CID 3676

C₁₄H₂₂N₂O

Lidocaine

C 14
H 22
N 2
O 1

Ball-and-stick Stick Space-filling

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39 atoms, 39 bonds.

IUPAC name: 2-(diethylamino)-N-(2,6-dimethylphenyl)acetamide
Molar mass: 234.343(35) g/mol
Atoms: 39
SMILES: CCN(CC)CC(=O)NC1=C(C=CC=C1C)C
InChIKey: NNJVILVZKWQKPM-UHFFFAOYSA-N
PubChem CID: 3676

Made of

C H N O

Structural formula of lidocaine. Each unlabelled corner is a carbon atom, and the nine hydrogens on carbon are not drawn. It shows which atoms are joined to which, not the shape. The model above shows the shape.

Lidocaine’s United States patent, number 2441498, dates from 1948 and carries the names N. M. Lofgren and B. J. Lundqvist. ChEMBL, a database of drugs and bioactive molecules, gives the same year for its first approval. The Hazardous Substances Data Bank (HSDB) groups it with the synthetic, non-narcotic substitutes for cocaine. The US Food and Drug Administration’s (FDA) pharmacological classes call it an amide local anaesthetic, which removes feeling from one area. They also call it an antiarrhythmic, a drug against irregular heart rhythms.

PubChem’s systematic (IUPAC) name is 2-(diethylamino)-N-(2,6-dimethylphenyl)acetamide: an acetamide whose nitrogen carries a benzene ring with two methyl groups, and whose second carbon holds a nitrogen bearing two ethyl groups. On HSDB’s figures, lidocaine itself is a white or slightly yellow crystalline powder that melts at 68 °C and dissolves in oils and very readily in alcohol. The National Cancer Institute’s (NCI) Drug Dictionary describes lidocaine hydrochloride as the drug’s salt form.

Structure and bonding

An amide link joins lidocaine’s two halves: a carbonyl carbon, double-bonded to oxygen, bonded to a nitrogen carrying the molecule’s only N–H. One half is a ring of six carbon atoms; in the other, a CH₂ group leads to a second nitrogen with two ethyl groups. Labels marks all 39 atoms: fourteen C, twenty-two H, two N and one O. In Ball-and-stick, a methyl group stands on each side of the ring carbon bonded to the amide nitrogen, the 2 and 6 of the IUPAC name.

Edge-on, the ring lies flat, while each CH₂ and CH₃ carbon points four bonds at a tetrahedron’s corners, as Chem1 describes for carbon’s bonding orbitals. The ring appears with double and single bonds in turn, one way of writing a benzene ring whose second-bond electrons Chem1 describes as delocalised, spread round all six carbons. The model draws the uncharged parent, not the hydrochloride salt.

Space-filling packs the carbon and hydrogen into a single mass, the oxygen and the N–H near its middle. In the liver, HSDB reports, ethyl groups come off the amine nitrogen first and the amide C–N is cut after, releasing xylidine.

Where it turns up

As the hydrochloride, HSDB records, lidocaine serves for infiltration anaesthesia, numbing by injection into the tissue, and nerve blocks, epidural and spinal among them. FDA’s National Drug Code Directory lists products from a tattoo numbing cream and a pain-relief gel patch to an anorectal preparation. Xylocaine, a US brand name in the NCI Drug Dictionary, is among them. FDA describes oral viscous lidocaine solution as a prescription drug for certain kinds of mouth pain.

The World Health Organization’s drug classification also files lidocaine under throat preparations, ear and eye anaesthetics and haemorrhoid treatments. It has veterinary uses too: HSDB lists it as a local anaesthetic for animals, and FDA’s Green Book of approved animal drugs carries it. It is made from 2,6-dimethylaniline and chloroacetyl chloride, with diethylamine added in a second stage, according to HSDB. US Consumer Product Safety Commission rules put lidocaine on the list of substances needing special packaging, the rule described on the methyl salicylate page.

Why it matters

A nerve impulse depends on the nerve-cell membrane opening briefly to sodium ions, through voltage-gated sodium channels. Lidocaine blocks that opening, the NCI Drug Dictionary explains, so impulses are neither started nor carried along, and sensation is lost reversibly. In MeSH, the medical vocabulary of the US National Library of Medicine, nearly all local anaesthetics work by making these channels less ready to activate.

Sodium flow matters in the heart too. As a class IB antiarrhythmic, lidocaine reduces sodium entry into heart muscle, especially in the Purkinje network, according to the NCI. That network is the conducting tissue of the ventricles, the heart’s lower chambers.

Its effect is stronger in ischaemic cells, those short of blood, and at fast heart rates. That is why HSDB rates it most effective at ending rapid ventricular tachycardia, a racing heartbeat. In HSDB’s account it is also an alternative to amiodarone in cardiac arrest brought on by ventricular fibrillation. Among the essential medicines chosen by the World Health Organization, it is listed for both roles, as an antiarrhythmic and as a local anaesthetic.

