SPECTROPHOTOMETRIC DETERMINATION OF PIZOTIFEN MALEATE IN BULK DRUG AND TABLETS USING N-BROMOSUCCINIMIDE AND THREE DYES

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1 Innovre Acdemic Sciences Interntionl Journl of Phrmcy nd Phrmceuticl Sciences ISSN Vol 6, Issue 4, 2014 Originl Article SPECTROPHOTOMETRIC DETERMINATION OF PIZOTIFEN MALEATE IN BULK DRUG AND TABLETS USING N-BROMOSUCCINIMIDE AND THREE DYES ALAA S. AMIN 1, RAGAA EL SHEIKH 2, MOSTAFA M. MOSTAFA 1, AYMAN A. GOUDA 2,3 *, EMAN H. YOUSSEF 1 1 Chemistry Deprtment, Fculty of Sciences, Benh University, Benh, Egypt, 2 Chemistry Deprtment, Fculty of Sciences, Zgzig University, Zgzig, Egypt, 3 Fculty of Public Helth nd Informtics, Umm AL-Qur University, Mkkh, Sudi Arbi. Emil: ymngoud77@gmil.com, Received: 03 Feb 2014 Revised nd Accepted: 26 Feb 2014 ABSTRACT Objective: Three sensitive spectrophotometric methods re presented for the ssy of pizotifen mlete (PZT) in bulk drug nd phrmceuticl formultion (tblets) using N-bromosuccinimide (NBS) nd three dyes, methyl ornge, mrnth nd indigo crmine, s regents. Methods: The methods involve the ddition of known excess of NBS to drug in cid medium, followed by determintion of unrected oxidnt by recting with fixed mount of methyl ornge nd mesuring the bsorbnce t 522 nm (method A), mrnth nd mesuring the bsorbnce t 507 nm (method B) or indigo crmine nd mesuring the bsorbnce t 610 nm (method C). Results: In ll methods, the mount of NBS rected corresponds to the mount of drug nd the mesured bsorbnce is found to increse linerly with the concentrtion of drug which is corroborted by the correltion coefficients of The systems obey Beer s lw for , nd μg ml -1 for methods A, B nd C, respectively. The limits of detection nd quntifiction re lso reported. Intr-dy nd inter-dy precision nd ccurcy of the methods hve been evluted. Conclusion: The methods were successfully pplied to the ssy of PZT in tblets preprtions nd the results were sttisticlly compred with those of the reference method by pplying Student s t-test nd F-test. No interference ws observed from the common tblet excipients. The ccurcy of the methods ws further scertined by performing recovery studies vi stndrd-ddition method. Keywords: Spectrophotometry; Pizotifen mlete; N-bromosuccinimide; Methyl ornge; Amrnth; Indigo crmine; Tblets. INTRODUCTION Pizotifen mlte (PZT), chemiclly known s 9, 10-dihydro-4-(1- methylpiperidin-4-ylidene)-4h benzo [4,5] cyclohept [1, 2-b] thiophene hydrogen mlte (Fig. 1) [1]. Pizotifen is sedting ntihistmine tht hs strong serotonin ntgonist nd wek ntimuscrinic properties. It lso ntgonises the ction of tryptmine. Pizotifen is used, usully s the mlte, for the prophylxis of migrine nd for the prevention of hedche ttcks during cluster periods. It is not effective in treting n cute ttck [2]. The drug is officil in British Phrmcopoei [1], which describes potentiometric titrtion with perchloric cid in nhydrous cetic cid medium. Fig. 1: The chemicl structure of pizotifen mlte (PZT) Severl nlyticl methods hve been reported for the determintion of PZT in pure drug, phrmceuticl dosge forms nd in biologicl smples using high performnce liquid chromtogrphy[3 7], tomic bsorption spectroscopy [8], spectrophotomety [8, 9] nd spectrofluorimetry [9]. Severl visible spectrophotometric methods bsed on colour rections involving the mino or thiophene of the pizotifen molecule cn be found in the literture. El-Kousy nd Bebwy [8] hve developed three methods for the ssy of PZT in bulk drug nd in tblets; the first method ws bsed on extrction of drug-coblt thiocynte ternry complex with methylene chloride nd estimtion by indirect tomic bsorption method vi the determintion of the coblt content in the complex fter extrction in 0.1M hydrochloric cid t nm in concentrtion rnges from μg ml -1. The second method is bsed on the formtion of ornge red ion pir by the rection of PZT nd molybdenum