In-vitro and in-vivo assessment of nirmatrelvir penetration into CSF, central nervous system cells, tissues, and peripheral blood mononuclear cells.

Three years after SARS-CoV-2 emerged as a global infectious threat, the virus has become endemic. The neurological complications such as depression, anxiety, and other CNS complications after COVID-19 disease are increasing. The brain, and CSF have been shown as viral reservoirs for SARS-CoV-2, yielding a potential hypothesis for CNS effects. Thus, we investigated the CNS pharmacology of orally dosed nirmatrelvir/ritonavir (NMR/RTV). Using both an in vitro and an in vivo rodent model, we investigated CNS penetration and potential pharmacodynamic activity of NMR. Through pharmacokinetic modeling, we estimated the median CSF penetration of NMR to be low at 18.11% of plasma with very low accumulation in rodent brain tissue. Based on the multiples of the 90% maximal effective concentration (EC90) for SARS-CoV-2, NMR concentrations in the CSF and brain do not achieve an exposure level similar to that of plasma. A median of only 16% of all the predicted CSF concentrations in rats were > 3xEC90 (unadjusted for protein binding). This may have implications for viral persistence and neurologic post-acute sequelae of COVID-19 if increased NMR penetration in the CNS leads to decreased CNS viral loads and decreased CNS inflammation.

Quality assessment of oral antimalarial and antiretroviral medicines used by public health systems in Sahel countries.

Malaria and Human Immunodeficiency Virus infections are among the top 10 causes of death in low income countries. Furthermore, many medicines used in these treatment areas are substandard, which contributes to the high death rate. Using a monitoring system to identify substandard and falsified medicines, the study aims to evaluate the quality of antimalarial and antiretroviral medicines in Sahel countries, assessing site conditions, compliance of medicines with pharmacopoeia tests, formulation equivalence with a reference medicine, and the influence of climate on quality attributes. Ultra Performance Liquid Chromatography methods for eight active pharmaceutical ingredients were validated following the International Conference for Harmonization guideline for its detection and quantification. Quality control consists of visual inspections to detect any misinformation or imperfections and pharmacopeial testing to determine the quality of pharmaceutical products. Medicines which complied with uniformity dosage units and dissolution tests were stored under accelerated conditions for 6 months. Artemether/Lumefantrine and Lopinavir/Ritonavir formulations failed uniformity dosage units and disintegration tests respectively, detecting a total of 28.6% substandard medicines. After 6 months stored under accelerated conditions (40 °C // 75% relative humidity) simulating climatic conditions in Sahel countries, some medicines failed pharmacopeia tests. It demonstrated the influence of these two factors in their quality attributes. This study emphasizes the need of certified quality control laboratories as well as the need for regulatory systems to maintain standards in pharmaceutical manufacturing and distribution in these countries, especially when medicines are transported to rural areas where these climatic conditions are harsher.

Clinical assessment of momelotinib drug-drug interactions via CYP3A metabolism and transporters.

Momelotinib-approved for treatment of myelofibrosis in adults with anemia-and its major active metabolite, M21, were assessed as drug-drug interaction (DDI) victims with a strong cytochrome P450 (CYP) 3A4 inhibitor (multiple-dose ritonavir), an organic anion transporting polypeptide (OATP) 1B1/1B3 inhibitor (single-dose rifampin), and a strong CYP3A4 inducer (multiple-dose rifampin). Momelotinib DDI perpetrator potential (multiple-dose) was evaluated with CYP3A4 and breast cancer resistance protein (BCRP) substrates (midazolam and rosuvastatin, respectively). DDI was assessed from changes in maximum plasma concentration (Cmax), area under the concentration-time curve (AUC), time to reach Cmax, and half-life. The increase in momelotinib (23% Cmax, 14% AUC) or M21 (30% Cmax, 24% AUC) exposure with ritonavir coadministration was not clinically relevant. A moderate increase in momelotinib (40% Cmax, 57% AUC) and minimal change in M21 was observed with single-dose rifampin. A moderate decrease in momelotinib (29% Cmax, 46% AUC) and increase in M21 (31% Cmax, 15% AUC) were observed with multiple-dose rifampin compared with single-dose rifampin. Due to potentially counteracting effects of OATP1B1/1B3 inhibition and CYP3A4 induction, multiple-dose rifampin did not significantly change momelotinib pharmacokinetics compared with momelotinib alone (Cmax no change, 15% AUC decrease). Momelotinib did not alter the pharmacokinetics of midazolam (8% Cmax, 16% AUC decreases) or 1'-hydroxymidazolam (14% Cmax, 16% AUC decreases) but increased rosuvastatin Cmax by 220% and AUC by 170%. Safety findings were mild in this short-term study in healthy volunteers. This analysis suggests that momelotinib interactions with OATP1B1/1B3 inhibitors and BCRP substrates may warrant monitoring for adverse reactions or dose adjustments.

