Medical Editor: John P. Cunha, DO, FACOEP
What Is TPOXX?
TPOXX (tecovirimat) is an inhibitor of the orthopoxvirus VP37 envelope wrapping protein and is indicated for the treatment of human smallpox disease in adults and pediatric patients weighing at least 13 kg.
What Are Side Effects of TPOXX?
Common side effects of TPOXX include:
- abdominal pain, and
TPOXX may cause serious side effects including:
- difficulty breathing, and
- swelling of your face, lips, tongue, or throat
Get medical help right away, if you have any of the symptoms listed above.
Seek medical care or call 911 at once if you have the following serious side effects:
- Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
- Serious heart symptoms such as fast, irregular, or pounding heartbeats; fluttering in your chest; shortness of breath; and sudden dizziness, lightheartedness, or passing out;
- Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors.
This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.
Dosage for TPOXX
The adult dose of TPOXX is 600 mg twice daily for 14 days. The pediatric dose of TPOXX is based on the child's bodyweight.
What Drugs, Substances, or Supplements Interact with TPOXX?
TPOXX may interact with repaglinide and midazolam. Tell your doctor all medications and supplements you use.
TPOXX During Pregnancy or Breastfeeding
Tell your doctor if you are pregnant or plan to become pregnant before using TPOXX; it is unknown how it would affect a fetus. It is unknown if TPOXX passes into breast milk. Consult your doctor before breastfeeding.
Our TPOXX (tecovirimat) Capsules Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
Clinical Trials Experience
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.
The safety of TPOXX has not been studied in patients with smallpox disease.
TPOXX Clinical Trial (Oral Administration)
The safety of TPOXX was evaluated in 359 healthy adult subjects ages 18-79 years in a Phase 3 clinical trial. Of the subjects who received at least one 600 mg dose of TPOXX, 59% were female, 69% were White, 28% were Black/African American, 1% were Asian, and 12% were Hispanic or Latino. Ten percent of the subjects who participated in the study were age 65 or older. Of these 359 subjects, 336 subjects received at least 23 of 28 doses of 600 mg TPOXX in a twice daily (every 12 hours) regimen for 14 days.
Most Frequently Reported Adverse Reactions
The most frequently reported adverse reactions were headache and nausea. Adverse reactions that occurred in at least 2% of subjects in the TPOXX treatment group are shown in Table 3.
Table 3: Treatment-Related Adverse Reactions Reported in ≥ 2% of Healthy Adult Subjects Receiving at Least One Dose of TPOXX Capsules 600 mg
|Adverse Reaction||TPOXX 600 mg
N = 359 (%)
N = 90 (%)
|aIncludes abdominal pain, abdominal pain upper, abdominal distension, abdominal discomfort, abdominal pain lower, epigastric pain|
Adverse Reactions Leading To Discontinuation Of TPOXX
Six subjects (2%) had their treatment with TPOXX discontinued due to adverse reactions. Each of these subject's adverse reactions (with severity) is listed below:
- EEG change, abnormal
- Mild upset stomach, dry mouth, decreased concentration and dysphoria
- Mild nausea and fever, moderate diarrhea, severe headache
- Mild palpable purpura
- Mild nausea, fever and chills
- Mild facial redness, facial swelling and pruritus
Less Common Adverse Reactions
Clinically significant adverse reactions that were reported in < 2% of subjects exposed to TPOXX and at rates higher than subjects who received placebo are listed below:
- Gastrointestinal: dry mouth, chapped lips, dyspepsia, eructation, oral paresthesia
- General and administration site: pyrexia, pain, chills, malaise, thirst
- Investigations: abnormal electroencephalogram, hematocrit decreased, hemoglobin decreased, heart rate increased
- Musculoskeletal and connective tissue: arthralgia, osteoarthritis
- Nervous system: migraine, disturbance in attention, dysgeusia, paresthesia
- Psychiatric: depression, dysphoria, irritability, panic attack
- Respiratory, Thoracic and Mediastinal Disorders: oropharyngeal pain
- Skin and subcutaneous tissue: palpable purpura, rash, pruritic rash, facial redness, facial swelling, pruritus
TPOXX Clinical Trial (Intravenous Administration)
The safety of multiple doses of 240 mg of TPOXX injection for IV infusion was evaluated in 26 healthy adult subjects ages 23-62 years, inclusive. An additional 6 subjects received placebo. TPOXX injection was administered over a 6 hour period via infusion pump twice daily (every 12 hours) for 7 days. Of the 26 subjects administered TPOXX, 42% were female, 69% were White, 23% were Black/African American, and 42% were Hispanic or Latino.
