Azvudine versus Paxlovid in COVID-19: A systematic review and meta-analysis.

This systematic review and meta-analysis aimed to compare the effectiveness and safety of azvudine versus nirmatrelvir/ritonavir (Paxlovid) in treating coronavirus disease 2019 (COVID-19). The researchers conducted searches on PubMed, Cochrane Library, Web of Science, medRxiv, and Google Scholar until January 2024. The Cochrane risk of bias tool was utilised to evaluate the quality of the included studies, and data analysis was performed using Comprehensive Meta-Analysis software. Thirteen studies, including 4949 patients, were analysed. The meta-analysis results showed no significant difference between the azvudine and Paxlovid groups in terms of mortality rate (odds rate [OR] = 0.84, 95% confidence interval [CI]: 0.59-1.21), negative polymerase chain reaction (PCR) conversion time (standard mean difference [SMD] = 1.52, 95% CI: -1.07-4.11), and hospital stay (SMD = -0.39, 95% CI: -1.12-0.33). However, a significant difference was observed between the two groups in terms of intensive care unit admission (OR = 0.42, 95% CI: 0.23-0.75) and the need for mechanical ventilation (OR = 0.61, 95% CI: 0.44-0.86) in favour of azvudine. The incidence of adverse events in the azvudine group was significantly lower (OR = 0.66, 95% CI: 0.43-0.99). The certainty of evidence was rated as low and moderate. Azvudine and Paxlovid demonstrated similar effectiveness in reducing mortality rates, negative PCR conversion time and hospital stay. However, azvudine showed better effectiveness in improving other outcomes. Regarding the level of certainty of evidence, further research is needed to validate or challenge these results.

Nirmatrelvir/Ritonavir Use and Hospitalizations or Death in a Previously Uninfected Nonhospitalized High-Risk Population With COVID-19: A Matched Cohort Study.

OBJECTIVE: To determine the association of nirmatrelvir/ritonavir (NMV/r) with hospitalization or death within 30 days as compared with untreated controls previously uninfected and nonhospitalized. METHODS: We used a matched cohort design using inverse probability of treatment weight (IPTW). Individuals prescribed NMV/r within 3 days of COVID-19 diagnosis were compared with IPTW-based untreated controls. Variables for IPTW included age, race, sex, body mass index, geographic location, vaccination status, and multiple comorbidities. Additional analyses were conducted on NMV/r-treated and propensity score-matched untreated controls. RESULTS: Among 7615 individuals prescribed NMV/r and 62 077 controls identified between 1 January 2022 and 25 February 2023, the risk of hospitalization/death was lower among NMV/r-treated persons vs untreated controls (243 vs 3468 events; absolute risk difference [ARD], -2.36 [95% CI, -2.57 to -2.14]). The difference was significant for those >60 and ≤60 years old (ARD, -3.86 [95% CI, -4.19 to -3.54] vs -0.27 [95% CI, -0.51 to -0.03]) and for persons asymptomatic and symptomatic (ARD, -7.09 [95% CI, -7.62 to -6.55] vs -1.46 [95% CI, -1.66 to -1.25]). Significant benefit was observed among individuals unvaccinated and vaccinated, with or without a booster dose. CONCLUSIONS: NMV/r is associated with a significant reduction in 30-day hospitalization or death among individuals previously uninfected and nonhospitalized.

Combined Treatment of Severe Acute Respiratory Syndrome Coronavirus 2 Reduces Molnupiravir-Induced Mutagenicity and Prevents Selection for Nirmatrelvir/Ritonavir Resistance Mutations.

We investigated the mutation profiles of severe acute respiratory syndrome coronavirus 2 in samples collected from a molnupiravir and nirmatrelvir/ritonavir combination therapy in macaques. We found that molnupiravir induced several nirmatrelvir resistance mutations at low abundance that were not further selected in combination therapy. Coadministration of nirmatrelvir/ritonavir lowered the magnitude of the mutagenetic effect of molnupiravir.

Persistence of an infectious form of SARS-CoV-2 post protease inhibitor treatment of permissive cells in vitro.

