Loratadine vs Cetirizine: what is the difference?
Cetirizine reaches the brain slightly more than loratadine, acting faster but sedating a little more, while the liver turns loratadine into desloratadine.
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, 7 of 27 atoms, is too small to align on.
Side by side
| Loratadine | Cetirizine | |
|---|---|---|
| Molecular weightCalculated PubChem | 382.9 g/molC22H23ClN2O2 | 388.9 g/molC21H25ClN2O3 |
| Hydrogen-bond donorsCalculated PubChem | 0 | 1 |
| Also sold asEditorial MoleculeFinder curated | Claritin, Alavert | Zyrtec |
| FamilyEditorial MoleculeFinder curated | Over-the-counter medicines | Over-the-counter medicines |
| Everyday groupEditorial MoleculeFinder curated | OTC medicine | OTC medicine |
| Chemical groupsCalculated Found by rule (RDKit) | Aromatics, Esters, Halogenated | Carboxylic Acids, Aromatics, Ethers, Halogenated |
| Hazard labelReported ECHA via PubChem | Danger | Warning |
| The supplier-filed hazard label's signal word, not a statement about ordinary use. | ||
| Oral LD50Measured HSDB via PubChem | 5,000 mg/kgpure loratadine, rat, 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.
- Also sold asfrom sourceMoleculeFinder curated
- 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 3957 (Loratadine) and 2678 (Cetirizine).
In more detail
Both are second generation antihistamines taken once a day and both block the H1 receptor. Cetirizine crosses into the brain slightly more than loratadine does, so it is a little more likely to cause drowsiness while also tending to act faster and more strongly on symptoms. Loratadine is a prodrug in effect: the liver converts much of it to desloratadine, which is what does most of the work, and that adds a step cetirizine does not have. Cetirizine is the heavier molecule at 388.9 against 382.9 and carries a carboxylic acid where loratadine carries a carbamate ester. Both are sold over the counter in the United States and the United Kingdom.
Sources and notes
- The paragraphfrom sourceMoleculeFinder comparison notes
Questions
- What is the difference between Loratadine and Cetirizine?
- Cetirizine reaches the brain slightly more than loratadine, acting faster but sedating a little more, while the liver turns loratadine into desloratadine.
- Is Loratadine bigger than Cetirizine?
- Cetirizine is the heavier molecule, 388.9 g/mol against 382.9 g/mol for Loratadine. Loratadine is C22H23ClN2O2 and Cetirizine is C21H25ClN2O3.
Sources and notes
- The answersfrom sourceMoleculeFinderThe first is the pair's answer line; the others are read off the table above.