Reversed phase high-performance liquid chromatography (RP-HPLC) and thin-layer chromatography (TLC)-spectrodensitometric methods have been developed and validated for the separation and quantitation of two binary mixtures: Ofloxacin (OFX) and dexamethasone (DXM) in eye preparation; ciprofloxacin hydrochloride (CIP) and hydrocortisone (HYD) in ear preparation. The linearity ranges of RP-HPLC methods were found to be (2.5–45 μg mL−1) for OFX, (2.5–50 μg mL−1) for DXM and (1–8 μg mL−1) for both CIP and HYD. The percentage recoveries/relative standard deviation (RSD) were found to be 100.36/1.38, 100.13/1.49, 99.98/0.61 and 100.28/1.27, respectively. The linearity ranges of TLC-spectrodensitometric methods were found to be (0.5–2 μg band−1), (0.5–3.5 μg band−1), (0.2–1.6 μg band−1), and (0.6–2 μg band−1) for OFX, DXM, CIP, and HYD, respectively. The percentage recoveries/RSD were found to be 99.98/1.06, 99.93/1.18, 99.74/1.27, and 99.94/1.54, respectively. A comparative study was conducted to show the advantages of the proposed methods which showed that the TLC-spectrodensitometric methods were simpler, more sensitive, and economic, while RP-HPLC methods were more precise and robust. The methods were validated in compliance with the ICH guidelines and were successfully applied for determination of the selected drugs in their laboratory-prepared mixtures and commercial dosage forms.

Abstract: A validated simple, rapid, and selective spectrofluorimetric method was developed for the determination of some non-sedating antihistamines (NSAs); namely cetirizine (CTZ), ebastine (EBS), fexofenadine (FXD), ketotifen (KET), and loratadine (LOR). The method is based on quenching effect of the cited drugs on the fluorescence intensity of erythrosine B (EB) by the formation of ion-pair complex measured without extraction at lex.. 311 nm/ lex.. 555 nm against a reagent blank. The fluorescence intensity of EB was diminished when the studied drugs were added. There was a linear relationship between the fluorescence quenching value of the system (ΔF = F EB – F Drug–EB) and the concentration of the investigated drug. Under the optimal conditions, the linear ranges of calibration curves for the determination of the studied NSAs were 0.25–2.0, 0.25–3.0, and 0.25–6.0
g/mL for (CTZ, KET, LOR), (EBS), and (FXD), respectively. The factors affecting the formation of the ion-pair complex were carefully studied and optimized. The method was validated according to ICH guidelines. The suggested method is applicable for the determination of the five investigated drugs in bulk and pharmaceutical dosage forms with excellent recoveries (98.23-103.77 %).

Abstract: A validated simple, rapid, and selective spectrofluorimetric method was developed for the determination of some non-sedating antihistamines (NSAs); namely cetirizine (CTZ), ebastine (EBS), fexofenadine (FXD), ketotifen (KET), and loratadine (LOR). The method is based on quenching effect of the cited drugs on the fluorescence intensity of erythrosine B (EB) by the formation of ion-pair complex measured without extraction at lex.. 311 nm/ lex.. 555 nm against a reagent blank. The fluorescence intensity of EB was diminished when the studied drugs were added. There was a linear relationship between the fluorescence quenching value of the system (ΔF = F EB – F Drug–EB) and the concentration of the investigated drug. Under the optimal conditions, the linear ranges of calibration curves for the determination of the studied NSAs were 0.25–2.0, 0.25–3.0, and 0.25–6.0
g/mL for (CTZ, KET, LOR), (EBS), and (FXD), respectively. The factors affecting the formation of the ion-pair complex were carefully studied and optimized. The method was validated according to ICH guidelines. The suggested method is applicable for the determination of the five investigated drugs in bulk and pharmaceutical dosage forms with excellent recoveries (98.23-103.77 %).

Abstract: A validated simple, rapid, and selective spectrofluorimetric method was developed for the determination of some non-sedating antihistamines (NSAs); namely cetirizine (CTZ), ebastine (EBS), fexofenadine (FXD), ketotifen (KET), and loratadine (LOR). The method is based on quenching effect of the cited drugs on the fluorescence intensity of erythrosine B (EB) by the formation of ion-pair complex measured without extraction at lex.. 311 nm/ lex.. 555 nm against a reagent blank. The fluorescence intensity of EB was diminished when the studied drugs were added. There was a linear relationship between the fluorescence quenching value of the system (ΔF = F EB – F Drug–EB) and the concentration of the investigated drug. Under the optimal conditions, the linear ranges of calibration curves for the determination of the studied NSAs were 0.25–2.0, 0.25–3.0, and 0.25–6.0
g/mL for (CTZ, KET, LOR), (EBS), and (FXD), respectively. The factors affecting the formation of the ion-pair complex were carefully studied and optimized. The method was validated according to ICH guidelines. The suggested method is applicable for the determination of the five investigated drugs in bulk and pharmaceutical dosage forms with excellent recoveries (98.23-103.77 %).