Reports have described SARS-CoV-2 rebound in COVID-19 patients treated with nirmatrelvir, a 3CL protease inhibitor. The cause remains a mystery, although drug resistance, re-infection, and lack of adequate immune responses have been excluded. We now present virologic findings that provide a clue to the cause of viral rebound, which occurs in ∼20% of the treated cases. Persistence of infectious SARS-CoV-2 was experimentally documented in vitro after treatment with nirmatrelvir or another 3CL protease inhibitor, but not with a polymerase inhibitor, remdesivir. This infectious form decayed slowly with a half-life of ∼1 day, suggesting that its persistence could outlive the treatment course to re-ignite SARS-CoV-2 infection as the drug is eliminated. Notably, extending nirmatrelvir treatment beyond 8 days abolished viral rebound in vitro. Our findings point in a particular direction for future investigation of virus persistence and offer a specific treatment recommendation that should be tested clinically.

Structural basis of nirmatrelvir and ensitrelvir activity against naturally occurring polymorphisms of the SARS-CoV-2 main protease.

SARS-CoV-2 is the causative agent of COVID-19. The main viral protease (Mpro) is an attractive target for antivirals. The clinically approved drug nirmatrelvir and the clinical candidate ensitrelvir have so far showed great potential for treatment of viral infection. However, the broad use of antivirals is often associated with resistance generation. Herein, we enzymatically characterized 14 naturally occurring Mpro polymorphisms that are close to the binding site of these antivirals. Nirmatrelvir retained its potency against most polymorphisms tested, while mutants G143S and Q189K were associated with diminished inhibition constants. For ensitrelvir, diminished inhibition constants were observed for polymorphisms M49I, G143S, and R188S, but not for Q189K, suggesting a distinct resistance profile between inhibitors. In addition, the crystal structures of selected polymorphisms revealed interactions that were critical for loss of potency. In conclusion, our data will assist the monitoring of potential resistant strains, support the design of combined therapy, as well as assist the development of the next generation of Mpro inhibitors.

Combined Protection of Vaccination and Nirmatrelvir-Ritonavir Against Hospitalization in Adults With COVID-19.

Among adults at risk for severe coronavirus disease 2019 (COVID-19), the lowest hospitalization rate was among those who received nirmatrelvir-ritonavir after 3 or more messenger RNA vaccine doses (adjusted hazard ratio, 0.22; 95% confidence interval, .19-.24). Eligible adults, including those previously vaccinated, should be considered for COVID-19 antiviral treatment.

Nirmatrelvir Resistance-de Novo E166V/L50V Mutations in an Immunocompromised Patient Treated With Prolonged Nirmatrelvir/Ritonavir Monotherapy Leading to Clinical and Virological Treatment Failure-a Case Report.

Resistance of SARS-CoV-2 to antivirals was shown to develop in immunocompromised individuals receiving remdesivir. We describe an immunocompromised patient who was treated with repeated and prolonged courses of nirmatrelvir and developed de-novo E166V/L50F mutations in the Mpro region. These mutations were associated with clinical and virological treatment failure.

Characteristics and Outcomes of US Veterans With Immunocompromised Conditions at High Risk of SARS-CoV-2 Infection With or Without Receipt of Oral Antiviral Agents.

OBJECTIVES: Molnupiravir and nirmatrelvir-ritonavir were the first oral antiviral agents to demonstrate reduced hospitalization or death in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but patients with immunocompromised conditions were not well-represented. The objective of this study was to characterize and compare the clinical outcomes of US veterans with immunocompromised conditions prescribed oral antivirals with those who did not receive oral antivirals for mild-to-moderate SARS-CoV-2 active infection. METHODS: This was a retrospective, observational, nationwide propensity-matched analysis of US veterans with immunocompromised conditions who developed documented SARS-CoV-2 infection. The primary outcome was the composite of any hospitalization or death within 30 days of diagnosis. Secondary outcomes included 30-day comparative rates of (1) any hospitalization, (2) death, (3) intensive care requirement, and (4) subset analyses of outcomes by oral antiviral used and vaccination status. RESULTS: The composite primary outcome was significantly lower in patients receiving oral antiviral therapy compared with those who did not (23/390 [5.9%] vs 57/390 [14.6%]; odds ratio, 0.37; 95% confidence interval, .22-.61). This difference was driven largely by fewer deaths in the oral antiviral group (1/390 [0.3%] vs 19/390 [4.9%]; odds ratio, 0.05; 95% confidence interval, .007-.38). There was no significant difference in rate of intensive care requirement. The composite outcome was improved in vaccinated patients (completing the first series or first booster dose) who received oral antiviral agents compared with those who did not receive oral antiviral agents. Compared with those prescribed nirmatrelvir-ritonavir, patients given molnupiravir were older, had a higher incidence of cautions/contraindications, greater prevalence of tobacco use, and more cardiovascular complications. CONCLUSIONS: Use of molnupiravir or nirmatrelvir-ritonavir was associated with lower incidences of hospitalization or death within 30 days of diagnosis in US veterans with immunocompromised conditions, regardless of vaccination status. These findings support the use of either oral antiviral in this patient population.

