key: cord-0712131-us1p0aht authors: Martens-Lobenhoffer, Jens; Bode-Böger, Stefanie M title: Mixed experiences with commercial calibrators and controls for COVID-19 drugs date: 2021-10-11 journal: J Appl Lab Med DOI: 10.1093/jalm/jfab130 sha: 1aa5903b3f9316c6c023181b6dfb4caf526ff5a4 doc_id: 712131 cord_uid: us1p0aht nan To the Editor: 23 24 In the midst of the pandemic caused by the new coronavirus SARS-CoV-2, medical 25 scientists and practitioners are scrambling to develop and test effective therapies 26 against the corresponding disease (COVID-19). Two of the experimental therapies 27 include the administration of the repurposed drugs hydroxychloroquine (Plaquenil®, 28 Sanofi-Aventis, France) (1) and remdesivir (Veklury®, Gilead Sciences Inc., USA) (2) . min. Extraction yields were 89.4%, 86.1% and 88.2% for remdesivir, GS-441524 and the 54 internal standard, and matrix effects were 11.3%, -1,7% and -3.0%, respectively. Calibration functions in these methods were linear in ranges of 50 -2000 ng/mL for 56 hydroxychloroquine and 25 -2500 ng/mL for remdesivir and GS-441524, respectively. 57 We achieved precision and accuracy levels at the lower limit of quantification of 1.25% 58 relative standard deviation and 5.39% deviation from the expected concentration for Table 1 . As can be seen, the measured values for hydroxychloroquine were near the expected 73 values within less than 8% difference. Furthermore, all differences pointed in the same 74 direction, implying a minor calibration offset between our in-house produced calibration Efficacy of chloroquine and hydroxychloroquine in the treatment of COVID-19 A Review on Remdesivir: A Possible Promising Agent for the Treatment of COVID-19 The Dilemma of Renal Involvement in COVID-19: A Systematic Review Clearance of chloroquine and hydroxychloroquine by the Seraph® 100 Microbind® Affinity blood filter -approved for the treatment of COVID-19 patients Quantification of plasma remdesivir and its metabolite GS-441524 using liquid chromatography coupled to tandem mass spectrometry. Application to a Covid-19 treated patient No authors declared any potential conflicts of interest.