Brincidofovir

Breast Feeding; Lactation; Milk, Human; Anti-Infective Agents; Antiviral Agents

FDA approved drugs -> Active ingredient

FDA approved drugs -> Active ingredient

In preregistration clinical trials of brincidofovir as prevention of cytomegalovirus and adenovirus infection in adults and children after hematopoietic stem cell transplantation (HSCT), serum aminotransferase elevations were more frequent with brincidofovir (22%) than placebo (16%) treatment, the usual rate of hepatic enzyme elevations being high after HSCT. ALT elevations above 5 times the upper limit of normal (ULN) arose in 1.8% vs 1.4% , and one of 269 brincidofovir recipients discontinued therapy because of ALT elevations above 10 times ULN. The ALT and AST elevations arose early as brincidofovir was given only 2 or 3 times, on days 1 and 8 and in some trials day 21 of treatment. In the same trials mild-to-moderate elevations in serum bilirubin arose in 6.5% of those on brincidofovir vs 5.9% of placebo recipients, again reflecting the high rate of bilirubin elevations in patients after HSCT. In small studies in healthy human volunteers abnormalities of liver tests were not observed. Since approval of brincidofovir, there have been no instances of smallpox infection that qualified for its use. However, the emergence of mpox infection shortly after its approval has led to its use for this non-approved indication. Aminotransferase elevations were frequent in the mpox virus infected subjects treated with brincidofovir but were invariably asymptomatic, transient and without symptoms or concurrent bilirubin elevations. Thus, the total clinical experience with use of brincidofovir is limited. While transient serum aminotransferase elevations have been reported with its use, there have been no reports of clinically apparent liver injury linked to brincidofovir therapy.

J - Antiinfectives for systemic use

QJ - Antiinfectives for systemic use

The pharmacologically active agent resulting from brincidofovir metabolism, cidofovir diphosphate, has an exceedingly long duration of action that allows for it to be dosed once weekly. The entirety of a brincidofovir smallpox treatment consists of only two doses, on days 1 and 8, which seemingly reduces the risk of adverse reactions. Regimens involving a longer duration of administration (i.e. more than a single dose on days 1 and 8) have been shown to increase mortality compared to placebo and should therefore be avoided. Brincidofovir is considered a potential human carcinogen and has demonstrated the potential to cause infertility - as such, its use should be restricted to situations in which it is absolutely necessary.

Brincidofovir is a pro-drug comprising [cidofovir] conjugated to a lipid molecule - the lipid component mimics an endogenous lipid, lysophosphatidylcholine, which allows the molecule to hijack endogenous lipid uptake pathways to enter infected cells. Following uptake, the lipid molecule is cleaved to generate cidofovir, which is then phosphorylated to generate the active antiviral compound, cidofovir disphosphate. The antiviral effects of cidofovir diphosphate appear to be the result of two distinct mechanisms. Mechanistic studies using recombinant vaccinia DNA polymerase suggest that it inhibits orthopoxvirus DNA polymerase-mediated DNA synthesis. In addition, cidofovir is an acyclic nucleotide analogue of deoxycytidine monophosphate - cidofovir diphosphate can therefore be incorporated into the growing viral DNA chain and consequently slow the rate of viral DNA synthesis.

Brincidofovir is a pro-drug of [cidofovir] and as such must undergo some basic metabolic reactions to become pharmacologically active. Upon entering the target cell, the phosphodiester bond of brincidofovir is hydrolyzed to generate cidofovir, which is then phosphorylated to generate the active agent: cidofovir diphosphate. The specific enzyme(s) responsible for this reaction have not been elucidated, but _in vitro_ findings suggest sphingomyelin phosphodiesterase plays a major role in the initial hydrolysis of brincidofovir. There are two major inactive metabolites of brincidofovir, CMX103 and CMX064, which are generated via carboxylation of the terminal carbon followed by several cycles of CYP-mediated oxidative reactions and fatty acid oxidation. These reactions are mediated, at least in part, by CYP4F2.

Agents used in the prophylaxis or therapy of VIRUS DISEASES. Some of the ways they may act include preventing viral replication by inhibiting viral DNA polymerase; binding to specific cell-surface receptors and inhibiting viral penetration or uncoating; inhibiting viral protein synthesis; or blocking late stages of virus assembly.

The oral bioavailability of brincidofovir is 13.4% in its tablet formulation and 16.8% in its suspension formulation. Following oral administration, the Cmax and AUCtau of brincidofovir were 480 ng/mL and 3400 ng·hr/mL, respectively. The Cmax and AUCtau of the active metabolite, cidofovir diphosphate, were 9.7 pg/106 cells and 1200 pg·hr/106 cells, respectively. Maximum plasma concentrations (Tmax) of brincidofovir are reached at approximately 3 hours post-administration, while maximal plasma concentrations for cidofovir diphosphate are reached at approximately 47 hours post-administration.

Brincidofovir is eliminated as metabolites in both the urine (~51%) and feces (~40%).

The apparent volume of distribution of brincidofovir is 1230 L.

The apparent clearance of brincidofovir in healthy adult patients is 44.1 L/h.