SARS-CoV-2 Antiviral Prescribing Gaps Among Nonhospitalized High-Risk Adults.

Within a multistate clinical cohort, SARS-CoV-2 antiviral prescribing patterns were evaluated from April 2022-June 2023 among nonhospitalized patients with SARS-CoV-2 with risk factors for severe COVID-19. Among 3247 adults, only 31.9% were prescribed an antiviral agent (87.6% nirmatrelvir/ritonavir, 11.9% molnupiravir, 0.5% remdesivir), highlighting the need to identify and address treatment barriers.

Identifying Veterans Who Benefit From Nirmatrelvir-Ritonavir: A Target Trial Emulation.

BACKGROUND: Nirmatrelvir-ritonavir is recommended for persons at risk for severe coronavirus disease 2019 (COVID-19) but remains underutilized. Information on which eligible groups are likely to benefit from treatment is needed. METHODS: We conducted a target trial emulation study in the Veterans Health Administration comparing nirmatrelvir-ritonavir treated versus matched untreated veterans at risk for severe COVID-19 who tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from April 2022 through March 2023. We measured incidence of any hospitalization or all-cause mortality at 30 days. Outcomes were measured for the entire cohort, as well as among subgroups defined by 30-day risk of death or hospitalization, estimated using an ensemble risk prediction model. RESULTS: Participants were 87% male with median age 66 years and 16% unvaccinated. Compared with matched untreated participants, those treated with nirmatrelvir-ritonavir (n = 24 205) had a lower 30-day risk for hospitalization (1.80% vs 2.30%; risk difference [RD], -0.50% points [95% confidence interval {CI}: -.69 to -.35]) and death (0.11% vs 0.30%; RD, -0.20 [95% CI: -.24 to -.13]). The greatest reductions in combined hospitalization or death were observed in the highest risk quartile (RD -2.85 [95% CI: -3.94 to -1.76]), immunocompromised persons (RD -1.91 [95% CI: -3.09 to -.74]), and persons aged ≥75 years (RD -1.16 [95% CI: -1.73 to -.59]). No reductions were observed in the 2 lowest risk quartiles or persons younger than 65 years. CONCLUSIONS: Nirmatrelvir-ritonavir was effective in reducing 30-day hospitalization and death in older veterans, those at highest predicted risk for severe outcomes, and immunocompromised groups. Benefit was not observed in younger veterans or groups at lower predicted risk for hospitalization and death.

Effectiveness of Vaccines and Antiviral Drugs in Preventing Severe and Fatal COVID-19, Hong Kong.

We compared the effectiveness and interactions of molnupiravir and nirmatrelvir/ritonavir and 2 vaccines, CoronaVac and Comirnaty, in a large population of inpatients with COVID-19 in Hong Kong. Both the oral antiviral drugs and vaccines were associated with lower risks for all-cause mortality and progression to serious/critical/fatal conditions (study outcomes). No significant interaction effects were observed between the antiviral drugs and vaccinations; their joint effects were additive. If antiviral drugs were prescribed within 5 days of confirmed COVID-19 diagnosis, usage was associated with lower risks for the target outcomes for patients >60, but not <60, years of age; no significant clinical benefit was found if prescribed beyond 5 days. Among patients >80 years of age, 3-4 doses of Comirnaty vaccine were associated with significantly lower risks for target outcomes. Policies should encourage COVID-19 vaccination, and oral antivirals should be made accessible to infected persons within 5 days of confirmed diagnosis.

Longitudinal outcomes of COVID-19 in solid organ transplant recipients from 2020 to 2023.

