Valganciclovir is a virostatic agent used to treat cytomegalovirus retinitis (inclusion body disease) occurring in AIDS patients. The drug belongs to the group of nucleoside analogues and is widely used. As a prodrug of the substance ganciclovir, it has essentially the same effects and side effects as the latter.
What is valganciclovir?
Valganciclovir is a virus-inhibiting agent (a virostatic agent) that belongs to the group of nucleoside analogues and is a major part of the treatment of AIDS patients. It is administered to treat cytomegalovirus retinitis (inclusion body disease). This is a disease caused by the human cytomegalovirus and is particularly dangerous for people with weak immune systems. Valganciclovir is taken perorally (by mouth) and is usually well and quickly absorbed by the body. The active ingredient itself only becomes active within the body. After metabolization (metabolization), it converts to the related substance ganciclovir. Valganciclovir is therefore considered to be its prodrug. The active ingredient is described by the chemical molecular formula C 14 – H 22 – N 6 – O 5, which corresponds to a moral mass of 354.36 g/mol. In Germany, Austria, and Switzerland, valganciclovir is sold under the name Valcyte as a prescription and pharmacy-only drug.
Pharmacologic Action
Valganciclovir is composed of two stereocenters, which basically makes possible the presence of four so-called stereoisomers. However, the stereocenters of valganciclovir are uniformly configured as Ss. The actual number of stereoisomers is therefore limited to only two, which has implications for the pharmacological action of the compound. Once metabolized in the human body, this inhibits the replication of the human cytomegalovirus (HCMV), also known as human herpesvirus 5 (HHV 5). The virus is especially dangerous for those people who – like AIDS patients – have only a very weak immune system. Valganciclovir achieves its virus-inhibiting effect by converting the basically inactive substance within the human body into the pharmacologically very effective substance ganciclovir. This makes it impossible for HHV 5 or HCMV to produce an enzyme essential for reproduction. Valganciclovir is thus considered a so-called prodrug, which is why it has positive pharmacokinetics and high bioavailability.
Medical application and use
Cytomegalovirus (HCMV) therapy represents the main application of valganciclovir. The virus is usually harmless to a healthy person because the immune system is able to reduce replication to tolerable levels. However, if the immune system is massively weakened, for example due to AIDS, infection with HCMC or HHV 5 can be life-threatening. This is because in these cases the body itself is no longer capable of keeping the number of viruses down. These can spread almost uncontrollably. Valganciclovir counteracts this by inhibiting the multiplication of the viruses. The active ingredient, which is basically taken orally as a film-coated tablet, is thus a virostatic agent.
Risks and side effects
Valganciclovir may cause side effects. However, this is not necessarily the case. Because valganciclovir is a prodrug and is converted into the active ingredient ganciclovir within the human body, the side effects are largely the same as those of ganciclovir. Accordingly, a pathogenic reduction of neutrophil granulocytes may occur (so-called neutropenia). A marked deficiency of granulocytes in the blood (agranulocytosis) is also a typical side effect of ganciclovir and valganciclovir. In addition, a very low hemoglobin content in the blood (anemia) can also be caused by valganciclovir. In addition, gastrointestinal complaints such as diarrhea, abdominal pain, stomach cramps, and vomiting are among the conceivable side effects. Occasionally, damage to liver cells or neuropathy may also occur. If an intolerance to valganciclovir or ganciclovir is known, the active substances must not be taken.
