Pharmacokinetics and dose recommendations for cyclosporine and tacrolimus when coadministered with ABT-450, ombitasvir, and dasabuvir

Toward Analytical Performance Specifications for Immunosuppressive Drug Quantification in Transplantation: An Opinion Article

BACKGROUND

Analytical methods require performance that meets the clinical needs. Different approaches for setting up permissible analytical imprecision goals (pCVA%) for drug analyses have been reported. The aim of this study was to calculate the pCVA% for cyclosporine, tacrolimus, everolimus, sirolimus, and mycophenolic acid using 4 alternative approaches, to compare the results and to critically discuss advantages and disadvantages of each model.

METHODS

The approaches to evaluate pCVA% were (A) based on biological variation observed in routine measurement results between 2022 and 2023 in the authors' laboratory, (B) derived from the terminal elimination half-life and dosing interval of the drugs, and (C and D) explored from the width of the therapeutic ranges (TR) by the 2 methods. For approach A, routine measurement data for cyclosporine and tacrolimus, obtained through liquid chromatography-tandem mass spectrometry and electrochemiluminescence immunoassays, were evaluated separately.

RESULTS

The 4 alternative approaches for deriving pCVA% yielded similar results, for cyclosporine and tacrolimus in an analytical method dependent manner. The average pCVA% was 5.2%, 5.6%, 5.1%, 4.8%, and 7.7% for cyclosporine, tacrolimus, everolimus, sirolimus, and mycophenolic acid, respectively. The most challenging goals were those using TR-related approaches, while those using the biological variation approach were most easily achievable. Approach B resulted in more stringent goals for drugs with longer elimination half-lives (eg, everolimus and sirolimus).

CONCLUSIONS

There is no single ideal approach for setting goals of drug analysis. However, the pCVA% values derived from the various approaches are similar and confirm that a <6% target proposed by the International Association of Therapeutic Drug Monitoring and Clinical Toxicology is adequate and realistic in combination with state-of-the-art measurement technologies. In the authors' opinion, approaches based on the width of the TR are preferable, as they represent a common basis for clinical decisions and reflect elements of biological variation and analytics used to establish the TR.

Case report and literature review: management of Paxlovid (nirmatrelvir/ritonavir)-induced acute tacrolimus toxicity in a patient with systemic lupus erythematosus

Despite the availability of effective vaccines and treatments for SARS-CoV-2, managing COVID-19 in patients with systemic lupus erythematosus (SLE) remains challenging, particularly considering drug-drug interactions (DDIs). Here, we present a case of DDIs between Tacrolimus (Tac) and nirmatrelvir/ritonavir (NMV/r) in a 32-year-old male with SLE. Following self-administration of NMV/r and resumption of Tac after 5 days, the patient experienced acute nephrotoxicity and neurotoxicity, accompanied by supratherapeutic Tac levels, despite Tac being withheld during NMV/r. The primary cause of this acute toxicity is attributed to ritonavir's inhibitory effect on both CYP3A4 enzymes and P-glycoprotein. Upon admission, Tac was discontinued, and supportive therapies were initiated. Phenytoin, a CYP3A4 inducer, was administered to lower Tac levels under the guidance of clinical pharmacists, effectively alleviating the patient's acute toxic symptoms. The half-life of Tac during the treatment of phenytoin was calculated to be 55.87 h. And no adverse reactions to phenytoin were observed. This case underscores the persistence of enzyme inhibition effects and demonstrates the effectiveness and safety of utilizing CYP3A4 enzyme inducers to mitigate Tac concentrations. Furthermore, it emphasizes the importance of healthcare providers and patients being vigilant about DDIs in Tac recipients. Lastly, it highlights the indispensable role of pharmacist involvement in clinical decision-making and close monitoring in complex clinical scenarios. Although our findings are based on a single case, they align with current knowledge and suggest the potential of individualized combination therapy in managing challenging COVID-19 cases in immunocompromised patients.

Case report: Paralytic ileus resulted from nirmatrelvir/ritonavir-tacrolimus drug-drug interaction in a systemic lupus erythematosus patient with COVID-19

Patients with systemic autoimmune rheumatic diseases are at a high risk for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and effective antiviral treatments including nirmatrelvir/ritonavir can improve their outcomes. However, there might be potential drug-drug interactions when these patients take nirmatrelvir/ritonavir together with immunosuppressants with a narrow therapeutic window, such as tacrolimus and cyclosporine. We present a case of paralytic ileus resulting from tacrolimus toxicity mediated by the use of nirmatrelvir/ritonavir in a patient with systemic lupus erythematosus (SLE). A 37-year-old female SLE patient was prescribed nirmatrelvir/ritonavir without discontinuing tacrolimus. She presented to the emergency room with symptoms of paralytic ileus including persistent abdominal pain, nausea, and vomiting, which were verified to be associated with tacrolimus toxicity. The blood concentration of tacrolimus was measured >30 ng/mL. Urgent medical intervention was initiated, while tacrolimus was withheld. The residual concentration was brought within the appropriate range and tacrolimus was resumed 8 days later. Physicians must be aware of the potential DDIs when prescribing nirmatrelvir/ritonavir, especially to those taking immunosuppresants like tacrolimus.

Effectiveness and safety of nirmatrelvir-ritonavir in kidney transplant recipients with severe kidney dysfunction infected with COVID-19

Transplant patients face an elevated risk of coronavirus disease 2019 (COVID-19) morbidity and mortality and commonly encounter renal dysfunction. Nirmatrelvir is primarily excreted through the kidneys. The dosage of nirmatrelvir/ritonavir (NR) needs to be adjusted according to the degree of renal function impairment. Nevertheless, NR is not recommended for patients with severe renal impairment (estimated glomerular filtration rate < 30 mL/min) due to a dearth of associated research. In this study, we focus on kidney transplant patients and document and analyze the experiences of using NR in individuals with severe kidney dysfunction. This was a retrospective multicenter study that included transplant recipients hospitalized for COVID-19 in five major tertiary hospitals in China from December 2022 to June 2023. The outcomes consisted of the disease progression rate by day 28, individual disease progression events, safety outcomes, information on adverse events (AEs), and the blood drug concentrations of immunosuppressants. Data were presented with descriptive statistics. All analyses were performed using SPSS version 22. In total, 40 patients were included in the analysis. Considering the potential interaction between drugs, all patients temporarily discontinued their immunosuppressants during the NR treatment. None of the 32 moderate patients experienced disease progression. However, among the eight patients with critical COVID-19, unfortunately, two of them died. During the medication period, four patients experienced a total of six AEs associated with NR. None of them experienced AEs with a maximum grade of ≥3. Blood drug concentrations of immunosuppressants were monitored in 22 of 40 patients, and the blood drug concentrations of immunosuppressants did not show a significant increase, but some patients experienced lower blood drug concentrations. Our findings supported the use of NR therapy for the treatment of COVID-19 in transplant patients with severe renal insufficiency. A modified dose of NR was well-tolerated.

The effects of nirmatrelvir/ritonavir on tacrolimus levels in lung transplant recipients: A single-center study

BACKGROUND

Lung transplant recipients (LTRs) have a higher risk of hospitalization and mortality due to COVID-19 compared with the immunocompetent population. The use of nirmatrelvir/ritonavir (NR), an effective oral treatment for COVID-19, is quite challenging due to its potent drug-drug interactions with immunosuppressants and azole antifungals. As there are few clinical reports of the use of NR in LTRs, we measured tacrolimus levels in patients receiving NR in our hospital to improve safety when prescribing NR.

