July 08, 2024
I’m a venerable medication with significant downsides.
What molecule am I?
Image of Amitriptyline 3D Image of Amitriptyline

Amitriptyline is a tricyclic molecule with a cycloheptane ring in the center and an amino group in the sidechain. It is an antidepressant that was developed by Merck (Rahway, NJ) in the 1950s and approved by the US Food and Drug Administration in 1961. It was originally sold under the trade name Elavil.

In addition to major depressive disorders, amitriptyline is used to treat chronic pain conditions, including neuropathy, fibromyalgia, migraine, and tension headache. Its mode of action is to increase the availability of monoamines in the central nervous system postsynaptic clefts.

Today the drug’s numerous and sometimes severe side effects make it a second-line treatment for these disorders. Among its more serious side effects are blurred vision, tachycardia, fatigue, suicidal thoughts among young people, overdose, and dependence.

In 2021, T. Umaharan*, S. Sivayokan, and S. Sivansuthan at Jaffna Teaching Hospital (Sri Lanka) published a case report and literature review of amitriptyline dependence. The authors confirmed that vulnerable individuals are subject to dependence on the drug and suggest that “a clear protocol should be implemented when dispensing medications from pharmacy to patients.”

Amitriptyline hazard information*

Hazard class**GHS code and hazard statement
Acute toxicity, oral, category 3H301—Toxic if swallowedChemical Safety Warning
Acute toxicity, dermal, category 3H311—Toxic in contact with skinChemical Safety Warning
Serious eye damage/eye irritation, category 1H318—Causes serious eye damageChemical Safety Warning
Acute toxicity, inhalation, category 3H331—Toxic if inhaledChemical Safety Warning
Specific target organ toxicity, single exposure; narcotic effects, category 3H336—May cause drowsiness or dizzinessChemical Safety Warning
Reproductive toxicity, category 2H361—Suspected of damaging fertility or the unborn childChemical Safety Warning
Reproductive toxicity, effects on or via lactationH362—May cause harm to breast-fed children
Short-term (acute) aquatic hazard, category 1H400—Very toxic to aquatic lifeChemical Safety Warning
Long-term (chronic) aquatic hazard, category 1H410—Very toxic to aquatic life with long-lasting effectsChemical Safety Warning

*Compilation of multiple safety data sheets.
**Globally Harmonized System (GHS) of Classification and Labeling of Chemicals. Explanation of pictograms.

Molecules in the News

Diisononyl phthalate1 (DINP) and diisodecyl phthalate2 (DIDP) are branched long-chain phthalic acid3 esters that are widely used as plasticizers to make hard plastics such as poly(vinyl chloride)4 softer and more flexible. Originally developed in the 1950s and 1960s, these plasticizers and others have come under scrutiny in recent years for being possible carcinogens and for causing other health problems.

This May, the US Environmental Protection Agency completed a draft review of risk evaluations for DINP and DIDP that had mixed findings. EPA’s preliminary results indicated that:

  • DINP has a greater chance of causing liver damage than DIDP.
  • DINP in high concentrations can cause cancer, whereas DIDP poses no cancer risk.

With one exception, the agency gave DIDP a clean bill of health for all uses.

1. CAS Reg. No. 28553-12-0.
2. CAS Reg. No. 26761-40-0.
3. CAS Reg. No. 88-99-3.
4. CAS Reg. No. 9002-86-2.

Molecules in the News

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Amitriptyline fast facts

CAS Reg. No.50-48-6
Molar mass277.40 g/mol
AppearanceWhite crystals or powder
Melting point196–197 °C
10 mg/L (25 °C)
Chemical Abstract Service - a division of ACS

Learn more about this molecule from CAS, the most authoritative and comprehensive source for chemical information.

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