A liquid chromatography/tandem mass spectrometry assay for the analysis of atomoxetine in human plasma and in vitro cellular samples

Spectrophotometric Quantification of Atomoxetine Hydrochloride Based on Nucleophilic Substitution Reaction with 1,2-Naphthoquinone-4-Sulfonic Acid Sodium Salt (NQS)

Objectives

A simple, sensitive, selective, and cost-effective colorimetric method has been established for the quantitative estimation of atomoxetine hydrochloride in bulk and formulation.A simple, sensitive, selective and cost effective colorimetric method has been entrenched for the quantitative estimation of Atomoxetine hydrochloride in bulk and formulation.

Materials and Methods

It was established based on the visible reaction between atomoxetine hydrochloride and 1,2-naphthoquinone-4-sulfonic acid sodium salt in a basic medium (potassium hydroxide). The resulting orange colored chromogen exhibited an absorption maximum at 474 nm.

Results

Based on the optimization studies, distilled water as the solvent, 1% w/v potassium hydroxide (2 mL), and 0.3% w/v 1,2-naphthoquinone-4-sulfonic acid sodium salt (2 mL) were used in the method. The developed method was validated per the International Council for Harmonization (ICH) guidelines. The linearity was found at a concentration of 10-50 μg/mL. The method showed a good correlation between the concentration of atomoxetine hydrochloride and its absorbance. The correlation coefficient (r2) of 0.999 evidenced the same. The limits of detection and quantification were 0.20 and 0.606 μg/mL, respectively, for atomoxetine hydrochloride. The accuracy and precision of the method were also evaluated and the results obtained were within the acceptance criteria (relative standard deviation % < 2.00). The percentage assay of atomoxetine hydrochloride proved to be 101.52, which is in accordance with its label claim.

Conclusion

The developed method is non-complex and can be effectively employed in the analytical practices of atomoxetine hydrochloride in pharmaceutical dosage forms.

Two green spectrofluorimetric methods for the assay of atomoxetine hydrochloride in pure form and commercial capsules with application to content uniformity testing

Atomoxetine hydrochloride (ATX) is a potent and non-stimulant drug which was approved for the treatment of attention-deficit hyperactivity disorder. Owing to its importance, two green, simple and validated spectrofluorimetric methods were developed for its sensitive assay in pure and capsule forms. The first method (Method I) relied on measuring the enhanced fluorescence of ATX by the use of sodium dodecyl sulfate in alkaline medium at λ _ex 227 nm/λ _em 298 nm. The second method (Method II) involved complex formation of ATX with Erythrosine B (EB) in aqueous acidic solution resulting in quantitative quenching of the EB naive fluorescence. This complex was formed in the presence of Britton-Robinson buffer (pH 4.0). The difference in fluorescence intensity was measured at λ _ex 527/λ _em550 nm. The calibration curves were linear through the ranges of 0.2-2.0 µg ml^-1 for Method I, 0.2-4.0 µg ml^-1 for Method II with good correlation coefficient (r = 0.9998) for both methods. The suggested methods were perfectly applied for determination of ATX in its commercial capsules and content uniformity test. The greenness of the proposed methods was confirmed by three different assessment tools and it was found that both methods were green, eco-friendly and environmentally safe.