thiocynte with bsorption mxim t nm in dichloromethne in the concentrtion rnges μg ml -1. The third method ws chrge trnsfer rection between PZT nd 2,3- dichloro-5,6-dicyno-p-benzoquinone in cetonitrile medium t 588 nm in concentrtion rnge µg ml -1. Dessouky et l., hve determined PZT in tblets using three spectrophotometric nd one spectrofluorimetric methods, the first spectrophotometric method ws bsed upon mesuring the bsorbnce of the investigted drug t λ = 317 nm fter its tretment with concentrted sulfuric cid in concentrtion rnges µg ml -1. The second method comprised rection between formldehyde nd PZT in the presence of concentrted sulfuric cid nd mesured t λ = 480 nm in concentrtion rnges µg ml -1. In the third method, PZT ws determined spectrophotometriclly by pplying the first derivtive technique (D1). Quntittive determintion ws crried out by mesuring the first derivtive (D1) of the trough t λ = 238 nm in concentrtion rnges µg ml -1. The spectrofluorimetric method involved the rection of the cited drug nd citric cid/cetic nhydride system nd mesuring the reltive fluorescence intensity of the rection product t 485 nm fter excittion t 385 nm in the concentrtion rnge µg ml -1 [9]. However, the reported spectroscopic techniques suffer from some other disdvntge such s poor sensitivity, dependence on criticl experimentl vribles, tedious nd time-consuming extrction steps, heting step, nd/or use of expensive regent or lrge mounts of orgnic solvents.

2 Goud et l. Int J Phrm Phrm Sci, Vol 6, Issue 4, From the foregoing prgrphs, it is cler tht N-bromosuccinimide (NBS) despite its strong oxidizing power, verstility, high oxidtion potentil nd high stbility in solution hs not been pplied for the ssy of PZT in pure form nd tblets. This pper describes for the first time the ppliction of cidic N-bromosuccinimide (NBS) to the spectrophotometric determintion of PZT using methyl ornge, mrnth nd indigo crmine s chromogenic gents. N-bromosuccinimide (NBS) hs erlier been widely pplied for the ssy of vriety of phrmceuticls [10 16]. The proposed methods hve the dvntges of speed nd simplicity besides being ccurte nd precise, nd cn be dopted by the phrmceuticl lbortories for industril qulity control. MATERIALS AND METHODS Apprtus All bsorption spectr were mde using Kontron Unikon 930 (UV- Visible) spectrophotometer (Germn) with scnning speed of 200 nm/min nd bnd width of 2.0 nm, equipped with 10 mm mtched qurtz cells. Mterils nd Regents All chemicls nd regents used were of nlyticl or phrmceuticl grde nd ll solutions were prepred fresh dily. Double distilled wter ws used throughout the investigtion. Mterils Phrmceuticl grde pizotifen mlete (PZT) ws supplied from (Novrtis, Egypt). Mosegor tblets, lbeled to contin (0.5 mg PZT per tblet) were purchshed from locl commercil mrkets. Stndrd PZT solution A stock stndrd solution of PZT (100 μg ml -1 ) ws prepred by dissolving n exct weight (10 mg) of pure drug in bidistilled wter nd diluted to 100 ml with bidistilled wter in 100 ml mesuring flsk. The solution ws diluted stepwise to get working concentrtion of 10 μg ml -1. The stndrd solutions were found stble for t lest one week without ltertion when kept in n mber coloured bottle nd stored in refrigertor when not in use. Regents - N-bromosuccinimide (NBS): An pproximtely 0.01M NBS solution ws prepred by dissolving bout 1.8 g of chemicl (Sigm- Aldrish) in wter with the id of het nd diluted to one liter with wter nd stndrdized iodometriclly [17]. The solution ws kept in n mber coloured bottle nd ws diluted ppropritely to get 100 μg ml -1 NBS for use in ll methods. The NBS solution ws stored in refrigertor when not in use. - Potssium bromide, KBr (1.0% w/v). - Hydrochloric cid (5.0 M): A 5.0 mol L 1 of HCl ws prepred by diluting 43 ml of concentrted cid (Merck, Drmstdt, Germny, Sp. gr. 1.18, 37%) to 100 ml with bidistilled wter nd stndrdized s recommended