and in vivo studies from trilayer dissolving microneedle

Alzheimer's disease (AD) is a neurological illness. AD is often treated with rivastigmine (RV). The present study developed trilayer dissolving microneedle (TDMN) RV delivery system to overcome challenges in RV conventional forms. To enable the assessment of TDMN by ex vivo and in vivo methods, we developed a UV–Visible spectrophotometric method to quantify RV in four media using cobalt thiocyanate as a derivatization reagent. Guidelines set by the International Conference on Harmonization (ICH) were used to validate this approach. Results indicate a correlation coefficient of 0.9999 for all media, with the lower limit of quantification values for Phosphate Buffer Saline, rats’ plasma, skin, and brain matrices were 1.29, 0.67, 0.67, and 0.89 µg/mL, respectively. Significantly, the method is precise and accurate. Finally, to support this study's objective, TDMN formulation was developed, and direct application of the proposed method for quantifying RV in ex vivo and in vivo studies was conducted.