Data regarding coronavirus disease 2019 (COVID-19) outcomes in solid organ transplant recipients (SOTr) across severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) waves, including the impact of different measures, are lacking. This cohort study, conducted from March 2020 to May 2023 in Toronto, Canada, aimed to analyze COVID-19 outcomes in 1975 SOTr across various SARS-CoV-2 waves and assess the impact of preventive and treatment measures. The primary outcome was severe COVID-19, defined as requiring supplemental oxygen, with secondary outcomes including hospitalization, length of stay, intensive care unit (ICU) admission, and 30-day and 1-year all-cause mortality. SARS-CoV-2 waves were categorized as Wildtype/Alpha/Delta (318 cases, 16.1%), Omicron BA.1 (268, 26.2%), Omicron BA.2 (268, 13.6%), Omicron BA.5 (561, 28.4%), Omicron BQ.1.1 (188, 9.5%), and Omicron XBB.1.5 (123, 6.2%). Severe COVID-19 rate was highest during the Wildtype/Alpha/Delta wave (44.6%), and lower in Omicron waves (5.7%-16.1%). Lung transplantation was associated with severe COVID-19 (OR: 4.62, 95% CI: 2.71-7.89), along with rituximab treatment (OR: 4.24, 95% CI: 1.04-17.3), long-term corticosteroid use (OR: 3.11, 95% CI: 1.46-6.62), older age (OR: 1.51, 95% CI: 1.30-1.76), chronic lung disease (OR: 2.11, 95% CI: 1.36-3.30), chronic kidney disease (OR: 2.18, 95% CI: 1.17-4.07), and diabetes (OR: 1.97, 95% CI: 1.37-2.83). Early treatment and ≥3 vaccine doses were associated with reduced severity (OR: 0.29, 95% CI: 0.19-0.46, and 0.35, 95% CI: 0.21-0.60, respectively). Tixagevimab/cilgavimab and bivalent boosters did not show a significant impact. The study concludes that COVID-19 severity decreased across different variants in SOTr. Lung transplantation was associated with worse outcomes and may benefit more from preventive and early therapeutic interventions.

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.

Resistance-associated mutations to the anti-SARS-CoV-2 agent nirmatrelvir: Selection not induction.

Mutations associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) resistance to antiprotease nirmatrelvir were reported. We aimed to detect them in SARS-CoV-2 genomes and quasispecies retrieved in our institute before drug availability in January 2022 and to analyze the impact of mutations on protease (3CLpro) structure. We sought for 38 3CLpro nirmatrelvir resistance mutations in a set of 62 673 SARS-CoV-2 genomes obtained in our institute from respiratory samples collected between 2020 and 2023 and for these mutations in SARS-CoV-2 quasispecies for 90 samples collected in 2020, using Python. SARS-CoV-2 protease with major mutation E166V was generated with Swiss Pdb Viewer and Molegro Molecular Viewer. We detected 22 (58%) of the resistance-associated mutations in 417 (0.67%) of the genomes analyzed; 325 (78%) of these genomes had been obtained from samples collected in 2020-2021. APOBEC signatures were found for 12/22 mutations. We also detected among viral quasispecies from 90 samples some minority reads harboring any of 15 nirmatrelvir resistance mutations, including E166V. Also, we predicted that E166V has a very limited effect on 3CLpro structure but may prevent drug attachment. Thus, we evidenced that mutations associated with nirmatrelvir resistance pre-existed in SARS-CoV-2 before drug availability. These findings further warrant SARS-CoV-2 genomic surveillance and SARS-CoV-2 quasispecies characterization.

Clinical effectiveness of nirmatrelvir plus ritonavir on the short- and long-term outcome in high-risk children with COVID-19.

This study investigated the clinical effectiveness of nirmatrelvir plus ritonavir (NMV-r) on short-term outcome and the risk of postacute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (PASC) among pediatric patients with coronavirus disease 2019 (COVID-19). This retrospective cohort study used the TriNetX research network to identify pediatric patients between 12 and 18 years with COVID-19 between January 1, 2022 and August 31, 2023. The propensity score matching (PSM) method was used to match patients receiving NMV-r (NMV-r group) with those who did not receive NMV-r (control group). Two cohorts comprising 633 patients each (NMV-r and control groups), with balanced baseline characteristics, were identified using the PSM method. During the initial 30 days, the NMV-r group showed a lower incidence of all-cause hospitalization, mortality, or ED visits (hazard ratio [HR] = 0.546, 95% confidence interval [CI]: 0.372-0.799, p = 0.002). Additionally, the NMV-r group had a significantly lower risk of all-cause hospitalization compared with the control group (HR = 0.463, 95% CI: 0.269-0.798), with no deaths occurring in either group. In the 30-180-day follow-up period, the NMV-r group exhibited a non-significantly lower incidence of post-acute sequelae of SARS-CoV-2 infection (PASC), encompassing symptoms such as fatigue, cardiopulmonary symptoms, pain, cognitive impairments, headache, dizziness, sleep disorders, anxiety, and depression, compared to the control group. This study underscores the potential effectiveness of NMV-r in treating high-risk pediatric patients with COVID-19, demonstrating significant reductions in short-term adverse outcomes such as emergency department visits, hospitalization, or mortality within the initial 30-day period. Additionally, NMV-r shows promise in potentially preventing the development of PASC.

