Tecovirimat   中文名称: 特考韦瑞

Antiviral

ST-246（Tecovirimat）是一种小型合成抗病毒化合物，正在开发用于治疗人类致病性正痘病毒感染。该化合物是作为高通量筛选的一部分被发现的，该筛选旨在鉴定痘苗病毒诱导的细胞病变效应的抑制剂。抗病毒活性对正痘病毒是特异性的，并且该化合物在抗病毒的化合物浓度下不抑制其他含有RNA和DNA的病毒的复制或抑制细胞增殖。ST-246靶向痘苗病毒p37，一种包裹和分泌细胞外形式的病毒所需的病毒蛋白[2]。

该化合物可口服生物利用，保护多种动物免受致命的正痘病毒攻击。对小鼠和非人类灵长类动物的临床前安全药理学研究表明，ST-246易于通过口服途径吸收，耐受性良好，小鼠2000 mg/kg时无明显不良反应水平（NOAEL），非人灵长类动物300 mg/kg时无显著影响水平（NOEL）。已经开发了原料药和药品工艺，并使用良好生产工艺（GMP）生产了商业规模的批次。人体I期临床试验表明，ST-246在健康人体志愿者中是安全且耐受性良好的。根据临床评估结果，每天一次给药应提供基于正痘病毒疾病动物模型疗效研究数据预测的抗病毒范围内的血浆药物暴露。这些数据支持使用ST-246作为治疗人类致病性正痘病毒感染的药物[2]。

ST-246在CPE测定中对广谱正痘病毒表现出强大的抗病毒活性，而对不相关的RNA和含DNA的病毒表现出很少的活性。抑制病毒复制的EC50值范围从牛痘病毒的0.01μM到电子商务病毒的0.07μM，再到无关病毒的大于40μM。值得注意的是，与相同细胞系相比，牛痘似乎对ST-246不太敏感（5到50倍）。对ST-246易感性降低的机制尚不清楚，但可能反映了一种不同的病毒传播模式，这种模式较少依赖于细胞外病毒的形成。ST-246对CDV抗性（CDVr）牛痘病毒（EC50=0.05μM）具有活性，表明ST-246抑制病毒复制的机制与CDV不同。此外，ST-246在细胞培养中抑制猴痘和天花病毒两个主要分支的临床分离株。ST-246抑制正痘病毒在多种细胞类型中的复制，包括人胚胎肺成纤维细胞、原代人角质形成细胞和器官型内皮筏培养物[2]。

关于Tecovirimat耐药的报道有限。早期的体外研究是利用抗牛痘病毒的变种来帮助阐明Tecovirimat的靶标。对耐药变异的分析显示，编码p37蛋白的病毒V061基因(与天花病毒中的F13L基因同源)发生了单碱基变化。这种碱基变化导致蛋白质中277位的氨基酸从甘氨酸(G)变为半胱氨酸(C)。由此产生的药物有效浓度可以保护一半的细胞免受病毒诱导的破坏(EC50 > 40μM)，比野生型牛痘病毒(EC50 = 0.050 μM)高出800多倍。[3]

Efficacy of ST-246 in Small Animal Models of Orthopoxvirus Disease[2]
Models of orthopoxvirus disease were developed in mice, including BALB/c, NMRI, ANC/R and Nu/nu, rabbits, prairie dogs, and ground squirrels. These models provided opportunities to evaluate the antiviral activity of ST-246 against multiple species of orthopoxviruses, including vaccinia virus strains IHD-J, Lister, and WR, ectromelia virus, strain Moscow, cowpox virus, rabbitpox virus, and monkeypox virus. Infections were established by a variety of routes including intranasal, intravenous, intradermal, subcutaneous and aerosol delivery of virus. In all cases, ST-246 protected animals from severe disease and death. ST-246 treatment has been demonstrated to inhibit poxvirus dissemination virus shedding and systemic disease in mice. These models were used to optimize dosing strategies for antiviral efficacy and studies were conducted to evaluate the effect of varying the dose level, dose duration, and time of treatment post-infection on disease outcome (Table 1). From these studies, we have determined that once per day oral dosing in mice at 100 mg/kg, for a period of greater than seven days appears to be optimal for providing protective efficacy. Treatment can be initiated as late as 72 hours post-infection for full protection. In one experiment in prairie dogs infected with monkeypox virus, treatment initiated 10 days post-infection resulted in 100% protection from death. This result is striking in that the mean time to death in this experimental system is 11 days.
Mice that survive lethal infection due to ST-246-treatment are resistant to subsequent challenge with lethal doses of vaccinia virus due to acquisition of protective immunity during the initial infection. ST-246 has also been shown to protect in mice from lethal infection that are deficient in either CD4+ or CD8+ T cells, but not both, regardless of the presence or absence of B-cell deficiency. ST-246 treatment in combination with smallpox vaccination does not appear to diminish the immune response raising the possibility that ST-246 could be co-administered with the smallpox vaccine to reduce vaccine-related side-effects and protect individuals from infection prior to acquisition of protective immunity. Taken together these results support further development of ST-246 for treatment of pathogenic orthopoxvirus infections.