Impact of loperamide on the pharmacokinetics and tissue disposition of ritonavir-boosted oral docetaxel therapy; a preclinical assessment.

PURPOSE: An oral docetaxel formulation boosted by the Cytochrome P450 (CYP) 3 A inhibitor ritonavir, ModraDoc006/r, is currently under clinical investigation. Based on clinical data, the incidence of grade 1-2 diarrhea is increased with this oral docetaxel formulation compared to the conventional intravenous administration. Loperamide, a frequently used diarrhea inhibitor, could be added to the regimen as symptomatic treatment. However, loperamide is also a substrate of the CYP3A enzyme, which could result in competition between ritonavir and loperamide for this protein. Therefore, we were interested in the impact of coadministered loperamide on the pharmacokinetics of ritonavir-boosted oral docetaxel. METHODS: We administered loperamide simultaneously or with an 8-hour delay to humanized CYP3A4 mice (with expression in liver and intestine) receiving oral ritonavir and docetaxel. Concentrations of docetaxel, ritonavir, loperamide and two of its active metabolites were measured. RESULTS: The plasma exposure (AUC and Cmax) of docetaxel was not altered during loperamide treatment, nor were the ritonavir plasma pharmacokinetics. However, the hepatic and intestinal dispositions of ritonavir were somewhat changed in the simultaneous, but not 8-hour loperamide treatment groups, possibly due to loperamide-induced delayed drug absorption. The pharmacokinetics of loperamide itself did not seem to be influenced by ritonavir. CONCLUSION: These results suggest that delayed loperamide administration can be added to ritonavir-boosted oral docetaxel treatment, without affecting the overall systemic exposure of docetaxel.

Cost-effectiveness of nirmatrelvir/ritonavir for high-risk adult outpatients with COVID-19 in Japan.

INTRODUCTION: This study aimed to evaluate the cost-effectiveness of nirmatrelvir/ritonavir (Nir/Rit) for adult outpatients with COVID-19 from the perspective of a Japanese public healthcare payer. METHODS: A cost-effectiveness simulation was conducted comparing Nir/Rit for the outpatient treatment of high-risk COVID-19 patients to best supportive care (BSC) without antiviral or antibody drugs. The analytical model was divided into two phases: the treatment phase, lasting 35 days from the start of COVID-19 treatment, and the post-treatment phase. Patients who survived the treatment phase were assumed to follow a general population survival curve. Expected costs and expected quality-adjusted life years (QALYs) for both BSC and Nir/Rit were calculated for ages 40 to 80 to obtain the incremental cost-effectiveness ratio (ICER). The robustness of the results was evaluated through deterministic and probabilistic sensitivity analysis (PSA). RESULTS: The ICERs for patients aged 40, 50, 60, 70, and 80 were 18,854,276 Japanese Yen (JPY)/QALY, 8,482,034 JPY/QALY, 4,976,612 JPY/QALY, 2,636,096 JPY/QALY, and 1,597,783 JPY/QALY, respectively. In the deterministic sensitivity analysis, both the mortality risk during the treatment phase and the relative mortality risk with Nir/Rit had a high impact on ICER across all ages. In the PSA, when the willingness-to-pay (WTP) threshold was set at 5 million JPY/QALY, the probability of the ICER being below the WTP threshold was 0%, 0.2%, 45.4%, 99.9%, and 100% at ages 40, 50, 60, 70, and 80, respectively. CONCLUSION: Nir/Rit is cost-effective for older individuals aged 60 and over but not for younger age groups.

