Cefpodoxime Proxetil: A New Stability Indicating RP-HPLC Method

The present work describes the development of a sensitive and economic stability indicating high performance liquid chromatographic (HPLC) method for the determination of cefpodoxime proxetil (CP) as bulk drug and as pharmaceutical formulation. Both R and S isomers of the drug were separated using Phenomenex ( ？mm, 5？μm particle size) ODS column with a flow rate of 1？mL？min？1 and an SPD 20？A UV detector to monitor the eluate at 252？nm. The isocratic method used a mobile phase consisting of methanol and phosphate buffer of pH 4.0 in the ratio 65？:？35. The linear regression analysis data for the calibration plots showed good linear relationship with in the working concentration range of 5–100？μg？mL？1. The LOD and LOQ were 53 and 160？ng？mL？1, respectively. CP was subjected to stress degradation using acid, alkali, hydrogen peroxide, dry heat, wet heat, and UV light. The standard drug peaks were well resolved from the degradation products’ peaks with significantly different retention time (Rt), and the resolution factor for the R and S isomers of CP was found to be greater than 2. 1. Introduction Stability indicating methods are the quantitative analytical methods that are based on the characteristic structural, chemical, or biological properties of each active ingredient of a drug product and that will distinguish each active ingredient from its degradation products so that the active ingredient content can be accurately measured [1]. The International Conference on Harmonization (ICH) guideline entitled “Stability Testing of New Drug Substances and Products” requires that stress testing be carried out to elucidate the inherent stability characteristics of the active substance [2]. Acidic, alkaline, oxidative, and photolytic stabilities are required. An ideal stability indicating method is the one that quantifies the standard drug alone and also resolves it from its degradation products [3]. Stability indicating method is an analytical procedure that is capable of discriminating between the major active pharmaceutical ingredient (API) and any degradation (decomposition) product(s) formed under defined storage conditions during the stability evaluation period [4]. Cefpodoxime proxetil (CP) is a prodrug that is deesterified in vivo to its active metabolite, cefpodoxime, to exhibit antibiotic activity [5–9]. The structure of CP is given in Figure 1. It is active against most Gram positive and Gram negative organisms. It is commonly used in the treatment of a variety of infections of skin, respiratory tract, urinary tract, and systemic infections and also to