SHEET /vs/aciclovir-vs-valaciclovir · COMPARISON
Aciclovir vs Valaciclovir: what is the difference?
How they differ
Valaciclovir is aciclovir with the amino acid valine attached, and the body removes that valine almost completely on first pass through the liver, so what circulates is aciclovir. The attachment exists purely to solve an absorption problem: aciclovir taken by mouth is poorly absorbed, and valaciclovir raises the amount that reaches the blood several fold. Both therefore work the same way, being activated only inside virus-infected cells by a viral enzyme and then jamming the viral DNA polymerase, which is what makes them so selective. Valaciclovir is the heavier molecule at 324.34 against 225.2 because of the added valine, and fewer doses are needed. Aciclovir's discovery won a share of the 1988 Nobel Prize in Medicine.
Side by side
| Aciclovir | Valaciclovir | |
|---|---|---|
| Formula | C8H11N5O3 | C13H20N6O4 |
| Molecular weight | 225.2 g/mol | 324.34 g/mol |
| Family | Antivirals | Antivirals |
| Everyday group | Prescription medicine | Prescription medicine |
| Functional groups | Alcohols, Amines, Ethers | Amines, Esters, Ethers |
| GHS signal wordThe supplier-filed hazard label, not a statement about ordinary use. | Warning | Warning |
| Oral LD50A single acute animal measure. It ranks nothing about human safety. | 10,000 mg/kg (oral, mouse) | not recorded |
| CAS number | 59277-89-3 | 124832-26-4 |
| PubChem CID | 135398513 | 135398742 |
Structural similarity 0.67 of 1, computed as a Morgan fingerprint Tanimoto coefficient. It measures shape, not effect.
Common questions
- What is the difference between Aciclovir and Valaciclovir?
- Valaciclovir is aciclovir with the amino acid valine attached, and the body removes that valine almost completely on first pass through the liver, so what circulates is aciclovir. The attachment exists purely to solve an absorption problem: aciclovir taken by mouth is poorly absorbed, and valaciclovir raises the amount that reaches the blood several fold. Both therefore work the same way, being activated only inside virus-infected cells by a viral enzyme and then jamming the viral DNA polymerase, which is what makes them so selective.
- Is Aciclovir bigger than Valaciclovir?
- Valaciclovir is the heavier molecule, 324.34 g/mol against 225.2 g/mol for Aciclovir. Aciclovir is C8H11N5O3 and Valaciclovir is C13H20N6O4.
Read the full records: Aciclovir and Valaciclovir.