METHODS

In total, 48 adult LTRs who received NR between November 19, 2022, and January 19, 2023, at China-Japan Friendship Hospital were retrospectively included and followed for 20 days after initiating NR. Tacrolimus was held at least 12 h before initiating NR and re-administered based on the trough levels after completing NR treatment. All concomitant medications, drug concentrations, laboratory results, and genotypes were recorded and analyzed.

RESULTS

Most patients showed stable tacrolimus trough levels despite high individual variability. Four patients exhibited supratherapeutic trough levels of tacrolimus (more than 15 ng/mL). Two patients who received 0.5 mg of tacrolimus during NR treatment had trough levels below 3.0 ng/mL. In addition, we found that in 13 patients, the trough levels were 130% of baseline after cessation of tacrolimus, and logistic regression revealed that increased trough level was significantly associated with age more than 60 years.

CONCLUSIONS

NR can be safely used in LTRs with close monitoring of tacrolimus levels and appropriate dose adjustments. However, more attention should be paid to elderly patients, as NR may more severely affect their drug metabolism. Due to the limited sample size, further studies are needed to guide the optimal use of tacrolimus following treatment with NR and explore the risk factors significantly affecting the interactions between NR and tacrolimus.

Drug Interaction Between Tacrolimus and Paxlovid (Nirmatrelvir/Ritonavir) in an Adolescent with Inflammatory Bowel Disease

The coronavirus disease of 2019 (COVID-19) led to a worldwide pandemic. The emergency use of a combination of nirmatrelvir/ritonavir (paxlovid) was approved for high-risk individuals (such as immunocompromised) testing positive for the disease. We present a patient with ulcerative colitis being treated with tacrolimus, as well as ustekinumab, who was diagnosed with COVID-19 and placed on paxlovid due to her immunosuppressed state. She stopped her tacrolimus while on paxlovid and did well clinically. Tacrolimus was restarted 12 hours after completion of paxlovid, but she became symptomatic with vomiting, headache, and malaise and was found to have a toxic tacrolimus level. Tacrolimus was stopped and symptoms resolved, but levels remained elevated for a prolonged period. There is a paucity of literature on this drug-drug interaction, and with the resurgence of COVID-19, it is important to be cognizant of the potential for adverse effects and toxicity.

Management of COVID-19 Infection in a Small Bowel Transplant Recipient: A Case Report

The COVID-19 pandemic has caused millions of people to become infected worldwide. Some patients may have disease progression and may need treatment with an anti-COVID-19 agent, hospitalization, and even intensive care. The risk factors for disease progression include old age, diabetes mellitus, pulmonary disease, cardiac disease, immunodeficiency, and immunosuppressant treatment. Therefore, managing COVID-19 infection in transplant patients under immunosuppressant treatments needs specific consideration, especially the side effects of anti-COVID-19 agents and the interaction between immunosuppressants and anti-COVID-19 agents. In this report, we present the case of a small bowel transplant patient who had a COVID-19 infection. The patient was initially treated for paxlovid, and she developed bloody stools and dizziness. The treatment was then changed to molnupiravir without discontinuation of tacrolimus. The patient recovered smoothly after a 5-day treatment with molnupiravir. Here, we discuss the management experience of such patients and review the relevant literature.

Drug-drug interaction of Nirmatrelvir/ritonavir and tacrolimus: A potential risk disproportionality analysis of nephrotoxicity from COVID-19 reports in FAERS

BACKGROUND

Nirmatrelvir/ritonavir is a new oral antiviral agent for COVID-19, and tacrolimus is a widely used immunosuppressant. Drug-drug interaction between Nirmatrelvir/ritonavir and tacrolimus is expected. However, information regarding the drug-drug interaction in a real-world setting is limited. We aim to evaluate drug-drug interaction between tacrolimus and Nirmatrelvir/ritonavir and perform a disproportionality analysis to assess the potential risk of nephrotoxicity due to their combination for COVID-19 treatment based on the FAERS database.

RESEARCH DESIGN AND METHODS

Disproportionality analysis was performed using the reporting odds ratio (ROR) method, and subset analysis was conducted based on the background of COVID-19 drugs combined with tacrolimus more than 10 times.

RESULTS

In disproportionality analysis, combination of Nirmatrelvir/ritonavir and tacrolimus was significantly associated with acute kidney injury (41.13%), serum creatinine increased (14.18%), renal failure (2.84%), and renal impairment (2.84%). These positive signals of acute kidney injury and serum creatinine increased still strongly retained in subset analysis. No similar positive signals were detected in Nirmatrelvir/ritonavir-single group. Only in Cilgavimab/Tixagevimab-tacrolimus group and Remdesivir-tacrolimus group, acute kidney injury was recognized as weakly positive signals and disappeared in subset analysis.

CONCLUSIONS

The study results show significant drug-drug interaction between Nirmatrelvir/ritonavir and tacrolimus and confirm that their combination for COVID-19 treatment greatly increases risk of acute kidney injury.

Switch from a ritonavir to a cobicistat containing antiretroviral regimen and impact on tacrolimus levels in a kidney transplant recipient

BACKGROUND

Solid-organ transplantation due to end-stage organ disease is increasingly performed in people living with HIV. Despite improved transplant outcomes, management of these patients remains challenging due to higher risk for allograft rejection, infection and drug-drug interactions (DDIs). Complex regimens for multi-drug resistant HIV-viruses may cause DDIs particularly if the regimen contains drugs such as ritonavir or cobicistat.

CASE PRESENTATION

Here we report on a case of an HIV-infected renal transplant recipient on long-term immunosuppressive therapy with mycophenolate mofetil and tacrolimus dosed at 0.5 mg every 11 days due to the co-administration of a darunavir/ritonavir containing antiretroviral regimen. In the presented case the pharmacokinetic booster was switched from ritonavir to cobicistat for treatment simplification. A close monitoring of tacrolimus drug levels was performed in order to prevent possible sub- or supratherapeutic tacrolimus trough levels. A progressive decrease in tacrolimus concentrations was observed after switch requiring shortening of tacrolimus dosing interval. This observation was unexpected considering that cobicistat is devoid of inducing properties.

CONCLUSIONS

This case highlights the fact that the pharmacokinetic boosters ritonavir and cobicistat are not fully interchangeable. Therapeutic drug monitoring of tacrolimus is warranted to maintain levels within the therapeutic range.

Clinical efficacy analysis of paxlovid in children with hematological diseases infected with the omicron SARS-CoV-2 new variant

Objective

To summarize the clinical characteristics of children with hematological malignancies co-infected with novel coronavirus and explore the safety and effectiveness of Paxlovid treatment.

Methods

From December 10, 2022, to January 20, 2023, the clinical data of children with hematological diseases diagnosed with novel coronavirus infection in the outpatient and emergency department of the Seventh Affiliated Hospital of Sun Yat-sen University were retrospectively analyzed.

Results

According to whether to give paxlovid or not, it is divided into group A (paxlovid group) and group B (non-paxlovid group). The length of fever was 1-6 days in group A and 0-3 days in group B. The viral clearance time was shorter in group A than in group B. The inflammatory indexes CRP and PCT were significantly higher in group A than in group B (P < 0.05). Twenty patients were followed up for 1 month after leaving the hospital, and there were 5 cases of reappearance of fever, 1 case of increased sleep, 1 case of physical fatigue and 1 case of loss of appetite within 2 weeks.

Conclusions

Paxlovid has no apparent adverse reactions in children 12 years old and younger with underlying hematological diseases infected with the new coronavirus. Focusing on the interaction between paxlovid and other drugs is necessary during the treatment.

