Phenylephrine Hcl (phenylephrine HCl)
Last reviewed · Source: First Databank (FDB) drug data
Overview
Phenylephrine hydrochloride is an alpha1-adrenergic receptor agonist.
Phenylephrine hydrochloride, synthetic sympathomimetic amine, is a vasoconstrictor.
The phenylephrine activation of alpha1-adrenergic receptors on vascular smooth muscle cells results in vasoconstriction. Following IV administration of phenylephrine hydrochloride, systolic and diastolic blood pressure, mean arterial blood pressure, and total peripheral vascular resistance are increased. Vasoconstriction occurs in most vascular beds, including renal, pulmonary, and splanchnic arteries, but minimal to no effect is observed on cerebral blood vessels.
Hepatic vascular beds are also affected. In some patients, phenylephrine can substantially reduce cardiac output, presumably due to increased afterload; however, the exact effects of the drug on global cardiac output depend on the dose and contributory effects of the arterial and venous vasculature. Although phenylephrine reduces venous compliance and can potentially increase venous return, accompanying increases in arterial and venous resistance can negate this potential benefit.
With increased blood pressure following IV administration, there is increased vagal activity, resulting in reflex bradycardia. Phenylephrine constricts both arterial and venous blood vessels, although its effects on arterial vessels are more pronounced. At clinically relevant dosages, phenylephrine increases myocardial work and oxygen requirements.
Following an IV bolus of phenylephrine hydrochloride, blood pressure increase is rapid, typically occurring within minutes. Blood pressure effects from a phenylephrine bolus may persist for up to 20 minutes. Phenylephrine is widely distributed into organs and peripheral tissues.
It is not known if phenylephrine or its metabolite are distributed into human or animal milk following parenteral administration.
Phenylephrine is extensively metabolized in the liver. Phenylephrine primarily undergoes metabolism by sulfotransferase and monoamine oxidase (MAO) to pharmacologically inactive metabolites. The 2 major metabolites are m-hydroxymandelic acid and sulfate conjugates.
Following IV administration of phenylephrine, approximately 86% of the dose is excreted in urine within 48 hours, principally as metabolites; approximately 16% of the dose is excreted in urine as unchanged drug. The terminal elimination half-life of phenylephrine averages 2.5 hours following IV administration. The observed effective half-life is approximately 5 minutes following IV infusion of the drug.
Patients with hepatic cirrhosis may have a reduced response to phenylephrine, potentially requiring higher dosages of the drug. Patients with end-stage renal disease may have an increased response to phenylephrine, potentially requiring lower dosages of the drug.
Generic name: phenylephrine HCl
Reference product & biosimilars
No reference, biosimilar or interchangeable associated with this drug.
Today’s intelligence on Phenylephrine Hcl
Indications
The following indications are listed for Phenylephrine Hcl:
- Acute Hypotension
- Hypotension Secondary To Spinal Anesthesia
Also known as: Acutely Decreased Blood Pressure, Decreased Blood Pressure Secondary To Spinal Anesthesia.
Dosing
To produce decongestion of the conjunctiva, 1 or 2 drops of a 0.12-0.25% ophthalmic solution of phenylephrine hydrochloride may be applied topically to the conjunctiva every 3-4 hours (up to 4 times daily for self-medication) as needed. Vasoconstriction for diagnosis of ocular congestion or to improve visualization of ocular blood vessels in sickle-cell disease may be achieved by application of 1 or 2 drops of a 2.5% solution. In the ''blanching test'', congestion probably is caused by conjunctivitis rather than iridocyclitis if the drug produces perilimbal blanching in the congested eye. A 2.5 or 10% solution of the drug may also be administered prior to surgery to produce mydriasis and aid in controlling hemorrhage. (See Phenylephrine Hydrochloride 52:24.)
