Why is antiviral drug development difficult

Are We Powerless Against Viruses?

Drug research is in full swing, and not just looking for a suitable active ingredient against the coronavirus. But why is it so difficult to find drugs to treat viral infections?

Viruses have a unique strategy to ensure their existence: They attack body cells and reprogram them in such a way that they lose their original function and instead produce many new viruses. This ensures their continued existence.

In many cases, the body manages to fight viral infections on its own. The immune system recognizes pathogens as a threat and begins to activate defense cells and produce antibodies in order to ultimately render them harmless. Vaccinations are also based on the same principle: the vaccine prepares the immune system for potential pathogens, i.e. trains the defense mechanisms so that the body is already equipped and fends off in the event of an actual infection with the respective pathogen. However, if the body cannot defend itself against the viruses on its own or if there is no appropriate vaccination protection, drug treatment is possible for special - but by no means all - viral diseases. However, there are limits to the therapy.

+++ More on the topic: Vaccinations of the future +++

No causal therapy

In contrast to bacteria - which can be treated well with antibiotics - viruses do not have their own metabolism. So they are not "independent" organisms, but need a host cell (somatic cell) for their own survival and reproduction. It is precisely this fact that makes the treatment of a viral disease with drugs (antivirals) difficult. Once the virus has penetrated the body cells, it is difficult to eliminate. Some antivirals only inhibit virus replication (HIV, hepatitis B, herpes), others (hepatitis C) can completely destroy the virus.

Stop virus replication

Although to date there are only a few drugs that kill viruses or eliminate them from the body (hepatitis C), with the help of special active ingredients - so-called "antivirals" - it has been possible for some diseases to at least prevent the viruses from multiplying and thus further To prevent spread. Although this does not completely heal the disease, symptoms can often be prevented, the infectiousness significantly reduced and the overall duration of the disease shortened. The most prominent example of this is HIV therapy, which has succeeded in preventing the virus from multiplying to such an extent that it is practically no longer detectable and those affected have an almost normal life expectancy. Antiretroviral therapies have also proven effective for other viral infections such as herpes, influenza or hepatitis B and C. In any case, it is important to start therapy as quickly as possible.

+++ More on the topic: HIV drugs +++

Side effects of antiviral therapy

However, side effects - as they can occur to varying degrees with all active ingredients - are also observed with this form of therapy. These include symptoms such as a feeling of weakness, general fatigue and headaches up to a high fever. The benefits and risks of antiviral therapy should therefore always be weighed up by the attending physician, discussed with the patient and regularly evaluated.

+++ More on the topic: side effects, allergies and intolerance +++

Symptomatic therapy

Viral diseases for which antiviral therapy is not yet available - such as the common cold - can only be treated symptomatically to date. The treatment is not directed specifically against the pathogen, but only alleviates the symptoms that are associated with the disease. Depending on the individual complaints, anti-inflammatory and / or antipyretic medication, pain relievers, decongestant nasal drops or the like are used.

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Authors:
Astrid Leitner
Medical review:
Dr. Horst Michael Schalk
Editorial editing:
Mag. Julia Wild

Updated on:

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