Validated stability-indicating spectrofluorimetric methods for the determination of ebastine in pharmaceutical preparations

Two sensitive, selective, economic, and validated spectrofluorimetric methods were developed for the determination of ebastine (EBS) in pharmaceutical preparations depending on reaction with its tertiary amino group. Method I involves condensation of the drug with mixed anhydrides (citric and acetic anhydrides) producing a product with intense fluorescence, which was measured at 496 nm after excitation at 388 nm.     

Spectrophotometric stability-indicating methods for the determination of leflunomide in the presence of its degradates

Five simple and sensitive methods were developed for the determination of leflunomide (I) in the presence of its degradates 4-trifluoromethyl aniline (II) and 3-methyl-4-carboxy isoxazole (III). Method A was based on differential derivative spectrophotometry by measuring the delta(1)D value at 279.5 nm. Beer's law was obeyed in the concentration range of 2.00-20.00 microg/mL with mean percentage accuracy of 100.07 +/- 1.32. Method B depended on first-derivative spectrophotometry and measuring the amplitude at 253.4 nm. Beer's law was obeyed in the concentration range of 2.00-16.00 microg/mL with mean percentage accuracy of 98.42 +/- 1.61. Method C was based on the reaction of degradate (II) with 2,6-dichloroquinone-4-chloroimide (Gibbs reagent). The colored product was measured at 469 nm. Method D depended on the reaction of degradate (II) with para-dimethyl aminocinnamaldehyde (p-DAC). The absorbance of the colored product was measured at 533.4 nm. Method E utilized 3-methyl-2-benzothiazolinone hydrazone in the presence of cerric ammonium sulfate with degradate (II). The green colored product was measured at 605.5 nm. The linearity range was 40.00-280.00, 2.40-24.00, and 30-250 microg/mL with mean percentage accuracy of 100.75 +/- 1.21, 100.13 +/- 1.45, and 99.74 +/- 1.39 for Methods C-E, respectively. All variables were studied to optimize the reaction conditions. The proposed methods have been successfully applied to the analysis of leflunomide in pharmaceutical dosage forms and the results were statistically compared with that previously reported.     

Validated HPLC and HPTLC stability-indicating methods for determination of alfuzosin hydrochloride in bulk powder and pharmaceutical formulations

Two sensitive, selective, and precise stability-indicating, high-performance liquid chromatography and high-performance thin-layer chromatography methods have been developed for the determination of alfuzosin hydrochloride in the presence of its degradation products. Alfuzosin.HCl was subjected to stress alkaline, acidic, oxidative, thermal, and photo-degradation. The drug could be well separated from the degradation products upon applying the two methods. Separation by HPLC was achieved using an Xterra RP18 column and acetonitrile/0.02 M KH2PO4 (pH=3) in a ratio of 20:80 as mobile phase. The flow rate was 1 mL/min. The linearity range was 0.25 to 11 microg/mL with mean percentage recovery of 100.26 +/- 1.54. The HPTLC method used ALUGRAM Nano-SIL silica gel 60 F254 plates; the optimized mobile phase was methanol/ammonia (100:1.2). Quantitatively the spots were scanned densitometrically at 245 nm. A second order polynomial equation was used for the regression. The range was 0.5-7 microg/spot. The mean percentage recovery was 100.13 +/- 1.67. Two main degradation products were obtained in most stress conditions, separated, and identified by FT-IR and NMR spectral analysis, from which the degradation pathway was proposed. The two methods were validated according to the International Conference on Harmonization. In addition, the HPLC method was used to study the kinetics of alkaline and acid degradation of the drug.     

Validated stability-indicating HPLC-UV method for simultaneous determination of glipizide and four impurities