Nirmatrelvir/ritonavir treatment in SARS-CoV-2 positive kidney transplant recipients - a case series with four patients

BACKGROUND

Despite vaccination coronavirus disease 2019 (COVID-19)-associated mortality caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains high in kidney transplant recipients. Nirmatrelvir is a protease inhibitor with activity against SARS-CoV-2. Nirmatrelvir reduces the risk for mortality and hospitalization, which is approved for treating adults at risk for severe disease. Nirmatrelvir is metabolized by the cytochrome P-450 (CYP) 3A4 isozyme CYP3A4 and is therefore co-administered with the irreversible CYP3A4 inhibitor ritonavir, which results in a drug interaction with tacrolimus. A limited number of patients with nirmatrelvir/ritonavir and tacrolimus therapy after kidney transplantation have been reported to date. It has been reported that tacrolimus was paused during the five-day nirmatrelvir/ritonavir therapy and subtherapeutic tacrolimus levels were observed after finishing nirmatrelvir/ritonavir in two patients. Therefore, optimization of tacrolimus dosing is urgently needed in transplant recipients receiving nirmatrelvir/ritonavir treatment.

CASE PRESENTATION

Here, we present our first-hand experience with four patients receiving tacrolimus therapy following kidney transplantation and nirmatrelvir/ritonavir therapy due to COVID-19. Tacrolimus was paused during nirmatrelvir/ritonavir therapy in all patients, which resulted in stable therapeutic tacrolimus levels. Tacrolimus was continued directly after finishing nirmatrelvir/ritonavir to avoid subtherapeutic levels in the first patient treated. This patient received his usual tacrolimus maintenance dose, which resulted in toxic levels. Based on this observation, tacrolimus therapy was continued 24 h after finishing nirmatrelvir/ritonavir treatment at a reduced dose in the subsequent patients. In these patients, therapeutic to supratherapeutic tacrolimus levels were observed despite the therapeutic break and dose reduction.

DISCUSSION AND CONCLUSIONS

Based on altered CYP3A4 metabolism, tacrolimus levels have to be closely monitored after treatment with nirmatrelvir/ritonavir. Our study suggests that tacrolimus treatment should be paused during nirmatrelvir/ritonavir medication and be continued 24 h after completing nirmatrelvir/ritonavir therapy at a reduced dose and under close monitoring. Based on the limited number of patients in this study, results must be interpreted with caution.

Therapeutic Drug Monitoring and Dosage Adjustments of Immunosuppressive Drugs When Combined With Nirmatrelvir/Ritonavir in Patients With COVID-19

ABSTRACT

Nirmatrelvir/ritonavir (Paxlovid) consists of a peptidomimetic inhibitor (nirmatrelvir) of the SARS-CoV-2 main protease and a pharmacokinetic enhancer (ritonavir). It is approved for the treatment of mild-to-moderate COVID-19. This combination of nirmatrelvir and ritonavir can mediate significant and complex drug-drug interactions (DDIs), primarily due to the ritonavir component. Indeed, ritonavir inhibits the metabolism of nirmatrelvir through cytochrome P450 3A (CYP3A) leading to higher plasma concentrations and a longer half-life of nirmatrelvir. Coadministration of nirmatrelvir/ritonavir with immunosuppressive drugs (ISDs) is particularly challenging given the major involvement of CYP3A in the metabolism of most of these drugs and their narrow therapeutic ranges. Exposure of ISDs will be drastically increased through the potent ritonavir-mediated inhibition of CYP3A, resulting in an increased risk of adverse drug reactions. Although a decrease in the dosage of ISDs can prevent toxicity, an inappropriate dosage regimen may also result in insufficient exposure and a risk of rejection. Here, we provide some general recommendations for therapeutic drug monitoring of ISDs and dosing recommendations when coadministered with nirmatrelvir/ritonavir. Particularly, tacrolimus should be discontinued, or patients should be given a microdose on day 1, whereas cyclosporine dosage should be reduced to 20% of the initial dosage during the antiviral treatment. Dosages of mammalian target of rapamycin inhibitors (m-TORis) should also be adjusted while dosages of mycophenolic acid and corticosteroids are expected to be less impacted.

"Saving lives with nirmatrelvir/ritonavir one transplant patient at a time"

BACKGROUND

Solid organ transplant (SOT) recipients are at risk of complications from COVID-19. Nirmatrelvir/ritonavir (Paxlovid) can reduce mortality from COVID-19 but is contraindicated in patients receiving calcineurin inhibitors (CI), which depend on cytochrome p4503A (CY3PA). In this study, we aim to show the feasibility of nirmatrelvir/ritonavir administration to SOT recipients receiving CI with coordination of medication management and limited tacrolimus trough monitoring.

METHODS

We reviewed adult SOT recipients treated with nirmatrelvir/ritonavir from 4/14 to 11/1/2022 and assessed for changes in tacrolimus trough and serum creatinine after therapy.

RESULTS

Of 47 patients identified, 28 were receiving tacrolimus and had follow-up laboratory testing. Patients had a mean age of 55 years, 17 (61%) received a kidney transplant and 23 (82%) received three or more doses of SARS-CoV-2 mRNA vaccine. Patients had mild-moderate COVID-19 and started nirmatrelvir/ritonavir within 5 days of symptom onset. Median baseline tacrolimus trough concentration was 5.6 ng/mL (Interquartile range 5.1-6.7), while median follow-up tacrolimus trough concentration was 7.8 ng/mL (Interquartile range 5.7-11.5, p = 0.0017). Median baseline and follow-up serum creatinine levels were 1.21 mg/dL (Interquartile range 1.02-1.39) and 1.21 mg/dL (interquartile range 1.02-1.44, p = 0.3162), respectively. One kidney recipient had a follow up creatinine level >1.5 times baseline. No patients were hospitalized or died from COVID-19 in the follow up period.

CONCLUSION

While administration of nirmatrelvir/ritonavir resulted in a significant increase in tacrolimus concentration, this did not result in significant nephrotoxicity. Early oral antiviral treatment in SOT recipients is feasible with medication management, even with limited tacrolimus trough monitoring.

Management of drug-drug interactions with nirmatrelvir/ritonavir in patients treated for Covid-19: Guidelines from the French Society of Pharmacology and Therapeutics (SFPT)

Objectives

Nirmatrelvir in association with ritonavir (PAXLOVID™, Pfizer) is an antiviral agent targeting the 3-chymotrypsin–like cysteine protease enzyme (3C-like protease or Mpro) which is a key enzyme of the viral cycle of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This combination with a well-known pharmacokinetic enhancer leads to a high risk for drug-drug interactions in a polymedicated elected population for treatment. The aim of this work was to provide recommendations on behalf of the national French society of pharmacology (French Society of Pharmacology and Therapeutics; SFPT), by suggesting optimal and pragmatic therapeutic strategies if nirmatrelvir/ritonavir is to be given together with drugs commonly used, in order to ensure secured physicians’ prescription.

Methods

Six clinical pharmacologists search the scientific literature to provide a first draft of recommendations. Thereafter, twelve other clinical pharmacologists verified the recommendations and proposed modifications. The final draft was then validated by all 18 participants.

Results

Five distinct recommendations were issued: i) contra-indications, ii) “PAXLOVID™ not recommended with the comedication”, iii) “PAXLOVID™ possible whether the comedication is discontinued”, iv) “PAXLOVID™ possible only after an expert advice” and v) “PAXLOVID™ possible without modification of the associated treatment”. The final document comprises recommendations for 171 drugs/therapeutic classes aiming to secure prescription. In complex situations, clinicians are advised to contact their pharmacology department to obtain specific recommendations on the management of drug-drug interactions with nirmatrelvir/ritonavir.

