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A simple, precise and accurate stability-indicating isocratic reverse phase ultra-performance liquid chromatographic (RP-UPLC) method was developed for the determination of lamotrigine (LMT) in bulk drug and in its tablets. The method was developed using Waters Aquity BEH C18 (100 mm × 2.1 mm, 1.7 µm) column with mobile phase consisting of a mixture of potassium dihydrogen phosphate buffer of pH 3.5 and an equal ratio of methanol and acetonitrile (50:50 v/v). The eluted compound was detected at 228 nm with a UV detector. The standard curve of mean peak area versus concentration showed an excellent linearity over a concentration range 1.0 . 75 µg/mL. Within-day and between-days RSD were less than 1.3% pronounces precision of the method. The accuracy of the method was further ascertained by recovery studies via standard addition procedure and the recoveries obtained were 98 - 100%. Forced degradation of the bulk sample was conducted in accordance with the ICH guidelines. Acidic, basic, hydrolytic, oxidative, thermal and photolytic degradation were used to assess the stability indicating power of the method. LMT was found to degrade significantly in acidic, basic and oxidative stress conditions and stable in thermal, hydrolytic and photolytic conditions. [ABSTRACT FROM AUTHOR]

Two direct, simple, sensitive and rapid extraction-free spectrophotometric methods have been developed for the determination of lamotrigine (LMT) in pure form and in its dosage forms. The methods are based on formation of ion-pair complex between the drug and two sulphonthalein acidic dyes namely, bromothymol blue (method A) and bromocresol green (method B), followed by the measurement of absorbance at 410 nm in both the methods. Conformity to Beer's law enabled the assay of the drug in the range 1-12 μg mL-1 in both the methods with apparent molar absorptivities of 2.06 × 104 and 1.787 × 104 L mol-1cm-1 for method A and method B, respectively. The Sandell sensitivity values, limits of detection (LOD) and quantification (LOQ) values have also been reported for both the methods. The stoichiometry of the ion-pair complexes as evaluated by Job's continuous variations method was 1:1 and the conditional stability constant (log Kf) were calculated to be 7.05 and 8.24 for method A and method B, respectively. The accuracy and precision of the methods were evaluated on intra-day and inter-day basis; the relative error (%RE) was < 2.0% and the relative standard deviation (RSD) was < 1.60%. The methods were successfully applied to the determination of drug in tablets without interference by the common coformulated substances. Statistical comparison of the results with the reference method showed good agreement and indicated no significant difference in accuracy and precision. [ABSTRACT FROM AUTHOR]

One titrimetric and two spectrophotometric methods which are simple, selective, sensitive, accurate, precise and economical for the determination of etamsylate (ETM) in bulk drug and in tablets employing permanganate as the oxidimetric reagent are described. In titrimetry, ETM is titrated directly with permanganate in sulphuric acid medium. A direct spectrophotometry (method A) involves treating the aqueous solution of the drug with permanganate in alkaline medium and measuring the bluish green product at 610 nm. In indirect spectrophotometry (method B), the drug solution was treated with a fixed concentration of permanganate in H2SO4 medium, and after a specified time, the unreacted permanganate was measured at 545 nm. The molar combining ratio in titrimetry and the optimum assay conditions were studied. Titrimetry is applicable over 1-10 mg range and the calculations are based on a 1:4 (ETM:KMnO4) molar ratio. In spectrophotometry, Beer's law is obeyed over 0.5- 5.0 and 1.5- -15 μg ml-1 for method A and B, respectively. The molar absorptivity values are calculated to be 2.79x104 and 4.17x104 l mol-1 cm-1 for method A and B, respectively and the corresponding sandell sensitivity values are 0.0094 and 0.0063 μg cm-2. The limits of detection (LOD) and quantification (LOQ) are also reported for spectrophotometric methods. The applicability of the developed methods was demonstrated by the determination of etamsylate in pure drug as well as in commercial dosage forms. [ABSTRACT FROM AUTHOR]