Action and Spectrum

Drug Interaction

Adverse Reaction

Frequency defined 

>10% 

Headache 

1-10% 

Nausea 

Abdominal pain 

Vomiting 

Black Box Warning

Actions and Spectrum: 

tecovirimat, also known as ST-246, is an antiviral drug that was developed to treat infections caused by the smallpox virus. It works by inhibiting the virus’s ability to spread and replicate in the body. 

The mechanism of action of tecovirimat involves blocking the formation of viral envelops, preventing the virus from escaping the infected cell and infecting new cells. Tecovirimat selectively targets the A-type inclusion body formation protein (ATI), which is essential for the production of viral envelops. 

tecovirimat has a broad-spectrum activity against a range of ortho poxviruses, including monkeypox, cowpox, and vaccinia viruses. It has also demonstrated efficacy against other DNA viruses, including the herpes simplex virus (HSV) and cytomegalovirus (CMV). 

tecovirimat is taken orally and is generally well-tolerated. It has been shown to be effective in both preventing and treating smallpox infections in animal models and has been approved by the U.S. Food and Drug Administration (FDA) for the treatment of smallpox in humans. 

Contraindication / Caution

Contraindication/Caution: 

Contraindications: 

tecovirimat is contraindicated in patients who have a known hypersensitivity or allergy to the drug or any of its components. 

Cautions: 

• tecovirimat should be used with caution in patients with liver or kidney disease, as the drug is primarily metabolized by the liver and excreted through the kidneys. 
• The safety and efficacy of tecovirimat in pregnant and breastfeeding women have not been established, and it should be used only if the potential benefits outweigh the risks. 
• tecovirimat may interact with other medications, and caution should be exercised when used concomitantly with drugs that are metabolized by the same liver enzymes. 
• tecovirimat may cause adverse effects, such as headache, nausea, diarrhea, and skin rash. If any of these occur, patients should inform their healthcare provider. 

Pregnancy / Lactation

Pregnancy consideration:  

No data is available for the use of tecovirimat in pregnant women. 

Breastfeeding warnings:  

Consider the mother’s need for the drug and their potential side effects  

Pregnancy category: 

• Category A: Satisfactory and well-controlled studies show no risk to the fetus in the first or later trimester. 
• Category B: There is no affirmation of risk to the fetus found in animal reproduction studies, and there are not enough studies on pregnant women. 
• Category C: Adverse effects on the fetus found with evidence in animal reproduction studies and no adequate evidence for a product in humans; Pregnant women must take care of the potential risks. 
• Category D: There is adequate data available with sufficient evidence of human fetal risk from various platforms. However, despite potential dangers may be used only in emergency cases for potential benefits. 
• Category X: Drugs listed in this category outweigh risks over benefits. The drug is not for pregnant women. 
• Category N: No data is available for the drug under this category. 

Pharmacology

Pharmacology: 

tecovirimat is a small molecule antiviral drug that inhibits the replication of the smallpox virus. It belongs to a class of drugs called viral egress inhibitors, which prevent the formation and release of viral particles from infected cells. 

tecovirimat selectively targets the A-type inclusion body formation protein (ATI), which is essential to produce viral envelopes. By inhibiting ATI, tecovirimat blocks the formation of mature viral particles and prevents their release from the infected cells. This mechanism of action limits the spread of the virus to uninfected cells, reducing the viral load and allowing the immune system to clear the infection. 

Pharmacodynamics: 

The pharmacodynamics of tecovirimat is related to its mechanism of action as a viral egress inhibitor. tecovirimat selectively targets the A-type inclusion body formation protein (ATI), which is essential to produce viral envelopes. By inhibiting ATI, tecovirimat blocks the formation of mature viral particles and prevents their release from the infected cells. 

The antiviral activity of tecovirimat is measured by its ability to inhibit viral replication and spread in vitro and in animal models of infection. tecovirimat has demonstrated efficacy against a range of orth poxviruses, including the smallpox virus, as well as other DNA viruses, such as the herpes simplex virus (HSV) and cytomegalovirus (CMV). 

The pharmacodynamic properties of tecovirimat are influenced by various factors, including the dose, duration of treatment, and route of administration. In clinical studies, tecovirimat has been shown to reduce the severity and duration of smallpox symptoms, decrease the viral load, and improve survival rates in animal models of infection. 

The pharmacodynamic profile of tecovirimat is also affected by its interaction with other drugs or substances. For example, concomitant use of tecovirimat with drugs that induce or inhibit liver enzymes may affect the metabolism and clearance of the drug, leading to altered efficacy or toxicity. 

Pharmacokinetics: 

Absorption 

The peak plasma concentration is achieved in 4-6 hours 

The peak plasma concentration is 2106 ng/mL 

The minimum plasma concentration is 587 ng/mL 

The area under the curve is 28,791 hr·ng/mL  

Distribution 

The protein bound is 77-82% 

The volume of distribution is 1030L 

Metabolism 

Metabolism occurs through hydrolysis, UGT1A4, and UGT1A1d pathways 

Elimination and Excretion 

The half-life is 20 hours 

The rate of clearance is 31 L/hr 

73% of drug is excreted in the urine and 23% in feces  

Adminstartion

Administration: 

tecovirimat is administered orally in the form of tablets. The tablets are available in a strength of 200 mg and should be taken with food to improve absorption. The recommended dosage for the treatment of smallpox is 600 mg twice daily for 14 days. 

It is important to take tecovirimat as prescribed by a healthcare provider, and not to alter the dosage or duration of treatment without consulting a healthcare professional. Skipping doses or stopping treatment prematurely may lead to a reduced efficacy and increase the risk of developing drug-resistant strains of the virus. 

If a dose of tecovirimat is missed, it should be taken as soon as possible, unless it is almost time for the next scheduled dose. In this case, the missed dose should be skipped, and the regular dosing schedule should be resumed. Patients should not take a double dose to make up for a missed dose. 

tecovirimat should be stored at room temperature (between 20-25°C or 68-77°F), away from heat and moisture. The tablets should be kept in their original container until ready to use, and the container should be tightly closed after each use. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: tecovirimat 

Pronounced: Teco-viri-mat 

Why do we use tecovirimat? 

tecovirimat is used for the treatment of smallpox, a highly contagious and often fatal viral disease caused by the variola virus. Smallpox has been eradicated worldwide, but it is considered a potential bioterrorism agent, and there is a risk of the virus being used as a biological weapon. 

tecovirimat is a specific antiviral drug that inhibits the replication of the smallpox virus by blocking the formation and release of viral particles from infected cells. It has been shown to reduce the severity and duration of smallpox symptoms, decrease the viral load, and improve survival rates in animal models of infection. 

In the event of a smallpox outbreak or bioterrorist attack, tecovirimat may be used as a treatment option for infected individuals, along with other public health measures such as vaccination and isolation. The use of tecovirimat may help to limit the spread of the virus, reduce the morbidity and mortality associated with the disease, and facilitate the containment of the outbreak.