Vaccine Info

Tembexa Oral Antiviral

Authored by
Last reviewed
July 26, 2022
Fact checked by
Robert Carlson, MD

Tembexa® Oral Antiviral Description

Tembexa® (brincidofovir) is an oral antiviral approved by the U.S. Food and Drug Administration (FDA) in June 2021, in tablet and oral suspension formulations, for treating smallpox disease in adult and pediatric patients. Tembexa was developed with the U.S. Department of HHS’ Biomedical Advanced Research and Development Authority (BARDA). The initial U.S. Approval was in 1996. In addition, Tembexa received U.S. FDA Priority Review, Fast Track, and Orphan Drug designations. 

Brincidofovir is an orthopoxvirus nucleotide analog DNA polymerase inhibitor and a lipid conjugate of the nucleotide analog cidofovir and is indicated for treating human smallpox disease. The full chemical name is: Phosphonic acid, P-[[(1S)-2-(4-amino-2-oxo-1(2H)-pyrimidinyl)-1- (hydroxymethyl)ethoxy]methyl]-, mono[3-(hexadecyloxy)propyl] ester.

Chimerix is a biopharmaceutical company located in North Carolina with a mission to develop medicines that meaningfully improve and extend the lives of patients facing deadly diseases.

Tembexa Indication

Tembexa is a medical countermeasure recently approved for treating smallpox in all age groups, including infants, and for patients with difficulty swallowing. According to the U.S. CDC, the variola virus is ranked in the highest risk category for bioterrorism agents (Category A) due to its ease of transmission, high mortality rate, and potential to cause public panic and social disruption.

TEMBEXA should not be co-administered with intravenous cidofovir.

Tembexa Dosage

TEMBEXA is an oral antiviral formulated as 100 mg tablets and 10 mg/mL oral suspension dosed once weekly for two weeks. Tembexa is available in both tablets and oral suspension. It was the first antiviral to be approved for the treatment of smallpox in all age groups, including infants and patients with difficulty swallowing.

Tembexa Preparation

Tembexa is considered a potential human carcinogen. Therefore, do not crush or divide Tembexa tablets and avoid direct contact with broken or crushed tablets or oral suspension.

Tembexa Side Effects

BOXED WARNING: An increased incidence of mortality was seen in TEMBEXA-treated subjects compared to placebo-treated subjects in a 24-week clinical trial when TEMBEXA was evaluated in another disease. Therefore, safety information to support approval of Tembexa was derived from clinical trials of the drug for a non-smallpox indication, primarily from patients who received hematopoietic stem cell transplants. The following clinically significant adverse reactions: Elevations in hepatic transaminases and bilirubin; Diarrhea, and other GI adverse events.

Common adverse reactions (adverse events assessed as causally related by the investigator in ≥ 2% of subjects) experienced in the first two weeks of dosing with TEMBEXA were diarrhea, nausea, vomiting, and abdominal pain.

You are encouraged to report the adverse side effects of prescription drugs to the FDA. Visit or call 1-800-FDA-1088.

Tembexa Fertility

Male Infertility: Based on testicular toxicity in animal studies, Tembexa may irreversibly impair fertility in individuals of reproductive potential.

Based on findings from animal reproduction studies, TEMBEXA may cause fetal harm when administered to pregnant individuals. Pregnancy testing should be performed before initiation of TEMBEXA in individuals of childbearing potential to inform risk. An alternative therapy should be used to treat smallpox during pregnancy, if feasible.

Tembexa News

June 24, 2022 - Chimerix announced Public Health Agency of Canada awarded Chimerix a contract up to a $25.3 million agreement to procure TEMBEXA® (brincidofovir). Execution of this contract will be the responsibility of Chimerix.

June 23, 2022 - Chimerix announced a $9.3 million agreement to procure TEMBEXA with a third party outside of North America.

May 16, 2022 - Chimerix announced a definitive agreement with Emergent BioSolutions Inc. to acquire its exclusive worldwide rights to brincidofovir, including TEMBEXA®.

June 4, 2021 - The U.S. FDA approved Tembexa (brincidofovir) to treat smallpox. 

Clinical Trials

No clinical trials found