Stopping lopinavir/ritonavir in COVID-19 patients: duration of the drug interacting effect

Effect of rifampicin administration on CYP induction in a dermatomyositis patient with vasospastic angina attributable to nilmatrelvir/ritonavir-induced blood tacrolimus elevation: A case report

Ritonavir (RTV), which is used in combination with nilmatrelvir (NMV) to treat coronavirus disease 2019 (COVID-19), inhibits cytochrome P450 (CYP) 3A, thereby increasing blood tacrolimus (TAC) levels through a drug-drug interaction (DDI). We experienced a case in which a DDI between the two drugs led to markedly increased blood TAC levels, resulting in vasospastic angina (VSA) and acute kidney injury (AKI). Rifampicin (RFP) was administered to induce CYP3A and promote TAC metabolism. A 60-year-old man with dermatomyositis who was taking 3 mg/day TAC contracted COVID-19. The patient started oral NMV/RTV therapy, and he was admitted to the hospital after 4 days because of chest pain and AKI. On day 5, his blood TAC level increased markedly to 119.8 ng/mL. RFP 600 mg was administered once daily for 3 days, and his blood TAC level decreased to the therapeutic range of 9.6 ng/mL on day 9, leading to AKI improvement. Transient complete atrioventricular block and nonsustained ventricular tachycardia were present during chest pain. In the coronary spasm provocation test, complete occlusion was observed in the right coronary artery, leading to a diagnosis of VSA. VSA and AKI are possible side effects of high blood TAC levels caused by DDI, and attention should be paid to cardiovascular side effects such as VSA and AKI associated with increased blood levels of TAC when it is used together with NMV/RTV. When blood levels of TAC increase, oral RFP can rapidly decrease TAC blood levels and potentially reduce its toxicity.

Nirmatrelvir/ritonavir treatment of patients with COVID-19 taking tacrolimus: case series describing the results of drug-drug interactions

Nirmatrelvir/ritonavir is a novel drug combination that is authorized by the Food and Drug Administration for the treatment of coronavirus disease 2019 (COVID-19). Ritonavir is a cytochrome P450 3A inhibitor and a P-glycoprotein inhibitor that increases the plasma concentration of tacrolimus and other medications. We describe the cases of two patients treated with nirmatrelvir/ritonavir: a patient who had undergone kidney transplantation and another with a history of hematopoietic stem cell transplantation. Toxic concentrations of tacrolimus were induced in both. This case series highlights the risk associated with the concomitant administration of tacrolimus and nirmatrelvir/ritonavir.

A Comprehensive Review of the Clinical Pharmacokinetics, Pharmacodynamics, and Drug Interactions of Nirmatrelvir/Ritonavir

Nirmatrelvir is a potent and selective inhibitor of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) main protease that is used as an oral antiviral coronavirus disease 2019 (COVID-19) treatment. To sustain unbound systemic trough concentrations above the antiviral in vitro 90% effective concentration value (EC90), nirmatrelvir is coadministered with 100 mg of ritonavir, a pharmacokinetic enhancer. Ritonavir inhibits nirmatrelvir's cytochrome P450 (CYP) 3A4-mediated metabolism which results in renal elimination becoming the primary route of nirmatrelvir elimination when dosed concomitantly. Nirmatrelvir exhibits absorption-limited nonlinear pharmacokinetics. When coadministered with ritonavir in patients with mild-to-moderate COVID-19, nirmatrelvir reaches a maximum concentration of 3.43 µg/mL (11.7× EC90) in approximately 3 h on day 5 of dosing, with a geometric mean day 5 trough concentration of 1.57 µg/mL (5.4× EC90). Drug interactions with nirmatrelvir/ritonavir (PAXLOVIDTM) are primarily attributed to ritonavir-mediated CYP3A4 inhibition, and to a lesser extent CYP2D6 and P-glycoprotein inhibition. Population pharmacokinetics and quantitative systems pharmacology modeling support twice daily dosing of 300 mg/100 mg nirmatrelvir/ritonavir for 5 days, with a reduced 150 mg/100 mg dose for patients with moderate renal impairment. Rapid clinical development of nirmatrelvir/ritonavir in response to the emerging COVID-19 pandemic was enabled by innovations in clinical pharmacology research, including an adaptive phase 1 trial design allowing direct to pivotal phase 3 development, fluorine nuclear magnetic resonance spectroscopy to delineate absorption, distribution, metabolism, and excretion profiles, and innovative applications of model-informed drug development to accelerate development.