Reavaliação do nirmatrelvir/ritonavir para o tratamento de pacientes com COVID-19 não hospitalizados e com alto risco de doença grave / Revalidation of nirmatrelvir/ritonavir for the treatment of patients with COVID-19 who are not hospitalized and with a high risk of serious illness

INTRODUÇÃO: Pacientes com fatores de risco como idade avançada, imunodepressão, obesidade e doenças cardiovasculares têm risco aumentado de internação, intubação e morte. De acordo com dados brasileiros, o risco de morte por covid-19 aumenta com o número de fatores de risco que o paciente apresenta, sendo igual a 17% em pacientes com 2 fatores de risco e 76% na presença de 8 fatores de risco. Além disso, mesmo aqueles pacientes que sobrevivem a uma internação em terapia intensiva frequentemente enfrentam sequelas e representam alto custo para o sistema público. O medicamento nirmatrelvir associado ao ritonavir têm o objetivo de prevenir internações, complicações e morte. Ele é indicado para pacientes com Covid-19 leve a moderada, não hospitalizados, até 5 dias do início dos sintomas. Apesar dos avanços da vacinação no Brasil, evidências sobre a falha vacinal em idosos e imunodeprimidos destacam a importância da disponibilidade de alternativas terapêuticas para essas populações. O presente relatório teve por objetivo avaliar evidências sobre a efetividade do tratamento em pacientes vacinados com alto risco de agravamento da doença. PERGUNTA: O medicamento nirmatrelvir/ritonavir é eficaz, seguro e custo-efetivo para pacientes com covid19 leve a moderada não hospitalizados vacinados que apresentam alto risco de agravamento da doença? EVIDÊNCIAS CLÍNICAS: Resultados obtidos a partir de estudos observacionais de mundo real confirmaram os resultados do ensaio clínico do medicamento nirmatrelvir/ritonavir, demonstrando que o tratamento de pacientes de grupos de risco é capaz de reduzir o risco de desfechos desfavoráveis como internação e óbito entre cerca de 50% e 70%, inclusive entre pacientes previamente vacinados. ANÁLISE DE IMPACTO ORÇAMENTÁRIO: A análise de impacto orçamentário do relatório de recomendação do nirmatrelvir/ritonavir foi atualizada considerando-se o cenário atual da pandemia no Brasil. De acordo com a nova análise, o uso do nirmatrelvir/ritonavir por pacientes com idade ≥ 65 anos e imunossuprimidos com idade ≥ 18 anos, resultaria em uma economia de recursos de R$ 408.957.111,38 em 5 anos. Ressalta-se, no entanto, que devido à dinâmica de difícil previsão da pandemia, este montante está sujeito à incerteza. Considerando-se a análise realizada anteriormente no relatório de recomendação, pode-se concluir que o montante economizado se reduz proporcionalmente à redução do número de casos da doença na população alvo. CONSIDERAÇÕES FINAIS: De acordo com as evidências atualmente disponíveis, o uso do nirmatrelvir/ritonavir é efetivo e seguro para pacientes com covid-19 leve a moderada não hospitalizados vacinados que apresentam alto risco de agravamento da doença. O impacto orçamentário está sujeito a incertezas já que o número de casos da doença no horizonte temporal da análise é de difícil previsão. RECOMENDAÇÃO PRELIMINAR DA CONITEC: Diante do exposto, os membros do Comitê de Medicamentos da Conitec, em sua 16ª Reunião Extraordinária, realizada no dia 1º de novembro de 2023, deliberaram que a matéria fosse disponibilizada em Consulta Pública com recomendação preliminar favorável à incorporação no SUS do nirmatrelvir/ritonavir para o tratamento de pacientes com Covid-19 não hospitalizados com idade a partir de 65 anos ou pacientes imunossuprimidos a partir de 18 anos de idade. Os membros do Comitê concordaram na manutenção da indicação de uso, não havendo ampliação do público-alvo, justificada pela restrição orçamentária, considerando que há incremento de custo da aquisição da tecnologia, ainda que haja economia de recursos ao serem evitadas internações e óbitos. CONSULTA PÚBLICA: Das nove contribuições recebidas, cinco contribuições foram de cunho técnico-científico e quatro contribuições de experiência ou opinião. Todas as contribuições concordaram com a recomendação preliminar da Conitec de incorporar o nirmatrelvir/ritonavir. Duas contribuições técnico-científicassugeriram ampliação da população elegível ao tratamento com o medicamento com a inclusão de indicação para pacientes com taxa de filtração glomerular menor que 30 ml/min/1,73m2 e de pacientes adultos com asma grave independentemente da faixa etária. Uma contribuição técnico-científica enviada pela empresa fabricante do medicamento expressou sua concordância com e solicitou a inclusão de informaçõea adicionais no relatório. As contribuições de experiência ou opinião ressaltaram a eficácia e segurança do medicamento para a população alvo. RECOMEDAÇÃO FINAL DA CONITEC: Diante do exposto, os membros do Comitê de Medicamentos, presentes na 126ª Reunião Ordinária da Conitec, realizada no dia 01 de fevereiro de 2024, deliberaram, por unanimidade, após reavaliação, manter a incorporação do nirmatrelvir/ritonavir, no SUS, para o tratamento da Covid-19 nos seguintes grupos de pacientes com sintomas leves a moderados, que não requerem oxigênio suplementar, independentemente do status vacinal: a) imunocomprometidos com idade ≥ 18 anos; b) com idade ≥ 65 anos. Foi assinado o registro de deliberação nº 874/2024. DECISÃO: manter a incorporação, no âmbito do Sistema Único de Saúde - SUS, de nirmatrelvir/ritonavir para o tratamento da Covid-19 para pacientes com sintomas leves a moderados, que não requerem oxigênio suplementar, independentemente do status vacinal e com idade igual ou superior a 65 anos ou imunocomprometidos com idade igual ou superior a 18 anos, publicada no Diário Oficial da União nº 46, seção 1, página 54, em 07 de março de 2024.