Conclusion

These recommendations intend to be a help for clinicians willing to prescribe nirmatrelvir/ritonavir and to prevent drug-drug interactions leading to adverse drug reactions or loss of efficacy. They constitute a guideline for primary care situations. Of course, some complex situations may require expert advices and here, again, clinical pharmacologists are at the forefront in providing therapeutic advice.

A Real-World Study to Compare the Safety and Efficacy of Paritaprevir/Ombitasvir/Ritonavir and Dasabuvir, with or without Ribavirin, in 587 Patients with Chronic Hepatitis C at the Fundeni Clinical Institute, Bucharest, Romania

BACKGROUND In the European Union, a tablet with fixed doses of ombitasvir, paritaprevir, and ritonavir combined with dasabuvir is an authorized treatment for patients with chronic hepatitis C virus (HCV) infection. Ribavirin is a broad-spectrum antiviral used in several treatment regimens for patients with HCV infection. This real-world study aimed to compare the safety and efficacy of ombitasvir, paritaprevir, and ritonavir combined with dasabuvir, with or without ribavirin, in 587 patients with chronic hepatitis C attending the Fundeni Clinical Institute, Bucharest, Romania. MATERIAL AND METHODS This is an observational prospective study including 315 patients with F4 degree of fibrosis and compensated cirrhosis, 185 patients with F3 fibrosis, and 83 patients with F2 fibrosis. Liver fibrosis was evaluated by liver biopsy or Fibromax. Efficacy was defined as undetectable HCV-RNA at 12 weeks after the end of treatment. In terms of safety, we monitored the development of adverse reactions, liver cytolysis, cholestasis, and hematologic disorders. RESULTS Of the 587 patients, 2 patients with B-cell lymphoma died during therapy. In total, 3/585 patients (0.51%) did not achieve sustained virologic response. Common adverse effects were nausea and asthenia (especially in patients with other medical treatments; P=0.03 and P=0.04, respectively) and anemia in patients who received ribavirin (P<0.01). None of the patients discontinued antiviral treatment. Patients with kidney transplant or end-stage kidney disease did not receive or discontinued ribavirin. CONCLUSIONS Ombitasvir, paritaprevir, and ritonavir combined with dasabuvir, with or without ribavirin had an efficacy rate of over 99% in HCV genotype 1b infection. We report no serious adverse reactions.

Drug-Drug Interactions With Cyclosporine in the Anti-Hepatitis C Viral PrOD Combination Regimen of Paritaprevir/Ritonavir-Ombitasvir and Dasabuvir in Organ Transplant Recipients With Severe Hepatic Fibrosis or Cirrhosis

BACKGROUND

The clinical guidelines suggest that the dosing of cyclosporine (CsA), during combination therapy with paritaprevir/ritonavir-ombitasvir and dasabuvir (PrOD), would be only one-fifth of the pre-PrOD total daily dose to be administered once daily. However, this dosing may not be applicable to all patients depending on their clinical condition. This study focuses on the pharmacokinetic dynamics of PrOD with CsA in Asian organ transplant recipients with severe liver fibrosis or cirrhosis who undergo concurrent treatment with PrOD treatment and CsA. The efficacy and safety of PrOD treatment was also evaluated.

METHODS

Data from 7 patients obtained between January 2017 and September 2017 were retrospectively analyzed. Determinations of the blood concentrations of CsA were made, whether used as a single treatment or in combination therapy with PrOD.

RESULTS

The combination regimen compared with CsA administered alone resulted in a 4.53-fold and 5.52-fold increase in the area under the concentration-time curve from time 0-12 hours (AUC0-12 h) of CsA on days 1 and 15, respectively. In addition, the maximal concentration, time to maximum concentration, and terminal phase elimination half-life (t1/2) of CsA were increased during the combined treatment of PrOD and CsA. The authors proposed reducing the CsA dosage during PrOD treatment to one-seventh of that of the pre-PrOD treatment of the total daily dose to maintain target CsA levels. All patients achieved sustained virologic responses at week 12. There were no episodes of serious adverse events or graft rejections observed.

CONCLUSIONS

Although the combination with PrOD significantly affects the pharmacokinetics of CsA, it is effective and safe with regular monitoring of the CsA blood concentrations and appropriate CsA dose adjustment.

Drug-induced CYP induction as therapy for tacrolimus intoxication

Management of calcineurin inhibitor (CNI) therapy in kidney transplant recipients may be complicated due to polypharmacy. As CNI undergo extensive metabolism by cytochrome-P450 enzymes (CYP), drug-mediated CYP inhibition poses a risk for elevated CNI blood concentrations. Here, we report on 2 kidney transplant recipients treated with tacrolimus who presented with signs of tacrolimus intoxication at admission. Patient A was started on antiviral medication ombitasvir, paritaprevir, ritonavir, and dasabuvir for hepatitis C virus treatment 3 days prior to hospitalization. Patient B was treated with clarithromycin for pneumonia. Both therapies cause drug-mediated CYP inhibition, and both patients displayed highly elevated tacrolimus serum concentrations and acute kidney injury (Table 1). After application of the CYP-inducing agents rifampicin and phenytoin, respectively, tacrolimus levels were rapidly reduced, and renal function recovered. Treating severe CNI intoxication is an infrequent yet emergent condition. These results add to the knowledge of therapeutic drug-induced CYP induction as rescue therapy.

Supratherapeutic tacrolimus concentrations with nirmatrelvir/ritonavir in solid organ transplant recipients requiring hospitalization: A case series using rifampin for reversal

Nirmatrelvir/ritonavir was recently granted emergency use authorization for mild to moderate coronavirus disease 2019. Drug–drug interactions between ritonavir and tacrolimus are underappreciated by nontransplant providers. We describe 2 solid organ transplant recipients prescribed nirmatrelvir/ritonavir for outpatient use who developed tacrolimus toxicity requiring hospitalization and were managed with rifampin for toxicity reversal.

Early clinical experience with nirmatrelvir/ritonavir for the treatment of COVID-19 in solid organ transplant recipients

Nirmatrelvir/ritonavir (NR) use has not yet been described in solid organ transplant recipients (SOTRs) with mild COVID-19. The objective was to evaluate outcomes among SOTR and describe the drug-drug interaction of NR. This is an IRB-approved, retrospective study of all adult SOTR on a calcineurin inhibitor (CNI) or mammalian target of rapamycin inhibitor who were prescribed NR between December 28, 2021 and January 6, 2022. A total of 25 adult SOTR were included (n = 21 tacrolimus, n = 4 cyclosporine, n = 3 everolimus, n = 1 sirolimus). All patients were instructed to follow the following standardized protocol during treatment with 5 days of NR: hold tacrolimus or mTOR inhibitor or reduce cyclosporine dose to 20% of baseline daily dose. Four patients (16%) were hospitalized by day 30; one for infectious diarrhea and three for symptoms related to COVID-19. No patients died within 30 days of receipt of NR. Median tacrolimus level pre- and post-NR were 7.4 ng/ml (IQR, 6.6-8.6) and 5.2 (IQR, 3.6-8.7), respectively. Four patients experienced a supratherapeutic tacrolimus concentration after restarting tacrolimus post-NR. Our results show the clinically significant interaction between NR and immunosuppressive agents can be reasonably managed with a standardized dosing protocol. Prescribers should carefully re-introduce CNI after the NR course is complete.

Direct-Acting Antivirals in the Treatment of Hepatitis C Virus Recurrence after Liver Transplantation: Real-life Experience in a Mexican Cohort

BACKGROUND

Hepatitis C virus (HCV) infection is one of the most frequent causes of liver transplantation (LT) worldwide. Patients with HCV viremia at the time of LT universally develop recurrent HCV in the allograft, leading to accelerated fibrosis and graft loss. Treatment with direct-acting antivirals (DAA) is highly effective and safe in this population.

