A simple, sensitive, precise and stability indicating liquid chromatographic method has been developed for the estimation of desvenlafaxine succinate in pharmaceutical dosage form. A Hypersil C-18, 5 μm-column with a mobile phase containing 0.05 M potassium dihydrogen phosphate:methanol (60:40 v/v), pH 7, was used. The flow rate was 1.0 mL/min and effluents were monitored at 226 nm. The retention time of desvenlafaxine was 7.4 min and the method was linear in the range of 0.1-20 µg/mL. Desvenlafaxine stock solution was subjected to acid and alkali hydrolysis, chemical oxidation and dry heat degradation. The drug was found to be susceptible to base hydrolysis and developed method was found to give good separation between the pure drug and the degraded product. The method was successfully applied to the estimation of desvenlafaxine in tablet dosage forms.Desvenlafaxine succinate (DVX) is chemically RS-4-[2-dimethylamino-1-(1-hydroxycyclohexyl)ethyl]-phenol succinate monohydrate. It is a salt form of the major active metabolite of venlafaxine. Desvenlafaxine inhibits serotonergic and noradrenergic reuptake receptors with minimal affinity for muscarinic, cholinergic, histaminergic, and α 1 -adrenergic receptors [1]. Desvenlafaxine lacks monoamine oxidase inhibitory activity. Serotonergic receptors are inhibited approximately 10-fold more than noradrenergic receptors. Based on the in vitro results and the relationship between desvenlafaxine and venlafaxine, desvenlafaxine is classified as a selective serotonin and norepinephrine reuptake inhibitor (SNRI). Approximately 75% of venlafaxine is metabolized into O-desmethylvenlafaxine or desvenlafaxine by the action of CYP2D6 on parent drug [2]. Desvenlafaxine is not predominately metabolized by the cytochrome P450 (CYP) system and is eliminated primarily by phase II metabolism; as a result, it has lower potential for drug interactions, especially with the CYP 2D6 pathway. It has been approved for the treatment of major depressive disorder (MDD) and has also been studied for the treatment of vasomotor symptoms associated with menopause [3][4]. Preliminary evidence also suggests the clinical usefulness of DVX in the treatment of anxiety symptoms, and painful physical symptoms [5][6].A literature survey regarding quantitative analysis of the drug revealed that attempts have been made to develop analytical methods for the estimation of DVX in human plasma using HPLC with fluorescence detection [7][8][9], HPLC with UV detection [10], LC-MS/MS [11][12][13] and HPLC-ESI/MS [14].The International Conference on Harmonization (ICH) guidelines [15] require the implementation of stress testing procedures for the identification of degradation products that are potentially occurring in drug substances which can help to understand the possible degradation pathway for the drug. The apparent lack of a method for the estimation of desvenlafaxine in pharmaceutical dosage form prompted us to develop an accurate, specific and sensitive liquid chromatographic method. EXPERIMENTAL ApparatusThe ...

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