Journal of Colloid and Interface Science 313 (2007) 254–260 www.elsevier.com/locate/jcis Cathodic adsorptive stripping voltammetric studies on lamivudine: An antiretroviral drug Rajeev Jain ∗ , Nimisha Jadon, Keisham Radhapyari School of Studies in Chemistry, Jiwaji University, Gwalior - 474011, India Received 19 February 2007; accepted 3 April 2007 Available online 11 May 2007 Abstract The electrochemical reduction and adsorption of lamivudine, a systemic antiviral drug, were studied in a phosphate buffer medium at a hanging mercury drop electrode (HMDE). Cyclic voltammetry studies showed one well-defined reduction peak in the potential range from −1.2 to −1.8V under different pH conditions, but the best results were obtained at pH 3.4. The reduction was irreversible and exhibited diffusion-controlled adsorption. The response was evaluated with respect to preconcentration time, pH effect, accumulation potential, accumulation time, and scan rate. The number of electrons transferred in the reduction process was calculated and the probable reduction mechanism was proposed. A systemic study of the experimental parameters that affect the square-wave stripping response was carried out and experimental conditions were optimized.  2007 Elsevier Inc. All rights reserved. Keywords: Lamivudine; Cathodic adsorptive stripping voltammetry; HMDE; Cyclic voltammetry; Pharmaceutical formulations 1. Introduction Lamivudine is a potent reverse transcriptase inhibitor of the class of nucleoside analogue reverse transcriptase inhibitors (NARTI) [1]. It has been used for the treatment of human immunodeficiency virus type 1 (HIV-1), which causes the ac- quired immunodeficiency syndrome (AIDS) [2], and of chronic [3,4] and acute [5] hepatitis B (HBV). It improves the serocon- version of e-antigen positive hepatitis B [6] and also improves histology staging of the liver [7]. It has the following structure: * Corresponding author. Fax: +91 751 2346209. E-mail address: rajeevjain54@yahoo.co.in (R. Jain). Therapeutically lamivudine is a synthetic nucleoside ana- logue of cytidine, which is phosphorylated in the body to its active metabolites. In the active form it inhibits both types (1 and 2) of HIV reverse transcriptase enzyme and also the re- verse transcriptase of hepatitis B virus polymerase [8]. Lamivu- dine is metabolized by both infected and uninfected cells to the active form of the parent compound. Lamivudine drug and its tablets are described by an official monograph in the U.S. Pharmacopoeia (USP) [9], which de- scribes high-performance liquid chromatography (HPLC) pro- cedures for their quantitations. However, although the selectiv- ity and the detection limit have been improved in these methods, they are rather time-consuming and require a large number of complicated steps for analysis. Therefore, a simple and easy technique for the detection of lamivudine is urgently desired. A survey of the literature reveals that electrochemical tech- niques have demonstrated large applicability in studies of electrodic reaction mechanisms of pharmaceutical compounds. Electrochemical techniques are time-saving, quantitative, and qualitative with improved sensitivity over other available meth- ods [10,11]. Application of voltammetric methods to the esti- mation of very important pharmaceuticals such as lamivudine 0021-9797/$ – see front matter  2007 Elsevier Inc. All rights reserved. doi:10.1016/j.jcis.2007.04.003