Spectrophotometric determination of dropropizine in pure form and phrmaceutical formulation

Three new simple, different and sensitive spectrophotometric methods are suggested for the determination of Dropropizine [DRO]. The first is based on the reduction of ferric into ferrous in presence of 0-phenanthroline by the mentioned drug to form a highly stable orange-red ferroin chelate[Fe-[Phen][3]][2+], measured at [lambda][max] 510.5 nm for zero-order [D[degree sign]] while the peak amplitude was measured at 537.5 the nm for the first derivative [D[1]] using distilled deionized water as a solvent. Beer's law was obeyed in the range of 0.5-2.2 micro g/ml for both D[degree sign] and D[1] with mean percentage recoveries of 100.08 +/- 1.370 and 100.03 +/- 1.064, respectively. The second method is based on the reaction of DRO with 7,7,8,8- tetracyanoquinodimethane [TCNQ] in acetonitrile solvent to form a highly stable charge transfer colored complex that was measured at 734.5 nm. Beer's law was obeyed in the range of 10-55 micro g/ml with mean percentage recovery of 99.93 +/- 1.070. The last method is based on the reaction of DRO with cerium [IV] ammonium sulphate in acidic medium to form a highly stable colored oxidative product that was measured at 486.5 nm. Beer's law was obeyed in a concentration range 145 - 335 micro g/ml with mean percentage recovery of 99.67 +/- 1.077. The optimum assay conditions and their applicability for the determination of the cited drug in pharmaceutical formulation were described. The proposed methods were statistically compared with the reported method revealing good accuracy and precision

Simultaneous determination of bisoprolol Fumarate and hydrochlorothiazide in tablets by derivative spectrophotometry and densitometry

Derivative spectrophotometry [second and fourth] and densitometry were used to determine bisoprolol fumarate [I] and hydrochlorothiazide [II] simultaneously in combined pharmaceutical dosage form. Using second derivative spectrophotometry, the amplitudes in the second derivative spectra at 272.6nm and 284.8nm were selected for simultaneous determination of [I] and [II], respectively, in the mixture. Where, the HZ concentration was calculated from the amplitude at 284.8 nm [where BSF showed no absorbance] and BSF concentration was calculated from the amplitude at 272.6 nm after subtraction of the amplitude due to HZ. While, applying fourth-derivative spectrophotometry technique, the peak amplitudes at 289.8 nm and 272.8 nm were selected to determine [I] and [II], respectively. The calibration graphs were linear in the range of 30-280 microg/ml for [I] and 3-24 microg/ml for [II] in both methods. Furthermore, a densitometric procedure with ultraviolet detection at 223nm was applied using chloroform: ethanol: Glacial acetic acid [7:3:2 by volume] as a developing system. The plot of peak area of [I] and [II] to the respective concentrations of each drug was found to be linear in the range of 2.5-30micro g/spot and 1-7 micro g/spot, respectively. The suggested methods were used to determine both compounds in synthetic mixtures and in commerical tablets. The validity of the proposed methods was further assessed by applying standard addition technique. The obtained results were statistically compared with compandial HPLC method, showing no significant difference with respect to accuracy and precision