Phenylephrine: Difference between revisions
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==General== | ==General== | ||
*Type: [[Vasopressors]] | *Type: [[Is DrugClass::Vasopressors]] | ||
*Dosage Forms: | *Dosage Forms: Commonly 50 mg per 5 mL (10 mg/mL) | ||
*Common Trade Names: Neosynephrine | *Common Trade Names: Neosynephrine | ||
*Onset of action: About 1 minute | |||
*Duration of action: 10-20 minutes | |||
==Adult Dosing== | ==Adult Dosing== | ||
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*"[[Push dose pressors|Push dose]]" | *"[[Push dose pressors|Push dose]]" | ||
**Inject | **Inject 1 mL (10 mg) into 100 mL NS Bag = 100 mcg/mL | ||
**Draw this into a syringe, | **Draw this into a syringe, with a concentration of 100mcg/mL | ||
** | **Administer 0.5-2 mL (50-200 mcg) every 2-5 minutes | ||
===Low Flow [[Priapism]]=== | ===Low Flow [[Priapism]]=== | ||
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==Contraindications== | ==Contraindications== | ||
*Allergy to class/drug | *Allergy to class/drug | ||
*Severe hypertension | *Severe [[hypertension]] | ||
*Ventricular tachycardia | *[[Ventricular tachycardia]] | ||
*Closed angle glaucoma | *[[Closed angle glaucoma]] | ||
*Caution if: | *Caution if: | ||
**Heart failure or cardiogenic shock (cardiac output may decrease with increased SVR) | **[[Heart failure]] or [[cardiogenic shock]] (cardiac output may decrease with increased SVR) | ||
**Spinal cord injury or other autonomic dysfunction (may experience exaggerated increase in blood pressure) | **[[Spinal cord injury]] or other autonomic dysfunction (may experience exaggerated increase in blood pressure) | ||
**Hyperthyroidism | **[[Hyperthyroidism]] | ||
==Adverse Reactions== | ==Adverse Reactions== | ||
| Line 67: | Line 69: | ||
==Pharmacology== | ==Pharmacology== | ||
*Half-life: 2 | *Half-life: 2.5 hours | ||
*Metabolism: extensively in intestinal wall, moderately in liver | *Metabolism: extensively in intestinal wall, moderately in liver | ||
*Excretion: Urinary | *Excretion: Urinary | ||
| Line 75: | Line 77: | ||
===Relative Effects=== | ===Relative Effects=== | ||
*↑SVR | *↑SVR | ||
*↓HR (reflex bradycardia) | *↓HR (reflex bradycardia) | ||
==Notes== | ==Notes== | ||
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==See Also== | ==See Also== | ||
*http://www.atsjournals.org/doi/abs/10.1164/rccm.201006-0972CI?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dpubmed#readcube-epdf | |||
==References== | ==References== | ||
<references/> | <references/> | ||
[[Category:Pharmacology]] [[Category:Critical Care]] | [[Category:Pharmacology]] [[Category:Critical Care]] | ||
Latest revision as of 16:02, 25 July 2025
General
- Type: Vasopressors
- Dosage Forms: Commonly 50 mg per 5 mL (10 mg/mL)
- Common Trade Names: Neosynephrine
- Onset of action: About 1 minute
- Duration of action: 10-20 minutes
Adult Dosing
Hypotension
- Start 100-200 mcg/min then taper down
- 40-60 mcg/min works for most
- "Push dose"
- Inject 1 mL (10 mg) into 100 mL NS Bag = 100 mcg/mL
- Draw this into a syringe, with a concentration of 100mcg/mL
- Administer 0.5-2 mL (50-200 mcg) every 2-5 minutes
Low Flow Priapism
- Dilute phenylephrine 1mg in 9mL NS for final concentration of 100mcg/mL
- For 500 mcg/ml, take 0.5 ml of 10mg/ml phenylephrine, and dilute in 9.5 cc NS
- Inject base of penis with 29-Ga needle (after blood aspiration to confirm position)
- 100-500 mcg every 3-5min (max 1000 mcg) until resolution or 1 hour
Pediatric Dosing
- Hypotension/Shock
- IV Bolus: 5-20mcg/kg q10-15min prn, 1st dose should not exceed 500mcg with a max dose of 1000mcg
- IV Infusion: 0.1-0.5mcg/kg/min, titrate to desired BP
- Nasal Congestion (OTC)
- 4-<6yrs: 2.5mg q4hr prn for <7 days
- 6-<12yrs: 5mg q4hr prn for <7 days
Special Populations
- Pregnancy Rating: C
- Lactation: infant risk cannot be ruled out
- Renal Dosing
- Adult
- Pediatric
- Hepatic Dosing
- Adult
- Pediatric
Contraindications
- Allergy to class/drug
- Severe hypertension
- Ventricular tachycardia
- Closed angle glaucoma
- Caution if:
- Heart failure or cardiogenic shock (cardiac output may decrease with increased SVR)
- Spinal cord injury or other autonomic dysfunction (may experience exaggerated increase in blood pressure)
- Hyperthyroidism
Adverse Reactions
- Baroreceptor-mediated reflex bradycardia, particularly in patients with preexisting cardiac dysfunction or severe CAD
- If extravasates use phentolamine
Serious
- Bradycardia
- Pulmonary edema
- Metabolic acidosis
- Decreased renal perfusion
- Extravasation
Common
- Hypertension
- Anxiety
- Headache
- Rebound congestion, sneezing
- Nausea, gastric irritation
Pharmacology
- Half-life: 2.5 hours
- Metabolism: extensively in intestinal wall, moderately in liver
- Excretion: Urinary
- Mechanism of Action: selective α1 agonist causes vasoconstriction
Primary Receptor
- α1
Relative Effects
- ↑SVR
- ↓HR (reflex bradycardia)
Notes
- Use with caution in patients with spinal cord injury-related bradycardia
- Useful for treatment of vasodilatory shock when norepinephrine or dopamine have precipitated tachyarrhythmias
- In patients with ↓LV function, unopposed α1 may lead to decreased CO or myocardial ischemia
- However clinical trials do not support these effects when used in clinically appropriate dose range
- Commonly used as an alternative to norepinephrine in the setting of atrial fibrillation with rapid ventricular response (associated with lower heart rate after initiation of vasopressor) [1]
Indication
- Neurogenic Shock
- Second line agent for septic shock
See Also
References
- ↑ Law AC, Bosch NA, Peterson D, Walkey AJ. Comparison of Heart Rate After Phenylephrine vs Norepinephrine Initiation in Patients With Septic Shock and Atrial Fibrillation. Chest. 2022;162(4):796-803. doi:10.1016/j.chest.2022.04.147