AIM OF THE STUDY

To describe the efficacy and safety of DAA in treating post LT HCV recurrence in a Mexican cohort.

METHODS

We designed a retrospective cohort study that included all LT patients from 2000-2019 with HCV recurrence after LT who received DAA. Clinical and biochemical characteristics were collected from clinical records. Patients who received treatment before LT and those who received interferon-based therapies after LT achieving sustained viral response at 12 weeks were excluded; patients who didn´t complete DAA therapy were eliminated. The primary outcome was SVR-12.

RESULTS

Fifty-six patients received DAA after the LT with 98% SVR-12. The most frequent genotypes were 1b (54%) and 1a (34%). The most common antiviral scheme used was sofosbuvir/ledipasvir for 12 weeks in 59% of the patients. No severe adverse effects were observed. Ribavirin was used in 82% of the patients, of which 23.9% had adverse effects, mostly mild. The median follow-up after LT was 55 months (IQR 43-51), with a global and graft survival at one and three years of 100%.

CONCLUSION

In a Mexican cohort, DAA therapy in LT patients with recurrence of HCV infection showed high efficacy and an acceptable safety profile.

Multi-factorial pharmacokinetic interactions: unraveling complexities in precision drug therapy

Introduction: Precision drug therapy requires accounting for pertinent factors in pharmacokinetic (PK) inter-individual variability (i.e., pharmacogenetics, diseases, polypharmacy, and natural product use) that can cause sub-therapeutic or adverse effects. Although each of these individual factors can alter victim drug PK, multi-factorial interactions can cause additive, synergistic, or opposing effects. Determining the magnitude and direction of these complex multi-factorial effects requires understanding the rate-limiting redundant and/or sequential PK processes for each drug.Areas covered: Perturbations in drug-metabolizing enzymes and/or transporters are integral to single- and multi-factorial PK interactions. Examples of single factor PK interactions presented include gene-drug (pharmacogenetic), disease-drug, drug-drug, and natural product-drug interactions. Examples of multi-factorial PK interactions presented include drug-gene-drug, natural product-gene-drug, gene-gene-drug, disease-natural product-drug, and disease-gene-drug interactions. Clear interpretation of multi-factorial interactions can be complicated by study design, complexity in victim drug PK, and incomplete mechanistic understanding of victim drug PK.Expert opinion: Incorporation of complex multi-factorial PK interactions into precision drug therapy requires advances in clinical decision tools, intentional PK study designs, drug-metabolizing enzyme and transporter fractional contribution determinations, systems and computational approaches (e.g., physiologically-based pharmacokinetic modeling), and PK phenotyping of progressive diseases.

Immunosuppressant quantification in intravenous microdialysate - towards novel quasi-continuous therapeutic drug monitoring in transplanted patients

OBJECTIVES

Therapeutic drug monitoring (TDM) plays a crucial role in personalized medicine. It helps clinicians to tailor drug dosage for optimized therapy through understanding the underlying complex pharmacokinetics and pharmacodynamics. Conventional, non-continuous TDM fails to provide real-time information, which is particularly important for the initial phase of immunosuppressant therapy, e.g., with cyclosporine (CsA) and mycophenolic acid (MPA).

METHODS

We analyzed the time course over 8 h of total and free of immunosuppressive drug (CsA and MPA) concentrations measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in 16 kidney transplant patients. Besides repeated blood sampling, intravenous microdialysis was used for continuous sampling. Free drug concentrations were determined from ultracentrifuged EDTA-plasma (UC) and compared with the drug concentrations in the respective microdialysate (µD). µDs were additionally analyzed for free CsA using a novel immunosensor chip integrated into a fluorescence detection platform. The potential of microdialysis coupled with an optical immunosensor for the TDM of immunosuppressants was assessed.

RESULTS

Using LC-MS/MS, the free concentrations of CsA (fCsA) and MPA (fMPA) were detectable and the time courses of total and free CsA comparable. fCsA and fMPA and area-under-the-curves (AUCs) in µDs correlated well with those determined in UCs (r≥0.79 and r≥0.88, respectively). Moreover, fCsA in µDs measured with the immunosensor correlated clearly with those determined by LC-MS/MS (r=0.82).

CONCLUSIONS

The new microdialysis-supported immunosensor allows real-time analysis of immunosuppressants and tailor-made dosing according to the AUC concept. It readily lends itself to future applications as minimally invasive and continuous near-patient TDM.

Recommendations of the Polish Group of Experts for HCV for the treatment of hepatitis C in 2020

The recommendations set out the principles of diagnosis and treatment of hepatitis C virus (HCV) infections according to the most recent knowledge. The main goal of therapy for HCV infection is to eliminate the virus from the body, which consequently leads to arrest of progress or regression of changes in the liver. Current version of the recommendations prioritise pangenotypic regimens and provide guidelines in special populations of patients, such as children, cirrhotics, human immunodeficiency virus (HIV) and hepatitis B virus (HBV) coinfected, those with renal failure, hepatic decompensation and non-responders to previous therapies.

Safety and efficacy of direct-acting antivirals for chronic hepatitis C in patients with chronic kidney disease

BACKGROUND

This is a real-world evidence study that aims to analyze the efficacy, tolerability and safety profile of paritaprevir/ombitasvir/ritonavir and dasabuvir, in patients with renal impairment.

METHODS

We conducted an observational prospective study, on 232 patients with chronic kidney disease, undergoing treatment with paritaprevir/ombitasvir/ritonavir and dasabuvir, for chronic hepatitis C infection - genotype 1b. Renal and liver function were assessed at the beginning of therapy, monthly during treatment and three months after therapy completion.

RESULTS

All patients achieved sustained virologic response. Common side effects were nausea, fatigue and headache. Close monitoring of tacrolimus blood levels and dose reduction was required in kidney transplant recipients.

CONCLUSIONS

HCV therapy in the setting of renal dysfunction has always been a challenging topic. Direct-acting antivirals have shown promising effects, demonstrating good tolerance and efficacy in patients with HCV infection and renal impairment. Sustained virologic response within our study population was 100%.

High rate of acute kidney injury in patients with chronic kidney disease and hepatitis C virus genotype 4 treated with direct-acting antiviral agents

BACKGROUND

Direct-acting antivirals (DAAs) have significantly improved the efficacy and safety of treating chronic hepatitis C (CHC), but their effectiveness and safety among patients with chronic kidney disease (CKD) remains poorly understood. Sofosbuvir/daclatasvir regimen is supposed to be used for patients with creatinine clearance more than 30 mL/min, while ombitasvir/paritaprevir/ritonavir regimen is used for patients with creatinine clearance less than 30 mL/min.

AIM

The aim of the study was to assess the safety and efficacy of DAAs among patients with CKD.

METHODS

Eighteen CKD stage 2-3b patients received sofosbuvir for 3 months. In addition, 42 CKD stage-4 patients received ritonavir-boosted paritaprevir plus ombitasvir for 3 months. Finally, ribavirin was added for 30 of them.

RESULTS

The patients'age was 49.2 ± 12 years. Baseline serum creatinine was 3.76 ± 1.67 mg/dL. Fifty patients were HCV genotype 4. A 3-month sustained viral response was achieved in 56 patients and 49 patients achieved a 6-month viral response. There were 11 relapsers. Acute kidney injury (AKI) upon CKD (AKI/CKD) occurred in 28 patients, of which 20 needed hemodialysis. Fifteen/28 recovered from AKI, whereas 13 were maintained on hemodialysis. In multivariate analysis, there were only two independent risk factors for developing AKI/CKD, i.e., being cirrhotic as defined by baseline abdominal ultrasound findings [odds ratio 4.15 (1.33-12.97); p = 0.013] and having had as DAA therapy OMV/PTV/RTV [odds ratio 7.35 (1.84-29.35); p = 0.001].