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.

Cost-Utility Model of Nirmatrelvir/Ritonavir in Brazil: Analysis of a Vaccinated Population.

OBJECTIVES: The aim of this study is to conduct a cost-utility analysis of the use of the antiviral nirmatrelvir/ritonavir, applied to a vaccinated Brazilian population against COVID-19, from the perspective of the Brazilian Public Health System (SUS). METHODS: A microsimulation model was created with individual-level data and daily cycles, with a 1-year time horizon, to compare the current scenario of standard care with a scenario in which nirmatrelvir/ritonavir is offered to the population. Adults of any age group that received ≥2 doses of the COVID-19 vaccine formed the investigated population. Direct medical costs of the outpatients and inpatients admitted to the ward or intensive care unit were included. The effectiveness of the model was measured in quality-adjusted life-years (QALYs). RESULTS: In all simulations, the use of nirmatrelvir/ritonavir resulted in incremental costs per patient of US dollar (USD)245.86 and incremental effectiveness of 0.009 QALY, over a year. The incremental cost-utility ratio was USD27 220.70/QALY. The relative risk of the vaccinated population was the factor that affected the outcome most, according to the univariate sensitivity analysis. The probabilistic sensitivity analysis resulted in 100% of the simulations being more costly and effective, but that only 4% of them were below the established cost-effectiveness threshold of USD24 000.00/QALY. In the scenario considering only the population over 60 years old and immunosuppressed (of any age), the incremental cost-utility ratio was USD7589.37/QALY. CONCLUSIONS: The use of nirmatrelvir/ritonavir in the treatment of COVID-19 in a vaccinated population was cost-effective only for immunosuppressed individuals and people over 60 years of age.

Budget impact of oral nirmatrelvir/ritonavir in adults at high risk for progression to severe COVID-19 in the United States.

