PHENYLEPHRINE HYDROCHLORIDE IN 0.9% SODIUM CHLORIDE
Clinical safety rating: safe
No 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. |
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 | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
No significant drug interactions Can cause hypernatremia and fluid overload.
| FDA category | Animal |
| Breastfeeding | Phenylephrine is excreted into breast milk in minimal amounts, with an estimated M/P ratio of approximately 0.2. The relative infant dose is low (<1% of maternal weight-adjusted dose). Oral bioavailability is poor, making significant exposure to the infant unlikely. However, use with caution, especially in preterm infants or those with cardiovascular instability. |
| Teratogenic Risk |
■ FDA Black Box Warning
None.
| Common Effects | fluid replacement |
| Serious Effects |
Hypersensitivity to phenylephrine; severe hypertension; ventricular tachycardia; narrow-angle glaucoma; concurrent use with MAO inhibitors or within 14 days of MAOI therapy.
| 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. |
Loading safety data…
| 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. |