A model-based pharmacokinetic assessment of drug-drug interaction between tacrolimus and nirmatrelvir/ritonavir in a kidney transplant patient with COVID-19

We experienced a patient with a remarkable and prolonged increase in tacrolimus blood concentrations when nirmatrelvir/ritonavir was concomitantly used. The inhibitory intensity and duration of nirmatrelvir/ritonavir on tacrolimus pharmacokinetics were examined using a model-based analysis. A renal transplant patient taking oral tacrolimus continuously was treated with nirmatrelvir/ritonavir for 5 days. The baseline tacrolimus trough blood concentration was 4.2 ng/mL. Tacrolimus was discontinued on Day 6 after the concomitant administration of nirmatrelvir/ritonavir, and the trough concentration increased to 96.4 ng/mL on Day 7. The model-based analysis showed that tacrolimus clearance decreased to 35% and bioavailability increased by 18.7-fold after the coadministration of nirmatrelvir/ritonavir, compared with before the coadministration. Therefore, nirmatrelvir/ritonavir drastically decreased both the apparent clearance and apparent volume of distribution. Simulated tacrolimus concentrations could be best fitted to the observed concentrations when the inhibitory effects of nirmatrelvir/ritonavir were modeled to disappear over about 10 days by first-order elimination. In conclusion, nirmatrelvir/ritonavir greatly increases tacrolimus concentrations by not only reducing clearance, but also increasing bioavailability. Interactions between nirmatrelvir/ritonavir and low-bioavailability drugs which are substrates for CYP3A and P-glycoprotein, such as tacrolimus, are harmful, and concomitant use of these medicines should be avoided.

Metabolic and toxicological considerations regarding CGRP mAbs and CGRP antagonists to treat migraine in COVID-19 patients: a narrative review

INTRODUCTION

Migraine pharmacological therapies targeting calcitonin gene-related peptide (CGRP), including monoclonal antibodies and gepants, have shown clinical effect and optimal tolerability. Interactions between treatments of COVID-19 and CGRP-related drugs have not been reviewed.

AREAS COVERED

An overview of CGRP, a description of the characteristics of each CGRP-related drug and its response predictors, COVID-19 and its treatment, the interactions between CGRP-related drugs and COVID-19 treatment, COVID-19 and vaccination-induced headache, and the neurological consequences of Covid-19.

EXPERT OPINION

Clinicians should be careful about using gepants for COVID-19 patients, due to the potential drug interactions with drugs metabolized via CYP3A4 cytochrome. In particular, COVID-19 treatment (especially nirmatrelvir packaged with ritonavir, as Paxlovid) should be considered cautiously. It is advisable to stop or adjust the dose (10 mg atogepant when used for episodic migraine) of gepants when using Paxlovid (except for zavegepant). CGRP moncolconal antibodies (CGRP-mAbs) do not have drug - drug interactions, but a few days' interval between a COVID-19 vaccination and the use of CGRP mAbs is recommended to allow the accurate identification of the possible adverse effects, such as injection site reaction. Covid-19- and vaccination-related headache are known to occur. Whether CGRP-related drugs would be of benefit in these circumstances is not yet known.

Potential drug-drug interactions among U.S. adults treated with nirmatrelvir/ritonavir: A cross-sectional study of the National Covid Cohort Collaborative (N3C)

STUDY OBJECTIVE

To estimate the prevalence of potential moderate to severe drug-drug interactions (DDIs) involving nirmatrelvir/ritonavir, identify interacting medications, and evaluate risk factors associated with potential DDIs.

DESIGN

Cross-sectional study.

DATA SOURCE

Electronic health records from the National COVID Cohort Collaborative Enclave, one of the largest COVID-19 data resources in the United States.

PATIENTS

Outpatients aged ≥18 years and started nirmatrelvir/ritonavir between December 23, 2021 and March 31, 2022.

INTERVENTION

Nirmatrelvir/ritonavir.

MEASUREMENTS

The outcome is potential moderate to severe DDIs, defined as starting interacting medications reported by National Institutes of Health 30 days before or 10 days after starting nirmatrelvir/ritonavir.

MAIN RESULTS

Of 3214 outpatients who started nirmatrelvir/ritonavir, the mean age was 56.8 ± 17.1 years, 39.5% were male, and 65.8% were non-Hispanic white. Overall, 521 (16.2%) were potentially exposed to at least one moderate to severe DDI, most commonly to atorvastatin (19.2% of all DDIs), hydrocodone (14.0%), or oxycodone (14.0%). After adjustment for covariates, potential DDIs were more likely among individuals who were older (odds ratio [OR] 1.16 per 10-year increase, 95% confidence interval [CI] 1.08-1.25), male (OR 1.36, CI 1.09-1.71), smokers (OR 1.38, CI 1.10-1.73), on more co-medications (OR 1.35, CI 1.31-1.39), and with a history of solid organ transplant (OR 3.63, CI 2.05-6.45).

CONCLUSIONS

One in six of individuals receiving nirmatrelvir/ritonavir were at risk of a potential moderate or severe DDI, underscoring the importance of clinical and pharmacy systems to mitigate such risks.

An update on drug-drug interactions for care of the acutely ill in the era of COVID-19

PURPOSE

To provide key pharmacological concepts underlying drug-drug interactions (DDIs), a decision-making framework, and a list of DDIs that should be considered in the context of contemporary acutely ill patients with COVID-19.