previously [18] prior to use. - Methyl ornge (50 μg ml -1 ): A 500 μg ml -1 dye solution ws first prepred by dissolving ccurtely weighed 58.8 mg of dye (Sigm-ldrish, 85% dye content) in wter nd diluting to 100 ml in clibrted flsk nd filtered using glss wool. It ws further diluted to obtin working concentrtion of 50 μg ml Amrnth (200 μg ml -1 ): A 1000 μg ml -1 stock stndrd solution ws first prepred by dissolving ccurtely weighed 112 mg of dye (Sigm-ldrish, 90% dye content) in wter nd diluting to volume in 100 ml clibrted flsk. The solution ws then diluted 5.0-fold to get the working concentrtion of 200 μg ml Indigo crmine (200 μg ml -1 ): A 1000 μg ml -1 stock stndrd solution ws first prepred by dissolving ccurtely weighed 112 mg of dye (Sigm-ldrish, 90% dye content) in wter nd diluting to volume in 100 ml clibrted flsk. The solution ws then diluted 5.0-fold to get the working concentrtion of 200 μg ml -1. Recommended generl procedures Different liquots ( ml), ( ml) nd ( ml) of stndrd 10 μg ml -1 PZT solution for methods A, B nd C, respectively were trnsferred into series of 10 ml clibrted flsks by mens of micro burette nd the totl volume ws djusted to 5.0 ml by dding dequte quntity of wter. To ech flsk were dded 1.0 ml ech of 5.0 M HCl; 1.0 ml of NBS solution (100 μg ml - 1 ) nd 1.0 ml of 1.0% KBr were dded successively. The flsks were stoppered, content mixed nd let stnd for 15 min with occsionl shking. Finlly, 1.0 ml of (100 μg ml -1 ) methyl ornge nd (200 μg ml -1 ) mrnth or indigo crmine solution ws dded (ccurtely mesured) nd the volume ws diluted to the mrk with wter nd mixed well. The bsorbnce of ech solution ws mesured t 522, 507 nd 610 nm for methods A, B nd C respectively fter 5.0 min ginst regent blnk. In ll methods, stndrd grph ws prepred by plotting the bsorbnce versus the concentrtion of drug. The concentrtion of the unknown ws red from the clibrtion grph or computed from the regression eqution derived using Beer s lw dt. Procedure for phrmceuticl formultions (tblets) The contents of twenty Mosegor tblets (0.5 mg PZT per tblet) were weighed ccurtely nd ground into fine powder. An ccurte weight equivlent to 0.5 mg PZT ws dissolved in 20 ml of 0.2 M HCl with shking for 5.0 min nd filtered using Whtmn No. 42 filter pper.. The filtrte ws diluted to the mrk with 0.1 M HCl in 50 ml mesuring flsk to give nd 10 μg ml -1 stock solution of PZT for nlysis by spectrophotometric methods A, B nd C, respectively. A convenient liquot ws then subjected to nlysis by the spectrophotometric procedures described bove. Determine the nominl content of the tblets either from previously plotted clibrtion grph or using the corresponding regression eqution. RESULTS Absorption spectr A close exmintion of the literture serch presented in the introduction revels tht NBS hs not yet been used for the spectrophotometric determintion of GMF or MXF. NBS is strong oxidizing gent nd perhps the most importnt positive bromine contining orgnic compound; it is used for the specific purpose of brominting lkenes t the llylic position [19]. Fig. 2: Absorption spectr for the unrected oxidnt tht determined by recting with fixed mount of dyes nd mesuring the bsorbnce t 522, 507 nd 610 nm for methods A, B nd C, respectively. 219

3 Goud et l. Int J Phrm Phrm Sci, Vol 6, Issue 4, The present work involves the bromintion of PZT by NBS followed by determintion of surplus NBS fter llowing the bromintion rection to complete. The bility of NBS to oxidize PZT nd blech the colors of methyl ornge, mrnth nd indigo crmine dyes hs been used for the indirect spectrophotometric ssy of the drugs. In the three methods, the drugs re rected with known excess of NBS in cid medium nd the unrected oxidnt is determined by recting with fixed mount of dyes nd mesuring the bsorbnce t 522, 507 nd 610 nm for methods A, B nd C, respectively, the bsorbnce incresed linerly with incresing