COVID-19 infection in a kidney transplant recipient—special emphasis on pharmacokinetic interactions: A case report

BACKGROUND: Solid organ transplant recipients are considered to be at high-risk of developing coronavirus disease 2019 (COVID-19)-related complications. The optimal treatment for this patient group is unknown. Consequently, the treatment of COVID-19 in kidney transplant recipients should be determined individually, considering patient age and comorbidities, as well as graft function, time of transplant, and immunosuppressive treatment. Immunosuppressive treatments may give rise to severe COVID-19. On the contrary, they may also lead to a milder and atypical presentation by diminishing the immune system overdrive. CASE SUMMARY: A 50-year old female kidney transplant recipient presented to the transplant clinic with a progressive dry cough and fever that started three days ago. Although the COVID-19 test was found to be negative, chest computed tomography images showed consolidation typical of the disease; thus, following hospital admission, anti-bacterial and COVID-19 treatments were initiated. However, despite clinical improvement of the lung consolidation, her creatinine levels continued to increase. Ultrasound of the graft showed no pathology. The tacrolimus blood level was determined and the elevation in creatinine was found to be related to an interaction between tacrolimus and azithromycin. CONCLUSION: During the COVID-19 pandemic, various single or combination drugs have been utilized to find an effective treatment regimen. This has increased the possibility of drug interactions. A limited number of studies published in the literature have highlighted some of these pharmacokinetic interactions. Treatments used for COVID-19 therapy; azithromycin, atazanavir, lopinavir/ritonavir, remdesivir, favipiravir, chloroquine, hydroxychloroquine, nitazoxanide, ribavirin, and tocilizumab, interact with immunosuppressive treatments, most importantly with calcineurin inhibitors. Thus, their levels should be frequently monitored to prevent toxicity.