# Determination of antihistaminic drugs alcaftadine and olopatadine hydrochloride via ion-pairing with eosin Y as a spectrofluorimetric and spectrophotometric probe: application to dosage forms

## TL;DR

This paper introduces new methods to detect and measure two antihistamine drugs using fluorescence and absorbance techniques with high accuracy.

## Contribution

The study presents the first spectrofluorimetric methods for determining Alcaftadine and Olopatadine hydrochloride via ion-pairing with eosin Y.

## Key findings

- Fluorescence quenching was linear for Alcaftadine (150–2000 ng/mL) and Olopatadine hydrochloride (200–2000 ng/mL).
- Absorbance measurements followed Beer's law in specific concentration ranges for both drugs.
- The methods met ICH requirements and achieved high recovery rates in dosage forms.

## Abstract

Four sensitive and fast analytical approaches relied on ion pairing with eosin Y were built up and evaluated using spectroscopy for determination of Alcaftadine and Olopatadine hydrochloride with high sensitivity and selectivity. Two spectrofluorimetric techniques were employed to observe the quenching effect of Alcaftadine or Olopatadine hydrochloride on the intrinsic fluorescence of eosin Y in a 0.1 M acetate buffer solution at pH 3.8 and 3.3 for Alcaftadine and Olopatadine hydrochloride, respectively. Those methods are considered the first spectrofluorimetric methods for Alcaftadine and Olopatadine hydrochloride assay. The fluorescence quenching effect was linear with concentration ranging from 150 to 2000 and 200 to 2000 ng mL−1 for Alcaftadine and Olopatadine hydrochloride, respectively. In the two spectrophotometric techniques, the absorbance of the produced ion-pair was monitored at 548 and 547 nm in aqueous buffered solution at pH 3.8 and 3.3 for Alcaftadine and Olopatadine hydrochloride, respectively. Beer's law was obeyed in the concentrations range of 0.8–8.0 and 1.0–10.0 µg mL−1. The four techniques were evaluated in accordance with ICH requirements and were effectively used to analyze dosage forms with a high percent recovery.

The online version contains supplementary material available at 10.1186/s13065-024-01137-y.