Aciclovir vs Valaciclovir: what is the difference?
Valaciclovir is aciclovir with the amino acid valine attached, which the body removes, so swallowed valaciclovir delivers far more aciclovir to the blood.
Sources and notes
- The sentence under the titlefrom sourceMoleculeFinder comparison notesThe pair's answer line.
- The two drawingscomputedMoleculeFinder rule (RDKit MCS)Drawn the same way round on the skeleton they share. Aligned; 7 atoms differ, too many to mark as one group.
- Structural similaritycomputedRDKit Morgan/Tanimoto0.67 of 1, a Morgan fingerprint Tanimoto coefficient. It measures shape, not effect.
Side by side
| Aciclovir | Valaciclovir | |
|---|---|---|
| Molecular weightCalculated PubChem | 225.2 g/molC8H11N5O3 | 324.34 g/molC13H20N6O4 |
| Hydrogen-bond donorsCalculated PubChem | 3 | 3 |
| FamilyEditorial MoleculeFinder curated | Antivirals | Antivirals |
| Everyday groupEditorial MoleculeFinder curated | Prescription medicine | Prescription medicine |
| Chemical groupsCalculated Found by rule (RDKit) | Alcohols, Amines, Ethers | Amines, Esters, Ethers |
| Hazard labelReported ECHA via PubChem | Warning | Warning |
| The supplier-filed hazard label's signal word, not a statement about ordinary use. | ||
| Oral LD50Measured HSDB via PubChem | 10,000 mg/kgpure aciclovir, mouse, oral | Not recorded |
| A single acute animal measure. It ranks nothing about human safety. | ||
Sources and notes
- Molecular weightcomputedPubChemComputed from the structure; the formula is under each weight.
- Hydrogen-bond donorscomputedPubChemThe hydrogens on nitrogen or oxygen that each molecule can lend to a hydrogen bond, counted from its structure.
- Familyfrom sourceMoleculeFinder curated
- Everyday groupfrom sourceMoleculeFinder curated
- Chemical groupscomputedFound by rule (RDKit)Each group is found in the structure by a chemical pattern.
- Hazard labelfrom sourceECHA via PubChem
- Oral LD50from sourceHSDB via PubChem
- ECHAfrom sourceAttributionSource: European Chemicals Agency, echa.europa.eu.
- Identifiersfrom sourcePubChemPubChem CID 135398513 (Aciclovir) and 135398742 (Valaciclovir).
In more detail
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.
Sources and notes
- The paragraphfrom sourceMoleculeFinder comparison notes
Questions
- What is the difference between Aciclovir and Valaciclovir?
- Valaciclovir is aciclovir with the amino acid valine attached, which the body removes, so swallowed valaciclovir delivers far more aciclovir to the blood.
- 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.
Sources and notes
- The answersfrom sourceMoleculeFinderThe first is the pair's answer line; the others are read off the table above.