BACKGROUND: Nirmatrelvir/ritonavir (NMV/r) is indicated for the treatment of mild-to-moderate COVID-19 in adults who are at high risk for progression to severe COVID-19. NMV/r has also been authorized for emergency use by the US Food and Drug Administration for the treatment of mild-to-moderate COVID-19 in pediatric patients (aged 226512 years and weighing at least 40 kg) who are at high risk for progression to severe COVID-19. Understanding the budget impact of introducing NMV/r for the treatment of adults with COVID-19 is of key interest to US payers. OBJECTIVE: To estimate the annual budget impact of introducing NMV/r in a US commercial health plan setting in the current Omicron COVID-19 era. METHODS: A budget impact model was developed to assess the impact of NMV/r on health care costs in a hypothetical 1-million-member commercial health insurance plan over a 1-year period in the US population; clinical and cost inputs were derived from published literature with a focus on studies in the recent COVID-19 era that included vaccinated population and predominance of the Omicron variant. In the base-case analysis, it was assumed the only effect of NMV/r was a reduction in incidence (not severity) of hospitalization or death; its potential effect on post-COVID conditions was assessed in a scenario analysis. Outcomes included the number of hospitalizations, total cost, per patient per year (PPPY) costs, and per member per month (PMPM) costs. Sensitivity and scenario analyses were conducted to assess uncertainty around key model inputs. RESULTS: An estimated 29,999 adults were eligible and sought treatment with oral antiviral for COVID-19 over 1 year. The availability of NMV/r was estimated to reduce the number of hospitalizations by 647 with a total budget impact of $2,733,745, $91 PPPY, and $0.23 PMPM. NMV/r was cost saving when including post-COVID conditions with a -$1,510,780 total budget impact, a PPPY cost of -$50, and a PMPM cost of -$0.13. Sensitivity analyses indicated results were most sensitive to the risk of hospitalization under supportive care, risk of hospitalization with NMV/r treatment and cost of NMV/r. CONCLUSIONS: Treatment with NMV/r in the current COVID-19 era is estimated to result in substantial cost offsets because of reductions in hospitalization and modest budget impact to potential overall cost savings.

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.

Anti-SARS-CoV-2 Pharmacotherapies Among Nonhospitalized US Veterans, January 2022 to January 2023.

Importance: Several pharmacotherapies have been authorized to treat nonhospitalized persons with symptomatic COVID-19. Longitudinal information on the use of these therapies is needed. Objective: To analyze trends and factors associated with prescription of outpatient COVID-19 pharmacotherapies within the Veterans Health Administration (VHA). Design, Setting, and Participants: This cohort study evaluated nonhospitalized veterans in VHA care who tested positive for SARS-CoV-2 from January 2022 through January 2023 using VHA and linked Community Care and Medicare databases. Exposures: Demographic characteristics, underlying medical conditions, COVID-19 vaccination, and regional and local systems of care, including Veterans Integrated Services Networks (VISNs). Main Outcomes and Measures: Monthly receipt of any COVID-19 pharmacotherapy (nirmatrelvir-ritonavir, molnupiravir, sotrovimab, or bebtelovimab) was described. Multivariable logistic regression was used to identify factors independently associated with receipt of any vs no COVID-19 pharmacotherapy. Results: Among 285 710 veterans (median [IQR] age, 63.1 [49.9-73.7] years; 247 358 males [86.6%]; 28 444 Hispanic [10.0%]; 61 269 Black [21.4%] and 198 863 White [69.6%]) who tested positive for SARS-CoV-2 between January 2022 and January 2023, the proportion receiving any pharmacotherapy increased from 3285 of 102 343 veterans (3.2%) in January 2022 to 5180 of 21 688 veterans (23.9%) in August 2022. The proportion declined to 2194 of 10 551 veterans (20.8%) by January 2023. Across VISNs, the range in proportion of patients who tested positive who received nirmatrelvir-ritonavir or molnupiravir during January 2023 was 41 of 692 veterans (5.9%) to 106 of 494 veterans (21.4%) and 2.1% to 120 of 1074 veterans (11.1%), respectively. Veterans receiving any treatment were more likely to be older (adjusted odds ratio [aOR] for ages 65-74 vs 50-64 years, 1.18; 95% CI, 1.14-1.22; aOR for ages ≥75 vs 50-64 years, 1.19; 95% CI, 1.15-1.23) and have a higher Charlson Comorbidity Index score (aOR for CCI ≥6 vs 0, 1.52; 95% CI, 1.44-1.59). Compared with White veterans, Black veterans (aOR, 1.06; 95% CI, 1.02-1.09) were more likely to receive treatment, and compared with non-Hispanic veterans, Hispanic veterans (aOR 1.06; 95% CI, 1.01-1.11) were more likely to receive treatment. Conclusions And Relevance: This study found that prescription of outpatient COVID-19 pharmacotherapies in the VHA peaked in August 2022 and declined thereafter. There were large regional differences in patterns of nirmatrelvir-ritonavir and molnupiravir use.

Population pharmacokinetic modeling and simulation for nirmatrelvir exposure assessment in Chinese older patients with COVID-19 infection.

