American Journal of Pharmacology and Toxicology 7 (1): 1-7, 2012 ISSN 1557-4962 © 2012 Science Publications 1 Electroanalytical Determination of Doripenem using a Screen-Printed Electrode Nora H. Al-Shaalan Department of Chemistry, College of Science, Princess Nora Bint Abdul Rahman University, Riyadh, Saudi Arabia Abstract: Problem statement: The performance characteristics of Sensitive Screen-Printed (SPE) and Carbon Paste (CPE) electrodes were investigated for the Determination of Doripenem (DP) in pure, pharmaceutical preparations and biological fluids. Approach: The proposed electrodes is characterized in terms of plasticizer type, response time, pH and temperature. Results: The two electrodes showed nearly Nernstian behaviours over the concentration range of 2×10 -4 -5×10 -2 mol/l of the drug with slopes of 58 and 57 mV/decade for SPE and CPE electrodes, respectively. The electrodes exhibited good selectivity for DP with respect to a large number of inorganic cations and organic substances present in the biological fluids. The method was precise, as shown by the mean recoveries of 99.49-100 and 98.49-99.49% with mean relative standard deviations 0.38-0.78 and 0.60-0.90% for SPE and CPE electrodes, respectively. Conclusion: Doripenem was determined successfully in pure solutions, in vials or in biological fluids using the standard addition and potentiometric titration methods. Key words: Screen-printed electrode, potentiometric titration, doripenem, biological fluids INTRODUCTION Doripenem (DP) (S-4661) (Fig. 1) is a recently developed member of the carbapenem class of beta- lactam antibiotics. Similarly to meropenem and ertapenem, but unlike imipenem, doripenem has a 1-β- methyl side chain that provides resistance to the renal enzyme I-dehydropeptidase. It was approved by the US Food and Drug Administration (FDA) in 2007 for the management of patients with complicated intra- abdominal infections (dAIs) and complicated Urinary Tract Infections (cUTIs), including pyelonephritis (Mori et al., 1996). DP has been shown to have broad- spectrum activity against Gram-negative and Gram- positive pathogens, including strains of Pseudomonas aeruginosa (Jones et al., 2005; Wexler et al., 2005). DP, similar to other carbapenems, was developed for the treatment of hospitalised patients with moderate or severe bacterial infections (Jones et al., 2004) Doripenem has been determined in its pharmaceutical formulation and in plasma using different techniques, including spectrophotometry (Piontek and Ska, 2010) chromatography High Performance Liquid Chromatography (HPLC) with various detection methods (Sutherland and Nicolau, 2007; Ikeda et al., 2008) and liquid chromatography (Dailly et al., 2011; Ohmori et al., 2011). The development and application of ion-selective electrodes for pharmaceutical analysis continue to be of interest because these sensors offer the advantage of simple design and operation, reasonable selectivity, fast response, applicability to coloured and turbid solutions and possible interface with automated and computerised systems (Santini et al., 2008). For these advantages, ISEs have found various applications: in clinical chemistry, environmental protection, water, soil and analytical chemistry in general (Kormosh et al., 2008). Over the past five decades, carbon paste (i.e., a mixture of carbon (graphite) powder and a binder (pasting liquid)) has become one of the most popular electrode materials used for the laboratory preparation of various electrodes, sensors and detectors. Chemically Modified Carbon Paste Electrodes (CMCPEs) possess important advantages, such as ease of preparation, or regeneration and very stable response in addition to very low Ohmic resistance (Svancara et al., 2009). Therefore, CMCPEs have found direct application in a variety of analytical situations, such as amperometry (Ozoemena et al., 2004; Malongo et al., 2008), voltammetry (Mashhadizadeh and Akbarian, 2009) and potentiometry (Mostafa and Homoda, 2008). In this study, we introduced new potentiometric sensors for selective determination of DP in pharmaceutical preparations and biological fluids. The present study describes the preparation, characterisation and application of Carbon Paste (CPE) and Screen- Printed (SPE) electrodes for the continuous determination of DP in pharmaceutical preparations.