A selective stability-indicating HPLC-UV method for simultaneous determination of glipizide and four impurities (DPs I-IV) formed under hydrolytic conditions was developed and validated. The drug and impurities were resolved on an XTerra C18 column (250 x 4.5 mm id) in a single gradient run using buffer (0.005 M KH2PO4; pH 3.0)-methanol (60 + 40, v/v; mobile phase A) and (20 + 80, v/v; mobile phase B) at a flow rate of 0.5 mL/min with 230 nm detection wavelength. The method was linear across concentration ranges of 0.2-100, 0.1-100, 0.5-100, 0.2-100, and 0.1-50 microg/mL for glipizide and DPs I-IV, respectively. The RSD for intraday and interday precision for the drug and impurities was < 1 and < 1.2%, respectively. Satisfactory recoveries (96.58-99.97%) of each of the three concentrations selected across the linearity range of each analyte were obtained, proving the method was sufficiently accurate. The LOD was 0.07, 0.05, 0.16, 0.08, and 0.05 microg/mL and the LOQ was 0.20, 0.14, 0.50, 0.23, and 0.14 microg/mL for the drug and DPs I-IV, respectively. Each peak was resolved with resolution of > 2 from the nearest peak. Insignificant changes in retention time (< 4%) and calculated amount (< 1.65%) of drug and each impurity upon small but deliberate changes in various chromatographic parameters were observed, suggesting the method was robust. The method was applied successfully to stability testing of glipizide tablets.     

HPLC, TLC, and first-derivative spectrophotometry stability-indicating methods for the determination of tropisetron in the presence of its acid degradates

Three stability-indicating assay methods were developed for the determination of tropisetron in a pharmaceutical dosage form in the presence of its degradation products. The proposed techniques are HPLC, TLC, and first-derivative spectrophotometry (1D). Acid degradation was carried out, and the degradation products were separated by TLC and identified by IR, NMR, and MS techniques. The HPLC method was based on determination of tropisetron in the presence of its acid-induced degradation product on an RP Nucleosil C18 column using methanol-water-acetonitrile-trimethylamine (65 + 20 + 15 + 0.2, v/v/v/v) mobile phase and UV detection at 285 nm. The TLC method was based on the separation of tropisetron and its acid-induced degradation products, followed by densitometric measurement of the intact spot at 285 nm. The separation was carried out on silica gel 60 F254 aluminum sheets using methanol-glacial acetic acid (22 + 3, v/v) mobile phase. The 1D method was based on the measurement of first-derivative amplitudes of tropisetron in H2O at the zero-crossing point of its acid-induced degradation product at 271.9 nm. Linearity, accuracy, and precision were found to be acceptable over concentration ranges of 40-240 microg/mL, 1-10 microg/spot, and 6-36 micro/mL for the HPLC, TLC, and 1D methods, respectively. The suggested methods were successfully applied for the determination of the drug in bulk powder, laboratory-prepared mixtures, and a commercial sample.     

Stability-indicating methods for determination of pyritinol dihydrochloride in the presence of its precursor and degradation product by derivative spectrophotometry

A first-derivative spectrophotometric (1D) method and a derivative-ratio zero-crossing spectrophotometric (1DD) method were used to determine pyritinol dihydrochloride (I) in the presence of its precursor (II) and its degradation product (III) with 0.1N hydrochloric acid as a solvent. Linear relationships were obtained in the ranges of 6-22 microg/mL for the (1D) method and 6-20 microg/mL for the (1DD) method. By applying the proposed methods, it was possible to determine pyritinol dihydrochloride in its pure powdered form with an accuracy of 100.36 +/- 1.497% (n = 9) for the (1D) method and an accuracy of 99.92 +/- 1.172% (n = 8) for the (1DD) method. Laboratory-prepared mixtures containing different ratios of (I), (II), and (III) were analyzed, and the proposed methods were valid for concentrations of < or = 10% (II) and < or = 50% (III). The proposed methods were validated and found to be suitable as stability-indicating assay methods for pyritinol in pharmaceutical formulations.     

Validated chromatographic methods for determination of hydrochlorothiazide and spironolactone in pharmaceutical formulation in presence of impurities and degradants

Two specific, sensitive, and precise stability indicating chromatographic methods have been developed, optimized, and validated for Hydrochlorothiazide (HCT) and Spironolactone (SPR) determination in their mixtures and in presence of their impurities and degradation products. The first method was based on thin layer chromatographic (TLC) combined with densitometric determination of the separated spots. The separation was achieved using silica gel 60 F(254) TLC plates and ethyl acetate-chloroform-formic acid-triethyl amine (7:3:0.1:0.1, by volume) as a developing system. Good correlations were obtained between the integrated peak area of the studied drugs and their corresponding concentrations in different ranges. The second method was based on the high-performance liquid chromatography with ultraviolet detection, by which the proposed components were separated on a reversed phase C(18) analytical column using gradient elution system with deionized water-acetonitrile (97:3, v/v) for 8 min. Then acetonitrile was successively increased to 35% in the next 2 min, and kept constant in the following 10 min, finally 3% acetonitrile was regained again to stabilize the chromatographic system. The flow rate was maintained at 2 mL/min and the detection wavelength was at 230 nm. Linear regressions were obtained in the range of 4.0-50 μg/mL and 5.0-50 μg/mL for both HCT and SPR, respectively. Different parameters affecting the suggested methods were optimized for maximum separation of the cited components. System suitability parameters of the two developed methods were also tested. The suggested methods were validated in compliance with the ICH guidelines and were successfully applied for determination of HCT and SPR in their commercial tablets. Both methods were also statistically compared to each other and to the reported method with no significant difference in performance.     