Nirmatrelvir is an effective component of Paxlovid, the first oral antiviral drug granted emergency use authorization by the FDA. Nirmatrelvir is prescribed extensively in older adult patients to treat the coronavirus disease 2019 (COVID-19) infection. In this study, population pharmacokinetic modeling with clinical study data was employed to explore the pharmacokinetic profile of nirmatrelvir in older adult Chinese patients with COVID-19 infection. The result suggests that the pharmacokinetic profile of nirmatrelvir can be described by a one-compartment model with first-order absorption and elimination in this study population. The calculated apparent clearance (CL/F), apparent volumes of distribution (V/F), and absorption rate constant (ka) for the typical patient were 4.16 L/h, 39.1 L, and 0.776, respectively. The area under the curve (AUC) of nirmatrelvir in the typical Chinese older adult was approximately three-fold higher than the AUCs in Chinese and Western young adult volunteers. At the same doses, the simulated AUCs were increased by 26%, 43%, 72%, and 135% in virtual populations with creatinine clearances of 60, 45, 30, and 15 mL/min, respectively. Our research provides an instructive reference for nirmatrelvir dose selection in older Chinese adults.

Estimation of Intangible Costs for Factors Associated with Oral Antiviral Drugs for COVID-19 Treatment: A Conjoint Analysis in Japan.

INTRODUCTION: During the recent coronavirus disease 2019 (COVID-19) pandemic, preferences for factors associated with vaccines have been evaluated. Three oral antiviral drugs have been approved in Japan for patients with mild-to-moderate I COVID-19 symptoms. Although preferences for the drugs may also depend on various factors, these have not been fully evaluated. METHODS: A conjoint analysis was performed based on an online survey in August 2022 to estimate the intangible costs of factors associated with oral antiviral drugs for COVID-19. Respondents were individuals aged 20-69 across Japan. The attributes included the company (Japanese/foreign) that developed the drug, formulation and size of the drug, frequency of administration per day, number of tablets/capsules per dose, number of days until no longer infectious to others, and out-of-pocket expenses. A logistic regression model was applied to estimate the utility of each level for each attribute. The intangible costs were calculated by comparing the utility to the out-of-pocket attribute. RESULTS: Responses were collected from 11,303 participants. The difference between levels was the largest for companies that developed a drug; the intangible costs were JPY 5390 higher for the foreign company than for the Japanese company. The next largest difference was in the number of days until one is no longer infectious. For the same formulation, the intangible cost was lower for small sizes than large sizes. For similar-sized tablets and capsules, the intangible cost was lower for tablets than capsules. These tendencies were similar regardless of COVID-19 infection history and the presence of risk factors for severe COVID-19 in the respondents. CONCLUSION: Intangible costs for factors associated with oral antiviral drugs among the Japanese population were estimated. The results may change as the number of people with a history of COVID-19 infection increases and significant progress is made regarding treatments.

Short-term toxicity assessment of combined use of zidovudine, lamivudine and lopinavir/ritonavir in vitro and in vivo.

INTRODUCTION: A combination of zidovudine (AZT), lamivudine (3TC) and lopinavir/ritonavir (LPV/r) is one of the most effective drugs for preventing mother-to-child transmission (PMTCT) of HIV. However, limited information is available regarding its systemic toxicity. This study aimed to investigate its potential toxicity. METHOD: An acute oral toxicity test was conducted to assess the potential acute toxicity of AZT + 3TC + LPV/r. Bacterial reverse mutation, mammalian erythrocyte micronucleus and mouse spermatogonia chromosomal aberration tests were conducted to assess its potential genotoxicity. A 28-day feeding test was conducted to assess the potential subacute toxicity. RESULTS: In mice, the LD50 of the AZT + 3TC + LPV/r mixture was greater than 2000 mg/kg body weight (BW). The rate of micronucleated polychromatic erythrocytes (PCEs) increased in a dose-dependent manner in mice (P < 0.01). After treatment with AZT + 3TC + LPV/r for 28 days, the BW gain of male and female rats in the high-dose group was lower than that in the control group (P < 0.05); the relative weights of the liver, kidney, spleen and brain increased (P < 0.05); and pathological abnormalities appeared in the thyroid and spleen of male and female rats in the high-dose group. The haemoglobin (HGB) and red blood cells (RBCs) count in male and female rats decreased, but the white blood cells (WBCs) and lymphocyte apoptosis rates in male and female rats in the high-dose group increased (P < 0.05). The total protein, albumin, cholesterol and blood glucose levels of male and female rats in the high-dose group were significantly decreased (P < 0.05). The alanine aminotransferase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), creatinine (Cr) and blood urea nitrogen (BUN) levels of male and female rats in the medium- and high-dose groups increased significantly (P < 0.05). CONCLUSION: The results suggest that AZT + 3TC + LPV/r may exhibit genotoxicity and subacute toxicity under experimental conditions.