CONCLUSION

Treatment of HCV among stage 2, 3a, and 3b patients was achieved safely with a sofosbuvir-based regimen. We recommend that stage-4 patients wait until starting hemodialysis or transplantation.

Efficacy and safety of the new antiviral agents for the treatment of hepatitis C virus infection in Egyptian renal transplant recipients

PURPOSE

Hepatitis C virus (HCV) infection in kidney transplant recipients (KTRs) is common and can impact on patient and graft survival rates. The efficacy and safety of direct-acting antivirals (DAAs) to treat genotype-4 HCV-infected KTRs have not been fully established.

METHODS

A prospective, single-arm, single-center study was conducted at Mansoura Urology/Nephrology Center (Mansoura University, Egypt). 114 HCV RNA(+) genotype 4 KTRs were enrolled in this study after a hepatology consultation and consented to start treatment with interferon-free DAAs. A sofosbuvir-based regimen was given to 109 recipients that had creatinine clearance (Crcl) of > 30 mL/min/1.73 m². Ritonavir-boosted paritaprevir/ombitasvir was prescribed to five recipients with Crcl < 30 mL/min/1.73 m².

RESULTS

The mean age of the cohort was 45.2 ± 11.2 years; most were male. The mean duration with a transplant was 14.2 ± 3.5 years, with different immunosuppressive regimens, mostly based on calcineurin inhibitors. A rapid virological response (RVR), i.e., clearance of viral load, was achieved in 100% at 4 weeks after starting treatment. All patients had a sustained virological response (SVR) at 12 and 24 weeks posttreatment, with one exception. During DAA therapy serum creatinine increased in 12 patients. In three, this was concomitant with elevated calcineurin inhibitor and sirolimus trough levels. Graft biopsies were performed in 8 of these 12 patients: these revealed an acute rejection in 4 cases (acute cellular rejection grade-1A: n = 2, and grade-1B: n = 2). The rejection episodes occurred at 4-6 weeks after starting treatment.

CONCLUSION

DAAs were highly efficacious and safely treated genotype-4 HCV-infected KTRs and had no significant adverse effects on graft function/survival.

Pharmacokinetics and drug interactions of medications used to treat hepatitis C virus infection in the setting of chronic kidney disease and kidney transplantation

Hepatitis C infection in patients with chronic kidney disease or kidney transplant carries higher morbidity and mortality compared to noninfected patients. Historically, patients with advanced kidney disease and kidney transplant recipients were undertreated given the multiple adverse effects and limited efficacy of interferon-based therapies for chronic hepatitis C. The development of direct-acting antivirals in the past few years has opened an unprecedented opportunity for treating these populations. However, the impaired renal clearance of some of these medications in patients with kidney disease, and the potential interactions of antiviral therapies with immunosuppressants after kidney transplantation, present some challenges in choosing the proper regimen. This review provides an overview of the essential pharmacokinetics and drug interactions of relevant antiviral therapies in the treatment of chronic hepatitis C in patients with advanced kidney disease and after kidney transplantation.

Drug-Drug Interactions of Tacrolimus or Cyclosporine With Glecaprevir and Pibrentasvir in Healthy Subjects

A fixed-dose combination of glecaprevir and pibrentasvir is approved for treatment of chronic infection with hepatitis C virus (HCV) genotypes 1-6. Three phase 1 open-label studies were conducted in healthy volunteers to evaluate the potential for clinically relevant drug-drug interactions of the glecaprevir 300-mg and pibrentasvir 120-mg combination with the immunosuppressants tacrolimus (1 mg) or cyclosporine (100 and 400 mg). Glecaprevir and pibrentasvir exposure was unaffected by tacrolimus, whereas the tacrolimus area under the curve (AUC) value was 45% higher with glecaprevir and pibrentasvir. Cyclosporine 100 mg had a limited effect on glecaprevir or pibrentasvir exposure (≤37% AUC increase), but cyclosporine 400 mg increased exposure of both glecaprevir and pibrentasvir (410% and 93% AUC increase, respectively). Cyclosporine concentration was unaffected by glecaprevir and pibrentasvir at either cyclosporine dose (≤14% AUC change). Adverse events were all grade 1 (mild), with the most common nausea and flushing attributed to cyclosporine. Findings from these studies supported evaluation of glecaprevir/pibrentasvir in HCV-infected kidney and liver transplant recipients receiving tacrolimus without additional dose adjustment or receiving cyclosporine up to 100 mg per day.

A SEVERE CASE OF HYPERGLYCEMIA IN A KIDNEY TRANSPLANT RECIPIENT UNDERGOING INTERFERON-FREE THERAPY FOR CHRONIC HEPATITIS C

CONTEXT

Hepatitis C and diabetes represent important health problems globally. The new-onset diabetes after transplantation is a particular entity that appears due to the use of immunosuppression among transplanted patients.

OBJECTIVE

We aim to describe the clinical and biological aspects of severe hyperglycemia in a kidney transplant recipient undergoing Interferon-free therapy for chronic hepatitis C, discussing the interference of different factors with the glucose metabolism.

DESIGN

The occurrence of diabetes in a patient with history of renal transplantation and Interferon-free treated hepatitis C was studied from both clinical and paraclinical points of view.

SUBJECTS AND METHODS

When presenting to the hospital, extensive blood tests were performed on the patient, revealing significant hyperglycemia and an elevated level of blood tacrolimus. Creatinine clearance was calculated. ECG presented T-wave alterations. Intensive insulin protocol was applied, the case being managed in a multidisciplinary approach.

RESULTS

Blood glucose and tacrolimus were slowly normalized, under therapy. The antiviral treatment was continued, with the achievement of sustained virologic response.

CONCLUSIONS

Diabetes mellitus can have many causes, hepatitis C and transplantation both having an impact on glucose metabolism. The association of the three entities should be carefully managed, due to its enhancing effect on morbidity and mortality.

Ombitasvir-Paritaprevir-Ritonavir Therapy in a Kidney Transplant Recipient With Chronic Hepatitis C Virus Genotype 1 Infection: A Case Report on the Importance of Considering Drug-Drug Interactions and Monitoring Cyclosporine Levels

A 74-year-old Japanese man with a history of chronic hepatitis C and kidney transplant (KT) was administered pegylated-interferon plus ribavirin therapy. However, this therapy was ineffective. The patient was then hospitalized to receive ombitasvir (OBV) plus paritaprevir (PTV) plus ritonavir (r) antiviral combination therapy. He tested negative for the virus after 4 weeks, and completed 12 weeks of treatment. The patient ultimately achieved a sustained virological response after the 12 weeks of treatment. Cyclosporine (CyA) trough levels, during the OBV-PTV-r therapy, reached a peak within 5 days of initiating therapy, and increases in serum creatinine and total bilirubin were also observed. However, onset of irreversible nephropathy and hepatopathy were avoided by reducing the CyA dosage. The OBV-PTV-r therapy demonstrated a sufficient antiviral effect and could be safely administered postoperatively to patients having undergone KT. When a combination therapy with interferon-free, direct-acting antivirals is used in patients post-transplantation, consideration of drug-drug interactions with and monitoring CyA are of vital importance.