Validated spectrofluorometric methods for determination of amlodipine besylate in tablets

Two simple and sensitive spectrofluorometric methods have been developed and validated for determination of amlodipine besylate (AML) in tablets. The first method was based on the condensation reaction of AML with ninhydrin and phenylacetaldehyde in buffered medium (pH 7.0) resulting in formation of a green fluorescent product, which exhibits excitation and emission maxima at 375 and 480 nm, respectively. The second method was based on the reaction of AML with 7-chloro-4-nitro-2,1,3-benzoxadiazole (NBD-Cl) in a buffered medium (pH 8.6) resulting in formation of a highly fluorescent product, which was measured fluorometrically at 535 nm (lambda(ex), 480 nm). The factors affecting the reactions were studied and optimized. Under the optimum reaction conditions, linear relationships with good correlation coefficients (0.9949-0.9997) were found between the fluorescence intensity and the concentrations of AML in the concentration range of 0.35-1.8 and 0.55-3.0 microg ml(-1) for ninhydrin and NBD-Cl methods, respectively. The limits of assays detection were 0.09 and 0.16 microg ml(-1) for the first and second method, respectively. The precisions of the methods were satisfactory; the relative standard deviations were ranged from 1.69 to 1.98%. The proposed methods were successfully applied to the analysis of AML in pure and pharmaceutical dosage forms with good accuracy; the recovery percentages ranged from 100.4-100.8+/-1.70-2.32%. The results were compared favorably with those of the reported method.     

Validated polarographic methods for the determination of certain antibacterial drugs.

Two simple, precise, inexpensive and sensitive voltammetric methods for the determination of lomefloxacin (LFX), sparfloxacin hydrochloride (SFX), gatifloxacin (GFX), and moxifloxacin (MFX) were developed. The present methods were first used to explore the adsorption behavior of the four investigated antibacterial agents at a hanging mercury dropping electrode (HMDE), by a direct method and secondly by a modification via their complexation with PdCl(2). For the direct method, drugs were accumulated on HMDE, and a well-defined reduction peak was obtained in Britton-Robinson buffer of pH 7 for LFX and SFX, and pH 6 for GFX and MFX. The adsorptive stripping response was evaluated as a function of some variables such as the scan rate, pH, accumulation time and potential. For the modified method, the adsorptive behavior of Pd(II)-4-quinolone complexes at the HMDE developed a strippining voltammetry peak at a more negative potential than that of the free Pd(II) ions (-1.05 V). The limits of detection (LOD) were 2 x 10(-8) M, while the limits of quantification (LOQ) were 6 x 10(-8) M for the investigated drugs. The methods were applied to the determination of LFX, SFX, GFX, and MFX in biological samples and pharmaceutical preparations, and also compared with the official reference methods. Complete validation of the proposed methods was also done.     

Stability-indicating derivative spectrophotometry method for the determination of biapenem in the presence of its degradation products

A first-derivative UV spectrophotometric method, with or without the subtraction technique, was developed for the determination of biapenem in pharmaceutical dosage form in the presence of its degradation products. The method was based on the measurement of first-derivative amplitudes at zero crossing point (λ = 312 nm) and the peak-to-zero technique and validated with regard to linearity, limits of detection and quantitation, selectivity and precision. The observed rate constants for the degradation of biapenem were comparable to those obtained in the stability-indicating HPLC method.      