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Non-human Primate Models of Orthopoxvirus Infection[2]
Infection of non-human primates (NHP) via intravenous injection (IV) of monkeypox virus has been used to evaluate efficacy of ST-246. ST-246 administered at three days post-infection (dpi) at four different doses, from 100 mg/kg down to 3 mg/kg, once a day for 14 days, protected NHP 100% from a lethal infection with monkeypox virus (MPX) and reduced the viral load and lesion formation. In NHP, a ST-246 dose of 10 mg/kg/day for 14 days resulted in blood exposure comparable to levels attained in humans administered 400 mg in the fed state. A randomized double blind, placebo controlled study was conducted to evaluate the efficacy of ST-246 in cynomolgous macaques inoculated with a lethal dose of monkeypox virus via intravenous injection. Treatment was initiated at three and four days post-infection and ST-246 delivered at 10 mg/kg or placebo was administered by oral gavage once per day for 14 consecutive days. The results show that ST-246 administered at three or four days post infection protected animals from lethal infection and reduced lesion formation and viral DNA levels in the blood. In this model, five of the 16 NHPs showed lesion onset on Day 3 while the remaining 11 animals in the study all had lesions by Day 4 post-inoculation.

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Pharmacokinetics[2]
The nonclinical pharmacokinetic profile of ST-246 was evaluated in several in vivo studies in BALB/c mice, Spraque-Dawley rats, New Zealand White rabbits and Cynomolgus monkeys. Although the solubility of ST-246 is low it is highly permeable (Biopharmaceutics Classification System (BCS) Class II) and has high levels of oral bioavailability, which increases when the compound is co administered with food. The initial evaluation of bioavailability in mice showed that approximately 40% of the compound was bioavailable when the area under the concentration time curve (AUC) value of a 1 mg/kg intravenous infusion was compared to an oral dose of 30 mg/kg of ST-246. Higher doses had lower apparent bioavailability. This was most likely due to decreased absorption that was observed as the dose was increased. In rats, the bioavailability was 90% and 33%, respectively, for males and females after oral administration of 30 mg/kg ST-246. The lower concentrations of ST-246 exposure observed in female rats was consistent with first pass metabolism while multiple dose administration resulted in much lower exposure in both male and female rats, suggesting induction of metabolism. Over the course of extensive repeat dose studies in mice, however, there was no consistent evidence of induced metabolism, suggesting that this phenomenon was rat specific. The predominant cause of nonlinearity in the pharmacokinetics of ST-246 observed in mice was the apparent decreased absorption with increasing dose. The decreased absorption was observed in both the observed maximum plasma concentrations as well as the exposure (as determined by AUC values). Thus, as the doses were increased, exposures also increased but not dose proportionally (Figure 3).

Absorption, Distribution and Excretion
Tecovirimat is readily absorbed following oral administration. Following oral administration of 600 mg tecovirimat in healthy adults, the mean steady-state AUC0-24hr was 29816 hr x ng/mL and the Cmax was 2159 ng/mL. Following intravenous administration of 200 mg tecovirimat every 12 hours, the mean steady-state AUC0-24hr was 39405 hr x ng/mL and the Cmax was 2630 ng/mL. The Tmax is about six hours. The steady-state is achieved within four to six days. The oral bioavailability of tecovirimat is increased when taken with food. A moderate fat and calories meal increased the drug exposure (AUC) by 39% when tecovirimat was orally administered in conjunction with food.
The major routes of elimination are through metabolism and renal elimination. Following oral administration, about 73% of the dose was excreted in urine, predominantly in the form of glucuronidated metabolites. About 23% of the dose was recovered in feces, predominantly as the unchanged parent drug. In urine, primary tecovirimat glucuronide conjugate and M4 glucuronide conjugate were the most abundant components accounting for means of 24.4% and 30.3% of dose, respectively.
The volume of distribution was 383 L following intravenous administration of 200 mg tecovirimat and 1030 L following oral administration of 600 mg tecovirimat. The blood-to-plasma ratio ranges from 0.62 to 0.90.
The clearance rate was 13 L/h following intravenous administration of 200 mg tecovirimat and 31 L/h following oral administration of 600 mg tecovirimat.

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Metabolism / Metabolites
Tecovirimat undergoes hydrolysis mediated by UGT1A1 and UGT1A4. Major metabolites are metabolites M4 (N-{3,5-dioxo-4-azatetracyclo[5.3.2.0{2,6}.0{8,10}]dodec-11-en-4-yl}amine), M5 (3,5-dioxo-4-aminotetracyclo[5.3.2.0{2,6}.0{8,10}]dodec-11-ene), and TFMBA (4 (trifluoromethyl) benzoic acid). None of the metabolites is pharmacologically active. None of the glucuronide conjugates was found as a major metabolite in plasma. The exact chemical structures of tecovirimat metabolites have not been fully characterized.

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Biological Half-Life
The elimination half-life (CV%) was 21 (45%) hours following intravenous administration of 200 mg tecovirimat and 19 (29%) hours following oral administration of 600 mg tecovirimat.

