Drug-drug Interactions in Kidney Transplant Patients with Coronavirus Disease 2019: A Report of Two Cases and Literature Review

On February 19, 2020, the first confirmed case of Coronavirus disease 2019, known as COVID-19, was identified in Iran. Afterward, the disease spread rapidly throughout the country. Some of the cases were asymptomatic, some had mild to severe symptoms, and some of them died. Transplant patients are highly at risk due to long-term immunosuppressive therapy, and precise treatment approaches are needed to not only cure the disease but also protect graft function. This study reports two kidney transplant patients with COVID-19 pneumonia, both of whom showed respiratory and gastrointestinal symptoms. High cyclosporine and tacrolimus trough levels were observed despite initial dose reduction. After a treatment program containing reduced immunosuppressant dose and the addition of pulsatile hydrocortisone, these patients recovered effectively. We also discuss the importance of drug-drug interactions related to COVID-19 treatment protocol medications, especially with immunosuppressants, in these patients. In conclusion, frequent monitoring of the trough levels of calcineurin and mammalian target of rapamycin inhibitors during hospitalization is recommended since it helps to determine the ideal treatment and prevent serious clinical toxicity.