A synthetic nucleoside analogue with a pronounced antiviral effect. It has a broad spectrum of activity against various viruses.
Ribavirin is easily penetrates into the affected cells and virus rapidly phosphorylated intracellular adenosine mono- to ribavirin, di- and triphosphate. These metabolites, especially ribavirin triphosphate, have pronounced antiviral activity.
The mechanism of action of ribavirin is not well understood. However, it is known that Ribavirin inhibits inosine monophosphate dehydrogenase , this effect leads to a marked decrease in the level of intracellular guanosine triphosphate , which is in turn accompanied by suppression of the synthesis of viral and virus-specific proteins. Ribavirin inhibits the replication of new virions that reduces viral load. Ribavirin selectively inhibits the synthesis of viral without inhibiting synthesis in the normally functioning cells.
Ribavirin is effective against many methandienone viruses. The most sensitive to ribavirin viruses include: Simplex herpes virus, poks-virus, virus of Marek’s illness. Insensitive to ribavirin viruses include: Varicella Zoster, pseudorabies, cow smallpox. The most sensitive to ribavirin viruses are: influenza paramyxovirus (parainfluenza, epidemic parotite, Nucasl’s illness), reoviruses, tumoral viruses. Insensitive to ribavirin viruses are: enteroviruses, rhinovirus, Semlicy Forest.
Ribavirin has activity against hepatitis . The mechanism of action of ribavirin against have not been fully elucidated. It is assumed that accumulates as phosphorylation ribavirin triphosphate competitively inhibits the formation of guanosine triphosphate, thereby reducing the synthesis of viral .It is also believed that the mechanism of the synergistic action of ribavirin and alpha interferon against due to increased phosphorylation of ribavirin with interferon.
Absorption: ribavirin when administered orally is absorbed quickly from the gastrointestinal tract. Moreover, its bioavailability is greater than 45%.
Distribution: ribavirin is distributed in plasma, mucous secretions and airway erythrocytes. A large number of ribavirin triphosphate accumulates in red blood cells, reaching a plateau at Day 4 and continue for several weeks after administration. Poluraspredeleniya period of 3.7 hours, the distribution volume methandienone. In exchange reception ribavirin accumulates in plasma in large quantities. The ratio of the bioavailability (AUC – area under “concentration / time” curve) and by repeated single dose equal to 6. The high ribavirin concentrations (over 67%) can be detected in cerebrospinal fluid after prolonged use. Slightly bound to plasma proteins.
The time to reach maximum plasma concentration – from 1 to 1.5 hours.
The time to reach a therapeutic concentration in the plasma depends on the minute blood volume.
The average value of the maximum concentration in the plasma of about 5 micromoles per liter at the end of 1 week of receiving 200 mg every 8 hours and about 11 micromoles per liter at the end of 1 week of receiving 400 mg every 8 hours.
Biotransformation: ribavirin phosphorylated in liver cells in active metabolites as mono-, di- and triphosphate, which is then metabolized into 1,2,4 – triazolkarboksamid (amide hydrolysis trikarboksilovuyu deribozilirovanie and acid to form a triazole carboxylic metabolite).
Excretion: ribavirin is excreted from the body slowly. half life after receiving a single 200 mg dose of from 1 to 2 hours due to the plasma and erythrocytes of 40 days. Upon termination of a course of reception T? Is about 300 hours. Ribavirin and its metabolites are primarily excreted in the urine. Only about 10% is excreted in the feces. The unchanged for about 7% of ribavirin is displayed for 24 hours and about 10% – for 48 hours.
Pharmacokinetics in special clinical conditions: When taking the drug in patients with renal insufficiency ribavirin increased, due to a decrease in the true clearance. Patients with liver failure pharmacokinetics ribavirin does not change. After receiving a single dose with food containing fat varies significantly ribavirin pharmacokinetics .
Chronic hepatitis methandienone (primary patients not previously treated with interferon alpha, with aggravation after a course of monotherapy with interferon alpha, in patients refractory to monotherapy with interferon alpha), treatment is carried out in combination with interferon alpha.