Brincidofovir, known commercially as Tembexa, is an antiviral medication. This prescription drug is designed to combat certain viral infections by interfering with how viruses reproduce. It is a lipid-conjugated prodrug, meaning it is an inactive compound that transforms into an active drug within the body. This unique design allows for more effective delivery of its active component to infected cells.
Treating Viral Infections
Brincidofovir is approved for treating human smallpox disease, caused by the variola virus. While smallpox was globally eradicated in 1980, the drug remains a preparedness measure. Its approval was based on animal studies, as human trials are not feasible for an eradicated disease.
The medication may also be used to treat mpox, another orthopoxvirus infection. Although not explicitly approved for mpox by the U.S. Food and Drug Administration (FDA), physicians can request its use for mpox treatment, especially in immunocompromised individuals. This includes adults and adolescents with HIV.
Beyond its approved uses, brincidofovir has been investigated for its activity against other double-stranded DNA viruses, including cytomegalovirus (CMV), adenoviruses, and BK virus. These viruses can cause significant issues in patient populations like transplant recipients, highlighting its potential utility.
How Brincidofovir Works
Brincidofovir functions as a nucleotide analog, a type of antiviral that mimics the building blocks of DNA. It is a prodrug of cidofovir, meaning brincidofovir is converted into cidofovir inside the body. This conversion happens within infected cells, where the lipid component of brincidofovir is cleaved away.
Once activated, cidofovir is processed into its active form, cidofovir diphosphate. This active metabolite interferes with viral DNA polymerase, an enzyme essential for the virus to copy its genetic material. By competing with natural substrates and incorporating into viral DNA, brincidofovir halts the replication process, preventing the virus from spreading. The lipid conjugation allows for more efficient entry into cells and helps reduce kidney toxicity often associated with cidofovir.
Important Safety Information
Taking brincidofovir requires careful consideration of potential side effects. Gastrointestinal issues are commonly reported, including diarrhea, nausea, vomiting, and abdominal pain. Severe issues might require medication discontinuation.
Liver function can be affected by brincidofovir, with elevations in liver enzymes observed. Regular monitoring of liver function is recommended before and during treatment. Although designed to reduce kidney toxicity compared to cidofovir, kidney function should also be monitored, especially in patients with pre-existing renal conditions.
A significant warning is an increased incidence of mortality with longer-than-recommended use. The typical smallpox regimen is two doses, one week apart. Using the drug beyond this short course has been linked to a higher risk of death.
Brincidofovir may cause fetal harm based on animal studies. Individuals who could become pregnant should undergo pregnancy testing and use effective contraception during treatment and for at least two months after the last dose. For males, animal studies suggest brincidofovir may irreversibly impair fertility. Male patients with female partners of childbearing potential should use condoms during treatment and for at least four months after the last dose.
The medication is available as oral tablets and an oral suspension. Tablets can be taken on an empty stomach or with a low-fat meal and should be swallowed whole. The oral suspension should be taken on an empty stomach and measured accurately. Avoid direct contact with broken or crushed tablets or the oral suspension. Healthcare providers will provide specific instructions on dosage and administration, which should be followed precisely.