SUMMARY

DDIs are frequently encountered in the acutely ill. The implications of DDIs include either increased risk of drug toxicity or decreased effectiveness, which may have severe consequences in the acutely ill due to lower physiological and neurocognitive reserves in these patients. In addition, an array of additional therapies and drug classes have been used for COVID-19 that were not typically used in the acute care setting. In this update on DDIs in the acutely ill, we provide key pharmacological concepts underlying DDIs, including a discussion of the gastric environment, the cytochrome P-450 (CYP) isozyme system, transporters, and pharmacodynamics in relation to DDIs. We also provide a decision-making framework that elucidates the identification of DDIs, risk assessment, selection of alternative therapies, and monitoring. Finally, important DDIs pertaining to contemporary acute care clinical practice related to COVID-19 are discussed.

CONCLUSION

Interpreting and managing DDIs should follow a pharmacologically based approach and a systematic decision-making process to optimize patient outcomes.

Real-World Evidence of the Top 100 Prescribed Drugs in the USA and Their Potential for Drug Interactions with Nirmatrelvir; Ritonavir

Nirmatrelvir (coadministered with ritonavir as PAXLOVIDTM) reduces the risk of COVID-19-related hospitalizations and all-cause death in individuals with mild-to-moderate COVID-19 at high risk of progression to severe disease. Ritonavir is coadministered as a pharmacokinetic enhancer. However, ritonavir may cause drug-drug interactions (DDIs) due to its interactions with various drug-metabolizing enzymes and transporters, including cytochrome P450 (CYP) 3A, CYP2D6, and P-glycoprotein transporters. To better understand the extent of DDIs (or lack thereof) of nirmatrelvir; ritonavir in a clinical setting, this study used real-world evidence (RWE) from the Optum Clinformatics Data Mart database to identify the top 100 drugs most commonly prescribed to US patients at high risk of progression to severe COVID-19 disease. The top 100 drugs were identified based on total counts associated with drugs prescribed to high-risk patients (i.e.,  ≥ 1 medical condition associated with an increased risk of severe COVID-19) who were continuously enrolled in the database throughout 2019 and had  ≥ 1 prescription claim. Each of the 100 drugs was then assessed for DDI risk based on their metabolism, excretion, and transport pathways identified from available US prescribing and medical literature sources. Seventy drugs identified were not expected to have DDIs with nirmatrelvir; ritonavir, including many cardiovascular agents, anti-infectives, antidiabetic agents, and antidepressants. Conversely, 30 drugs, including corticosteroids, narcotic analgesics, anticoagulants, statins, and sedatives/hypnotics, were expected to cause DDIs with nirmatrelvir; ritonavir. This RWE analysis is complementary to the prescribing information and other DDI management tools for guiding healthcare providers in managing DDIs.

Management and Outcome of COVID-19 Infection Using Nirmatrelvir/Ritonavir in Kidney Transplant Patients

BACKGROUND

Nirmatrelvir/ritonavir has been shown to reduce the risk of coronavirus disease 2019 (COVID-19)-related complications in patients at high risk for severe COVID-19. However, clinical experience of nirmatrelvir/ritonavir in the transplant recipient population is scattered due to the complex management of drug-drug interactions with calcineurin inhibitors. We describe the clinical experience with nirmatrelvir/ritonavir at The Ottawa Hospital kidney transplant program.

METHODS

Patients who received nirmatrelvir/ritonavir between April and June 2022 were included and followed up to 30 days after completion of treatment. Tacrolimus was withheld for 24 hours and resumed 72 hours after the last dose of nirmatrelvir/ritonavir (on day 8) on the basis of the drug level the day before. The first 30 patients had their dose adjusted according to drug levels performed twice in the first week and as needed thereafter. Subsequently, a simplified algorithm with less frequent calcineurin inhibitor-level monitoring was implemented. Outcomes, including tacrolimus-level changes, serum creatinine and AKI (defined as serum creatinine increase by 30%), and clinical outcomes were described globally and compared between algorithms.

RESULTS

Fifty-one patients received nirmatrelvir/ritonavir. Tacrolimus levels drawn at the first time point, 7 days after withholding of calcineurin inhibitor, and 2 days after discontinuing nirmatrelvir/ritonavir were within the therapeutic target in 17/44 (39%), subtherapeutic in 21/44 (48%), and supratherapeutic in 6/44 (14%). Two weeks after, 55% were within the therapeutic range, 23% were below, and 23% were above it. The standard and simplified algorithms provided similar tacrolimus level (median 5.2 [4.0-6.2] µg/L versus 4.8 [4.3-5.7] µg/L, P = 0.70). There were no acute rejections or other complications.

CONCLUSIONS

Withholding tacrolimus starting the day before initiation of nirmatrelvir/ritonavir with resumption 3 days after completion of therapy resulted in a low incidence of supratherapeutic levels but a short period of subtherapeutic levels for many patients. AKI was infrequent. The data are limited by the small sample size and short follow-up.

PODCAST

This article contains a podcast at https://dts.podtrac.com/redirect.mp3/www.asn-online.org/media/podcast/CJASN/2023_07_10_CJN0000000000000186.mp3.