concentrtion of drug (Fig. 2). Effect of cid concentrtion The hydrochloric cid ws found most pproprite. The effect of HCl ws studied nd ml of 5.0 M HCl in totl volume of 5.0 ml ws found to hve constnt effect on both rections (i.e. Drug with NBS, nd residul NBS with dyes). The results presented in Fig. 3 indicted tht, t ml of 5.0 M HCl, there ws lmost sme bsorbnce vlues were obtined in the presence of PZT, the bsorbnce vlues obtined were constnt nd were lmost the sme s those of the regent blnk. At the cid volumes less thn 1.0 ml, rection led to go slower nd incomplete. Therefore, 1.0 ml of 5.0 M HCl ws used though out the study (Fig. 3). Absorbnce Volume of HCl (5.0 M) Method A Method B Method C Fig. 3: Effect of volume of HCl (5.0 M) of the oxidtion product of PZT with NBS nd dyes. Effect of regents Preliminry experiments were performed to determine the mximum concentrtions of the dyes spectrophotometriclly in cid medium, nd these were found to be 10, 20 nd 20 μg ml -1 for methyl ornge, mrnth nd indigo crmine, respectively. A NBS concentrtion of 10 μg ml -1 ws found to irreversibly destroy the red colour of 10 μg ml -1 methyl ornge, wheres 10 μg ml -1 NBS ws required to destroy the red nd blue colours of 20 μg ml -1 mrnth nd indigo crmine, respectively in HCl medium. Hence, different concentrtions of drugs were rected with 1.0 ml of 100 μg ml -1 NBS in ll methods before determining the residul NBS s described under the respective procedures. 1.0 ml of KBr (1.0%) ws chosen s optimum volume in 10 ml totl volume to ccelerte the oxidtion process. Effect of time nd temperture The rection time between PZT nd NBS ws studied by stnding the drug solution fter mixing with NBS for different intervls of time in the presence of 1.0 ml of 5.0 M HCl nd the results indicted tht time of min ws required to complete of the rection. Therefore, 10 min rection time ws fixed s optimum fter the ddition of NBS. A sufficient time to completely blech dyes due to unrected NBS ws found to be 5.0 min, nd the sme ws fixed in ll subsequent studies. Rising the temperture does not ccelerte the oxidtion process nd does not give reproducible results, so the optimum temperture is the mbient (25±1 C). The mesured colour ws found to be stble for severl hours in the presence of the rection product/s in the three methods. Effect of sequence of ddition Drug cid NBS KBr-(dye) is the optimum sequence of ddition; other sequences gve lower bsorbnce vlues under the sme experimentl conditions. Method of vlidtion The proposed methods hve been vlidted for linerity, sensitivity, precision, ccurcy, selectivity nd recovery. Linerity nd sensitivity: Under the optimum conditions liner correltion ws found between bsorbnce λmx nd concentrtion of PZT in the rnge of ( μg ml -1 ). The clibrtion grph is described by the eqution: A = + b C (1) (where A = bsorbnce, = intercept, b = slope nd C = concentrtion in μg ml -1 ) obtined by the method of lest squres. Correltion coefficient, intercept nd slope for the clibrtion dt re summrized in Tble 1. For ccurte determintion, Ringbom concentrtion rnge [21] ws clculted by plotting log concentrtion of drug in μg ml -1 ginst trnsimittnce % from which the liner portion of the curve gives ccurte rnge of microdetermintion of PZT nd represented in Tble 1. Sensitivity prmeters such s pprent molr bsorptivity nd Sndell s sensitivity vlues, s well s the limits of detection nd quntifiction, were clculted s per the current ICH guidelines [22] nd illustrted in Tble 1. The high molr bsorptivity nd lower Sndell sensitivity vlues reflect the good nd high sensitivity of the proposed methods. The vlidity of the proposed methods ws evluted by sttisticl nlysis [23] between the results chieved from the proposed methods nd tht of the reported method. Regrding the clculted Student s t-test nd vrince rtio F-test (Tble 1), there is no significnt difference between