PHENYLEPHRINE HYDROCHLORIDE IN 0.9% SODIUM CHLORIDE
Clinical safety rating
safeNo significant drug interactions Can cause hypernatremia and fluid overload.
Phenylephrine is a selective α1-adrenergic receptor agonist causing vasoconstriction, increasing peripheral vascular resistance and blood pressure.
| Metabolism | Primarily metabolized by monoamine oxidase (MAO) and sulfotransferase in the liver and gastrointestinal tract; subject to first-pass metabolism. |
| Excretion | Primarily renal (80-90% as unchanged drug and metabolites); minor biliary/fecal elimination (<10%). |
| Half-life | Terminal elimination half-life: 2-3 hours; clinical context: requires repeated dosing or continuous infusion for sustained effect. |
| Protein binding | Approximately 95% bound, primarily to albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | Volume of distribution: 2-4 L/kg; clinical meaning: extensive tissue distribution with limited CNS penetration. |
| Bioavailability | Oral: <1% due to extensive first-pass metabolism; intranasal: up to 50% (variable); IM/SC: 100% bioavailable. |
| Onset of Action | IV: immediate (seconds to 1 minute); IM: 10-15 minutes; SC: 10-15 minutes; intranasal: 15-20 minutes. |
| Duration of Action | IV: 15-20 minutes; IM: 30 minutes to 2 hours; SC: 50 minutes to 2 hours; intranasal: 1-2 hours. |
| Molecular Weight | 203.67 |
Intravenous infusion: initial rate 100-180 mcg/min, titrate to effect; maintenance 40-60 mcg/min. Concentrations: 100 mcg/mL (10 mg in 100 mL NS) or 200 mcg/mL (20 mg in 100 mL NS). Administer via central line preferred.
| Dosage form | SOLUTION |
| Renal impairment | No dose adjustment required for GFR >15 mL/min. For GFR <15 mL/min or on dialysis: use with caution; no specific dose adjustment guidelines; monitor blood pressure and adjust infusion rate accordingly due to potential reduced clearance. |
| Liver impairment | Child-Pugh A: no adjustment. Child-Pugh B and C: consider starting at lower infusion rates (e.g., 50-100 mcg/min) and titrate carefully due to reduced clearance and increased sensitivity. |
| Pediatric use | Intravenous infusion: 0.5-1 mcg/kg/min, titrate to effect; maximum 10 mcg/kg/min. Administer via central line preferred. For bolus: 0.5-1 mcg/kg every 10-15 min as needed (off-label; use with caution). |
| Geriatric use | Elderly patients may have increased sensitivity; start at lower infusion rates (e.g., 50-100 mcg/min) and titrate slowly; monitor blood pressure closely due to risk of hypertension and bradycardia. |
| 1st trimester | Phenylephrine hydrochloride in 0.9% sodium chloride is generally avoided in the first trimester due to risk of reduced placental perfusion and potential teratogenic effects from maternal hypertension. Use only if clearly needed and no alternative exists. |
| 2nd trimester | May be used when necessary for hypotension, but caution is advised due to vasoconstriction and potential uteroplacental insufficiency. Monitor maternal blood pressure and fetal heart rate. |
| 3rd trimester | Use with caution in the third trimester; may cause fetal hypoxia, bradycardia, and decreased placental perfusion. Avoid near term as it can delay labor and cause neonatal hypertension. |
Clinical note
No significant drug interactions Can cause hypernatremia and fluid overload.
| FDA category | Animal |
| Placental transfer | Phenylephrine crosses the placenta; studies show limited transfer, but vasoconstrictive effects on uterine and placental vessels can reduce blood flow. Degree of transfer is dose-dependent. |
| Breastfeeding | Phenylephrine is excreted into breast milk in minimal amounts; oral bioavailability is low due to first-pass metabolism. However, intravenous or high doses may affect milk production and cause irritability in the infant. Caution is advised; monitor infant for side effects. |
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | Phenylephrine is a sympathomimetic amine used as a vasopressor. For the first trimester, there is no evidence of increased risk of major congenital malformations based on human data, although animal studies are limited. For the second and third trimesters, maternal use may reduce uteroplacental blood flow due to vasoconstriction, potentially causing fetal hypoxia and bradycardia. It is generally avoided in pregnancy unless clearly needed. |
| Fetal Monitoring | Monitor maternal blood pressure, heart rate, and signs of vasoconstriction. Fetal heart rate monitoring is recommended during infusion, as phenylephrine may cause fetal bradycardia and reduced variability. Observe for signs of uteroplacental insufficiency. |
| Fertility Effects | No specific data on human fertility effects. Animal studies have not shown significant impairment. Indirect effects from severe hypotension could theoretically impact fertility, but no direct evidence. |
■ FDA Black Box Warning
None.
| Common Effects | fluid replacement |
| Serious Effects |
Severe hypertension (e.g., hypertensive crisis)Ventricular fibrillation or tachycardiaHypersensitivity to phenylephrine or any componentUse with potent vasopressors (e.g., epinephrine) in same IV linePheochromocytomaSevere peripheral vascular diseaseAngle-closure glaucoma
| Precautions | May cause severe hypertension, bradycardia, or arrhythmias; use with caution in patients with hyperthyroidism, bradycardia, partial heart block, myocardial disease, or severe arteriosclerosis; extravasation may cause tissue necrosis. |
| Food/Dietary | No known food interactions with intravenous phenylephrine. Maintain usual diet unless directed otherwise by your healthcare provider. |
| Clinical Pearls | Phenylephrine hydrochloride in 0.9% sodium chloride is used for the prevention and treatment of hypotension during anesthesia. Administer via IV infusion with careful titration to avoid reflex bradycardia. Monitor blood pressure continuously, especially in patients with preexisting hypertension or bradyarrhythmias. Use with caution in patients with hyperthyroidism, severe atherosclerosis, or narrow-angle glaucoma. Not recommended for patients with severe hypertension or ventricular tachycardia. In obstetrics, may decrease uterine blood flow; use only if clearly needed. |
| Patient Advice | This medication is given intravenously to raise your blood pressure during surgery or medical procedures. · Inform your healthcare provider if you have high blood pressure, heart problems, thyroid disease, or glaucoma. · Tell your doctor about all medications you are taking, especially MAO inhibitors, antidepressants, or other blood pressure medications. · Report any chest pain, slow heartbeat, headache, or difficulty breathing during the infusion. · This medication is not for self-administration; it is given only in a hospital setting. |
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