A simple, sensitive and rapid spectrophotometric method was developed and validated for the determination of two skeletal muscle relaxants namely, tizanidine hydrochloride (I) and orphenadrine citrate (II) in pharmaceutical formulations. The proposed method is based on the formation of a binary complex between the studied drugs and eosin Y in aqueous buffered medium (pH 3.5). Under the optimum conditions, the binary complex showed absorption maxima at 545 nm for tizanidine and 542 nm for orphenadrine. The calibration plots were rectilinear over concentration range of 0.5-8 μg/mL and 1-12 μg/mL with limits of detection of 0.1 μg/mL and 0.3 μg/mL for tizanidine and orphenadrine respectively. The different experimental parameters affecting the development and stability of the complex were studied and optimized. The method was successfully applied for determination of the studied drugs in their dosage forms; and to the content uniformity test of tizanidine in tablets.

A simple, sensitive and rapid spectrofluorimetric method for the simultaneous determination of metoclopramide (MET) and aspirin (ASP) was executed.

A simple and selective reversed-phase high-performance liquid chromatography method was developed for the estimation of cromolyn sodium (CRM) with either oxymetazoline hydrochloride (OMZ) or xylometazoline hydrochloride (XMZ) in their binary mixtures. The method is based on the simultaneous separation of each drug in a reversed-phase Waters symmetry C18 column (250 mm × 4.6 mm intradermally, 5-µm particle size) at 25°C. Elution was performed with a mobile phase consisting of methanol : 0.1 M phosphate buffer (60:40, v/v, pH 4.0). Quantitation was achieved with ultraviolet detection at 220 nm. The method could determine the three drugs, with linearity, in the range of 2.0-100.0 µg/mL for CRM and 0.8-8.0 µg/mL for OMZ and for XMZ. Aspirin was used as internal standard. Optimization of the separation in terms of mobile phase composition is critical to the method development, which is discussed in detail. The suggested procedure was successfully applied to the analysis of the studied drugs in their nasal preparations. Statistical evaluation of the data obtained by the proposed and comparison methods revealed good accuracy of the proposed method.

Bambuterol (BAM) and terbultaline (TER) are well known and effective bronchodilators. In this article highly sensitive, green and cost‐effective spectrofluorimetric methods are designed to determine low concentrations of such drugs. The proposed methods are based on an investigation of the native fluorescence properties of aqueous solutions of BAM at 298 nm after excitation at 263 nm and of TER at 313 nm after excitation at 275 nm. Under optimum conditions, the plots of the relative fluorescence intensity versus concentration were rectilinear over the range 0.1–1.2 μg/mL for BAM and 0.05–0.5 μg/mL for TER with a limit of quantitation of 0.067 μg/mL for BAM and 0.018 μg/mL for TER. The methods are simple and hence suitable for application to the quantification of BAM and TER in syrups and tablets without interference from common excipients. Furthermore, based on United States Pharmacopeia (USP) guidelines, the application was extended to determine the content uniformity of the cited drugs in low dose tablets. The developed methods were fully validated according to the guidelines of the International Conference on Harmonization (ICH).