Clinical Pharmacokinetics of Paritaprevir

Paritaprevir is a potent hepatitis C virus (HCV) nonstructural (NS) protein 3/4A protease inhibitor that is used in combination with other direct-acting antivirals (DAAs) for the treatment of chronic HCV infection. Paritaprevir is primarily metabolized by cytochrome P450 (CYP) 3A4 and is administered with a low dose of ritonavir to achieve drug concentrations suitable for once-daily dosing. Coadministration of paritaprevir with ritonavir increases the half-life of single-dose paritaprevir from approximately 3 h to 5-8 h, doubles the time to maximum plasma concentration (T _max) from 2.3 to 4.7 h, and increases exposures 30-fold for maximum observed plasma concentration (C _max), 50-fold for area under the plasma concentration-time curve (AUC), and >300-fold for trough concentration (C ₂₄). Paritaprevir displays highly variable, nonlinear pharmacokinetics, with C _max and AUC increasing in a greater than dose proportional manner when administered with or without ritonavir. In the presence of ritonavir, paritaprevir is excreted mostly unchanged in feces via biliary excretion. Paritaprevir exposures are higher in Japanese subjects compared with Caucasian subjects; however, no dose adjustment is needed for Japanese patients as the higher exposures are safe and well tolerated. The pharmacokinetic characteristics of paritaprevir are similar between healthy subjects and HCV-infected patients, and are not appreciably altered by mild or moderate hepatic impairment or mild, moderate, or severe renal impairment, including those on dialysis. Paritaprevir exposures are increased in patients with severe hepatic impairment. Although the presence of a low dose of ritonavir in paritaprevir-containing regimens increases the likelihood of drug-drug interactions, results from several drug interaction studies demonstrated that paritaprevir-containing regimens can be coadministered with many comedications that are commonly prescribed in HCV-infected patients.

Clinical Pharmacokinetics of Dasabuvir

Dasabuvir is a nonstructural (NS) 5B non-nucleoside inhibitor of the hepatitis C virus (HCV) used in combination with ombitasvir/paritaprevir/ritonavir for the treatment of chronic HCV infection. It is primarily metabolized by cytochrome P450 (CYP) 2C8, with a minor contribution from CYP3A. Biotransformation of dasabuvir forms the M1 metabolite, which retains antiviral activity. Dasabuvir exhibits linear pharmacokinetics with a terminal half-life of approximately 5-8 h, allowing for twice-daily dosing. The M1 metabolite of dasabuvir is the major metabolite in plasma and has a half-life similar to that of dasabuvir. Dasabuvir exposures in Asian subjects are comparable with Caucasian subjects. The pharmacokinetic characteristics of dasabuvir are similar between healthy subjects and HCV-infected patients, and are not appreciably altered by mild, moderate, or severe renal impairment or dialysis. Dasabuvir pharmacokinetic parameters were not significantly altered in subjects with mild or moderate hepatic impairment; however, exposures were significantly increased in subjects with severe hepatic impairment. Dasabuvir should be administered with food to maximize absorption. Coadministration of dasabuvir with a strong CYP2C8 inhibitor increased dasabuvir exposures by greater than tenfold, whereas coadministration with strong CYP3A inhibitors increased dasabuvir exposures by less than 50%. Furthermore, coadministration of dasabuvir with a CYP3A inducer decreased dasabuvir exposures by 55-70%. Coadministration of dasabuvir with strong CYP2C8 inhibitors or strong CYP3A/CYP2C8 inducers is contraindicated. Results from several drug interaction studies demonstrated that dasabuvir in combination with ombitasvir/paritaprevir/ritonavir can be coadministered with most comedications that are commonly prescribed in HCV-infected patients.

Clinical Pharmacokinetics of Ombitasvir

Ombitasvir is a potent, nonstructural protein 5A inhibitor of the hepatitis C virus (HCV) that is used in combination with other direct-acting antivirals for the treatment of chronic HCV infection. Ombitasvir is predominantly metabolized by amide hydrolysis followed by oxidative metabolism and is a substrate of P-glycoprotein. Ombitasvir displays linear pharmacokinetics with minimal accumulation and is eliminated via metabolism and biliary excretion. A negligible amount of unchanged drug is excreted in urine. Exposures are comparable across Chinese, Japanese, and non-Asian subjects. The pharmacokinetic characteristics of ombitasvir are similar in healthy subjects and HCV-infected patients, and are not appreciably altered by hepatic or renal impairment. Results from several drug interaction studies demonstrated that ombitasvir has a low potential for drug interactions.

Three renal failure cases successfully treated with ombitasvir/paritaprevir/ritonavir for genotype 1b hepatitis C virus reinfection after liver transplantation

We report three cases of genotype 1b hepatitis C virus (HCV) reinfection after liver transplantation. When antiviral treatment was considered, all three patients had renal dysfunction and had been treated with immunosuppressive agents for a long time; one with tacrolimus (TAC) and the others with cyclosporine A (CyA). Therefore, the possible antiviral regimens among direct-acting antivirals (DAA) were limited and so we treated all three patients with ombitasvir/paritaprevir/ritonavir (OBV/PTV/r). Because ritonavir is known to markedly increase the blood concentration of TAC and CyA through drug-drug interactions, close monitoring of blood concentrations of TAC or CyA and dose adjustments of immunosuppressive agents were needed. Sustained virus response was achieved in all the patients treated, and there were no adverse effects or transplant rejection. OBV/PTV/r might be a useful DAA regimen for patients with genotype 1 HCV reinfection in the setting of renal dysfunction.

Ombitasvir/paritaprevir/ritonavir plus dasabuvir regimen may be used safely in combination with sirolimus for the treatment of chronic hepatitis C

The era of direct acting antivirals has revolutionised the management of chronic hepatitis C infection and improved patient outcomes. The optimal management of patients who require liver transplantation remains a matter of ongoing discussion. Treatment in the post-transplantation setting may be complicated by significant drug-drug interactions between antiviral agents and standard immune suppressive treatment regimens. We describe what we believe to be the first reported case of a patient successfully treated for CHC with ombitasvir/paritaprevir/ritonavir plus dasabuvir, while taking sirolimus following liver transplantation.

Intrahepatic Sampling for the Elucidation of Antiviral Clinical Pharmacology

Although the importance of the liver in clinical pharmacology is widely recognized, little is known in humans concerning its function in vivo at the hepatocyte level and how pharmacological functions are altered in the setting of advanced liver disease. Several recent proof-of-principle studies with first-generation DAAs have demonstrated the feasibility of serial liver sampling for pharmacological studies. These studies have begun to describe the liver-to-plasma concentration ratio and how this ratio is altered in the setting of advanced liver disease. These data are particularly relevant to individuals with substance-use disorders because many have advanced liver disease as a consequence of long-standing viral hepatitis infection or continued use of hepatotoxins such as alcohol. Future research should attempt to develop standardized and reproducible methods to assess liver drug concentration, complex drug interactions, and pharmacogenomics in humans to permit elucidation of the clinical pharmacology within the liver.

The Drug-Drug Interaction Potential of Antiviral Agents for the Treatment of Chronic Hepatitis C Infection

Several safe and highly effective direct-acting antiviral (DAA) drugs for chronic hepatitis C virus (HCV) have been developed and greatly increase the number of therapeutic options available to successfully treat HCV infection. However, because treatment regimens contain at least two drugs (e.g., elbasvir and grazoprevir, glecaprevir and pibrentasvir, or sofosbuvir with daclatasvir, simeprevir, ledipasvir, or velpatasvir) and up to five drugs (ombitasvir/paritaprevir/ritonavir plus dasabuvir with or without ribavirin), the potential for drug-drug interactions (DDIs) becomes an important consideration for HCV-infected individuals with comorbidities that require concomitant medications, such as human immunodeficiency virus/HCV coinfection or immunosuppression after liver transplantation. This review details the pharmacokinetics and DDI potential of approved DAAs for the treatment of HCV infection.