the proposed nd reported method [8] regrding ccurcy nd precision. The limits of detection (LOD) nd quntifiction (LOQ) were clculted ccording to the sme guidelines using the formuls [22, 23]: LOD=3.3σ/s nd LOQ=10σ/s (2) Where σ is the stndrd devition of five regent blnk determintions, nd s is the slope of the clibrtion curve. Accurcy nd precision In order to evlute the precision of the proposed methods, solutions contining three different concentrtions of PZT were prepred nd nlyzed in six replictes. The nlyticl results obtined from this investigtion re summrized in Tble 2. The low vlues of the reltive stndrd devition (% R.S.D) nd percentge reltive error (% R.E) indicte the precision nd ccurcy of the proposed methods. The percentge reltive error is clculted using the following eqution: % R.E. = found - tken tken (3) x 100 The ssy procedure ws repeted six times, nd percentge reltive stndrd devition (% R.S.D) vlues were obtined within the sme dy to evlute repetbility (intr-dy precision), nd over five different dys to evlute intermedite precision (inter-dy precision). For the sme concentrtions of drugs inter- nd intr-dy ccurcy of the methods were lso evluted. The percentge recovery vlues with respect to found concentrtions of ech drug were evluted to scertin the ccurcy of the methods. The recovery vlues close to 100% s compiled in Tble 2 shows tht the proposed methods re very ccurte. 220

4 Goud et l. Int J Phrm Phrm Sci, Vol 6, Issue 4, Tble 1: Anlyticl nd regression prmeters of proposed oxidtion spectrophotometric methods for determintion of PZT Prmeters Method A Method B Method C Beer s lw limits, µg ml Ringboom limits, µg ml Molr bsorptivity, x 10 4 L mol -1 cm Sndell sensitivity, ng cm Regression eqution, Intercept () Stndrd devition of intercept (S) Slope (b) Stndrd devition of slope (Sb) Correltion coefficient, (r) Men ± SD ± ± ±1.30 RSD% RE% Limit of detection, µg ml Limit of quntifiction, µg ml Clculted t-vlue b Clculted F-vlue b A = + bc, where C is the concentrtion in µg ml 1, A is the bsorbnce units, is the intercept, b is the slope., b The theoreticl vlues of t nd F re 2.57 nd 5.05, respectively t confidence limit t 95% confidence level nd five degrees of freedom (p= 0.05). Tble 2: Results of intr-dy nd inter-dy ccurcy nd precision study for PZT obtined by the proposed methods. Method PZT tken Recovery % Precision RSD % Accurcy RE % Confidence Limit b Intr-dy A ± ± ± B ± ± ± C ± ± ± Inter-dy A ± ± ± B ± ± ± C ± ± ± RSD%, percentge reltive stndrd devition; RE%, percentge reltive error. b Men ± stndrd error. Tble 3: Results of method robustness nd ruggedness (ll vlues in %RSD) studies Nominl mount Methods concentrtion RSD% Robustness Ruggedness Vrible lerted Acid volume Rection time Different nlysts Different instruments A B C Volume of 5.0 M HCl is (1.0±0.2 ml) nd rection time is (10±2.0 min) (fter dding NBS) were used. Robustness nd ruggedness: For the evlution of method robustness, volume of HCl nd rection time (between NBS nd drug) were slightly vried delibertely. The nlysis ws performed with ltered conditions by tking three different concentrtions of 221

5 Goud et l. Int J Phrm Phrm Sci, Vol 6, Issue 4, drug nd the methods were found to remin unffected s shown by the RSD vlues in the rnges of %. Methods ruggedness ws expressed s the RSD of the sme procedure pplied by three different nlysts s well s using three different instruments (spectrophotometers). The inter-nlysts RSD were in the rnges % wheres the inter-instruments RSD rnged from % suggesting tht the developed methods were rugged. The results re shown in Tble 3. Recovery studies To study the relibility nd ccurcy of the proposed methods, stndrd ddition technique ws followed. This study ws performed by spiking fixed mount of tblet preprtion to three different levels of pure drug. The totl concentrtion ws found by the proposed methods. The determintion with