To produce nasal decongestion in adults and children 12 years of age or older, the usual dosage is 2 or 3 drops, 1-3 sprays, or 1-3 metered sprays instilled in each nostril. In cases of extreme nasal congestion in adults, a 1% solution may be used initially. To produce nasal decongestion in children 6-12 years of age, 2 or 3 drops or 1 or 2 sprays of a 0.25% solution may be instilled in each nostril. Doses of the drug as drops or spray may be repeated in 4 hours if needed. Phenylephrine nasal solutions should not be used for self-medication for longer than 3 days; if symptoms persist, the drug should be discontinued and a physician consulted. Intranasal application of phenylephrine should generally be used for no longer than 3-5 days.
For use with local anesthetics, phenylephrine hydrochloride may be used in concentrations of 1:2500 to 1:20,000.
Phenylephrine hydrochloride is administered by IV bolus or continuous IV infusion for the treatment of clinically important hypotension. The drug is available as a 10 mg/mL phenylephrine hydrochloride injection concentrate that must be diluted prior to administration and as a ready-to-use phenylephrine hydrochloride 100 mcg/mL (Immphentiv(R), Biorphen(R)) injection. Ready-to-use phenylephrine hydrochloride 100 mcg/mL (Immphentiv(R), Biorphen(R)) injection should not be further diluted before IV bolus administration.
For treatment of hypotension during anesthesia, the manufacturers recommend administration of phenylephrine hydrochloride as an IV bolus or continuous infusion; when used in the treatment of septic shock, the drug should be administered as a continuous IV infusion with no initial bolus dose. Phenylephrine hydrochloride injection should be stored at 20-25degreesC, but may be exposed to temperatures ranging from 15-30degreesC; single-dose and pharmacy bulk vials should be kept in their original carton until time of use and protected from light.
Commercially available phenylephrine hydrochloride injection concentrate must be diluted with a compatible IV solution prior to administration. Diluted solutions may be stored at room temperature for up to 4 hours or under refrigeration for up to 24 hours; any unused portions should be discarded.
Commercially available phenylephrine hydrochloride bulk vials are intended for use in a pharmacy admixture program for preparation of single doses to be dispensed to multiple patients. Each vial should be penetrated only one time with a suitable sterile transfer device or dispensing set. Dispensing from a pharmacy bulk vial should be completed within 4 hours after the vial is penetrated.
Prior to administration, phenylephrine hydrochloride solutions should be inspected visually for particulate matter and discoloration; the drug should be discarded if the solution is colored, cloudy, or contains any particulate matter.
Care should be taken to avoid extravasation and the infusion site should be checked for free flow.
Phenylephrine hydrochloride ophthalmic solutions are applied topically to the conjunctiva. Digital pressure should be applied on the lacrimal sac for 1-2 minutes following topical instillation of ophthalmic solutions to minimize drainage into the nose and throat and reduce the risk of absorption and systemic reactions. Excess solution around the eye should be removed with a tissue.
For intranasal applications, phenylephrine may be administered in solution as drops or spray. Vicks Sinex(R) (with mist spray nozzle) nasal solution is administered by nasal inhalation using a special nasal inhaler that produces metered droplet sprays. Care must be taken to avoid contamination of the dropper, inhaler, or spray. Except in young children in whom sprays are difficult to use, nasal sprays may be preferable to drops because of the lesser risk of swallowing the drug and resultant systemic absorption. Drops should be applied to the dependent (lower) nostril, with the patient in a lateral head-low position. The patient should remain in the same position for 5 minutes, then the solution should be applied to the other nostril in a similar manner. Alternatively, drops may be instilled when the patient is reclining with the head tilted back as far as possible. Sprays should be delivered or pumped (Vicks Sinex(R) metered spray) into each nostril with the patient's head erect so that excess solution is not released. The nose should be blown thoroughly 3-5 minutes later. Prior to initial use of the metered sprays, the nasal inhaler must be primed by depressing the pump firmly several times. To minimize the risk of spreading infections, droppers, inhalers, and spray dispensers should not be used by more than one person, and tips of the dispensers, inhalers, or droppers should be rinsed with hot water following use.
