Merit Research Journal of Medicine and Medical Sciences (ISSN: 2354-323X) Vol. 3(2) pp. 047-052, February, 2015 Available online http://www.meritresearchjournals.org/mms/index.htm Copyright © 2015 Merit Research Journals Original Research Article Stability-indicating Colorimetric method for the analysis of Niclosamide *Shaza Wagiealla Shantier, Elrasheed Ahmed Gadkariem and Mohamed Obeid Adam Abstract Department of Pharmaceutical Chemistry, University of Khartoum *Corresponding Author’s E-mail: sshantier@yahoo.com Tel: +249 9 12637509 Simple, accurate and stability-indicating colorimetric method was developed for the determination of niclosamide in bulk and dosage forms. The method was based on the alkaline hydrolysis of niclosamide with 0.1M sodium hydroxide under the specified reaction conditions. The zero-order and first derivative spectra of the degradation product (yellow colored) were recorded at 380nm and 409nm respectively. Linearity was exhibited in the concentration range 4-20μg/ml with good correlation coefficient (not less than 0.999). The recovery percentage results (99.47 ± 1.30%, n=3) indicated the absence of interference by the tablets recipients. The results obtained by the developed method were statistically compared by the results of a reported method for determination of niclosamide, and evaluated at 95% confidence limits. Keyword: Colorimetry, Degradation product, Derivative spectrophotometry, Niclosamide, Zero-order INTRODUCTION Niclosamide (Figure 1) is orally administered anthelmintics drug. It is highly effective against cestodes infesting man-Taenia saginata, T.solium, Diphyllobo- thrium latum and Hymenolepis nana, as well as threadworm. It acts by inhibiting the oxidative phosphorylation in mitochondria and interfering with anaerobic generation of ATP by the tape-worm, as a result tape-worm get partly digested in the intestine (Tripathi, 2003; Rang and Dale, 2005; Goodman and Gillman’s, 2001). Recent reports claimed niclosamide as anticancer agent. Niclosamide reported to inhibits the Wnt/βcatenin, mTORC1, STAT3, NF-κB and Notch signaling pathways, and induce cell cycle arrest, growth inhibition and apoptosis (Li Y et al, 2014). Various methods had been reported for the analysis of niclosamide in bulk and dosage forms. These methods include stability-indicating methods (Shaza et al., 2015), chromatographic and spectrophotometric methods (Daabees, 2000; Cholifah et al., 2008; Feyyaz and Nigar, 1994) In the present work, a simple stability- indicating colorimetric method was developed for the determination of niclosamide in bulk and dosage form. Experimental/Instrumentation UV spectrophotometric studies were carried out on Shimadzu UV-1800ENG240V, (Koyoto, Japan). MATERIALS A drug sample of NA (Niclosamide tablets, 500mg) was obtained from AlexiPharma, Egypt. The reference standard, certified to contain 99%, was obtained from Egypt. Sodium hydroxide (BDH), Pool, England; Methanol Scharlau Chemie S.A., Spain; Acetone Scharlau Chemie S.A., Spain. Standard stock solution NA standard solution (2.5 mg/ml) was freshly prepared i n acetone. 1ml was further diluted with methanol to obtain