Effectiveness of nirmatrelvir-ritonavir on severe outcomes of COVID-19 in the era of vaccination and Omicron: An updated meta-analysis.

Nirmatrelvir-ritonavir (NR) was approved to treat SARS-CoV-2 positive outpatients at high risk of progression to severe disease, based on a randomized trial in unvaccinated patients. Effectiveness in vaccinated patients and against Omicron has not yet been confirmed by clinical trial data, but a recent meta-analysis suggested good real-world effectiveness based on 12 studies. We updated this meta-analysis by searching Medline and Embase databases for studies assessing effectiveness of NR on mortality, hospitalization, composite outcome of hospitalization and/or death, and progression to severe disease, published between October 1, 2022 and May 22, 2023. Random effects meta-analysis and subgroup analysis for vaccinated patients was performed. A total of 32 studies were included in the meta-analysis. Pooled RR for the effect of NR on mortality, hospitalization, hospitalization and/or mortality, and progression to severe disease were 0.36 (95% confidence interval [CI]: 0.25-0.52), 0.43 (CI: 0.37-0.51), 0.52 (CI: 0.45-0.61) and 0.54 (CI: 0.41-0.73), respectively. A subgroup analysis on vaccinated patients indicated lower effectiveness of NR on mortality (RR: 0.55, CI: 0.45-0.68), but similar effectiveness for hospitalization, hospitalization and/or mortality, or progression to severe disease (RR: 0.52, 0.58, and 0.66, respectively). This updated meta-analysis robustly confirms the protective effects of NR on severe COVID-19 outcomes.

Association of nirmatrelvir for acute SARS-CoV-2 infection with subsequent Long COVID symptoms in an observational cohort study.

Oral nirmatrelvir/ritonavir is approved as treatment for acute COVID-19, but the effect of treatment during acute infection on risk of Long COVID is unknown. We hypothesized that nirmatrelvir treatment during acute SARS-CoV-2 infection reduces risk of developing Long COVID and rebound after treatment is associated with Long COVID. We conducted an observational cohort study within the Covid Citizen Science (CCS) study, an online cohort study with over 100 000 participants. We included vaccinated, nonhospitalized, nonpregnant individuals who reported their first SARS-CoV-2 positive test March-August 2022. Oral nirmatrelvir/ritonavir treatment was ascertained during acute SARS-CoV-2 infection. Patient-reported Long COVID symptoms, symptom rebound and test-positivity rebound were asked on subsequent surveys at least 3 months after SARS-CoV-2 infection. A total of 4684 individuals met the eligibility criteria, of whom 988 (21.1%) were treated and 3696 (78.9%) were untreated; 353/988 (35.7%) treated and 1258/3696 (34.0%) untreated responded to the Long COVID survey (n = 1611). Among 1611 participants, median age was 55 years and 66% were female. At 5.4 ± 1.3 months after infection, nirmatrelvir treatment was not associated with subsequent Long COVID symptoms (odds ratio [OR]: 1.15; 95% confidence interval [CI]: 0.80-1.64; p = 0.45). Among 666 treated who answered rebound questions, rebound symptoms or test positivity were not associated with Long COVID symptoms (OR: 1.34; 95% CI: 0.74-2.41; p = 0.33). Within this cohort of vaccinated, nonhospitalized individuals, oral nirmatrelvir treatment during acute SARS-CoV-2 infection and rebound after nirmatrelvir treatment were not associated with Long COVID symptoms more than 90 days after infection.

Early administration of nirmatrelvir/ritonavir leads to faster negative SARS-CoV-2 nasal swabs than monoclonal antibodies in COVID 19 patients at high-risk for severe disease.

