Virustatics (often also called virostatics) are a group of drugs used to treat viral diseases. Unlike antibiotics, which are used for bacterial infections and are already an integral part of modern medicine, the development of antiviral agents is still in its early stages. Although initial experiments took place as early as the 1960s, targeted development of virus-inhibiting drugs was only made possible by advances in genetic research in the 1980s.
What are virustatics?
Most virustatics do not fight viruses directly but contain them by interrupting the reproductive process. Most virustatics do not fight viruses directly, but contain them by interrupting the reproductive process. Unlike bacteria, viruses cannot reproduce on their own and therefore rely on host cells. Antiviral drugs can interrupt this process at several points. For example, they can prevent viruses from gaining access to the receptors, i.e. the docking sites, of a host cell or prevent the virus from taking over the cell completely. Other agents prevent the proliferation of already infected cells by interrupting cell division. Still other drugs, such as the so-called interferons, support the immune system in fighting the pathogen. These endogenous messenger substances are produced by infected cells to alert the surrounding tissue to the virus and activate additional defense mechanisms. This process is intensified with the aid of synthetic interferons. Artificially produced antibodies have a similar effect. These bind to infected cells and thus accelerate their recognition and fight against them. The use of immunostimulatory drugs, among other procedures, is also known as immunotherapy.
Medical application, effect, and use
Among the most commonly used viral drugs are antiretroviral drugs. These are used in the treatment of HIV infection to slow the onset of AIDS. Although a cure cannot yet be expected, the virus-inhibiting effect is promising and has already significantly increased the life expectancy of HIV patients. Virustatics are also being used more and more frequently in other areas, often as a supplement to vaccinations. Preventive measures remain more effective, but influenza viruses mutate so rapidly that a new vaccine must be developed every year. If this is administered too late, antiviral medications can ease the course of the disease in at-risk groups. These include children, pregnant women, patients whose immune systems are weakened, or those suffering from chronic diseases that can cause complications. In cases of prolonged hepatitis, a similar approach can be taken to minimize severe damage to the liver. In the case of incurable herpes simplex disease, antivirals can reduce the duration, severity, and frequency of recurrent disease outbreaks. Additionally, in many cases, these drugs reduce the risk of transmission. Similar to antibiotics, antivirals have already caused the emergence of resistant viral diseases, which is taken into consideration when using them. Therefore, these agents are generally used in a very targeted manner when the benefits of treatment outweigh the risks.
Herbal, natural, homeopathic, and pharmaceutical virostatics.
Many viral inhibitors are made from natural ingredients. The basic ingredient of the well-known drug Tamiflu (active ingredient: oseltamivir) is derived from true star anise. During the bird flu epidemic, increased demand even led to supply shortages. The antiviral effect is attributed to the essential oils found in the plant. According to laboratory tests, these are also responsible for the effect of eucalyptus oil against herpes viruses. In addition, many fungal species contain antiviral components. However, purely natural medicines do not yet exist. All natural source materials additionally undergo several, often very complex, processing steps. The dosage forms vary; injection solutions and tablets are common. Drugs are often subdivided according to their mode of action, i.e. whether they affect the virus before, after or during infection of healthy cells. The spectrum of application is another factor.Virustatics can be targeted against single or a small number of related diseases or, like interferons, can exert a general antiviral effect.
Risks and side effects
Because the group of these drugs is very large, the spectrum of possible side effects is also correspondingly broad and depends on the type of application. For example, antiviral ointments that are applied externally are well tolerated, and side effects are usually limited to the area of application. Among the systemically acting drugs, i.e., those taken as tablets, nausea, headache, and diarrhea occur more frequently. Virustatics designed for specific pathogens are generally better tolerated, while agents that can be applied over large areas usually also cause more side effects. Since most active ingredients are processed via the liver, patients with liver disease are exposed to greater risks. Since death can occur in the rarest cases and many virus-inhibiting agents have only been on the market for a few years, side effects cannot always be predicted accurately. The most common emerging viral diseases heal without problems in healthy people and therefore justify the use of antiviral agents only in exceptional cases.