Most Frequently Reported Adverse Reactions
The most frequently reported adverse reactions included infusion site pain, infusion site swelling, infusion site erythema, infusion site extravasation, and headache. Adverse reactions that occurred in at least 4% of subjects in the TPOXX treatment group are shown in Table 4.
Table 4: Treatment-Related Adverse Reactions Reported in ≥ 4% of Healthy Adult Subjects Receiving at Least One Dose of TPOXX Injection 240 mg
|TPOXX 240 mg
N =26 (%)
N = 6 (%)
|Infusion Site Pain||73||67|
|Infusion Site Swelling||39||67|
|Infusion Site Erythema||23||67|
|Infusion Site Extravasation||19||50|
Adverse Reactions Leading To Discontinuation Of TPOXX Injection
Three subjects (12%) had their treatment with TPOXX injection discontinued due to adverse reactions. One subject had two adverse reactions. Each of these subject's adverse reactions (with severity) are listed below:
- Moderate Infusion site extravasation
- Mild Infusion site extravasation
- Mild Infusion site swelling and mild infusion site pain
Less Common Adverse Reactions
Clinically significant adverse reactions that were reported in < 4% of subjects exposed to TPOXX injection and at rates higher than subjects who received placebo are listed below:
- General and administration site: infusion site discomfort, infusion site edema
- Musculoskeletal and connective tissue: myalgia, arthritis, back pain, muscle tightness
- Gastrointestinal: diarrhea
- Eye: photophobia
- Skin and Subcutaneous Tissue: pruritus generalized
Effect Of TPOXX On Other Drugs
Tecovirimat is a weak inducer of cytochrome P450 (CYP)3A and a weak inhibitor of CYP2C8 and CYP2C19. However, the effects are not expected to be clinically relevant for most substrates of those enzymes based on the magnitude of interactions and the duration of treatment of TPOXX. See Table 5 for clinical recommendations for select sensitive substrates.
Established Drug Interactions
Table 5 provides a listing of established or significant drug interactions [see WARNINGS AND PRECAUTIONS and CLINICAL PHARMACOLOGY].
Table 5: Significant Drug Interactions
|Concomitant Drug Class: Drug Name||Effect on Concentrationa||Clinical Effect/Recommendation|
|Blood Glucose-Lowering Agent:|
|Repaglinideb||↑repaglinide||Monitor blood glucose and monitor for hypoglycemic symptoms in patients when TPOXX is co-administered with repaglinide [see WARNINGS AND PRECAUTIONS].|
|Midazolamb||↓midazolam||Monitor for effectiveness of midazolam.|
|a↓ = decrease, ↑ = increase
bThese interactions have been studied in healthy adults.
Drugs Without Clinically Significant Interactions With TPOXX
Based on a drug interaction study, no clinically significant drug interactions have been observed when TPOXX is co-administered with bupropion, flurbiprofen, or omeprazole [see CLINICAL PHARMACOLOGY].
No vaccine-drug interaction studies have been performed in human subjects. Some animal studies have indicated that co-administration of TPOXX at the same time as live smallpox vaccine (vaccinia virus) may reduce the immune response to the vaccine. The clinical impact of this interaction on vaccine efficacy is unknown.
Read the entire FDA prescribing information for TPOXX (Tecovirimat Capsules)
© TPOXX Patient Information is supplied by Cerner Multum, Inc. and TPOXX Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.
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