Chronic kidney disease (CKD) is a global health problem. Our study employed Raman spectroscopy for the first time to analyze potential biomarker such as tryptophan (Trp) on kidney failure and show the difference between normal and CKD groups. Adenine model of CKD characterized most of the physiological changes observed in human CKD. For that, 6‐week‐old Wistar male rats were assigned to the two groups: the control group, 0.5% carboxymethyl cellulose (CMC) was administered; the CKD group, adenine was administered to rats at a dose 600 mg/kg for 10 days. The Raman spectra were obtained in the spectral range of 100–2500 cm−1. The excitation source was 532 nm, the laser power was ~40 mW, and the analyzed tissue area was 10.02 × 82.12 μm2. The results showed a significant reduction in the case of Raman peak intensities at 748, 1359, 1554, and 1636 cm−1, which can be assigned as Trp. Moreover, it was shown that tyrosine at 1169 cm−1 and phenylalanine at 1001 cm−1 decreased in the CKD group. Trp and kynurenine (Kyn) levels in kidney tissue and plasma were analyzed by using the high‐performance liquid chromatography (HPLC). The Trp concentrations in plasma and kidney tissue significantly decreased in CKD 7.4 μg/ml and 0.1 μg/mg, respectively. However, Kyn level was not a statistically significant change in kidney tissue. In this work, we showed that Raman spectroscopy usage in CKD model and Raman spectroscopy can be considered a promising technique for semi‐quantitative analysis of potential biomarkers such as phenylalanine, tyrosine, and Trp of renal function because of the little or no need for sample preparation, and it is easily observing several biomarkers at the same time. The utilization of multivariate analysis method, such as partial least square analysis can be considered as a promising tool for the discrimination of control and CKD groups.

This study intends to develop an essential simultaneous analysis method for the stability study of the combination drugs hydrochlorothiazide, (S)-amlodipine besylate, and olmesartan medoxomil and identify degradation products. A stress test of the combination drug was performed under thermal/humidity conditions to identify decomposition products expected to be generated under long-term storage conditions. Six unidentified degradation products were generated from (S)-amlodipine besylate and olmesartan medoxomil, except for those identified.Unspecified degradation products were identified by degradation prediction software with LC-MS/MS, and genotoxicity was predicted by toxicity prediction software. In silico toxicity, six degradation products were expected to be nonmutagenic. This study describes the development of an analytical method to predict degradation products and determine whether the degradation products are genotoxic. This process will be helpful in further forced degradation studies to predict the toxicity of potential impurities.

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