Albuterol

C 13
H 21
N 1
O 3

Ball-and-stick Stick Space-filling

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38 atoms, 38 bonds.

IUPAC name: 4-[2-(tert-butylamino)-1-hydroxyethyl]-2-(hydroxymethyl)phenol
Molar mass: 239.315(34) g/mol
Atoms: 38
SMILES: CC(C)(C)NCC(C1=CC(=C(C=C1)O)CO)O
InChIKey: NDAUXUAQIAJITI-UHFFFAOYSA-N
PubChem CID: 2083

Made of

C H N O

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

Albuterol loosens the smooth muscle of the airways, and the US Food and Drug Administration (FDA) classes it as a beta2-adrenergic agonist, a drug that stimulates beta2 receptors. MeSH (Medical Subject Headings) calls it a short-acting bronchodilator, an agent that widens the bronchial tubes, used mainly against asthma. ChEBI, the Chemical Entities of Biological Interest database, gives its uses as asthma and chronic obstructive pulmonary disease (COPD). In ChEBI’s chemical terms it is a phenol, with an O–H on its ring, and a secondary amine, whose nitrogen carries one hydrogen. PubChem names it 4-[2-(tert-butylamino)-1-hydroxyethyl]-2-(hydroxymethyl)phenol.

The pure compound is a white to off-white crystalline solid, according to the Hazardous Substances Data Bank (HSDB). It dissolves in ethanol, very readily in chloroform and only sparingly in water. Its sulfate salt reverses the order, dissolving in water and only slightly in ethanol. In the drug dictionary of the US National Cancer Institute (NCI), the medicine is that salt, albuterol sulfate.

Structure and bonding

A ring of six carbon atoms anchors albuterol, one corner carrying a two-carbon chain that ends at a nitrogen bearing a tert-butyl group. The opposite corner holds an oxygen–hydrogen group, with a CH₂OH on the corner beside it. Labels picks out three O–H groups and one N–H; Space-filling turns the tert-butyl’s three methyls into a rounded knot at the nitrogen end. Ball-and-stick draws the ring’s double and single bonds in turn, yet all six measure 1.384 to 1.395 Å in the model. The real ring shares its electrons evenly, above and below the carbon plane, as in benzene.

The chain carbon bearing an O–H has four different neighbours: a hydrogen, that O–H, the ring and the CH₂–NH–tert-butyl arm. Albuterol therefore exists in two forms, R and S, a handedness explained under lactic acid. Medicinal albuterol is a racemic mixture, (R)- and (S)-albuterol in equal parts, as NCI and MeSH describe it. PubChem’s computed model is built as only one of the two, and the flat structural formula, drawn without wedges, shows neither. Both drawings are the neutral parent molecule, not the sulfate salt that inhalers hold.

Where it turns up

Albuterol inhalers using chlorofluorocarbon (CFC) propellants left US sale after 31 December 2008, a phase-out FDA ties to the Montreal Protocol, an ozone treaty covered under dichlorodifluoromethane. By then FDA had approved three inhalers using hydrofluoroalkane (HFA) propellants instead: ProAir HFA, Proventil HFA and Ventolin HFA, each holding albuterol sulfate. What an HFA propellant is and does is set out under tetrafluoroethane.

The agency found the three safe and effective for treating or preventing bronchospasm, a spasm of the bronchial muscle, in reversible obstructive airway disease, asthma and COPD included. Albuterol’s uses, in HSDB’s record, also take in reversible bronchospasm that can accompany bronchitis and emphysema.

Beyond the inhaler, albuterol comes as a solution for inhalation, a syrup and tablets, HSDB records. ChEMBL lists the drug as available on prescription only. FDA approval, as HSDB gives it, reaches horses too: relief of bronchospasm and airway narrowing that accompany reversible airway obstruction, limited to horses not intended for food.

Why it matters

The National Heart, Lung, and Blood Institute (NHLBI) describes asthma as a long-term condition of the airways in the lungs, affecting 1 in 13 Americans. At times the airways become inflamed and narrow, so air leaves them less easily on the out-breath. Pollen, exercise, viral infections and cold air can set symptoms off or make them worse. Albuterol is one of the inhaled short-acting beta2-agonists (SABAs), which NHLBI counts among the quick-relief medicines that open the airways during an attack.

In HSDB’s account, albuterol stimulates beta2-adrenergic receptors on airway smooth muscle, which activate the enzyme adenylcyclase and raise the cell’s cyclic adenosine monophosphate (cyclic AMP). Cyclic AMP switches on protein kinase A, which lowers the cell’s calcium ions and blocks the addition of phosphate to myosin, a muscle protein, so the muscle relaxes. The effect runs from the trachea, or windpipe, to the terminal bronchioles, whatever substance set off the spasm. Albuterol acts more weakly on beta1 receptors too, according to NCI, raising the force and rate of the heart’s contractions; beta receptors in general are introduced under epinephrine.

