Tacrolimus toxicity due to enzyme inhibition from ritonavir.

Tacrolimus is commonly used for immunosuppression in patients following solid organ transplantation. For transplant patients with COVID-19 infection, early treatment is indicated due to the risk of progression to severe disease. However, the first line agent, nirmatrelvir/ritonavir, has multiple drug-drug interactions. We report a case of tacrolimus toxicity in a patient with a history of renal transplant due to enzyme inhibition related to nirmatrelvir/ritonavir. An 85-year-old woman with a history of multiple comorbidities presented to the emergency department (ED) with weakness, increasing confusion, poor oral intake, and inability to walk. She had been recently diagnosed with COVID-19 infection and was prescribed nirmatrelvir/ritonavir due to her underlying comorbidities and immune suppression. In the ED, she was dehydrated and had an acute kidney injury (creatinine 2.1 mg/dL, up from a baseline of 0.8 mg/dL). The tacrolimus concentration on initial labs was 143 ng/mL (5-20 ng/mL) and it continued to rise despite being held, to a peak of 189 ng/mL on hospital day 3. The patient was treated with phenytoin for enzyme induction and the tacrolimus concentration began to fall. She was discharged to a rehabilitation facility after a 17 day hospitalization. ED physicians must be cognizant of drug-drug interactions when prescribing nirmatrelvir/ritonavir and evaluating patients recently treated with the drug to identify toxicity due to these interactions.

A multicentre, patient- and assessor-blinded, non-inferiority, randomised and controlled phase II trial to compare standard and torque teno virus-guided immunosuppression in kidney transplant recipients in the first year after transplantation: TTVguideIT.

BACKGROUND: Immunosuppression after kidney transplantation is mainly guided via plasma tacrolimus trough level, which cannot sufficiently predict allograft rejection and infection. The plasma load of the non-pathogenic and highly prevalent torque teno virus (TTV) is associated with the immunosuppression of its host. Non-interventional studies suggest the use of TTV load to predict allograft rejection and infection. The primary objective of the current trial is to demonstrate the safety, tolerability and preliminary efficacy of TTV-guided immunosuppression. METHODS: For this purpose, a randomised, controlled, interventional, two-arm, non-inferiority, patient- and assessor-blinded, investigator-driven phase II trial was designed. A total of 260 stable, low-immunological-risk adult recipients of a kidney graft with tacrolimus-based immunosuppression and TTV infection after month 3 post-transplantation will be recruited in 13 academic centres in six European countries. Subjects will be randomised in a 1:1 ratio (allocation concealment) to receive tacrolimus either guided by TTV load or according to the local centre standard for 9 months. The primary composite endpoint includes the occurrence of infections, biopsy-proven allograft rejection, graft loss, or death. The main secondary endpoints include estimated glomerular filtration rate, graft rejection detected by protocol biopsy at month 12 post-transplantation (including molecular microscopy), development of de novo donor-specific antibodies, health-related quality of life, and drug adherence. In parallel, a comprehensive biobank will be established including plasma, serum, urine and whole blood. The date of the first enrolment was August 2022 and the planned end is April 2025. DISCUSSION: The assessment of individual kidney transplant recipient immune function might enable clinicians to personalise immunosuppression, thereby reducing infection and rejection. Moreover, the trial might act as a proof of principle for TTV-guided immunosuppression and thus pave the way for broader clinical applications, including as guidance for immune modulators or disease-modifying agents. TRIAL REGISTRATION: EU CT-Number: 2022-500024-30-00.

Favipiravir therapy for Covid-19 infection and tacrolimus toxicity in a kidney transplant patient on chronic eculizumab therapy.

Although the latest data show that complement activation has an essential role in the pathogenesis and severity of Covid-19, the data on the prognosis of patients using complement inhibitors during Covid-19 infection are scarce. There is no specific treatment for Covid-19 yet. The introduction of novel agents such as favipiravir may affect metabolism of immunosuppressive drugs. We report the clinical course of Covid-19 in a kidney transplant patient with atypical haemolytic uraemic syndrome on chronic eculizumab therapy. The patient had mild Covid-19 but had severe tacrolimus toxicity, which may be associated with favipiravir and eculizumab. The mild course of Covid-19 in our patient is encouraging for eculizumab use; on the other hand, unusually high levels of tacrolimus that we observed underlines the importance of frequent drug level monitoring in transplanted patients who are receiving new drugs.

Drug-drug interactions of ritonavir-boosted SARS-CoV-2 protease inhibitors in solid organ transplant recipients: experience from the initial use of lopinavir-ritonavir.