Case Report: tacrolimus toxicity in the setting of concurrent Paxlovid use in a heart-transplant recipient

Background

Tacrolimus toxicity in patient's status post-orthotropic heart transplantation is not commonly reported. Given its narrow therapeutic window and drug-drug interactions, it must be closely monitored by providers who are experienced in transplant management. There are no case series of patients with tacrolimus toxicity in the setting of treatment for Sars-2-CoV-19 (COVID 19) for heart-transplant recipients. We present a case of tacrolimus toxicity in the setting of concurrent ritonavir-nirmatrelvir (Paxlovid) use.

Case summary

The patient was a 74-year-old male with a prior significant history of heart transplantation and on maintenance immunosuppression with tacrolimus. He contracted COVID-19 and was prescribed antiviral therapy with Paxlovid by an outside provider prior to admission. The patient complained of severe headaches, dehydration, and tremors. After eliminating acute intracranial processes with imaging, laboratory investigation revealed a severely elevated tacrolimus level with acute renal injury. The patient was taken off tacrolimus and treated conservatively with intravenous hydration. The symptoms improved, particularly the headaches. He was discharged with instructions to resume his home dosing of tacrolimus and return to clinic in 1 week with a repeat trough level. The subsequent trough level was no longer supra-therapeutic.

Discussion

Tacrolimus has a potent drug-drug interaction with Paxlovid (ritonavir-nirmatrelvir) and can be supra-therapeutic. Toxicity is associated with multiple adverse effects, including but not limited to, acute renal injury, neurotoxicity, and infections due to over-immunosuppression. As Paxlovid is effective in treating Sars-2-CoV-19 in heart-transplant recipients, knowledge and understanding of drug-drug interactions is crucial in preventing and mitigating toxicity.

Optimizing the use of nirmatrelvir/ritonavir in solid organ transplant recipients with COVID-19: A review of immunosuppressant adjustment strategies

The coronavirus disease 2019 (COVID-19) pandemic has caused a significant burden of morbidity and mortality worldwide, with solid organ transplant recipients (SOTRs) being particularly vulnerable. Nirmatrelvir and ritonavir have demonstrated the potential for reducing the risk of hospitalization and death in patients with mild-to-moderate COVID-19. However, ritonavir has a strong drug–drug interaction with CYP3A-dependent drugs such as calcineurin inhibitors, potentially leading to rapid increases in blood concentration. As SOTRs are commonly prescribed immunosuppressants, co-administration with nirmatrelvir/ritonavir requires careful consideration. To address this issue, we conducted a literature review to evaluate the use and adverse effects of nirmatrelvir/ritonavir in SOTRs and explore feasible immunosuppressant adjustment regimens. Our findings suggest that nirmatrelvir/ritonavir could be a feasible treatment option for COVID-19 in SOTRs, provided that appropriate immunosuppressive drug management is in place during co-administration. Although prescribing the novel anti-SARS-CoV-2 drug to transplant recipients poses challenges, potential strategies to overcome these issues are discussed. Further studies are needed to determine the optimal dosing strategies of nirmatrelvir/ritonavir, immunosuppressant adjustment, and monitoring in this patient population.

A case report of a prolonged decrease in tacrolimus clearance due to co-administration of nirmatrelvir/ritonavir in a lung transplant recipient receiving itraconazole prophylaxis

BACKGROUND

Drug-drug interaction management is complex. Nirmatrelvir/ritonavir is a potent cytochrome P450 (CYP) 3A inhibitor and influences pharmacokinetics of co-administered drugs. Although there are several reports about drug-drug interactions of nirmatrelvir/ritonavir, an influence of a concomitant use of nirmatrelvir/ritonavir and another potent CYP3A inhibitor on tacrolimus remains unclear. Here, we experienced a lung transplant patient with the novel coronavirus disease 2019 (COVID-19). In this patient, nirmatrelvir/ritonavir was administered, and the inhibitory effect of itraconazole on CYP3A was prolonged.

CASE PRESENTATION

We present a case in forties who had undergone lung transplantation. He was administered itraconazole and tacrolimus 1.0 mg/d, with a trough value of 8-12 ng/mL. The patient contracted the COVID-19, and a nirmatrelvir/ritonavir treatment was initiated. During the antiviral treatment, tacrolimus administration was discontinued for 5 d. Tacrolimus was resumed at 1.0 mg/d after completion of the nirmatrelvir/ritonavir treatment, but the trough value after 7 d was high at 31.6 ng/mL. Subsequently, the patient was placed on another 36-h tacrolimus discontinuation, but the trough value decreased to only 16.0 ng/mL.

CONCLUSIONS

Co-administration of ritonavir caused a prolonged decrease in tacrolimus clearance through its inhibitory effects on CYP3A in a patient taking itraconazole. Management of drug-drug interaction by pharmacists can be important for patients with multiple medications.

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.

