Also Known As: Ribavirin, Rebetron, Copegus, Rebetol, Ribasphere, Vilona, Virazole
Ribavirin (brand names: Copegus, Rebetol, Ribasphere, Vilona and Virazole) is an anti-viral drug indicated for severe RSV infection (individually), hepatitis C infection (used in conjunction with peginterferon alfa-2b or peginterferon alfa-2a) and other viral infections. Ribavirin is a prodrug, which when metabolised resembles purine RNA nucleotides. In this form it interferes with RNA metabolism required for viral replication. How it exactly affects viral replication is unknown; many mechanisms have been proposed for this (see Mechanisms of Action, below) but none of these has been proven to date. Multiple mechanisms may be responsible for its actions.
The primary observed serious adverse side effect of ribavirin is hemolytic anemia, which may worsen preexisting cardiac disease. The mechanism for this effect is due to ribavarin's buildup inside erythrocytes. Oxidative damage to erythrocyte cell membrane is usually inhibited by glutathione; however, with reduced ATP levels caused by ribavirin, glutathione levels are impaired, permitting oxidative erythrocyte cell lysis. The gradual loss of erythrocytes leads to anemia. The anemia is dose-dependent and may sometimes be compensated by decreasing dose. Ribavirin is also a teratogen in some animals species and thus poses a theoretical reproductive risk in humans, remaining a hazard as long as the drug is present, which can be as long as 6 months after a course of the drug has ended.
Ribavirin is active against a number of DNA and RNA viruses. It is a member of the nucleoside antimetabolite drugs that interfere with duplication of viral genetic material. Ribavirin is active against influenzas, flaviviruses and agents of many viral hemorrhagic fevers.
Ribavirin is the only known treatment for a variety of viral hemorrhagic fevers, including Lassa fever, Crimean-Congo hemorrhagic fever, Venezuelan hemorrhagic fever, and Hantavirus infection, although data regarding these infections are scarce and the drug might be effective only in early stages.
The aerosol form has been used in the past to treat respiratory syncytial virus-related diseases in children. However, its efficacy has been called into question by multiple studies, and most institutions no longer use it. It is still used in some cases.
Experimental data indicate that ribavirin may have useful activity against many viruses of interest, including avian influenza, hepatitis B, polio, measles, Canine distemper and smallpox. Ribavirin is active in a hamster model of yellow fever, a finding which is not surprising, given the familial relationship of yellow fever and hepatitis C viruses as flaviviridae. Ribavirin is active against other important flaviviridae such as West Nile virus and dengue fever.
Ribavirin has also been used as a treatment for herpes simplex virus. One small study found that ribavirin treatment reduced the severity of herpes outbreaks and promoted recovery, as compared with placebo treatment. Another study found that ribavirin potentiated the antiviral effect of acyclovir.
Ribavirin's present generic status is expected to slow research into new uses, however.