OBJECTIVES: To review the drug-drug interactions between tacrolimus and lopinavir/ritonavir in 23 patients who received solid organ transplant during the first wave of COVID-19 and to determine the efficacy as well as safety of prednisone monotherapy. METHODS: Observational study performed between March and June 2020 in solid organ transplant recipients admitted with an established diagnosis of SARS-CoV-2 infection who received lopinavir/ritonavir (≥2 doses). Once lopinavir/ritonavir therapy was initiated, calcineurin inhibitor treatment was temporarily switched to prednisone monotherapy (15-20 mg/d) to avoid drug-drug interactions and toxicity. After lopinavir/ritonavir treatment completion, immunosuppressive treatment was restarted with reduced doses of prednisone-tacrolimus (target minimum blood concentration -C0- approximately 5 ng/mL). Patients were observed for 3 months to confirm the absence of rejection. RESULTS: The median time from discontinuation of tacrolimus to initiation of lopinavir/ritonavir was 14 hours (interquartile range [IQR], 12-15) and from discontinuation of lopinavir/ritonavir to resumption of tacrolimus 58 hours (IQR, 47-81). The duration of lopinavir/ritonavir treatment was 7 days (IQR, 5-7). Nine of the 21 (42.8%) patients on tacrolimus treatment had C0 above the cutoff point after lopinavir/ritonavir initiation, despite having been substituted with prednisone before lopinavir/ritonavir initiation. Three patients had very high concentrations (>40 ng/mL) and developed toxicity. No episodes of acute rejection were diagnosed. DISCUSSION: We did not observe toxicity in patients for whom tacrolimus was discontinued 24 hours before starting lopinavir/ritonavir and reintroduced at half dose 48 to 72 hours after lopinavir/ritonavir discontinuation. Prednisone monotherapy during lopinavir/ritonavir therapy was safe with no episodes of acute rejection. Experience with lopinavir/ritonavir may be applicable to the use of nirmatrelvir/ritonavir, but larger multicentre studies are needed to confirm these findings.

Preliminary Clinical Experience of Molnupiravir to Prevent Progression of COVID-19 in Kidney Transplant Recipients.

BACKGROUND: Recently, different therapeutic lines have been tried in the initial stage of the disease of COVID-19, including remdesivir and molnupiravir. There is scarce evidence on the efficacy and safety of molnupiravir in kidney transplant recipients (KTRs). METHODS: ingle-center prospective cohort study' all adult KTRs diagnosed with COVID-19 and treated with molnupiravir or remdesivir from January to April 2022 were included. RESULTS: Nine KTRs with SARS-CoV-2 (Omicron variant) infection and mild symptoms received molnupiravir in an outpatient basis and were compared with a cohort of similar patients treated with remdesivir (n = 7). Three patients in the molnupiravir cohort were in the early posttransplant period and received a basiliximab (n = 2) or antithymocite globulin-based induction (n = 1). One of the patients had been treated with methylprednisolone bolus and antithymocite globulin for an episode of acute rejection in the previous months. They were all vaccinated with mRNA vaccines' and all but 1 had serological response. Only one of the patients experienced clinical worsening despite molnupiravir treatment and developed pneumonia requiring hospital admission. None of the patients suffered adverse effects attributed to molnupiravir' and no adjustment of tacrolimus dose was needed. None of the patients treated with remdesivir progressed in COVID-19 severity. CONCLUSIONS: Our study suggests that KTRs with SARS-CoV-2 infection under treatment with molnupiravir have a good clinical evolution with a probable lower risk for hospitalization and no adverse effects. At the renal level, molnupiravir was well tolerated, with no evidence of nephrotoxicity secondary to the drug nor interactions with the immunosuppressive therapy.

Increased Tacrolimus Exposure in Kidney Transplant Recipients With COVID-19: Inflammation-Driven Downregulation of Metabolism as a Potential Mechanism.

Kidney transplant recipients (KTRs) are at increased risk of severe COVID-19 disease compared to the general population. This is partly driven by their use of immunosuppressive therapy, which influences inflammatory responses and viral loads. Current guidelines suggest to withdraw mycophenolate while calcineurin inhibitors are often continued during a COVID-19 infection. However, clinical signs of calcineurin toxicity have been described in multiple COVID-19 positive KTRs. In this report we describe the course of tacrolimus exposure prior to, during, and post COVID-19 in observations from three clinical cases as well as four KTRs from a controlled trial population. We postulate inflammation driven downregulation of the CYP3A metabolism as a potential mechanism for higher tacrolimus exposure. To mitigate the risk of tacrolimus overexposure and toxicity therapeutic drug monitoring is recommended in KTRs with COVID-19 both in the in-, out-patient and home monitoring setting.