Paradoxical interaction between nirmatrelvir/ritonavir and voriconazole in a patient with COVID-19

This case is based on a drug interaction between nirmatrelvir/ritonavir (approved drug for COVID-19) and voriconazole is presented, possibly derived from the bidirectional effect of ritonavir on the 2 main voriconazole metabolising enzymes (cytochrome P450 3A and 2C19) ritonavir inhibits the former and induces the latter respectively. According to the main pharmacotherapeutic information databases, in the interaction between both drugs, a decrease in the area under the curve of voriconazole is expected due to the. inducing effect of its metabolism; however, in the case we present, unexpectedly, a paradoxical effect occurs, according to what is described in literature, with the result of sustained supratherapeutic levels of voriconazole. Given the short treatment period with nirmatrelvir/ritonavir (5 days), the induction effect of ritonavir proposed in the studies on which the recommendations are based, where treatment with ritonavir is longer, does not occur.

Drug interactions between common dermatological medications and the oral anti-COVID-19 agents nirmatrelvir-ritonavir and molnupiravir

Introduction: The oral antiviral agents nirmatrelvir-ritonavir (NMV/r) and molnupiravir are used to treat mild-to-moderate COVID-19 infection in outpatients. However, the use of NMV/r is complicated by significant drug-drug interactions (DDIs) with frequently prescribed medications. Healthcare professionals should be aware of the possible risk of DDIs, given the emergence of COVID-19 variants and the widespread use of oral COVID-19 treatments. We reviewed available data on DDIs between NMV/r, molnupiravir and common dermatological medications; summarised the potential side effects; and suggest strategies for safe COVID-19 treatment. Method: A systematic review using PubMed was conducted on data published from inception to 18 July 2022 to find clinical outcomes of DDIs between NMV/r, molnupiravir and dermatological medications. We also searched the Lexicomp, Micromedex, Liverpool COVID-19 Drug Interactions database and the National Institutes of Health COVID-19 Treatment Guidelines for interactions between NMV/r and molnupiravir, and commonly used dermatological medications. Results: NMV/r containing the cytochrome P-450 (CYP) 3A4 inhibitor ritonavir has DDIs with other medications similarly dependent on CYP3A4 metabolism. Dermatological medications that have DDIs with NMV/r include rifampicin, clofazimine, clarithromycin, erythromycin, clindamycin, itraconazole, ketoconazole, fluconazole, bilastine, rupatadine, dutasteride, ciclosporin, cyclophosphamide, tofacitinib, upadacitinib, colchicine and systemic glucocorticoids. With no potential DDI identified yet in in vitro studies, molnupiravir may be an alternative COVID-19 therapy in patients taking medications that have complicated interactions with NMV/r, which cannot be stopped or dose adjusted. Conclusion: NMV/r has significant DDIs with many common dermatological medications, which may require temporary discontinuation, dosage adjustment or substitution with other anti-COVID-19 agents such as molnupiravir. Keywords: COVID-19, dermatology, drug interactions, molnupiravir, nirmatrelvir-ritonavir, pharmacology

Recommendations for the Management of Drug-Drug Interactions Between the COVID-19 Antiviral Nirmatrelvir/Ritonavir (Paxlovid) and Comedications

The coronavirus disease 2019 (COVID-19) antiviral nirmatrelvir/ritonavir (Paxlovid) has been granted authorization or approval in several countries for the treatment of patients with mild to moderate COVID-19 at high risk of progression to severe disease and with no requirement for supplemental oxygen. Nirmatrelvir/ritonavir will be primarily administered outside the hospital setting as a 5-day course oral treatment. The ritonavir component boosts plasma concentrations of nirmatrelvir through the potent and rapid inhibition of the key drug-metabolizing enzyme cytochrome P450 (CYP) 3A4. Thus nirmatrelvir/ritonavir, even given as a short treatment course, has a high potential to cause harm from drug-drug interactions (DDIs) with other drugs metabolized through this pathway. Options for mitigating risk from DDIs with nirmatrelvir/ritonavir are limited due to the clinical illness, the short window for intervention, and the related difficulty of implementing clinical monitoring or dosage adjustment of the comedication. Pragmatic options are largely confined to preemptive or symptom-driven pausing of the comedication or managing any additional risk through counseling. This review summarizes the effects of ritonavir on drug disposition (i.e., metabolizing enzymes and transporters) and discusses factors determining the likelihood of having a clinically significant DDI. Furthermore, it provides a comprehensive list of comedications likely to be used in COVID-19 patients which are categorized according to their potential DDI risk with nirmatrelvir/ritonavir. It also discusses recommendations for the management of DDIs which balance the risk of harm from DDIs with a short course of ritonavir, against unnecessary denial of nirmatrelvir/ritonavir treatment.

Nirmatrelvir/ritonavir Use With Tacrolimus in Lung Transplant Recipients: A Single-center Case Series

BACKGROUND

Limited data and guidelines exist for using nirmatrelvir/ritonavir in solid organ transplant recipients stabilized on tacrolimus for the treatment of mild-to-moderate coronavirus disease. Concern exists regarding the impact of utilizing a 5-d course of nirmatrelvir/ritonavir with calcineurin inhibitors because of significant drug-drug interactions between ritonavir, a potent cytochrome P450 3A inhibitor, and other cytochrome P450 3A substrates, such as tacrolimus.