Hepatotoxicity
In preregistration trials of the safety of tecovirimat in healthy adult volunteers, serum aminotransferase elevations were uncommon and mild, and were no more frequent with tecovirimat than with placebo. Furthermore, among patients treated with tecovirimat for other orthopoxvirus infections, there were no reported episodes of marked serum aminotransferase elevations or instances of clinically apparent liver injury. Thus, tecovirimat has not been shown to cause liver injury, but the total clinical experience with its use is limited.
Likelihood score: E (unlikely cause of clinically apparent liver injury).

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Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
No information is available on the use of tecovirimat during breastfeeding. Because of relatively high protein binding and low oral absorption, exposure of the breastfed infant is likely to be low. Additionally, tecovirimat is approved for use in pediatric patients weighing as little as 3 kg. Amounts in breastmilk are unlikely to adversely affect the breastfed infant. However, individuals with smallpox are recommended not to breastfeed their infant because of the risk of passing variola virus to the infant through direct contact. This precaution probably applies to monkeypox, also. Providing pumped milk to the infant may be possible if no lesions are near the breast and adequate precautions are taken with respect to cleaning hands, breasts, breast pumps and any other apparatuses used to provide milk to the infant.
◉ Effects in Breastfed Infants
Relevant published information was not found as of the revision date.
◉ Effects on Lactation and Breastmilk
Relevant published information was not found as of the revision date.

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Protein Binding
Tecovirimat is 77-82% bound to human plasma proteins.

[1]. N Engl J Med.2018 Nov 22;379(21):2084-2085.
[2]. Viruses.2010 Nov;2(11):2409-35.
[3].Antimicrob Agents Chemother.2022 Dec 20;66(12):e0122622.

Pharmacodynamics
Tecovirimat is an antiviral drug that helps to prevent the spread of virus and reduce viremia. It is effective against all orthopoxviruses tested _in vitro_, including variola or smallpox virus.

C19H15F3N2O3

376.35

376.103

869572-92-9

Tecovirimat-d4

16124688

Typically exists as white to off-white solids at room temperature

2.732

66.48

1

6

1

27

705

6

O=C1N(NC(C2C=CC(C(F)(F)F)=CC=2)=O)C(=O)[C@H]2[C@H]3C=C[C@@H]([C@@H]12)[C@@H]1C[C@H]31

CSKDFZIMJXRJGH-VWLPUNTISA-N

InChI=1S/C19H15F3N2O3/c20-19(21,22)9-3-1-8(2-4-9)16(25)23-24-17(26)14-10-5-6-11(13-7-12(10)13)15(14)18(24)27/h1-6,10-15H,7H2,(H,23,25)/t10-,11+,12+,13-,14-,15+

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

配方 1 中的溶解度: 2.5 mg/mL (6.64 mM) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (这些助溶剂从左到右依次添加，逐一添加), 悬浮液；超声助溶。
例如，若需制备1 mL的工作液，可将100 μL 25.0 mg/mL澄清DMSO储备液加入到400 μL PEG300中，混匀；然后向上述溶液中加入50 μL Tween-80，混匀；加入450 μL生理盐水定容至1 mL。
*生理盐水的制备：将 0.9 g 氯化钠溶解在 100 mL ddH₂O中，得到澄清溶液。

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配方 2 中的溶解度: ≥ 2.5 mg/mL (6.64 mM) (饱和度未知) in 10% DMSO + 90% Corn Oil (这些助溶剂从左到右依次添加，逐一添加), 澄清溶液。
例如，若需制备1 mL的工作液，可将 100 μL 25.0 mg/mL 澄清 DMSO 储备液加入到 900 μL 玉米油中并混合均匀。

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请根据您的实验动物和给药方式选择适当的溶解配方/方案：
1、请先配制澄清的储备液(如：用DMSO配置50 或 100 mg/mL母液(储备液));
2、取适量母液，按从左到右的顺序依次添加助溶剂，澄清后再加入下一助溶剂。以 下列配方为例说明 (注意此配方只用于说明，并不一定代表此产品 的实际溶解配方):
10% DMSO → 40% PEG300 → 5% Tween-80 → 45% ddH2O (或 saline);
假设最终工作液的体积为 1 mL, 浓度为5 mg/mL: 取 100 μL 50 mg/mL 的澄清 DMSO 储备液加到 400 μL PEG300 中，混合均匀/澄清；向上述体系中加入50 μL Tween-80，混合均匀/澄清；然后继续加入450 μL ddH2O (或 saline)定容至 1 mL；
3、溶剂前显示的百分比是指该溶剂在最终溶液/工作液中的体积所占比例;
4、 如产品在配制过程中出现沉淀/析出，可通过加热(≤50℃)或超声的方式助溶;
5、为保证最佳实验结果，工作液请现配现用！
6、如不确定怎么将母液配置成体内动物实验的工作液，请查看说明书或联系我们;
7、 以上所有助溶剂都可在 Invivochem.cn网站购买。