Comparison of efficacy of roxadustat and erythropoietin for the treatment of renal anemia in patients with chronic kidney disease: a retrospective study

Hair and dietary supplements testing to identify contamination with roxadustat in an adverse analytical finding

Roxadustat is an oral inhibitor of hypoxia-inducible factor (HIF) prolyl hydroxylase, which increases endogenous erythropoiesis. WADA has included roxadustat and other HIF stabilizers on its list of prohibited substances. We describe here the case of an elite athlete (female, 31 years old, 168 cm and 53 kg) with an adverse analytical finding (AAF) with concentration of roxadustat in her urine at 0.289 ng/mL in the A sample and 0.529 ng/mL in the B sample (83% higher than A). A stability study was carried out, showing total stability of roxadustat at this concentration in urine exposed to light for 50 h, so photoisomerization degradation cannot explain the difference in concentration. Her urine had been completely negative in a control test carried out three days previously, while roxadustat had been shown to be present in urine for at least 20 days after administration of pharmacologically effective doses to an athlete. Hair concentration was 0.39 and 0.35 pg/mg in the segments corresponding to the presumed period of intake, with few adjacent segments also positive (0.29-0.33 pg/mg), likely explained by cosmetic treatments. Concentrations found in a patient treated with a pharmacologically active dose (between 100 and 120 mg 3 days a week) were more than 100 times higher (between 41 and 57 pg/mg). Numerous supplements and pharmaceuticals taken by the athlete were analyzed. Only collagen powder showed the presence of roxadustat, at a very low but highly variable concentration (100 pg/g-1000 pg/g). A female volunteer (58 years old, 169 cm and 65 kg), taking this powder at the same doses as the athlete (10 g of powder 5 times for 6 days) presented 7 roxadustat-positive urine samples (although lower than those observed in the athlete) out of 34 sampled over 7 days, the difference in powder sampling location, age, weight, height, pharmacokinetic parameters variability and level of sporting activity between the athlete and the volunteer probably explaining the difference in concentrations observed. All these results could be consistent with an AAF due to contamination by dietary supplements, which are becoming increasingly common due to the current exposome of athletes in our society.

First detection/quantification of roxadustat in hair with a new liquid chromatography with tandem mass spectrometry method: application to a treated patient

Roxadustat is an oral inhibitor of hypoxia-inducible factor prolyl hydroxylase which increases erythropoiesis. It can therefore be used as a doping agent. No data are available on how to measure roxadustat in hair and on the concentration found in treated patients. The aim of this study was to develop a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification of roxadustat in hair and to apply it to a chronically treated patient. After decontamination with dichloromethane, testosterone-D3 used as an internal standard and phosphate buffer pH 5.0 were added to 20 mg of hair and incubated for 10 min at 95°C. Four ml of dichloromethane were used for extraction and reconstituted into the mobile phase, 10 µl were injected into the chromatographic system. The method was linear in the range 0.5-200 pg/mg, accurate and precise (evaluated at 3 levels) and was successfully applied to measure roxadustat in a brown-haired patient treated pharmacologically with 100-120 mg 3 days a week. Results were stable between 41 and 57 pg/mg in the 6 proximal 1 cm segments. This first method describing the measurement of roxadustat in hair appears to be suitable for the quantification of this compound in clinical or doping control cases.

Correlation between blood concentration of roxadustat and clinical efficacy in patients with anemia of chronic kidney disease

Roxadustat has been associated with the efficacy and safety in patients with chronic kidney disease-related anemia. However, the relationship between roxadustat blood concentration and clinical efficacy is lacking. To explore of the correlation between clinical efficacy and blood concentration of roxadustat in patients with renal anemia of chronic kidney diseases, so as to provide reference for rational clinical drug use. A total of 46 patients were selected with a diagnosis of renal anemia who were prescribed roxadustat at the department of nephrology of the First Hospital of Hebei Medical University from December 2019 to March 2020. The roxadustat blood concentration was determined at 12 weeks of treatment, according to the cumulative response rate, patients were divided into the response group and the nonresponse group, and the relationship between roxadustat blood concentration and treatment effect was analyzed. We also explored the correlation between various factors and the blood concentration. The patients in the response group had higher roxadustat blood concentrations than the nonresponse group (P < .05), and there was no correlation between blood concentration and clinical characteristics such as age, gender, and dosage (P > .05). The blood concentration of roxadustat was correlated with clinical efficacy. The higher the blood concentration, the better the clinical efficacy, meaning it might be a predictor of efficacy.