Background: COVID-19 is a novel infectious disease caused by the severe acute respiratory distress (SARS)-coronavirus-2 (SARSCoV-2). Several therapeutic options are currently emerging but none with universal consensus or proven efficacy. Solid organ transplant recipients are perceived to be at increased risk of severe COVID-19 because of their immunosuppressed conditions due to chronic use of immunosuppressive drugs (ISDs). It is therefore likely that solid organ transplant recipients will be treated with these experimental antivirals. Methods: This article is not intended to provide a systematic literature review on investigational treatments tested against COVID-19; rather, the authors aim to provide recommendations for therapeutic drug monitoring of ISDs in transplant recipients infected with SARS-CoV-2 based on a review of existing data in the literature. Results: Management of drug–drug interactions between investigational anti-SARS-CoV-2 drugs and immunosuppressants is a complex task for the clinician. Adequate immunosuppression is necessary to prevent graft rejection while, if critically ill, the patient may benefit from pharmacotherapeutic interventions directed at limiting SARSCoV-2 viral replication. Maintaining ISD concentrations within the desired therapeutic range requires a highly individualized approach that is complicated by the pandemic context and lack of hindsight. Conclusions: With this article, the authors inform the clinician about the potential interactions of experimental COVID-19 treatments with ISDs used in transplantation. Recommendations regarding therapeutic drug monitoring and dose adjustments in the context of COVID-19 are provided.

COVID-19, SARS-CoV-2, drug interactions, transplant patients, therapeutic drug monitoring, experimental treatments, calcineurin inhibitors, mammalian target of rapamycin inhibitors, mycophenolic acid, tacrolimus, cyclosporin, sirolimus, everolimus, recommendations, immunocompromised, hydroxychloroquine, chloroquine, remdesivir, protease inhibitors, lopinavir, tocilizumab,
Therapeutic Drug Monitoring
Department of Clinical Chemistry

Elens, L, Langman, LJ, Hesselink, D.A, Bergan, S, Moes, D., Molinaro, M., … Lemâitre, F. (2020). Pharmacologic Treatment of Transplant Recipients Infected With SARS-CoV-2: Considerations Regarding Therapeutic Drug Monitoring and Drug-Drug Interactions. Therapeutic Drug Monitoring, 42(3), 360–368. doi:10.1097/ftd.0000000000000761