METHODS

We report the successful use of nirmatrelvir/ritonavir in 12 outpatient lung transplant recipients with confirmed severe acute respiratory syndrome coronavirus 2 infection stabilized on tacrolimus immunosuppression. All patients stopped tacrolimus and started nirmatrelvir/ritonavir 10 to 14 h after the last dose of tacrolimus. Tacrolimus was withheld and then reinitiated at a modified dose 48 h following the completion of nirmatrelvir/ritonavir therapy. Tacrolimus trough levels were checked during nirmatrelvir/ritonavir therapy and tacrolimus reinitiation.

RESULTS

Ten (10/12) patients were able to resume their original tacrolimus dose within 4 d of completing nirmatrelvir/ritonavir therapy and maintain therapeutic levels of tacrolimus. No patients experienced tacrolimus toxicity or acute rejection during the 30-d postcompletion of nirmatrelvir/ritonavir therapy.

CONCLUSIONS

In this cohort of lung transplant recipients on tacrolimus, we demonstrated that nirmatrelvir/ritonavir can be safely used with close monitoring of tacrolimus levels and appropriate dose adjustments of tacrolimus. Further confirmatory studies are needed to determine the appropriate use of therapeutic drug monitoring and tacrolimus dose following completion of nirmatrelvir/ritonavir in the solid organ transplant population.

Managing Covid-19 in patients with heart failure: current status and future prospects

INTRODUCTION

COVID-19 may contribute to decompensation of previously stable chronic HF or cause a de-novo heart failure, which may come from the hyperinflammatory response and subsequent increase in metabolic demand.

AREAS COVERED

Two independent investigators searched MEDLINE (via PubMed), Europe PMC, and ScienceDirect databases with the following search terms: COVID-19, heart failure, COVID-19 drugs, heart failure drugs, and device therapy. All of the included full-text articles were rigorously evaluated by both authors in case there was disagreement about whether research should be included or not. In total, 157 studies were included and underwent extensive reading by the authors.

EXPERT OPINION

The World Health Organization (WHO) and the National Institute of Health (NIH) have published COVID-19 drug recommendations, although recommendations for HF-specific drug choices in COVID-19 are still lacking. We hope that this review can answer the void of comprehensive research data regarding the management options of HF in the COVID-19 condition so that clinicians can at least choose a more beneficial therapy or avoid combination therapies that have a high burden of side effects on HF; thus, morbidity and mortality in COVID-19 patients with HF may be reduced.

Assessing the proportion of the Danish population at risk of clinically significant drug-drug interactions with new oral antivirals for early treatment of COVID-19

OBJECTIVES

The oral antiviral drugs nirmatrelvir/ritonavir (NMV/r) and molnupiravir have been approved for early outpatient treatment of COVID-19 to prevent severe disease. Ritonavir, contained in NMV/r, is known to have significant drug-drug interactions (DDI) with several drugs frequently used by the elderly. This communication puts the problem with DDI with oral antiviral COVID-19 treatment into perspective by assessing the percentage of the elderly population at risk of severe COVID-19, using drugs with significant DDI with oral antivirals.

METHODS

We estimated the size of the Danish population at risk of significant DDI with antiviral COVID-19 treatment using the number of claimed prescriptions for drugs predicted to interact with NMV/r in Denmark in 2020.

RESULTS

Danish prescription data demonstrate the extensive use of drugs likely to interact with NMV/r. Anticoagulants contraindicated during NMV/r treatment were used by 20% of people ≥65 years and 30% of people ≥80 years. Statins that must be paused during NMV/r treatment were used by 15-18%. More than one in five used either analgesics, calcium channel blockers, or digoxin.

CONCLUSION

There is major potential for significant DDI with NMV/r in the elderly population at risk of severe COVID-19 disease. This calls for clear guidance for prescribers to ensure patient safety and treatment success.

Clinically Relevant Interactions Between Ritonavir-Boosted Nirmatrelvir and Concomitant Antiseizure Medications: Implications for the Management of COVID-19 in Patients with Epilepsy

Ritonavir-boosted nirmatrelvir (RBN) has been authorized recently in several countries as an orally active anti-SARS-CoV-2 treatment for patients at high risk of progressing to severe COVID-19 disease. Nirmatrelvir is the active component against the SARS-CoV-2 virus, whereas ritonavir, a potent CYP3A inhibitor, is intended to boost the activity of nirmatrelvir by increasing its concentration in plasma to ensure persistence of antiviral concentrations during the 12-hour dosing interval. RBN is involved in many clinically important drug–drug interactions both as perpetrator and as victim, which can complicate its use in patients treated with antiseizure medications (ASMs). Interactions between RBN and ASMs are bidirectional. As perpetrator, RBN may increase the plasma concentration of a number of ASMs that are CYP3A4 substrates, possibly leading to toxicity. As victims, both nirmatrelvir and ritonavir are subject to metabolic induction by concomitant treatment with potent enzyme-inducing ASMs (carbamazepine, phenytoin, phenobarbital and primidone). According to US and European prescribing information, treatment with these ASMs is a contraindication to the use of RBN. Although remdesivir is a valuable alternative to RBN, it may not be readily accessible in some settings due to cost and/or need for intravenous administration. If remdesivir is not an appropriate option, either bebtelovimab or molnupiravir may be considered. However, evidence about the clinical efficacy of bebtelovimab is still limited, and molnupiravir, the only orally active alternative, is deemed to have appreciably lower efficacy than RBN and remdesivir.

