Amoxicillin vs Azithromycin: what is the difference?
Amoxicillin is a penicillin that blocks bacterial cell wall building, while azithromycin is a macrolide that stops protein synthesis and lingers for days.
Sources and notes
- The sentence under the titlefrom sourceMoleculeFinder comparison notesThe pair's answer line.
- The two drawingscomputedMoleculeFinder rule (RDKit MCS)Each molecule's own drawing, as its page shows it. The common core, 3 of 52 atoms, is too small to align on.
Side by side
| Amoxicillin | Azithromycin | |
|---|---|---|
| Molecular weightCalculated PubChem | 365.4 g/molC16H19N3O5S | 749 g/molC38H72N2O12 |
| Hydrogen-bond donorsCalculated PubChem | 4 | 5 |
| FamilyEditorial MoleculeFinder curated | Antibiotics | Antibiotics |
| Everyday groupEditorial MoleculeFinder curated | Prescription medicine | Prescription medicine |
| Chemical groupsCalculated Found by rule (RDKit) | Carboxylic Acids, Amines, Aromatics, Amides, Phenols | Alcohols, Esters, Ethers |
| Hazard labelReported ECHA, HSDB via PubChem; ECHA via PubChem | Danger | Danger |
| The supplier-filed hazard label's signal word, not a statement about ordinary use. | ||
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, HSDB via PubChem; ECHA via PubChem
- ECHAfrom sourceAttributionSource: European Chemicals Agency, echa.europa.eu.
- Identifiersfrom sourcePubChemPubChem CID 33613 (Amoxicillin) and 447043 (Azithromycin).
In more detail
Both are common antibiotics and they belong to different classes with different targets. Amoxicillin is a penicillin: it carries the four-membered beta-lactam ring that blocks bacterial cell wall construction, which is why it is inactivated by beta-lactamase enzymes and why it is often paired with clavulanic acid. Azithromycin is a macrolide, a large 15-membered ring that binds the bacterial ribosome and stops protein synthesis. Azithromycin accumulates inside tissue and clears very slowly, which is why a short course keeps working for days after the last dose, while amoxicillin clears in hours and must be taken repeatedly. Azithromycin is far the larger molecule at 749.0 against 365.4. Penicillin allergy is the usual reason a prescriber reaches for one class over the other.
Sources and notes
- The paragraphfrom sourceMoleculeFinder comparison notes
Questions
- What is the difference between Amoxicillin and Azithromycin?
- Amoxicillin is a penicillin that blocks bacterial cell wall building, while azithromycin is a macrolide that stops protein synthesis and lingers for days.
- Is Amoxicillin bigger than Azithromycin?
- Azithromycin is the heavier molecule, 749 g/mol against 365.4 g/mol for Amoxicillin. Amoxicillin is C16H19N3O5S and Azithromycin is C38H72N2O12.
Sources and notes
- The answersfrom sourceMoleculeFinderThe first is the pair's answer line; the others are read off the table above.