Application of biorelevant in vitro assays for the assessment and optimization of ASD-based formulations for pediatric patients.

Amorphous solid dispersions (ASD) have been a successful formulation strategy to overcome the poor aqueous solubility of many novel drugs, but the development of pediatric formulations presents a special challenge due to variable gastrointestinal conditions in children. It was the aim of this work to design and apply a staged biopharmaceutical test protocol for the in vitro assessment of ASD-based pediatric formulations. Ritonavir was used as a model drug with poor aqueous solubility. Based on the commercial ASD powder formulation, a mini-tablet and a conventional tablet formulation were prepared. Drug release from the three formulations was studied in different biorelevant in vitro assays (i.e. MicroDiss, two-stage, transfer model, tiny-TIM) to consider different aspects of human GI physiology. Data from the two-stage and transfer model tests indicated that by controlled disintegration and dissolution excessive primary precipitation can be prevented. However, this advantage of the mini-tablet and tablet formulation did not translate into better performance in tiny-TIM. Here, the in vitro bioaccessibility was comparable for all three formulations. In the future, the staged biopharmaceutical action plan established herein will support the development of ASD-based pediatric formulations by improving the mechanistic understanding so that formulations are developed for which drug release is robust against variable physiological conditions.

Nirmatrelvir and COVID-19: development, pharmacokinetics, clinical efficacy, resistance, relapse, and pharmacoeconomics.

Nirmatrelvir/ritonavir (N/R) is one of the most effective antiviral drugs against SARS-CoV-2. The preclinical development, pharmacodynamics and pharmacokinetics of N/R are reviewed herein. Randomized clinical trials have been conducted exclusively with pre-Omicron variants of concern, but in vitro studies show that efficacy against all Omicron sublineages is preserved, as confirmed by post-marketing observational studies. Nevertheless, investigations of large viral genome repositories have shown that mutation in the main protease causing resistance to N/R are increasingly frequent. In addition, virological and clinical rebounds after N/R discontinuation have been reported in immunocompetent patients. This finding is of concern when translated to immunocompromised patients, in whom N/R efficacy has not been formally investigated in clinical trials. Economical sustainability and perspectives for this therapeutic arena are discussed.

Early Treatment with Fluvoxamine among Patients with COVID-19: A Cost-Consequence Model.

To date, two published randomized trials have indicated a clinical benefit of early treatment with fluvoxamine versus placebo for adults with symptomatic COVID-19. Using the results of the largest of these trials, the TOGETHER trial, we conducted a cost-consequence analysis to assess the health system benefits of preventing progression to severe COVID-19 in outpatient populations in the United States. A decision-analytic model in the form of a decision tree was constructed to evaluate two treatment strategies for high-risk patients with confirmed, symptomatic COVID-19 in the primary analysis: treatment with a 10-day course of fluvoxamine (100 mg twice daily) and current standard-of-care. A secondary analysis comparing a 5-day course of nirmatrelvir-ritonavir was also conducted. We used a time horizon of 28 days. Reported outcomes included cost-savings and hospitalization days avoided. The results of our analysis indicated that administration of fluvoxamine to symptomatic outpatients at high risk of progressing to severe COVID-19 was substantially cost-saving, in the amount of $232 per eligible patient and prevented an average of 0.15 hospital days per patient treated, compared with standard of care. Nirmatrelvir-ritonavir was also shown to be cost-saving despite its higher acquisition cost and provided savings to the healthcare system of $625 per patient treated. These findings suggest that fluvoxamine is likely to be a cost-effective addition to frontline COVID-19 mitigation strategies in many settings, particularly where access to nirmaltrevir-ritonavir or monoclonal antibodies is limited.