Properties

Properties of albuterol Molar mass summed from IUPAC/CIAAW 2024 standard atomic weights; formula, atom and bond counts and PubChem's molecular weight from PubChem CID 2083.
Property	Value	Unit	Source
Molecular formula (Hill order)	C₁₃H₂₁NO₃
Molar mass	239.315(34) g/mol	g/mol	IUPAC/CIAAW 2024
Carbon atoms	13
Hydrogen atoms	21
Nitrogen atoms	1
Oxygen atoms	3
Bonds	38
Single bonds	35
Double bonds	3
PubChem molecular weight	239.31 g/mol	g/mol	PubChem

Safety

Tremor appears to be albuterol’s most often reported adverse effect, according to HSDB, with nervousness, nausea, a fast heartbeat, palpitations, chest pain and dizziness also frequent. The pure substance carries the GHS (Globally Harmonized System) signal word Warning, and 98 per cent of company reports to the European Chemicals Agency call it harmful if swallowed. The PubChem Laboratory Chemical Safety Summary for albuterol lists the rest.

Questions

How many atoms are in an albuterol molecule?

Thirty-eight. The formula C₁₃H₂₁NO₃ gives 13 carbon, 21 hydrogen, one nitrogen and three oxygen atoms, and the 3D model joins them with 38 bonds. Six of the carbons close the ring. Each of the other seven, the four of the tert-butyl group among them, aims its four bonds at the corners of a tetrahedron, in Chem1's hybrid-orbital model.

Is albuterol the same as salbutamol?

Yes: both names belong to one molecule, PubChem compound 2083, and the World Health Organization uses the second. Its Model List of Essential Medicines includes the drug among medicines for asthma and COPD, and WHO's Anatomical Therapeutic Chemical (ATC) classification files it with drugs for obstructive airway diseases, as a selective beta-2-adrenoreceptor agonist.

What is levalbuterol?

Levalbuterol is the R form of albuterol prepared on its own, as MeSH defines it, in place of the equal R and S mixture of ordinary albuterol. FDA describes a levalbuterol inhaler as holding albuterol's active form and doing the same work. In the body an enzyme, phenol sulfotransferase, turns albuterol into an inactive sulfate ester, and HSDB reports that it handles the R form about ten times faster than the S form.

When was albuterol first made?

HSDB credits its preparation to L. H. C. Lunts and co-workers, in patents dated 1968 and 1972. The pure compound melts at 151 °C by Lunts's measurement and at 157 to 158 °C by Collins's. The ChEMBL database puts its first approval in 1981, and FDA reports that patients in the United States have used HFA inhalers since 1998.

Made of the same elements

C₁₄H₂₂N₂O Lidocaine 39 atoms, 39 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.
C₉H₁₃NO₃ Epinephrine 26 atoms, 26 bonds.
C₂₀H₂₄N₂O₂ Quinine 48 atoms, 51 bonds.
C₁₁H₁₂N₂O₂ Tryptophan 27 atoms, 28 bonds.

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

C₉H₁₁NO₃ Tyrosine 24 atoms, 24 bonds.
C₉H₁₁NO₂ Phenylalanine 23 atoms, 23 bonds.
C₁₀H₁₂N₂O Serotonin 25 atoms, 26 bonds.
C₈H₁₁NO₂ Dopamine 22 atoms, 22 bonds.
C₆H₁₃NO₂ Isoleucine 22 atoms, 21 bonds.
C₆H₁₃NO₂ Leucine 22 atoms, 21 bonds.
C₈H₉NO₂ Acetaminophen 20 atoms, 20 bonds.
C₈H₁₀N₄O₂ Caffeine 24 atoms, 25 bonds.
C₅H₉NO₄ Glutamic acid 19 atoms, 18 bonds.
C₃H₇NO₂ Alanine 13 atoms, 12 bonds.
C₅H₆N₂O₂ Thymine 15 atoms, 15 bonds.
C₂H₅NO₂ Glycine 10 atoms, 9 bonds.
C₄H₄N₂O₂ Uracil 12 atoms, 12 bonds.
C₅H₄N₄O₃ Uric acid 16 atoms, 17 bonds.
C₄H₅N₃O Cytosine 13 atoms, 13 bonds.
C₅H₅N₅O Guanine 16 atoms, 17 bonds.
CO(NH₂)₂ Urea 8 atoms, 7 bonds.