Orciprenaline

Orciprenaline, also known as metaproterenol, is a bronchodilator used in the treatment of asthma.^[1][2] Orciprenaline is a moderately selective β₂ adrenergic receptor agonist that stimulates receptors of the smooth muscle in the lungs, uterus, and vasculature supplying skeletal muscle, with minimal or no effect on α adrenergic receptors. The pharmacologic effects of β adrenergic agonist drugs, such as orciprenaline, are at least in part attributable to stimulation through β adrenergic receptors of intracellular adenylyl cyclase, the enzyme which catalyzes the conversion of ATP to cAMP. Increased cAMP levels are associated with relaxation of bronchial smooth muscle and inhibition of release of mediators of immediate hypersensitivity from many cells, especially from mast cells.

Orciprenaline

Clinical data
Trade names	Alupent, Metaprel, Orcibest
Other names	Metaproterenol (USAN US)
AHFS/Drugs.com	Monograph
MedlinePlus	a682084
Pregnancy category	AU: A
Routes of administration	By mouth, inhalation
ATC code	R03AB03 (WHO) R03CB03 (WHO) R03CB53 (WHO)
Legal status
Legal status	AU: S4 (Prescription only) US: ℞-only
Pharmacokinetic data
Bioavailability	3% if inhaled, 40% if taken orally
Metabolism	Gastrointestinal and hepatic
Elimination half-life	6 hours
Identifiers
IUPAC name (RS)-5-[1-hydroxy-2-(isopropylamino)ethyl]benzene-1,3-diol
CAS Number	586-06-1 Y
PubChem CID	4086
IUPHAR/BPS	7250
DrugBank	DB00816 N
ChemSpider	3944 Y
UNII	53QOG569E0
KEGG	D08300 Y
ChEBI	CHEBI:82719 N
ChEMBL	ChEMBL776 Y
CompTox Dashboard (EPA)	DTXSID8048529
ECHA InfoCard	100.008.701
Chemical and physical data
Formula	C11H17NO3
Molar mass	211.261 g·mol−1
3D model (JSmol)	Interactive image
Chirality	Racemic mixture
Solubility in water	9.7 mg/mL (20 °C)
SMILES Oc1cc(cc(O)c1)C(O)CNC(C)C
InChI InChI=1S/C11H17NO3/c1-7(2)12-6-11(15)8-3-9(13)5-10(14)4-8/h3-5,7,11-15H,6H2,1-2H3 Y Key:LMOINURANNBYCM-UHFFFAOYSA-N Y
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Adverse effects

More common side effects of metaproterenol include tachycardia and nervousness.^[3][4] Additional side effects with >1% incidence include headache, nausea, and tremor.^[3] A non-exhaustive list of rare side effects includes other cardiovascular symptoms, dizziness, fatigue, etc.^[3][4]