Phenylephrine

Phenylephrine
Skeletal formula of phenylephrine
Ball-and-stick model of the phenylephrine molecule
Clinical data
Pronunciation/ˌfɛnəlˈɛfriːn, fiː-, -ɪn/
Trade namesNeosynephrine, Sudafed PE, numerous others[1][2][3][4]
Other namesPhenephrine; Fenefrine; L-m-Synephrine; Metaoxedrine; Neo-Oxedrine; Mesatonum; Neosynephrine; Adrianol; (R)-β,3-Dihydroxy-N-methylphenethylamine[1][2][4]
AHFS/Drugs.comMonograph
License data
Routes of
administration		By mouth, in the nose (nasal spray), on the eye (eye drop), intravenous, intramuscular, rectal (suppository)[5][6][7]
Drug classα1-Adrenergic receptor agonist; Sympathomimetic; Vasoconstrictor; Antihypotensive agent; Vasopressor
ATC code
Legal status
Legal status
Pharmacokinetic data
BioavailabilityOral: conflicting—38%[8][3][9][10] or 0.003%[11]
Protein binding95%[citation needed]
MetabolismLiver and intestines (via oxidative deamination by MAO-A and MAO-B; sulfation; glucuronidation)[5][8][3][11][9]
Metabolites• meta-Hydroxymandelic acid[9][3]
• Sulfate conjugates[9][3]
• Glucuronide conjugates[9]
Onset of actionIV: Very rapid[12]
Oral: 15–20 min[12][9]
Intranasal: <2 min[9]
Eye drop: <30 min[9]
Elimination half-life2.0–3.0 hours[8][5][3][13]
Duration of actionIV: 20 min–5 h[12][9]
Oral: 2–4 h[12][9]
Intranasal: 0.5–4 h[9]
Eye drop: 3–7 h[9]
ExcretionUrine: 86% (3–16% unchanged)[5][8][3]
Identifiers
  • 3-[(1R)-1-Hydroxy-2-(methylamino)ethyl]phenol
CAS Number
PubChem CID
IUPHAR/BPS
DrugBank
ChemSpider
UNII
KEGG
ChEBI
ChEMBL
CompTox Dashboard (EPA)
ECHA InfoCard100.000.386 Edit this at Wikidata
Chemical and physical data
FormulaC9H13NO2
Molar mass167.208 g·mol−1
3D model (JSmol)
  • O[C@H](c1cc(O)ccc1)CNC
  • 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 checkY
  • Key:SONNWYBIRXJNDC-VIFPVBQESA-N checkY
  (verify)

Phenylephrine, sold under the brand names Neosynephrine and Sudafed PE among numerous others, is a medication used as a decongestant for uncomplicated nasal congestion,[5] used to dilate the pupil, used to increase blood pressure (given intravenously in cases of low blood pressure), and used to relieve hemorrhoids (as a suppository).[12][14] It can be taken by mouth, as a nasal spray, given by injection into a vein or muscle, applied to the skin, or as a rectal suppository.[12][5]

Common side effects when taken by mouth or injected include nausea, vomiting, headache, and anxiety.[12] Use on hemorrhoids is generally well tolerated.[12] Severe side effects may include a slow heart rate, intestinal ischemia, chest pain, kidney failure, and tissue death at the site of injection.[12][14] It is unclear whether its use during pregnancy and breastfeeding is safe.[12] Phenylephrine is a selective α1-adrenergic receptor agonist with minimal to no β-adrenergic receptor agonist activity or induction of norepinephrine release.[5][8][15] It causes constriction of both arteries and veins.[12]

Phenylephrine was patented in 1933[16] and came into medical use in 1938.[17] It is available as a generic medication.[14][18][19] Unlike pseudoephedrine, abuse of phenylephrine is very uncommon.[20] Its effectiveness as a nasal decongestant has been questioned.[12][21][22] In 2023, a US Food and Drug Administration (FDA) panel concluded that the drug was ineffective as a nasal decongestant when taken orally.[23] In November 2024, the FDA proposed to remove oral phenylephrine as an active ingredient that can be used in over-the-counter (OTC) monograph drug products for the temporary relief of nasal congestion.[24]

  1. ^ a b Cite error: The named reference Elks2014 was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference IndexNominum2000 was invoked but never defined (see the help page).
  3. ^ a b c d e f g Cite error: The named reference DrugBank was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Drugs.com-International was invoked but never defined (see the help page).
  5. ^ a b c d e f g Richards E, Lopez MJ, Maani CV (2023). "Phenylephrine". StatPearls. Treasure Island, Florida: StatPearls Publishing. PMID 30521222. Retrieved 27 April 2023.
  6. ^ Cite error: The named reference Drugs@FDA was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference DailyMed was invoked but never defined (see the help page).
  8. ^ a b c d e Cite error: The named reference Eccles2007 was invoked but never defined (see the help page).
  9. ^ a b c d e f g h i j k l Cite error: The named reference ChuaBenrimojTriggs1989 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Medsafe2004 was invoked but never defined (see the help page).
  11. ^ a b Cite error: The named reference AtkinsonPottsAnderson2015 was invoked but never defined (see the help page).
  12. ^ a b c d e f g h i j k l "Phenylephrine Monograph for Professionals". Drugs.com. AHFS. 2 March 2022. Retrieved 9 May 2022. However, efficacy of oral phenylephrine for this use [as a decongestant] has been questioned.
  13. ^ Cite error: The named reference KanferDowseVuma1993 was invoked but never defined (see the help page).
  14. ^ a b c Joint Formulary Committee (2018). BNF 76 : September 2018 - March 2019. London: British Medical Association, Royal Pharmaceutical Society of Great Britain. pp. 188–189. ISBN 9780857113382. OCLC 1021215075.
  15. ^ Cite error: The named reference ODonnell1995 was invoked but never defined (see the help page).
  16. ^ U.S. patent 1,932,347, application 1928, expired 1950
  17. ^ Fischer J, Ganellin CR (2006). Analogue-based Drug Discovery. John Wiley & Sons. p. 541. ISBN 9783527607495.
  18. ^ "Competitive Generic Therapy Approvals". U.S. Food and Drug Administration (FDA). 29 June 2023. Archived from the original on 29 June 2023. Retrieved 29 June 2023.
  19. ^ "First Generic Drug Approvals 2023". U.S. Food and Drug Administration (FDA). 30 May 2023. Archived from the original on 30 June 2023. Retrieved 30 June 2023.
  20. ^ "Max Strength Decongestant Tablets" (PDF). www.mhra.gov.uk. p. 10. Archived from the original (PDF) on 19 August 2019. Retrieved 10 January 2019.
  21. ^ Hatton RC, Hendeles L (March 2022). "Why Is Oral Phenylephrine on the Market After Compelling Evidence of Its Ineffectiveness as a Decongestant?". Ann Pharmacother. 56 (11): 1275–1278. doi:10.1177/10600280221081526. PMID 35337187. S2CID 247712448.
  22. ^ Lowe D (March 2022). "The Uselessness of Phenylephrine". Science (blog).
  23. ^ Cite error: The named reference christensen23 was invoked but never defined (see the help page).
  24. ^ "FDA Proposes Ending Use of Oral Phenylephrine as OTC Monograph Nasal Decongestant Active Ingredient After Extensive Review". U.S. Food and Drug Administration (FDA) (Press release). 7 November 2024. Retrieved 10 November 2024.