Smart stability-indicating spectrophotometric methods for determination of binary mixtures without prior separation

Ratio subtraction and isosbestic point methods are 2 innovating spectrophotometric methods used to determine vincamine in the presence of its acid degradation product and a mixture of cinnarizine (CN) and nicergoline (NIC). Linear correlations were obtained in the concentration range from 8-40 microg/mL for vincamine (I), 6-22 microg/mL for CN (II), and 6-36 microg/mL for NIC (III), with mean accuracies 99.72 +/- 0.917% for I, 99.91 +/- 0.703% for II, and 99.58 +/- 0.847 and 99.83 +/- 1.039% for III. The ratio subtraction method was utilized for the analysis of laboratory-prepared mixtures containing different ratios of vincamine and its degradation product, and it was valid in the presence of up to 80% degradation product. CN and NIC in synthetic mixtures were analyzed by the 2 proposed methods with the total content of the mixture determined at their respective isosbestic points of 270.2 and 235.8 nm, and the content of CN was determined by the ratio subtraction method. The proposed method was validated and found to be suitable as a stability-indicating assay method for vincamine in pharmaceutical formulations. The standard addition technique was applied to validate the results and to ensure the specificity of the proposed methods.     

Development and validation of stability-indicating HPLC and UPLC methods for the determination of bicalutamide

Six new process related impurities (Imp-08, Imp-09, Imp-10, Imp-12, Imp-13 and Imp-14) of bicalutamide (BCT) have been reported in this paper. BCT was subjected to oxidative, acid, alkaline, hydrolytic, thermal and photolytic degradation conditions and found to degrade in alkaline condition, yielding Imp-11. Stability-indicating high-performance liquid chromatography and ultra-performance liquid chromatography methods were developed for the determination of BCT in the presence of its 14 process-related impurities and 1 degradant by using Zorbax SB phenyl column (150 × 4.6 mm × 3.5 μm) and HSS T3 column (100 × 2.1 mm × 1.8 μm), respectively. Both the methods were validated as per International Conference on Harmonization guidelines. Quantitation limits (QL) were found be in the ranges of 0.02-0.03% for both the methods. Precision was evaluated by replicate analysis in which % relative standard deviation (RSD) values for areas were found below 2.0. Linearity for the impurities was established in the range of QL to 200% of the specification level and the correlation coefficients derived from of the respective calibration curves were approximately 0.999. The recoveries obtained for purity (90-100%) and assay (98-102%) ensured the accuracy of the developed methods.     

Stability-indicating methods for the determination of linezolid in the presence of its alkaline-induced degradation products

Three methods are presented for the determination of linezolid in the presence of its alkaline-induced degradation products. The first method was based on separation of linezolid from its alkaline degradation product by TLC followed by densitometric measurement of the spots of intact drug at 244 nm. The separation was carried out on silica gel 60 F₂₅₄ using isobutanol:ammonia (9:1 v/v) as a mobile phase. The second method was based on first derivative ¹D ultraviolet spectrophotometry with zero crossing point and peak to base measurement. The ¹D value at 251.4 nm was selected for the assay of linezolid in the presence of degradation product. The third method was depended on the first derivative of the ratio spectra ¹DD by measurement of the value at 263.6 nm. The proposed methods were successfully applied to the determination of the drug in bulk powder, in laboratory prepared mixtures with its degradation product and in commercial tablets.     

Validated spectrophotometric methods for the simultaneous determination of ciprofloxacin hydrochloride and metronidazole in tablets

A binary mixture of ciprofloxacin hydrochloride (CIP) and metronidazole (MET) was determined by five simple and accurate methods, without prior separation. In the first method, CIP was determined by second derivative spectrophotometric method ((2)D) by measuring the amplitude at 282 nm (zero ordinate value of MET). On the other hand, the determination of MET was based on isosbestic point technique, where the total content of the mixture was determined at 294.5 nm (isosbestic point), then the content of MET could be calculated by subtraction. The second method was first derivative ratio spectrophotometric method ((1)DD) where the total amplitude at 261 and 285 nm and the amplitude at 295.5 nm were selected to simultaneously determine CIP and MET in binary mixture, respectively. The third method was based on dual wavelength analysis, in which two wavelengths were selected, at which the absorbances of the other component were the same. The fourth method depends on using Q-analysis method (absorbance ratio) which involves the formation of Q-absorbance equation using the respective absorptivity values at 294.5 nm (isosbestic point) and 281.5 nm (λ(max) of CIP). The fifth method is partial least-squares (PLS) chemometric technique for determination of CIP and MET. The developed methods were successfully applied to the analysis of CIP and MET in laboratory prepared mixtures and tablets with good recoveries and their validation was carried out following the International Conference on Harmonization (ICH) guidelines. The results obtained were statistically compared with each other showing no significant difference with respect to accuracy and precision.     

