An acyclovir analog that is a potent inhibitor of the Herpesvirus family including cytomegalovirus. Ganciclovir is used to treat complications from AIDS-associated cytomegalovirus infections. [PubChem]
Indication
For induction and maintenance in the treatment of cytomegalovirus (CMV) retinitis in immunocompromised patients, including patients with acquired immunodeficiency syndrome (AIDS). Also used in the treatment of severe cytomegalovirus (CMV) disease, including CMV pneumonia, CMV gastrointestinal disease, and disseminated CMV infections, in immunocompromised patients.
Pharmacology
Ganciclovir is a synthetic nucleoside analogue of 2'-deoxyguanosine that inhibits replication of herpes viruses both in vitro and in vivo. Sensitive human viruses include cytomegalovirus (CMV), herpes simplex virus -1 and -2 (HSV-1, HSV-2), Epstein-Barr virus (EBV) and varicella zoster virus (VZV), however clinical studies have been limited to assessment of efficacy in patients with CMV infection. Ganciclovir is a prodrug that is structurally similar to acyclovir. It inhibits virus replication by its encorporation into viral DNA. This encorporation inhibits dATP and leads to defective DNA, ceasing or retarding the viral machinery required to spread the virus to other cells.
Toxicity
Oral, mouse LD50: > 2g/kg. Intravenous, dog LD50: > 150mg/kg. Symptoms of overdose include irreversible pancytopenia, worsening GI symptoms, and acute renal failure. Suspected cancer agent.
Affected Organisms
Human Herpes Virus
Biotransformation
Little to no metabolism, about 90% of plasma ganciclovir is eliminated unchanged in the urine.
Absorption
Poorly absorbed systemically following oral administration. Bioavailability under fasting conditions is approximately 5%, and when administered with food, 6 to 9% (about 30% with a fatty meal).
Half Life
2.5 to 3.6 hours (mean 2.9 hours) when administered intravenously in adults. 3.1 to 5.5 hours when administered orally in adults. Renal function impairment causes a marked increase in half life (9 to 30 hours intravenously, 15.7 to 18.2 hours orally).
Protein Binding
1 to 2%
Elimination
Renal excretion of unchanged drug by glomerular filtration and active tubular secretion is the major route of elimination of ganciclovir.