ech level ws repeted three times nd the percent recovery of the dded stndrd (pure drug) ws clculted from: % Recovery = [C F - C T] x 100 C p (4) where CF is the totl concentrtion of the nlyte found, CT is concentrtion of the nlyte present in the tblet preprtion, CP is concentrtion of nlyte (pure drug) dded to tblet preprtion. Results of this study presented in Tble 4 reveled tht the ccurcy of the proposed methods ws unffected by the vrious excipients present in tblets. Methods Tble 4: Results of recovery experiments for Mosegor tblets by stndrd ddition method. Tken Conc. from tblet Pure drug dded Totl found Recovery% ± SD Method A ± ± ± 0.79 Method B ± ± ± 0.58 Method C ± ± ±1.16 Men vlue of three determintions Tble 5: Appliction of the proposed methods for the determintion of PZT in Mosegor tblets Proposed methods Reported method [8] A B C Recovery ± RSD 99.40± ± ± ± 0.91 t-vlue b F-Vlue b Men for six independent nlyses., b The theoreticl vlues of t nd F re 2.57 nd 5.05, respectively t confidence limit t 95% confidence level nd five degrees of freedom (p= 0.05). Appliction to formultions The proposed methods were pplied to the determintion of PZT in tblets. The results in Tble 5 showed tht the methods re successful for the determintion of PZT nd tht the excipients in the dosge forms do not interfere. The results obtined from the ssy of PZT by the proposed methods nd reference method [8] for the sme btch of mteril is presented in Tble 5. The results greed well with the lbel clim nd lso were in greement with the results obtined by the reference methods. When the results were sttisticlly compred with those of the reference methods by pplying the Student ' s t-test for ccurcy nd F-test for precision, the clculted t-vlue nd F-vlue t 95% confidence level did not exceed the tbulted vlues of 2.57 nd 5.05, respectively, for five degrees of freedom [23]. Hence, no significnt difference existed between the proposed methods nd the reference methods with respect to ccurcy nd precision. DISCUSSION PZT, when dded in incresing mounts to fixed mount of NBS, consumes the ltter nd there will be concomitnt fll in its concentrtion. When fixed mount of ech dye is dded to decresing mounts of NBS, concomitnt increse in the concentrtion of dye results. This is observed s proportionl increse in the bsorbnce t the respective wvelengths of mximum bsorption with incresing concentrtion of drug s indicted by the correltion coefficients rnged from of Unrected NBS M ethod A M ethyl ornge Method B Amrnth M ethod C Indigo crmine Unbleched colour of methyl ornge mesured t 522 nm Unbleched colour of mrnth mesured t 507 nm Unbleched colour of indigo crmine mesured t 610 nm Scheme 1: Tenttive rection scheme for the proposed spectrophotometric methods. The tenttive rection scheme of spectrophotometric methods is shown in Scheme 1. The bromintion of PZT will tke plce in position α to the crbonyl group [20]. Drug Known excess of NBS H + Rection product of drug Unrected NBS 222

6 Goud et l. Int J Phrm Phrm Sci, Vol 6, Issue 4, CONCLUSION Three methods hve been developed for determintion of PZT in bulk drug nd in its tblets nd vlidted s per the current ICH guidelines. The present spectrophotometric methods re chrcterized by simplicity since they do not involve ny criticl experimentl vrible nd re free from tedious nd timeconsuming extrction steps nd use of orgnic solvents unlike mny previous methods. The proposed methods hve dditionl dvntges of ese of opertion nd possibility of crrying them out with common lbortory instrument unlike mny other instrumentl methods reported for PZT. They re chrcterized by high selectivity nd comprble sensitivity with respect to the existing methods. The ccurcy, reproducibility, simplicity, nd costeffectiveness of the methods suggest their ppliction in the qulity control lbortories where the modern nd expensive instruments re not