Abstract: PHARMACOLOGY crossm Effect of Systemic Inflammatory Response to SARS-CoV-2 on Lopinavir and Hydroxychloroquine Plasma Concentrations Catia Marzolini,a Felix Stader,a Marcel Stoeckle,a Fabian Franzeck,a,b Adrian Egli,c,d Stefano Bassetti,e Alexa Hollinger,f Michael Osthoff,e Maja Weisser,a Caroline E. Gebhard,f Veronika Baettig,a Julia Geenen,e Nina Khanna,a Sarah Tschudin-Sutter,a Daniel Mueller,g Hans H. Hirsch,a,h Manuel Battegay,a Parham Sendia,i a Division of Infectious Diseases & Hospital Hygiene, University Hospital Basel and University of Basel, Basel, Switzerland b Research and Analysis Services, University Hospital Basel and University of Basel, Basel, Switzerland c Division of Clinical Bacteriology and Mycology, University Hospital Basel, Basel, Switzerland d Applied Microbiology Research, Department of Biomedicine, University of Basel, Basel, Switzerland e Division of Internal Medicine and Department of Clinical Research, University Hospital Basel and University of Basel, Basel, Switzerland f Intensive Care Unit, University Hospital Basel, Basel, Switzerland g Institute of Clinical Chemistry, University Hospital Zurich, Zurich, Switzerland h Transplantation & Clinical Virology, Department of Biomedicine, University of Basel, Basel, Switzerland i Institute for Infectious Diseases, University of Bern, Bern, Switzerland Manuel Battegay and Parham Sendi contributed equally to this study. Coronavirus disease 2019 (COVID-19) leads to inflammatory cytokine release, which can downregulate the expression of metabolizing enzymes. This cascade affects drug concentrations in the plasma. We investigated the association between lopinavir (LPV) and hydroxychloroquine (HCQ) plasma concentrations and the levels of the acute-phase inflammation marker C-reactive protein (CRP). LPV plasma concentrations in 92 patients hospitalized at our institution were prospectively collected. Lopinavir-ritonavir was administered every 12 hours, 800/200 mg on day 1 and 400/100 mg on day 2 until day 5 or 7. HCQ was given at 800 mg, followed by 400 mg after 6, 24, and 48 h. Hematological, liver, kidney, and inflammation laboratory values were analyzed on the day of drug level determination. The median age of study participants was 59 (range, 24 to 85) years, and 71% were male. The median durations from symptom onset to hospitalization and treatment initiation were 7 days (interquartile range [IQR], 4 to 10) and 8 days (IQR, 5 to 10), respectively. The median LPV trough concentration on day 3 of treatment was 26.5 ␮g/ml (IQR, 18.9 to 31.5). LPV plasma concentrations positively correlated with CRP values (r ⫽ 0.37, P ⬍ 0.001) and were significantly lower when tocilizumab was preadministered. No correlation was found between HCQ concentrations and CRP values. High LPV plasma concentrations were observed in COVID-19 patients. The ratio of calculated unbound drug fraction to published SARS-CoV-2 50% effective concentrations (EC50) indicated insufficient LPV concentrations in the lung. CRP values significantly correlated with LPV but not HCQ plasma concentrations, implying inhibition of cytochrome P450 3A4 (CYP3A4) metabolism by inflammation. KEYWORDS COVID-19, lopinavir-ritonavir, levels, hydroxychloroquine, inflammation C linical trials have been launched to find effective treatment against the novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of the respiratory illness termed coronavirus disease 2019 (COVID-19)..