phenylephrine (Neo-Synephrine, Mydrifin, sudafed PE, PE)

^[1]^[2]^[3]^[4]^[5]^[6]^[7]^[8]^[9]^[10]^[11]

Introduction

Tradename: Neo-Synephrine, sudafed PE^[6].

Indications

systemic agent
- treatment of vascular failure in shock syndromes (hypotension) including hypertrophic cardiomyopathy^[8]
- vasoconstriction to allow for regional spinal anesthesia
- paroxysmal supraventricular tachycardia (PSVT) uncontrolled by standard therapy
- decongestant for eustachian tube congestion
topical agent
- hemorrhoids, rectal pain, proctitis, anal pruritus
nasal spray
- symptomatic relief from cold symptoms*
  - nasal congestion, rhinitis, rhinorrhea, sneezing, cough
- allergic rhinitis*
  - seasonal allergic rhinitis
ophthalmic agent:
- mydriasis in ophthalmic procedures
- treatment of glaucoma (wide-angle) secondary to pupil block caused by aphakia or posterior synechiae
- prevention of echothiophosphate-induced iris cysts
- determination of refraction errors
- diagnosis of Horner's & Raeder's syndromes
- prevention & treatment of posterior synechiae in patients with anterior uveitis
- allergic conjunctivitis

* on list of medications to avoid for treatment of allergic rhinitis & viral rhinitis^[11]

cardiovascular risk cited

Contraindications

narrow-angle glaucoma

pregnancy category = c

safety in lactation = -

safety in lactation = ?

Dosage

hypotension
- adults
  - 2-5 mg SC every 1-2 hours PRN
  - 0.1-0.5 mg IV every 10-15 min PRN
  - 100-200 ug IV for severe hypotension
  - IV infusion: 0.1-0.5 ug/kg/min
  - infusion: 20 mg in 250 mL D5W (80 ug/mL) at 40-180 ug/min or 1-3 ug/kg/min (35-160 mL/hr)
- children
  - 0.1 mg/kg SC every 1-2 hours PRN; max 5 mg/dose
  - 5-20 ug/kg IV every 10-15 min PRN
  - IV infusion:
    - mix 10 mL in 250 mL of D5W or normal saline (40 ug/mL)
    - start at 100-180 ug/min (2-5 mL/min)
    - maintenance (after blood pressure has stabilized) 40-60 ug/min (0.8-1.2 mL/min)
PSVT: 0.25-0.5 mg over 20-30 seconds
nasal congestion: 2-3 sprays per nostril every 3-4 hours
Oral decongestant: 10 mg every 4 hours PRN (Sudafed PE)^[6]
ophthalmic agent
- ophthalmoscopy & retinal photography:
  - 1 drop
  - may repeat as needed in 10-60 minutes
- refraction:
  - instill 1 drop of 2.5% solution in between the administration of a cycloplegic drug
- diagnosis of Horner's & Raeder's syndromes
  - use appropriate concentration to perform testing
- ocular surgery:
  - 1-2 drops into the eye 30-60 minutes before surgery
  - usually used in conjunction with another mydriatic agent (i.e. atropine)
  - 1 drop of 10% solution into the eye TID along with atropine
- glaucoma secondary to pupil block:
  - 1 drop of 10% solution into the eye TID along with atropine for synergistic effect
  - may be given QID if needed
  - apply finger pressure to the lacrimal sac during & for 1-2 minutes following application to reduce frequency of systemic adverse effects
- mydriasis: 1 drop QD-TID for 5 days

Nasal spray: 0.125%, 0.25%, 0.5%, 1%. Ophthalmic agent: Tradenames: Neo-synephrine, Mydrifin. Ophthalmic agent: 2.5% (15 mL) 10% (5 mL).

Injection: 10 mg/mL (1 mL).

Pharmacokinetics

topical (intraocular, nasal) administration
- onset of action within minutes
- duration of action is 0.5 to 4 hours
IV administration
- immediate onset of action
- duration of action is 20-50 minutes
- metabolized by monoamine oxidase (MAO)

elimination via plasma

Adverse effects

Nasal
- common (> 10%)
  - nasal burning
  - rebound congestion (after 3-10 days)
  - sneezing
- less common (1-10%)
  - stinging, dryness
Ophthalmic
- common (> 10%)
  - transient stinging
- less common (1-10%)
  - headache, blurred vision, photophobia, lacrimation, browache
Systemic
- common (> 10%)
  - tremor
- less common (1-10%)
  - peripheral vasoconstriction, hypertension, angina, reflex bradycardia, arrhythmias, restlessness, excitability
other^[3]^[4]

Drug interactions

alpha-adrenergic receptor antagonists antagonize effects of phenylephrine
tricyclic antidepressants & MAO inhibitors increase the pressor effects of phenylephrine
acetaminophen may increase plasma levels of phenylephrine

drug interaction(s) of acetaminophen in combination with phenylephrine

Mechanism of action

alpha-1 adrenergic receptor agonist^[8]
potent vasoconstriction
dose-related increase in peripheral vascular resistance
elevation of blood pressure
sinus bradycardia associated with vagal reflexes
topical administration results in arteriole constriction
reduction in blood flow & nasal congestion