Selective and stability-indicating methods for the simultaneous determination of mexiletine hydrochloride and/or its related substance: 2,6-dimethylphenol

Four simple, rapid, sensitive, and selective analytical procedures were developed for determination of mexiletine hydrochloride (MX) and/or its related substance: 2,6-dimethylphenol (DMP). The latter is a synthetic impurity for which a maximum pharmacopeial limit is defined. The first method depends on derivative-ratio spectrophotometry, for which the first-derivative signals of the ratio spectra at 259 nm (Deltalambda = 3 nm) are selected for the determination of MX. The second method is based on the spectrofluorometric measurement of MX in alkaline solution in the presence of 15 mM sodium dodecyl sulfate micellar medium at 292 nm (lambdaEx 260 nm). The third method is based on liquid chromatographic (LC) separation of MX and DMP on an RP-C8 column with a mobile phase consisting of 50 mM Na2HPO4-acetonitrile (60 + 40, adjusted to pH 2.4), and quantification of the analytes is achieved with UV detection at 212 nm based on peak area. The fourth method uses the coupling reaction of DMP with 2,6-dibromo-quinone-4-chlorimide (DBQC) in borate buffer to form an intensely colored product that was spectrophotometrically measured using first-derivative amplitudes at 670 nm (Deltalambda = 6 nm) for the determination of DMP. Different variables affecting each method were carefully investigated and optimized. The reliability and analytical performance of the proposed methods, including linearity, range, precision, accuracy, and detection and quantitation limits, were statistically validated. The first 3 methods were successfully applied for the stability-indicating determination of MX in laboratory-prepared mixtures with DMP, as well as for the determination of MX in capsules. Also, the LC and the DBQC spectrophotometric methods permitted the selective determination of DMP in the presence of a large excess of the parent drug at or near the pharmacopeial limit (0.1-1%).     

Determination of rosuvastatin in the presence of its degradation products by a stability-indicating LC method

A forced degradation study was successfully applied for the development of a stability-indicating assay method for determination of rosuvastatin Ca in the presence of its degradation products. The method was developed and optimized by analyzing the forcefully degraded samples. Degradation of the drug was done at various pH values. Moreover, the drug was degraded under oxidative, photolytic, and thermal stress conditions. Mass balance between assay values of degraded samples and generated impurities was found to be satisfactory. The proposed method was able to resolve all of the possible degradation products formed during the stress study. The developed method was successfully applied for an accelerated stability study of the tablet formulation. The major impurities generated during the accelerated stability study of the tablet formulation were matches with those of the forced degradation study. The developed method was validated for determination of rosuvastatin Ca, and the method was found to be equally applicable to study the impurities formed during routine and forced degradation of rosuvastatin Ca.     

Green micellar stability-indicating high-performance liquid chromatography method for determination of rupatadine fumarate in the presence of its main impurity desloratadine: Oxidative degradation kinetics study

A green micellar stability-indicating high-performance liquid chromatography method was developed for rupatadine fumarate determination in existence with its main impurity desloratadine. Separation was attained using Hypersil ODS column (150 × 4.6 mm, 5 μm), the micellar mobile phase consisted of 0.13 M sodium dodecyl sulfate, 0.1 M disodium hydrogen phosphate adjusted by phosphoric acid to pH 2.8 and 10% n-butanol. The column was maintained at 45^◦C and detection was carried out at 267 nm. A linear response was achieved over the range of 2–160 μg/ml for rupatadine and 0.4–8 μg/ml for desloratadine. The method was applied for rupatadine determination in alergoliber tablets and alergoliber syrup without the interference of methyl paraben and propyl paraben present as main excipients. Rupatadine fumarate revealed pronounced susceptibility to oxidation; further study of oxidative degradation kinetics was carried out. Rupatadine was found to follow pseudo-first-order kinetics when exposed to 10% H₂O₂ at 60 and 80°C and the activation energy was found to be 15.69 Kcal/mol. At a lower temperature (40°C), degradation kinetics regression was best fitted as a polynomial quadratic relationship, thus rupatadine oxidation at a lower temperature tends to adopt a second-order kinetics rate. Oxidative degradation product structure was revealed using infrared and found to be rupatadine N-oxide at all temperature values.     