PURPOSE: Besides the well-established efficacy in preventing severe COVID-19, the impact of early treatments, namely antivirals and monoclonal antibodies (mAbs), on the time length to negativization of SARS-CoV-2 nasal swabs is still unclear. The aim of this study was to compare the efficacy of different early treatments in reducing the SARS-CoV-2 viral shedding, identifying a single drug that might potentially lead to a more rapid negativization of SARS-CoV-2 nasal swab. METHODS: This was a single-centre, retrospective, observational study conducted at Ospedale Luigi Sacco in Milan. Data of high-risk COVID-19 patients who received early treatments between 23 December 2021 and March 2023 were extracted. The comparison across treatments was conducted using the Kruskall-Wallis test for continuous variables. Dunn's test with Bonferroni adjustment was performed for post-hoc comparisons of days to negativization. Secondly, a negative binomial regression adjusted for age, sex, number of comorbidities, immunosuppression, and SARS-CoV-2 vaccination status was implemented. RESULTS: Data from 428 patients receiving early treatments were collected. The majority were treated with Nirmatrelvir/Ritonavir and were affected by SARS-CoV-2 Omicron infection with BA.2 sublineage. The median length time to SARS-CoV-2 nasal swab negativization was 9 days [IQR 7-13 days]. We found that Nirmatrelvir/Ritonavir determined a significant decrease of the length time to SARS-CoV-2 nasal swab negativization compared to mAbs (p = 0.003), but not compared to Remdesivir (p = 0.147) and Molnupiravir (p = 0.156). CONCLUSION: Our findings highlight the importance of promptly treating high-risk COVID-19 patients with Nirmatrelvir/Ritonavir, as it also contributes to achieving a faster time to negative SARS-CoV-2 nasal swabs.

Physiologically-based pharmacokinetic modelling guided dose evaluations of nirmatrelvir/ritonavir in renal impairment for the management of COVID-19.

We aimed to address factors contributing to the pharmacokinetic changes of nirmatrelvir/ritonavir in renal impaired (RI) patients and recommend dosing adjustment via a physiologically-based pharmacokinetic (PBPK) modelling approach. A PBPK model of nirmatrelvir/ritonavir was developed via Simcyp® Simulator. Sensitivity analysis of the influence of hepatic CYP3A4 intrinsic clearance and abundance, as well as hepatic non-CYP3A4 metabolism (other human liver microsomes [HLM] CLint) was performed to evaluate the effects of RI on oral clearance of nirmatrelvir. Other HLM CLint, the most sensitive parameter, was adjusted, and the simulated plasma concentration profiles of nirmatrelvir in severe RI subjects were within the therapeutic index of 292-10 000 ng/mL for dosing regimens of loading doses of 300/100 mg followed by 150/100 mg or 75/100 mg twice daily of nirmatrelvir/ritonavir. Considering that nirmatrelvir is available as a 150 mg tablet, we recommend 300/100 mg followed by 150/100 mg twice daily as the dosing regimen to be investigated in severe RI.

Cost-Effectiveness of Oral Nirmatrelvir/Ritonavir in Patients at High Risk for Progression to Severe COVID-19 in the United States.

OBJECTIVES: Nirmatrelvir/ritonavir (NMV/r) is an orally administered antiviral indicated for the outpatient treatment of patients with mild-to-moderate COVID-19 at high risk for disease progression to severe illness. We estimated the cost-effectiveness of NMV/r versus best supportive care for patients with mild-to-moderate COVID-19 at high risk for progression to severe illness from a US health sector perspective. METHODS: A cost-effectiveness model was developed using a short-term decision-tree (1 year) followed by a lifetime 2-state Markov model (alive and dead). The short-term decision-tree captured costs and outcomes associated with the primary infection and healthcare utilization; survivors of the short-term decision-tree were followed until death assuming US quality-adjusted life years (QALYs), adjusted in the short-term for survivors of mechanical ventilation. Baseline rate of hospitalization and NMV/r effectiveness were taken from an Omicron-era US real-world study. Remaining inputs were informed by previous COVID-19 studies and publicly available US sources. Sensitivity analyses were conducted for all model inputs to test the robustness of model results. RESULTS: NMV/r was found to decrease COVID-19 related hospitalizations (-0.027 per infected case) increase QALYs (+0.030), decrease hospitalization costs (-$1110), and increase total treatment cost (+$271), resulting in an incremental cost-effectiveness ratio of $8931/QALY. Results were most sensitive to baseline risk of hospitalization and NMV/r treatment effectiveness parameters. The probabilistic analysis indicated that NMV/r has a >99% probability of being cost-effective at a $100 000 willingness-to-pay threshold. CONCLUSIONS: NMV/r is cost-effective vs best supportive care for patients at high risk for severe COVID-19 from a US health sector perspective.