NOT as effective of pseudoephedrine^[7]

More general terms

Component of

References

↑ The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
↑ Faga LJ, American Family Physician 58:1795-1802, 1998
↑ ^3.0 ^3.1 Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998
↑ ^4.0 ^4.1 Kaiser Permanente Northern California Regional Drug Formulary, 1998
↑ Mangione CM, In: UCLA Intensive Course in Geriatric Medicine & Board Review, Marina Del Ray, CA, Sept 12-15, 2001
↑ ^6.0 ^6.1 ^6.2 Prescriber's Letter 12(3): 2005 Sudafed PE Nasal Decongestant Detail-Document#: http://prescribersletter.com/(5bhgn1a4ni4cyp2tvybwfh55)/pl/ArticleDD.aspx?li=1&st=1&cs=&s=PRL&pt=3&fpt=25&dd=210310&pb=PRL (subscription needed) http://www.prescribersletter.com
↑ ^7.0 ^7.1 Prescriber's Letter 13(12): 2006 Changes to OTC cough and Cold products Detail-Document#: http://prescribersletter.com/(5bhgn1a4ni4cyp2tvybwfh55)/pl/ArticleDD.aspx?li=1&st=1&cs=&s=PRL&pt=3&fpt=25&dd=221207&pb=PRL (subscription needed) http://www.prescribersletter.com
↑ ^8.0 ^8.1 ^8.2 Medical Knowledge Self Assessment Program (MKSAP) 16, 17. American College of Physicians, Philadelphia 2012, 2015
↑ Deprecated Reference
↑ Atkinson HC et al Increased Phenylephrine Plasma Levels with Administration of Acetaminophen. N Engl J Med 2014; 370:1171-1172March 20, 2014 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/24645960 <Internet> http://www.nejm.org/doi/full/10.1056/NEJMc1313942
↑ ^11.0 ^11.1 Therapeutics Letter #108. Therapeutics Initiative Drugs to Avoid. http://www.ti.ubc.ca/2018/01/04/108-drugs-avoid/

Database

[ref1-1] The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996

[ref2-2] Faga LJ, American Family Physician 58:1795-1802, 1998

[ref3-3] 3.0 ^3.1 Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998

[ref4-4] 4.0 ^4.1 Kaiser Permanente Northern California Regional Drug Formulary, 1998

[ref5-5] Mangione CM, In: UCLA Intensive Course in Geriatric Medicine & Board Review, Marina Del Ray, CA, Sept 12-15, 2001

[ref6-6] 6.0 ^6.1 ^6.2 Prescriber's Letter 12(3): 2005 Sudafed PE Nasal Decongestant Detail-Document#: http://prescribersletter.com/(5bhgn1a4ni4cyp2tvybwfh55)/pl/ArticleDD.aspx?li=1&st=1&cs=&s=PRL&pt=3&fpt=25&dd=210310&pb=PRL (subscription needed) http://www.prescribersletter.com

[ref7-7] 7.0 ^7.1 Prescriber's Letter 13(12): 2006 Changes to OTC cough and Cold products Detail-Document#: http://prescribersletter.com/(5bhgn1a4ni4cyp2tvybwfh55)/pl/ArticleDD.aspx?li=1&st=1&cs=&s=PRL&pt=3&fpt=25&dd=221207&pb=PRL (subscription needed) http://www.prescribersletter.com

[ref8-8] 8.0 ^8.1 ^8.2 Medical Knowledge Self Assessment Program (MKSAP) 16, 17. American College of Physicians, Philadelphia 2012, 2015

[ref9-9] Deprecated Reference

[ref10-10] Atkinson HC et al Increased Phenylephrine Plasma Levels with Administration of Acetaminophen. N Engl J Med 2014; 370:1171-1172March 20, 2014 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/24645960 <Internet> http://www.nejm.org/doi/full/10.1056/NEJMc1313942

[ref11-11] 11.0 ^11.1 Therapeutics Letter #108. Therapeutics Initiative Drugs to Avoid. http://www.ti.ubc.ca/2018/01/04/108-drugs-avoid/

[1]

[2]

[3]

[4]

[5]

[6]

[7]

[8]

[9]

[10]

[11]

phenylephrine (Neo-Synephrine, Mydrifin, sudafed PE, PE)

Contents

Introduction

Indications

Contraindications

Dosage

Pharmacokinetics

Adverse effects

Drug interactions

Mechanism of action

More general terms

Component of

References

Database

Navigation menu

phenylephrine (Neo-Synephrine, Mydrifin, sudafed PE, PE)

Introduction

Indications

Contraindications

Dosage

Pharmacokinetics

Adverse effects

Drug interactions

Mechanism of action

More general terms

Component of

References

Database

Navigation menu

Search