Valaciclovir is a so-called prodrug of the antiviral substance aciclovir. It belongs to the group of nucleic base analogues. It is used to treat systemic infections with the herpes simplex virus, such as herpes zoster. Valaciclovir is available only on prescription and is mainly taken in tablet form.



Valaciclovir, or its active form aciclovir, is a so-called antimetabolite for the DNA of the herpes virus. It is incorporated into the DNA of the virus due to its structural similarity to the nucleic base guanine. This causes the DNA strand to break and the virus cannot replicate further. It has no effect on the DNA of healthy cells.


The oral bioavailability of valaciclovir is approximately 54% and protein binding is 13-17%. Degradation is not catalyzed by enzymes of the CYP450 system, but by various other enzymes (dehydrogenases and oxidases). Over 90% of the ingested dose is excreted in the urine. The elimination half-life is about 2-3 hours.


Side effects

The most common are headache, dizziness or discomfort of the gastrointestinal tract.

Valaciclovir should not be taken by pregnant women.

Toxicological Data

LD50: Oral Rat - 903.5 mg/kg

Chemical & physical properties

ATC Code J05AB11
Formula C13H20N6O4
Molar Mass (g·mol−1) 324,34
Physical State solid
Melting Point (°C) 170-172
PKS Value 1.90
CAS Number 124832-26-4
PUB Number 135398742
Drugbank ID DB00577

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All information used for the content comes from verified sources (recognised institutions, experts, studies by renowned universities). We attach great importance to the qualification of the authors and the scientific background of the information. Thus, we ensure that our research is based on scientific findings.
Markus Falkenstätter, BSc

Markus Falkenstätter, BSc

Markus Falkenstätter is a writer on pharmaceutical topics in Medikamio's medical editorial team. He is in the last semester of his pharmacy studies at the University of Vienna and loves scientific work in the field of natural sciences.

Mag. pharm. Stefanie Lehenauer

Mag. pharm. Stefanie Lehenauer

Stefanie Lehenauer has been a freelance writer for Medikamio since 2020 and studied pharmacy at the University of Vienna. She works as a pharmacist in Vienna and her passion is herbal medicines and their effects.

The content of this page is an automated and high-quality translation from DeepL. You can find the original content in German here.


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