Stability-indicating assay method for determination of actarit, its process related impurities and degradation products: Insight into stability profile and degradation pathways☆

Abstract

The stability of the drug actarit was studied under different stress conditions like hydrolysis (acid, alkaline and neutral), oxidation, photolysis and thermal degradation as recommended by International Conference on Harmonization (ICH) guidelines. Drug was found to be unstable in acidic, basic and photolytic conditions and produced a common degradation product while oxidative stress condition produced three additional degradation products. Drug was impassive to neutral hydrolysis, dry thermal and accelerated stability conditions. Degradation products were identified, isolated and characterized by different spectroscopic analyses. Drug and the degradation products were synthesized by a new route using green chemistry. The chromatographic separation of the drug and its impurities was achieved in a phenomenex luna C18 column employing a step gradient elution by high performance liquid chromatography coupled to photodiode array and mass spectrometry detectors (HPLC-PDA-MS). A specific and sensitive stability-indicating assay method for the simultaneous determination of the drug actarit, its process related impurities and degradation products was developed and validated.

Keywords: Actarit; Forced degradation; Stability-indicating assay method.

Fig. 1

Chemical structures for the drug actarit, its process related impurities and degradation products.

Fig. 2

HPLC chromatograms of the drug under different forced conditions: (A) drug; (B) acid stress conditions; (C) base stress conditions; (D) neutral stress conditions; (E) photolytic stress conditions; (F) thermal stress conditions; (G) accelerated stress conditions; and (H) oxidative stress conditions.

Fig. 3

Schematic representation of the synthesis of the degradation product DP-I, the drug and degradation product DP-II.

Fig. 4

Chromatograms of the analytes (the drug, impurities and degradation products) under different pH conditions: (A) pH 3.0, (B) pH 5.0, (C) pH 6.0, (D) pH 7.0, and (E) analytes at lower concentrations at pH 5.0.

Fig. 5

Mass spectra of the analytes (the drug, impurities and degradation products) taken during the chromatographic run (pH 5.0) in HPLC–PDA–MS: (A) Imp-1; (B) the drug; (C) Imp-2; (D) Imp-3; (E) Imp-4; (F) Imp-5; and (G) Imp-6.

Fig. 6

Mechanism of formation of DP-I: (A) acid hydrolysis; (B) base hydrolysis conditions; (C) photolysis; and (D) mechanism of formation of DP-II, DP-III and DP-IV under oxidative reaction conditions.