Managing Drug-Drug Interaction Between Ombitasvir, Paritaprevir/Ritonavir, Dasabuvir, and Mycophenolate Mofetil

No drug-drug interaction study has been conducted to date for the combination of ombitasvir, paritaprevir/ritonavir, dasabuvir (3D), and mycophenolic acid (MPA). We here report the case of a hepatitis C virus-infected patient treated with 3D and MPA for vasculitis. In light of the threat of drug-drug interaction, the concentration of MPA was measured before, during, and 15 days after the end of the 3D treatment. Similar values were found at all 3 time points, thus indicating that there is probably no need to adapt MPA dosage to 3D.

Effective Treatment With Daclatasvir and Asunaprevir in Kidney Transplant Patients Infected With Hepatitis C Virus: A Report of Two Cases

BACKGROUND

Hepatitis C virus (HCV) infection is known to affect long-term patient and graft survivals after kidney transplantation (KT). Recently, combination therapy with the use of 2 oral direct-acting antivirals, daclatasvir (DCV) and asunaprevir (ASV) reportedly showed a high rate of HCV eradication. We report the safety and efficacy of DCV and ASV therapy in 2 KT patients.

METHODS

The safety and viral responses were investigated in a prospective study of KT patients infected with HCV genotype 1. Two patients received 60 mg DCV once daily plus 100 mg ASV twice daily for 24 weeks.

RESULTS

A 69-year-old woman and a 57-year-old man underwent DCV and ASV therapy for 24 weeks. In both cases, the HCV genotype was 1b. Case 1 had undergone KT twice and had received treatment with pegylated interferon and ribavirin. She received DCV and ASV therapy 12 years after the 2nd KT, and had undetectable virus after only 6 weeks of treatment and at 24 weeks after the end of treatment (SVR24). The post-transplantation immunosuppressive therapy at that time comprised tacrolimus, mycophenolate mofetil, and prednisolone. The other case, after failure of interferon treatment, received DCV and ASV therapy 27 years after his KT and achieved SVR24. His immunosuppressive regimen at that time was mizoribine and prednisolone. DCV and ASV therapy did not affect renal graft function or tacrolimus blood concentrations.

CONCLUSIONS

DCV and ASV therapy had high antiviral effect and a low rate of adverse events in KT patients.

Pharmacokinetics of Tacrolimus and Cyclosporine in Liver Transplant Recipients Receiving 3 Direct-Acting Antivirals as Treatment for Hepatitis C Infection

BACKGROUND

Interactions between tacrolimus and cyclosporine (CSA) and the 3 direct-acting antiviral regimen (3D) of ombitasvir, paritaprevir/ritonavir, and dasabuvir necessitate a priori dose adjustments for the immunosuppressants to achieve desired levels. Modeling and simulations based on data in healthy subjects predicted that tacrolimus 0.5 mg every 7 days or 0.2 mg every 3 days, and CSA at one-fifth the total daily dose administered once daily, would achieve desired trough concentrations (Ctrough) during 3D treatment. The success of these dosing recommendations was evaluated by analyzing pharmacokinetic data from liver transplant recipients in the CORAL-I study.

METHODS

A population pharmacokinetic model was developed using tacrolimus dosing and Ctrough data before and during 3D treatment (n = 29). The model was used to simulate various tacrolimus dosing regimens and predict tacrolimus concentration-time profiles during 3D treatment. CSA Ctrough data before and during 3D treatment (n = 5) were also summarized.

RESULTS

A one-compartment model with first-order absorption adequately described tacrolimus pharmacokinetic profiles during the first 4 weeks of 3D treatment. Estimated tacrolimus Ctrough values (median; interquartile range) before and during 3D treatment were comparable (5.7 ng/mL; 4.9-6.5 ng/mL versus 5.2 ng/mL; 4.2-6.3 ng/mL, respectively). Based on simulations, in a patient with a starting Ctrough of 6 ng/mL, 0.5 mg tacrolimus every 7 or 14 days or 0.2 mg tacrolimus every 3 days will result in Ctrough levels of 6-9 ng/mL, 4-6 ng/mL, and 6-10 ng/mL, respectively, during 3D treatment. For CSA, Ctrough values (median; interquartile range) before and during 3D treatment were comparable (126 ng/mL; 94-140 ng/mL versus 104 ng/mL; 82-140 ng/mL).

CONCLUSIONS

Observed data for tacrolimus and CSA in liver transplant recipients confirm that the recommended dosing strategies are valid and therapeutic levels of immunosuppression can be maintained during 3D treatment.

Recommendations for the treatment of hepatitis C virus infection in chronic kidney disease: a position statement by the Spanish association of the liver and the kidney

Hepatitis C virus (HCV) infection is one of the main causes of liver cirrhosis worldwide. The long-term impact of HCV infection is highly variable, ranging from minimal histological changes to extensive fibrosis with hepatocellular carcinoma. The development of HCV drugs has increased dramatically in recent years, even in special populations such as chronic kidney disease patients. Classical treatment of chronic hepatitis C was based on the administration of interferon and ribavirin for 24-48 weeks, which was associated with a poor viral response and a high rate of side effects, especially in patients with a lower estimated glomerular filtration rate. The current high availability of the new direct-acting antivirals renders the classification of these agents for this special population necessary. The Spanish Association of the Liver and the Kidney has produced a position statement on the treatment of HCV infection in chronic kidney disease patients since the evidence to guide this treatment is scant and what evidence does exist is weak. The recommendations are based on the results of clinical trials and controlled studies conducted to date, with data published hitherto by the authors of these studies. Since the indications for treatment have been evaluated by other societies or are dependent on internal clinical protocols, the main goal of this position statement is to assist in decision-making when choosing a therapeutic option.

Paritaprevir/ritonavir/ombitasvir plus dasabuvir with ribavirin for treatment of recurrent chronic hepatitis C genotype 1 infection after liver transplantation: Real-world experience

BACKGROUND/AIMS

The registered trial has demonstrated that paritaprevir/ritonavir/ombitasvir plus dasabuvir (PrOD) with ribavirin was effective for recurrent hepatitis C virus genotype 1 (HCV-1) infection after liver transplantation in patients with mild fibrosis; however, the real-world efficacy and safety of this regimen have not been determined.

METHODS

The efficacy (sustained virological response, SVR12, undetectable HCV RNA 12 weeks post-treatment) and safety were evaluated in 12 patients with recurrent HCV-1 infection after liver transplantation.

RESULTS

Nine patients were treated for 24 weeks, and three patients (two treatment-naïve patients and one interferon-intolerant patient) were treated for 12 weeks. HCV RNA was undetectable at treatment day 1, week 1, week 4, week 12, and at the end of treatment in 8.3% (n = 1), 25% (n = 3), 83.3% (n = 10), 100% (n = 12), and 100% (n = 12) of patients, respectively. All twelve patients achieved SVR12. Treatment was temporarily stopped in one patient because of leucopenia. The other patient with minimal fibrosis experienced an elevation in alanine aminotransferase concentration, which returned to normal levels after dose reduction. Seven (58.3%) patients required RBV dose reduction and two (16.7%) required transient RBV discontinuation during treatment. There were no serious adverse events, and most adverse events were related to ribavirin. No patient developed graft rejection or deterioration in hepatic or renal function during treatment. Treatment efficacy and safety were comparable between patients with and without advanced liver fibrosis.

CONCLUSION

PrOD plus ribavirin had a highly satisfactory real-world efficacy and safety profile in the treatment of recurrent HCV-1 infection after liver transplantation in Asian patients.