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Aims: To develop methods with complete validation according to ICH guidelines and to be applied for the determination of avanafil in pure form and in pharmaceutical formulation in the presence of its degradation products. Study Design: High performance thin layer chromatography (HPTLC) and different spectrophotometric methods (dual wavelength, first derivative, first derivative of ratio spectra and ratio difference are developed for simultaneous determination of avanafil in laboratory-prepared mixtures of avanafil with its degradation products and in pharmaceutical formulation. Place and Duration of Study: Sample: Department of Analytical Chemistry, Faculty of Pharmacy (Girls), Al-Azhar University, Cairo, Egypt, between May 2019 and September 2019. Methodology: Two techniques have been developed for the determination of avanafil in the presence of its degradation products. The first was HPTLC where separation was performed on silica gel 60 F254 plates, with chloroform: toluene: methanol: conc. ammonia (6:5:3:0.1, by volume) as a developing system and UV detection at 230 nm. The second one was UV- spectrophotometry which included dual wavelength between 267 and 292 nm, first derivative determination of the drug at 261 nm, first derivative of ratio of peak amplitudes at 275.6, 305.4 and 329 nm and the ratio difference with the amplitude difference between (266 and 250 nm). Results: HPTLC method was applied over the concentration range of 0.5-5. μg/spot, while spectrophotometric methods were linear over the concentration range 5-50 μg/mL for avanafil. Conclusion: Novel, simple and accurate method for the determination of avanafil in laboratory-prepared mixtures of avanafil with its degradation products and in pharmaceutical formulation.

The study is aimed at developing methods which have a complete validation as stipulated in the ICH guidelines and to be applied for the determination of Bepotastine besilate (BB) in pure form and in pharmaceutical formulations in the presence of its oxidative degradation product. High performance thin layer chromatography (HPTLC), Ultra high performance liquid chromatography (UHPLC) and different spectrophotometric methods (first derivative, first derivative of ratio spectra and ratio difference are developed for simultaneous determination of bepotastine besilate in laboratory-prepared mixtures of bepotastine besilate with its oxidative degradate and in pharmaceutical formulations were used in the study design. Firstly, HPTLC was performed and separation occurred on silica gel 60 F254 plates, with butanol: ammonia (8:2, v/v) as a developing system. UHPLC in which separation occurred on a Kinetex C 18 column using methanol- 0.1% O-phosphoric acid - acetonitrile (70:20:10, by volume) as mobile phase, followed. And lastly was UV/Vis spectrophotometry which included first derivative determination of the drug at 252.6 nm, first derivative of ratio of peak amplitudes at 233.4, 250 and 275.6 nm and the ratio difference with the amplitude difference between (240 nm and 260 nm). Result showed that HPTLC method was applicable over the concentration range of 0.5-5 μg / band, while UHPLC method was linear over the concentration 2- 12 μg/mL and spectrophotometric methods were linear over the concentration range 20-120 μg/mL for bepotastine besilate. The proposed three techniques are quite accurate and precise. They can be used for routine analysis of bepotastine besilate in pharmaceutical formulation and stability indicating methods.

Aims: To develop methods with complete validation according to ICH guidelines and to be applied for the determination of both drugs in laboratory prepared mixtures and in synthetic tablets. Study Design:  Ultra high performance liquid chromatography (UHPLC), High performance thin layer chromatography (HPTLC) and visible spectrophotometric methods are developed for determination of amlodipine besilate and azilsartan medoxomil in laboratory-prepared mixtures and in synthetic tablets. Methodology: Two techniques have been developed for the simultaneous determination of amlodipine besilate and azilsartan medoxomil in pure form and synthetic tablets. The first was UHPLC in which separation was achieved on a C18 column using 0.1% o-phosphoric acid - acetonitrile - methanol (60:10:30, by volume) as mobile phase with detection at 243nm. The second was HPTLC where separation was performed on silica gel 60 F254 plates using chloroform- tolune-methanol-glacial acetic acid (7: 1.5: 1.5: 0.5 by volume) as a developing system and UV detection at 243nm. In addition, visible- spectrophotometric method was developed for determination of amlodipine besilate in presence of azilsartan medoxomil through formation of yellowish orange colored product after reaction of amlodipine besilate with anisaldehde in acid medium with λmax at 443 nm. Results: UHPLC method was linear over the concentration ranges of 2-20 μg/ mL and 4-40 μg/ mL while HPTLC method was linear over the concentration ranges of 0.2 -4.0 μg/ spot and 0.5-8.0 μg/ spot for amlodipine besilate and azilsartan medoxomil, respectively. The visible spectrophotometric method was found to be valid over the concentration range of 10–80 μg/mL for amlodipine besilate. Conclusion: The proposed three techniques are rapid, accurate and precise, thus can be effectively applied for the routine estimation of both drugs in bulk and in their combined formulations.

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