Kinetic spectrophotometric method for the determination of ranitidine and nizatidine in pharmaceuticals

An accurate and simple kinetic method is described for the determination of ranitidine and nizatidine in pure form and in pharmaceuticals. The method is based on the reaction of the compounds with 7-chloro-4-nitrobenz-2-oxa-1,3-diazole in pH 7.4 borate buffer at 60 degrees C for a fixed time of 25 min for both compounds. The absorbance of the reaction product is measured at 495 nm for ranitidine and nizatidine. Calibration graphs were linear over the concentration range of 2-20 microg/mL, with limits of detection of 0.13 (3.7 x 10(-7) M) and 0.25 microg/mL (7.5 x 10(-7) M) for ranitidine and nizatidine, respectively. The proposed method was applied successfully to the determination of ranitidine in tablets and ampoules with average recoveries of 100.26+/-0.69 and 100.29+/-0.59%, respectively, and to the determination of nizatidine in capsules with an average recovery of 104.26+/-0.44%. The results obtained are in good agreement with those obtained by the other methods used for comparison. A proposal of the reaction pathway is also presented.     

Simultaneous HPTLC and RP-HPLC methods for determination of bumadizone in the presence of its alkaline-induced degradation product

Accurate, selective, sensitive and precise HPTLC‐densitometric and RP‐HPLC methods were developed and validated for determination of bumadizone calcium semi‐hydrate in the presence of its alkaline‐induced degradation product and in pharmaceutical formulation. Method A uses HPTLC‐densitometry, depending on separation and quantitation of bumadizone and its alkaline‐induced degradation product on TLC silica gel 60 F₂₅₄ plates, using hexane–ethyl acetate–glacial acetic acid (8:2:0.2, v/v/v) as a mobile phase followed by densitometric measurement of the bands at 240 nm. Method B comprises RP‐HPLC separation of bumadizone and its alkaline‐induced degradation product using a mobile phase consisting of methanol–water–acetonitrile (20:30:50, v/v/v) on a Phenomenex C₁₈ column at a flow‐rate of 2 mL/min and UV detection at 235 nm. The proposed methods were successfully applied to the analysis of bumadizone either in bulk powder or in pharmaceutical formulation without interference from other dosage form additives, and the results were statistically compared with the established method. Copyright © 2011 John Wiley & Sons, Ltd.     

Development and validation of three stability-indicating methods for determination of bisacodyl in pure form and pharmaceutical preparations

Three new, simple, sensitive, and accurate stability-indicating methods were developed for quantitative determination of bisacodyl in the presence of its degradation products, monoacetyl bisacodyl (I) and desacetyl bisacodyl (II), in enteric coated tablets, suppositories, and raw material. The first is a spectrodensitometric method in which the drug is separated from I and II on silica gel plates using chloroform-acetone (9 + 1, v/v) as the mobile phase with ultraviolet detection of the separated bands at 223 nm over a concentration range of 0.2-1.4 microg/band for bisacodyl with mean recovery 100.35 +/- 1.923%. The second method is fourth derivative D4 spectrophotometry, which allows determination of bisacodyl in the presence of its degradation products in raw material at 223 nm using acetonitrile as the solvent with adherence to Beer's law over the concentration range 2-18 microg/mL with mean recovery 99.77+/-1.056%. In the third method, the spectrophotometric data of bisacodyl, I, and II using absolute ethanol as solvent were processed by 3 chemometric techniques: classical least-squares, principal component regression, and partial least-squares. A training set consisting of 15 mixtures containing different ratios of bisacodyl, I, and II was used for construction of the 3 models. A validation set consisting of 6 mixtures was used to validate the prediction ability of the suggested models. The 3 chemometric methods were applicable over a concentration range between 2-14microg/mL for bisacodyl with mean recovery of 99.97+/-0.865, 100.01 +/- 0.749, and 99.97 +/- 0.616% for the 3 models, respectively. The proposed methods were checked using laboratory-prepared mixtures and were successfully applied to the analysis of raw material and pharmaceutical formulations containing bisacodyl, except for the second method that applies only for raw material. The validity of the suggested procedures was further assessed by applying the standard addition technique; the recoveries obtained were in accordance with those given by the reference method.