Phenylephrine hydrochloride

Phenylephrine

Clinical data
Pronunciation	/ˌfɛnəlˈɛfrin, fiː-, -ɪn/
Pregnancy category	US: C (Risk not ruled out)
Routes of administration	Oral, intranasal, ophthalmic, intravenous, intramuscular
ATC code	C01CA06 (WHO) R01AA04 (WHO), R01AB01 (WHO) (combinations), R01BA03 (WHO), S01FB01 (WHO), S01GA05 (WHO)
Legal status
Legal status	UK: General sales list (GSL, OTC) US: OTC
Pharmacokinetic data
Bioavailability	38% through GI tract
Protein binding	95%
Metabolism	Hepatic (monoamine oxidase)
Biological half-life	2.1–3.4 h
Identifiers
IUPAC name (R)-3-[-1-hydroxy-2-(methylamino)ethyl]phenol
CAS Number	59-42-7 Y 61-76-7 (hydrochloride)
PubChem CID	6041
IUPHAR/BPS	485
DrugBank	DB00388 Y
ChemSpider	5818 Y
UNII	1WS297W6MV
KEGG	D08365 Y
ChEBI	CHEBI:8093 Y
ChEMBL	CHEMBL1215 Y
ECHA InfoCard	100.000.386
Chemical and physical data
Formula	C9H13NO2
Molar mass	167.205 g/mol
3D model (JSmol)	Interactive image
SMILES O[C@H](c1cc(O)ccc1)CNC
InChI InChI=1S/C9H13NO2/c1-10-6-9(12)7-3-2-4-8(11)5-7/h2-5,9-12H,6H2,1H3/t9-/m0/s1 Y Key:SONNWYBIRXJNDC-VIFPVBQESA-N Y

Phenylephrine is a selective α₁-adrenergic receptor agonist of the phenethylamine class used primarily as a decongestant, as an agent to dilate the pupil, and to increase blood pressure. Phenylephrine is marketed as an alternative for the decongestant pseudoephedrine, although clinical trials show phenylephrine, taken orally at the recommended dose, to be no more effective than placebo for allergy relief. Phenylephrine can also cause a decrease in heart rate through reflex bradycardia.

Phenylephrine is used as a decongestant sold as an oral medicine or as a nasal spray. It is a common ingredient in over-the-counter decongestants in the United States. Other decongestants include oxymetazoline and pseudoephedrine.

Phenylephrine is used as an alternative for pseudoephedrine in decongestant medicines due to pseudoephedrine's use in the illicit manufacture of methamphetamine. Its efficacy as an oral decongestant has been questioned, with several recent independent studies finding that it provided no more relief to sinus congestion than a placebo.

Pharmacists Leslie Hendeles and Randy Hatton of the University of Florida suggested in 2006 that oral phenylephrine is ineffective as a decongestant at the 10-mg dose used, arguing that the studies used for the regulatory approval of the drug in the United States in 1976 were inadequate to prove effectiveness at the 10-mg dose, and safety at higher doses.

A 2007 meta-analysis by Hatton et al. concluded that the evidence for its effectiveness is insufficient, though another meta-analysis published shortly thereafter by researchers from GlaxoSmithKline found the standard 10-mg dose to be significantly more effective than a placebo; however, the fact that GSK markets many products containing phenylephrine has raised some speculation regarding selective publishing and other controversial techniques. A 2007 study by Wyeth Consumer Healthcare notes that 7 studies available in 1976 support the efficacy of phenylephrine at a 10 mg dosage.