vilble. CONFLICT OF INTERESTS The uthors declre tht they hve no conflict of interests with the compny nme used in the pper. REFERNCES 1. British Phrmcopoei. Monogrphs: Medicinl nd Phrmceuticl Substnces, pizotefin mlte, 2009; Volume I & II. 2. Sweetmn SC, Mrtindle: The Complete Drug Reference, 36 th Ed., The Phrmceuticl Press, London (U.K.), Sern-Jiménez CE, del Rio Sncho S, Cltyud-Pscul MA, Blguer-Fernández C, Femení-Font A, López-Cstellno A, Merino V, HPLC-UV nlyticl method for determintion of pizotifen fter in vitro trnsderml diffusion studies. Biomed Chromtogr 2012;26: Rhmn SM, Kbir AKL, Jhn A, Momen AR, Rouf ASS. Vlidtion nd ppliction of reversed phse high-performnce liquid chromtogrphic method for quntifiction of pizotifen mlte in phrmceuticl solid dosge formultions. Pk J Phrm Sci 2010;23: Abounssif MA, El-Obeid HA, Gdkriem EA. Stbility studies on some benzocycloheptne ntihistminic gents, J Phrm Biomed Anl 2005;36: Bsveswr Ro MV, Ngendrkumr AVD, Miti S, Chndrsekhr N. Vlidted RP-HPLC Method for the Estimtion of Pizotifen in Phrmceuticl Dosge Form. Chromtogr Res Int 2012;2012: Stout TH, Dorsey JG. High-Performnce Liquid Chromtogrphy. In: Ohnnesin L, Streeter AJ., (editors). Hnd book of Phrmceuticl Anlysis, Mrcel Dekker, Inc., New York, 2001; p El-Kousy N, Bebwy LI. Determintion of some ntihistminic drugs by tomic bsorption spectrometry nd colorimetric methods. J Phrm Biomed Anl 1999;20: Dessouky YM, Hssnein HH, Mohmmd MAA, Hnfy RS. Spectrophotometric nd spectrofluorimetric determintion of pizotifen mlte. Bull Fc Phrm Ciro Univ 2004;42: Amin AS, Ahmed IS, Dessouki HA, Goud EA. Utility of oxidtion reduction rection for the determintion of rntidine hydrochloride in pure form, in dosge forms nd in the presence of its oxidtive degrdtes. Spectrochimic Act A 2003;59: Bsvih K, Somsher BC. Titrimetric nd Spectrophotometric Determintion of Metprolol trtrte in Phrmceuticls Using N-Bromosuccinimide. E-J Chem 2007;4: Viny KB, Revnsiddpp HD, Devi OZ, Rmesh PJ, Bsvih K. Rpid titrimetric nd spectrophotometric determintion of ofloxcin in phrmceuticls using N-bromosuccinimide. Brz J Phrm Sci 2011;47: Viny KB, Revnsiddpp HD, Rjendrprsd N, Rghu MS, Rmesh PJ, Cijo MX, Bsvih K. Rpid titrimetric nd spectrophotometric ssy of trmdol in bulk drug nd in formultion using N-bromosuccinimide nd methyl ornge s regents. Thi J Phrm Sci 2011;35: Bsvih K, Anil kumr UR, Thrp K. Spectrophotometric Determintion of Pntoprzole Sodium in Phrmceuticls Using N-Bromosuccinimide, Methyl Ornge nd Indigo Crmine s Regents. Irn J Chem Chem Eng 2009;28: Goud AA, Amin AS, El Sheikh R, Akl MA. Sensitive spectrophotometric methods for determintion of some orgnophosphorus pesticides in vegetble smples. Chem Ind Chem Eng Qur 2010;16: El Sheikh R, Amin AS, Goud AA, Youssef AG. Utility of Oxidtion-Reduction Rection for Determintion of Gemifloxcin Mesylte nd Moxifloxcin HCl in Pure Form nd in Phrmceuticl Formultions using N-Bromosuccinimide. Phrm Anl Act 2013;4: Berk A, Vulterin J, Zyk J. Newer Redox Titrnts, first ed. Pergmon Press, London, 1965; p Jeffery GH, Bssett J, Mendhm J, Denney RC. Titrimetric Anlysis. In Vogel s Text Book of Quntittive Inorgnic Anlysis, 5 th Ed., ELBS: London, 1989; p Morrison RT, Boyd RN. Orgnic chemistry. 6.ed. New Jersey: Prentice-Hll, 2007; p Hssn A, Ibrhim R, Ibrhim D, Mostf M. Evlution of N- Bromosuccinimide s new-nlyticl regent for the spectrophotometric determintion of fluoroquinolone ntibiotics. Chem Phrm Bull 2007;55: Ringbom A. "Accurcy of clorimetric determintions" Z. Anl, Chem. 1939;115: Interntionl Conference on Hrmonistion of Technicl Requirements for Registrtion of Phrmceuticls for Humn Use. ICH Hrmonised Triprtite Guideline, Vlidtion of Anlyticl Procedures: Text nd Methodology Q2(R 1), Complementry Guideline on Methodology, London, November Miller JN, Miller JC. Sttistics nd chemometrics for nlyticl chemistry 5 th ed., Prentice Hll, Englnd,