Properties

Properties of lidocaine Molar mass summed from IUPAC/CIAAW 2024 standard atomic weights; formula, atom and bond counts and PubChem's molecular weight from PubChem CID 3676.
Property	Value	Unit	Source
Molecular formula (Hill order)	C₁₄H₂₂N₂O
Molar mass	234.343(35) g/mol	g/mol	IUPAC/CIAAW 2024
Carbon atoms	14
Hydrogen atoms	22
Nitrogen atoms	2
Oxygen atoms	1
Bonds	39
Single bonds	35
Double bonds	4
PubChem molecular weight	234.34 g/mol	g/mol	PubChem

Safety

FDA warns that gum medicines containing benzocaine or lidocaine can seriously injure or even kill children, and finds that for teething pain they give little or no benefit. For oral viscous lidocaine solution, FDA names seizures in infants and young children, heart problems and severe brain injury among the harms. HSDB names methaemoglobinaemia among the serious adverse effects of lidocaine and prilocaine, both amide-type anaesthetics; methaemoglobin is explained under potassium nitrate. The PubChem Laboratory Chemical Safety Summary gathers its hazard classifications, harmful if swallowed and organ damage among them.

Questions

Why is lidocaine called an amide anaesthetic?

Its two halves meet at an amide group: a carbon double-bonded to oxygen, joined to a nitrogen that carries a hydrogen. ChEBI, a database of chemicals of biological interest, describes the molecule as formally built from 2,6-dimethylaniline and N,N-diethylglycine. The US Food and Drug Administration's (FDA) drug classes file it as an amide local anaesthetic. In the 3D model the amide sits between the benzene ring and the CH₂ group of the chain.

Is lidocaine hydrochloride a different substance from lidocaine?

It is lidocaine's salt, as the National Cancer Institute's (NCI) Drug Dictionary describes it. HSDB, the Hazardous Substances Data Bank, describes it as white crystals that melt at 127 to 129 °C and dissolve very readily in water and alcohol. It also forms a monohydrate, melting at 77 to 78 °C. The 3D model draws the uncharged parent, C₁₄H₂₂N₂O, which HSDB describes as a powder melting at 68 °C.

How does lidocaine compare with procaine?

MeSH, the US National Library of Medicine's subject headings, rates lidocaine's actions as more intense and longer-lasting than procaine's. Bupivacaine and prilocaine, on MeSH's account, last longer still. Lidocaine and prilocaine are both amide-type local anaesthetics in the Hazardous Substances Data Bank, and the NCI Drug Dictionary calls lidocaine hydrochloride a prototypical member of that amide class.

Is lidocaine sold over the counter?

In some US products it is. FDA's over-the-counter rules list it as a local anaesthetic ingredient of anorectal products and as an anaesthetic ingredient of external analgesics. For oral health care products that are not antimicrobial, FDA found the data inadequate to establish that lidocaine or its hydrochloride is generally recognised as safe and effective. Oral viscous lidocaine solution needs a prescription.

Made of the same elements

C₁₃H₂₁NO₃ Albuterol 38 atoms, 38 bonds.
C₁₇H₂₁NO Diphenhydramine 40 atoms, 41 bonds.
C₁₄H₁₈N₂O₅ Aspartame 39 atoms, 39 bonds.
C₁₂H₁₇NO DEET 31 atoms, 31 bonds.
C₁₃H₁₆N₂O₂ Melatonin 33 atoms, 34 bonds.
C₂₀H₂₄N₂O₂ Quinine 48 atoms, 51 bonds.
C₁₀H₁₂N₂O Serotonin 25 atoms, 26 bonds.
C₁₁H₁₂N₂O₂ Tryptophan 27 atoms, 28 bonds.

All 25 compounds made of carbon, hydrogen, nitrogen and oxygen

C₉H₁₃NO₃ Epinephrine 26 atoms, 26 bonds.
C₉H₁₁NO₂ Phenylalanine 23 atoms, 23 bonds.
C₈H₁₁NO₂ Dopamine 22 atoms, 22 bonds.
C₆H₁₃NO₂ Isoleucine 22 atoms, 21 bonds.
C₆H₁₃NO₂ Leucine 22 atoms, 21 bonds.
C₉H₁₁NO₃ Tyrosine 24 atoms, 24 bonds.
C₈H₉NO₂ Acetaminophen 20 atoms, 20 bonds.
C₈H₁₀N₄O₂ Caffeine 24 atoms, 25 bonds.
C₅H₉NO₄ Glutamic acid 19 atoms, 18 bonds.
C₅H₆N₂O₂ Thymine 15 atoms, 15 bonds.
C₃H₇NO₂ Alanine 13 atoms, 12 bonds.
C₄H₅N₃O Cytosine 13 atoms, 13 bonds.
C₅H₅N₅O Guanine 16 atoms, 17 bonds.
C₄H₄N₂O₂ Uracil 12 atoms, 12 bonds.
C₂H₅NO₂ Glycine 10 atoms, 9 bonds.
CO(NH₂)₂ Urea 8 atoms, 7 bonds.
C₅H₄N₄O₃ Uric acid 16 atoms, 17 bonds.