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.

Prescribing Nirmatrelvir-Ritonavir: How to Recognize and Manage Drug-Drug Interactions

Nirmatrelvir–ritonavir (NMV/r) is now being used to treat high-risk patients with mild to moderate COVID-19. This article provides advice to clinicians regarding recognition of medications likely to interact with NMV/r and suggests approaches to managing such drug–drug interactions. An algorithm is provided to assist in decision making.

Foerster K, Terstegen T, Vogt C, Said A, Schulz M, E. Haefeli W. Oral Drugs Against COVID-19

BACKGROUND

Five-day oral therapies against early COVID-19 infection have recently been conditionally approved in Europe. In the drug combination nirmatrelvir + ritonavir (nirmatrelvir/r), the active agent, nirmatrelvir, is made bioavailable in clinically adequate amounts by the additional administration of a potent inhibitor of its first-pass metabolism by way of cytochrome P450 [CYP] 3A in the gut and liver. In view of the central role of CYP3A in the clearance of many different kinds of drugs, and the fact that many patients with COVID-19 are taking multiple drugs to treat other conditions, it is important to assess the potential for drug interactions when nirmatrelvir/r is given, and to minimize the risks associated with such interactions.

METHODS

We defined the interaction profile of ritonavir on the basis of information derived from two databases (Medline, GoogleScholar), three standard electronic texts on drug interactions, and manufacturer-supplied drug information. We compiled a list of drugs and their potentially relevant interactions, developed a risk min - imization algorithm, and applied it to the substances in question. We also compiled a list of commonly prescribed drugs for which there is no risk of interaction with nirmatrelvir/r.

RESULTS

Out of 190 drugs and drug combinations, 57 do not need any special measures when given in combination with brief, low-dose ritonavir treatment, while 15 require dose modification or a therapeutic alternative, 8 can be temporarily discontinued, 9 contraindicate ritonavir use, and 102 should preferably be combined with a different treatment.

CONCLUSION

We have proposed measures that are simple to carry out for the main types of drug that can interact with ritonavir. These measures can be implemented under quarantine conditions before starting a 5-day treatment with nirmatrelvir/r.

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.

Using nirmatrelvir/ritonavir in patients with epilepsy: an update from the Israeli ILAE Chapter

Presented herein are recommendations for use of nirmatrelvir/ritonavir in patients with epilepsy, as issued by the Steering Committee of the Israeli chapter of the International League Against Epilepsy. The recommendations suggest that patients on moderate‐to‐strong enzyme‐inducing antiseizure medications (ASMs) and everolimus should not be treated with nirmatrelvir/ritonavir; rectal diazepam may be used as an alternative to buccal midazolam; doses of ASMs that are cytochrome P450 (CYP3A4) substrates might be adjusted; and patients treated with combinations of nirmatrelvir/ritonavir and ASMs that are CYP3A4 substrates or lamotrigine should be monitored for drug efficacy and adverse drug reactions.

Global Genomic Analysis of SARS-CoV-2 RNA Dependent RNA Polymerase Evolution and Antiviral Drug Resistance

A variety of antiviral treatments for COVID-19 have been investigated, involving many repurposed drugs. Currently, the SARS-CoV-2 RNA-dependent RNA polymerase (RdRp, encoded by nsp12-nsp7-nsp8) has been targeted by numerous inhibitors, e.g., remdesivir, the only provisionally approved treatment to-date, although the clinical impact of these interventions remains inconclusive. However, the potential emergence of antiviral resistance poses a threat to the efficacy of any successful therapies on a wide scale. Here, we propose a framework to monitor the emergence of antiviral resistance, and as a proof of concept, we address the interaction between RdRp and remdesivir. We show that SARS-CoV-2 RdRp is under purifying selection, that potential escape mutations are rare in circulating lineages, and that those mutations, where present, do not destabilise RdRp. In more than 56,000 viral genomes from 105 countries from the first pandemic wave, we found negative selective pressure affecting nsp12 (Tajima’s D = −2.62), with potential antiviral escape mutations in only 0.3% of sequenced genomes. Potential escape mutations included known key residues, such as Nsp12:Val473 and Nsp12:Arg555. Of the potential escape mutations involved globally, in silico structural models found that they were unlikely to be associated with loss of stability in RdRp. No potential escape mutation was found in a local cohort of remdesivir treated patients. Collectively, these findings indicate that RdRp is a suitable drug target, and that remdesivir does not seem to exert high selective pressure. We anticipate our framework to be the starting point of a larger effort for a global monitoring of drug resistance throughout the COVID-19 pandemic.

