Sonlicromanol in Post-COVID

Inclusion Criteria: * Post COVID according to WHO criteria and verified by post COVID physician * Post-exertional malaise (PEM) according to DSQ-PEM questionnaire * Bell's disability score 20-70% * Mild initial SARS-CoV-2 infection (no hospitalisation) * WHO performance score of 0 before initial SARS-CoV-2 infection Exclusion Criteria: * Patients at risk for cardiac conduction disorders * History of clinical significant gastro-intestinal surgery or dysmotility that impairs the adsorption of the IMP * Clinically significant respiratory or cardiovascular disease * Unstable neurological disease * Clinically significant active psychiatric disorder that requires treatment * History of substance abuse * Active malignancy within the past 5 years * History of solid organ transplantation * Active HIV, hepatitis B or C infection * BMI \< 18.5 or \> 35 * Pregnancy or breastfeeding * Clinically relevant laboratory test value outside the reference range * Use of the following medication, unless stable for at least one month before study and remaining stable throughout the study: (multi)vitamins, co-enzyme Q10, Vitamin E, riboflavin, amino acids, antioxidant supplements and any medication negatively influencing mitochondrial functioning (including but not limited to valproic acid, glitazones, statins, antivirals, amiodarone and NSAIDs) * Use of the following medication: any moderate or strong Cytochrome P450 (CYP)3A4 inhibitors (all 'conazoles-anti-fungals', HIV antivirals, grapefruit), strong CYP3A4 inducers ((including HIV antivirals, carbamazepine, phenobarbital, phenytoin, rifampicin, St. John's wort, pioglitazone, troglitazone) or any medication metabolized by CYP3A4 with a narrow therapeutic index, medication known to be substrate of Organic Cation Transporter 1 (OCT1) and organic cation transporter 2 (OCT2) or strong P-glycoprotein inhibitors (including amiodarone, azithromycin, captopril, clarithromycin, cyclosporine, piperine, quercetin, quinidine, quinine, reserpine, ritonavir, tariquidar, and verapamil). * Use of any medication known to affect cardiac repolarization unless QTc interval at screening is normal during stable treatment for a period of two weeks, or 5 half-lives