Amitriptyline vs Nortriptyline: what is the difference?
Nortriptyline is amitriptyline minus one methyl group, made from it by the body, and it is the less sedating of the two tricyclics.
One methyl group apart.
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; the amber marks where the two differ.
- The captionfrom sourceMoleculeFinder curated
- What is highlightedfrom sourceMoleculeFinder curatedOne line under each drawing, written from the atoms the amber marks.
- Structural similaritycomputedRDKit Morgan/Tanimoto0.61 of 1, a Morgan fingerprint Tanimoto coefficient. It measures shape, not effect.
Side by side
| Amitriptyline | Nortriptyline | |
|---|---|---|
| Molecular weightCalculated PubChem | 277.4 g/molC20H23N | 263.4 g/molC19H21N |
| Hydrogen-bond donorsCalculated PubChem | 0 | 1 |
| FamilyEditorial MoleculeFinder curated | Tricyclic antidepressants | Tricyclic antidepressants |
| Everyday groupEditorial MoleculeFinder curated | Prescription medicine | Prescription medicine |
| Chemical groupsCalculated Found by rule (RDKit) | Aromatics | Amines, Aromatics |
| Hazard labelReported ECHA, HSDB via PubChem | Danger | Warning |
| The supplier-filed hazard label's signal word, not a statement about ordinary use. | ||
| Oral LD50Measured HSDB via PubChem | 140 mg/kgpure amitriptyline, mouse, oral | 387 mg/kgpure nortriptyline, mouse, oral |
| 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, HSDB via PubChem
- Oral LD50from sourceHSDB via PubChem
- ECHAfrom sourceAttributionSource: European Chemicals Agency, echa.europa.eu.
- Identifiersfrom sourcePubChemPubChem CID 2160 (Amitriptyline) and 4543 (Nortriptyline).
In more detail
Taking amitriptyline therefore produces nortriptyline as an active metabolite. Both are tricyclic antidepressants that block serotonin and norepinephrine reuptake, and the missing methyl shifts the balance: nortriptyline leans more toward norepinephrine and carries fewer antihistamine and anticholinergic effects. That is why nortriptyline is generally the less sedating of the two and causes less dry mouth and constipation. Both are used at low levels for nerve pain and migraine prevention as well as for depression. Weights differ by the methyl group alone, 277.4 against 263.4.
Sources and notes
- The paragraphfrom sourceMoleculeFinder comparison notes
Questions
- What is the difference between Amitriptyline and Nortriptyline?
- Nortriptyline is amitriptyline minus one methyl group, made from it by the body, and it is the less sedating of the two tricyclics.
- Is Amitriptyline bigger than Nortriptyline?
- Amitriptyline is the heavier molecule, 277.4 g/mol against 263.4 g/mol for Nortriptyline. Amitriptyline is C20H23N and Nortriptyline is C19H21N.
- Which has the lower reported LD50, Amitriptyline or Nortriptyline?
- Amitriptyline, at 140 mg/kg (oral, mouse), against 387 mg/kg (oral, mouse) for Nortriptyline. An LD50 is one acute animal measurement, and the two here were not necessarily measured in the same species, so it is a data point rather than a ranking of how dangerous either is to a person.
Sources and notes
- The answersfrom sourceMoleculeFinderThe first is the pair's answer line; the others are read off the table above.