Drug interactions: a review of the unseen danger of experimental COVID-19 therapies

As global health services respond to the coronavirus pandemic, many prescribers are turning to experimental drugs. This review aims to assess the risk of drug-drug interactions in the severely ill COVID-19 patient. Experimental therapies were identified by searching ClinicalTrials.gov for 'COVID-19', '2019-nCoV', '2019 novel coronavirus' and 'SARS-CoV-2'. The last search was performed on 30 June 2020. Herbal medicines, blood-derived products and in vitro studies were excluded. We identified comorbidities by searching PubMed for the MeSH terms 'COVID-19', 'Comorbidity' and 'Epidemiological Factors'. Potential drug-drug interactions were evaluated according to known pharmacokinetics, overlapping toxicities and QT risk. Drug-drug interactions were graded GREEN and YELLOW: no clinically significant interaction; AMBER: caution; RED: serious risk. A total of 2378 records were retrieved from ClinicalTrials.gov, which yielded 249 drugs that met inclusion criteria. Thirteen primary compounds were screened against 512 comedications. A full database of these interactions is available at www.covid19-druginteractions.org. Experimental therapies for COVID-19 present a risk of drug-drug interactions, with lopinavir/ritonavir (10% RED, 41% AMBER; mainly a perpetrator of pharmacokinetic interactions but also risk of QT prolongation particularly when given with concomitant drugs that can prolong QT), chloroquine and hydroxychloroquine (both 7% RED and 27% AMBER, victims of some interactions due to metabolic profile but also perpetrators of QT prolongation) posing the greatest risk. With management, these risks can be mitigated. We have published a drug-drug interaction resource to facilitate medication review for the critically ill patient.

Multicenter Interim Guidance on Use of Antivirals for Children With Coronavirus Disease 2019/Severe Acute Respiratory Syndrome Coronavirus 2

BACKGROUND

Although coronavirus disease 2019 (COVID-19) is a mild infection in most children, a small proportion develop severe or critical illness. Data describing agents with potential antiviral activity continue to expand such that updated guidance is needed regarding use of these agents in children.

METHODS

A panel of pediatric infectious diseases physicians and pharmacists from 20 geographically diverse North American institutions was convened. Through a series of teleconferences and web-based surveys, a set of guidance statements was developed and refined based on review of the best available evidence and expert opinion.

RESULTS

Given the typically mild course of COVID-19 in children, supportive care alone is suggested for most cases. For children with severe illness, defined as a supplemental oxygen requirement without need for noninvasive or invasive mechanical ventilation or extracorporeal membrane oxygenation (ECMO), remdesivir is suggested, preferably as part of a clinical trial if available. Remdesivir should also be considered for critically ill children requiring invasive or noninvasive mechanical ventilation or ECMO. A duration of 5 days is appropriate for most patients. The panel recommends against the use of hydroxychloroquine or lopinavir-ritonavir (or other protease inhibitors) for COVID-19 in children.

CONCLUSIONS

Antiviral therapy for COVID-19 is not necessary for the great majority of pediatric patients. For children with severe or critical disease, this guidance offers an approach for decision-making regarding use of remdesivir.

Effect of Systemic Inflammatory Response to SARS-CoV-2 on Lopinavir and Hydroxychloroquine Plasma Concentrations

Coronavirus disease 2019 (COVID-19) leads to inflammatory cytokine release, which can downregulate the expression of metabolizing enzymes. This cascade affects drug concentrations in the plasma. We investigated the association between lopinavir (LPV) and hydroxychloroquine (HCQ) plasma concentrations and the levels of the acute-phase inflammation marker C-reactive protein (CRP). LPV plasma concentrations in 92 patients hospitalized at our institution were prospectively collected. Lopinavir-ritonavir was administered every 12 hours, 800/200 mg on day 1 and 400/100 mg on day 2 until day 5 or 7. HCQ was given at 800 mg, followed by 400 mg after 6, 24, and 48 h. Hematological, liver, kidney, and inflammation laboratory values were analyzed on the day of drug level determination. The median age of study participants was 59 (range, 24 to 85) years, and 71% were male. The median durations from symptom onset to hospitalization and treatment initiation were 7 days (interquartile range [IQR], 4 to 10) and 8 days (IQR, 5 to 10), respectively. The median LPV trough concentration on day 3 of treatment was 26.5 μg/ml (IQR, 18.9 to 31.5). LPV plasma concentrations positively correlated with CRP values (r = 0.37, P < 0.001) and were significantly lower when tocilizumab was preadministered. No correlation was found between HCQ concentrations and CRP values. High LPV plasma concentrations were observed in COVID-19 patients. The ratio of calculated unbound drug fraction to published SARS-CoV-2 50% effective concentrations (EC₅₀) indicated insufficient LPV concentrations in the lung. CRP values significantly correlated with LPV but not HCQ plasma concentrations, implying inhibition of cytochrome P450 3A4 (CYP3A4) metabolism by inflammation.