Paxlovid (Nirmatelvir/Ritonavir) and Tacrolimus Drug-Drug Interaction in a Kidney Transplant Patient with SARS-2-CoV infection: A Case Report.

The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has had a significant impact on communities and health systems. New antiviral medications against this disease have not been properly tested yet, and their efficiency, side effects, and drug-drug interactions are not entirely known. Organ transplant recipients receive immunosuppressive medications such as tacrolimus to prevent graft rejection. Tacrolimus is metabolized by the cytochrome P450 3A4 enzyme system. Many medications can either induce or inhibit this enzyme and affect the level. Awareness of possible drug-drug interactions is vital because tacrolimus levels should be kept within a specific narrow range determined by the recipient's immunologic risk. Underexposure increases the risk of graft rejection, whereas overexposure may lead to adverse effects. Paxlovid, a novel antiviral medication approved for emergency use to treat SARS-CoV-2, is a combination of nirmatrelvir and ritonavir, a cytochrome P450 34A inhibitor. In this case report, we present a case of a kidney transplant patient receiving tacrolimus treated with Paxlovid, leading to an abruptly high tacrolimus level, significant symptoms, treatment interruption, and acute kidney injury. We conclude that the drug-drug interaction between Paxlovid and tacrolimus is indeed robust and noteworthy and leads to high tacrolimus levels and its metabolites, adverse effects, and acute kidney injury. Physicians managing immunocompromised patients receiving tacrolimus should be aware of this significant drug-drug interaction and consider other options or reduction of daily tacrolimus dose during treatment in addition to timely monitoring of both tacrolimus levels and serum creatinine. Consulting with the transplant pharmacist is foremost in alerting for these interactions.

Undetectable triglycerides related to the combined intake of ascorbic acid and tacrolimus.

Management of triglyceride (TG) levels is essential in intensive care units (ICU), especially to manage the risk of pancreatitis induced by propofol. However, some therapeutics in ICU such as intravenous ascorbic acid protocol, especially used in the context of Covid-19 could lead to false decrease of triglycerides by analytical disruption of Trinder reaction. We report here the case of a sample with unmeasurable triglyceride levels partly due to high plasma ascorbic acid levels. However, repeated measure on the same sample four days later revealed that interference mechanism on TG was still present whereas the level of ascorbic acid was very reduced by oxidation degradation. Hence, additional interference mechanism was suspected. After clinical investigation, we found that the patient had also received high doses of tacrolimus due to a transplant. As previous studies reported that tacrolimus treatment lead to a decrease of the measured plasma activity of lipoprotein lipase (LPL), we hypothesized that tacrolimus or related metabolites could also interfere by direct inhibition of LPL involved in TG analytical method used.

Kinetics of torquetenovirus DNA load in a recent kidney transplant recipient with mild SARS-CoV-2 infection and a failed antibody response.

Kidney transplant (KT) recipients are at an increased risk for severe COVID-19 because of their immunosuppressed state. A 42-year-old KT patient was diagnosed with COVID-19 three months after KT. Despite lymphopenia and several risk factors, he had a mild disease course. Nasopharyngeal real-time reverse transcriptase polymerase chain reaction for SARS-CoV-2 became negative 48 days after detection. SARS-CoV-2 IgG antibodies became negative after day 40. TTV DNA load increased with the onset COVID-19 and reduced after its resolution. This is the first report where TTV DNA load was measured during the course of COVID-19.

Invasive pulmonary aspergillosis associated with COVID-19 in a kidney transplant recipient.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) might increase the risk of invasive pulmonary aspergillosis (IPA). Although several case reports and small series have been reported in the general population, scarce information is available regarding coronavirus disease 2019 (COVID-19)-associated IPA in the setting of solid organ transplantation. We describe a case of a kidney transplant recipient with severe COVID-19 that was subsequently diagnosed with probable IPA on the basis of the repeated isolation of Aspergillus fumigatus in sputum cultures, repeatedly increased serum (1 â†’ 3)-ß-d-glucan levels, and enlarging cavitary nodules in the CT scan. The evolution was favorable after initiation of isavuconazole and nebulized liposomal amphotericin B combination therapy and the withdrawal of immunosuppression.