Stability-indicating UPLC, TLC-densitometric and UV-spectrophotometric methods for alcaftadine determination.

Three sensitive and precise stability-indicating methods were developed for the determination of alcaftadine in the presence of its degradation products. Efficient separation was achieved using UPLC-UV-MS method by gradient elution with a mobile phase of 0.1% aqueous formic acid (A) and 0.1% formic acid in acetonitrile (B) over concentration range of 0.10-1.00 µg mL-1. The accuracy was 100.89% ± 0.74 and 99.73% ± 0.78 for UV and MS detection, respectively. A TLC-densitometric method was adopted to separate of the intact drug from its degradation products. Methanol: chloroform: glacial acetic acid (5:4:0.1, v/v/v) was the developing system, detection wavelength was set to 282 nm. Rf values were 0.35, 0.65 and 0.88 for alcaftadine, its acidic and oxidative degradants, respectively. The linearity range was 2.00-27.00 µg/band with mean accuracy of 100.58% ± 0.86. The proposed TLC-densitometric method was utilized for the study of degradation rates of alcaftadine. Finally, a simple UV-spectrophotometric method where an induced dual wavelength was implemented, the method showed a linearity range of 2.00-27.00 µg mL-1 with mean recovery of 100.15% ± 0.70. The proposed methods were successful for quantitation of alcaftadine in ophthalmic solution and in plasma samples. The obtained results were in accordance with those obtained by previously reported methods.

Assessment of the greenness of new stability indicating micellar UPLC and HPTLC methods for determination of tenofovir alafenamide in dosage forms.

In this study, a green stability indicating chromatographic methods were developed and validated for the quantitative determination of tenofovir alafenamide in the presence of its degradation products in bulk powder as well as in dosage forms. The first method was micellar UPLC in which separation was achieved on kinetex ® 1.7 µm HILIC 100A, LC column using an ecofriendly micellar mobile phase consisting (0.05 M sodium dodecyl sulphate and 0.05 M sodium dihydrogen phosphate, (pH 5.5) and 10% 1-propanol (70:30) at a flow rate of 1 mL min-1 with a UV detection at 210 nm. The second method depended on HPTLC method performed on HPTLC plates pre-coated with silica gel 60 F254 using a mobile phase consisting of n-butanol-acetic acid (7:3, v/v) and detection at 260 nm. Tenofovir alafenamide was subjected to stress conditions including alkaline and acidic degradation. Beer' law was obeyed over the concentration range of 1-18 µg mL-1 and 0.1-4 µg/spot for micellar UPLC and HPTLC methods, respectively. Both methods are successfully applied to the analysis of the drug in its tablets and validated according to ICH guidelines. In addition, their greenness was assessed using three different tools indicating their least hazardous effect on the environment.

Stability-indicating methods for the determination of racecadotril in the presence of its degradation products.

Three stability-indicating methods were developed for the determination of racecadotril (RCT) in the presence of its alkaline degradation products. The first was an HPLC method in which efficient chromatographic separation was achieved on a C18 analytical column and a mobile phase of acetonitrile-methanol-water-acetic acid (52:28:20:0.1, v/v/v/v). Linearity was obtained in the range of 4-40 microg/mL with mean accuracy of 99.5 +/- 0.88%. The second method was a densitometric evaluation of thin-layer chromatograms of the drug using a mobile phase of isopropanol-ammonia (33%)-n-hexane (9:0.5:20, v/v/v). The chromatograms were scanned at 232 nm, a wavelength at which RCT can be readily separated from its degradation products and determined in the range of 2-20 microg per spot with mean accuracy of 99.5 +/- 0.56%. The third method is based on the use of first-derivative spectrophotometry (D1) at 240 nm, and the drug was determined in the range of 5-40 microg/mL with mean accuracy of 99.2 +/- 1.02%. The three methods provided satisfactory recovery of the intact drug (100.8 +/- 0.82, 100.4 +/- 0.55, and 99.9 +/- 0.72%, respectively) in the presence of up to 90% of its degradation products. Determination was also successful when analyzing RCT in a formulation in the form of acetorphan packets. Results were statistically analyzed and found to be in accordance with those given by a reported method.