Phenylephrine nasal solutions also may be applied to a tampon or nasal pack for insertion into nasal passages. However, this method of application should be restricted to use in diagnostic or surgical procedures performed under medical supervision because mechanical injury may occur.
No dosing information is available for this tab.
No dosing information is available for this tab.
Drug interactions
When applied topically to the conjunctiva (especially in concentrations of 2.5% or greater), phenylephrine hydrochloride must be administered under careful supervision and in reduced dosage if used within 21 days after the patient has received a monoamine oxidase (MAO) inhibitor because potentiation of the pressor effects of phenylephrine may result. Nasal solutions containing phenylephrine must not be given to a patient receiving an MAO inhibitor. The pressor response to phenylephrine may also be potentiated if a tricyclic antidepressant is administered concomitantly.
Concomitant administration of phenylephrine with cycloplegic antimuscarinic drugs such as atropine sulfate, cyclopentolate hydrochloride, homatropine hydrobromide, or scopolamine hydrobromide produces increased mydriatic effects.
There are no contraindication interactions for this drug.
There are no severe interactions for this drug.
There are no moderate interactions for this drug.
Contraindications
*Known hypersensitivity to phenylephrine or to any ingredient in the respective formulation.
There are no contraindication contraindications for this drug.
There are no severe contraindications for this drug.
There are no moderate contraindications for this drug.
Adverse reactions
The most commonly reported adverse effects in patients receiving IV phenylephrine hydrochloride were nausea, vomiting, and headache.
There are no severe adverse reactions for this drug.
There are no less severe adverse reactions for this drug.
Precautions
No enhanced messaging available.
The manufacturers state that safety and efficacy of parenteral preparations of phenylephrine hydrochloride have not been established in pediatric patients.
Data from randomized trials and meta-analyses with phenylephrine injection in pregnant women undergoing Cesarean section have not established a drug-associated risk of major birth defects or miscarriage. Additionally, the data did not identify adverse effects on maternal outcomes or infant Apgar scores. At recommended doses, phenylephrine does not appear to significantly affect fetal heart rate or fetal heart rate variability. Data are not available on phenylephrine use during the first or second trimester.
Untreated hypotension in pregnant women undergoing Cesarean delivery with neuraxial anesthesia has been associated with increased maternal nausea and vomiting. A sustained decrease in uterine blood flow caused by maternal hypotension has also been associated with fetal bradycardia and acidosis.
No data are available on the safety of phenylephrine injection during the period of organogenesis; therefore, conclusions cannot be drawn regarding the risk of birth defects from drug exposure. In addition, no data are available on the risk of miscarriage following fetal exposure to phenylephrine injection.
In animal studies, fetal malformations were observed following phenylephrine infusion over 1 hour during the period of organogenesis at a dosage of 1.2 times the human daily dosage. Decreased pup weight was also observed in offspring of pregnant rats who received 2.9 times the human daily dose of phenylephrine.
If a vasopressor is used in conjunction with oxytocic drugs, the vasopressor effect is potentiated and may result in serious adverse effects.
Animal reproduction studies have not been performed with phenylephrine. It is not known whether topically applied phenylephrine can cause fetal harm when administered to pregnant women. Parenterally administered phenylephrine in late pregnancy or labor may cause fetal anoxia. (See Cautions: Pregnancy and Lactation, in Phenylephrine Hydrochloride 12:12.04.) Topically applied phenylephrine should be used during pregnancy only when clearly needed.
There are no data on whether phenylephrine or its metabolite is distributed into human or animal milk following parenteral administration. The effects on the breast-fed infant and milk production are not known.
The developmental and health benefits of breast-feeding should be weighed along with the mother's clinical need for the drug and any potential adverse effects on the breast-fed infant from phenylephrine or from the underlying maternal condition.
Since it is not known whether phenylephrine is distributed into milk, the drug should be used with caution in nursing women.
If phenylephrine is used in geriatric patients, dosage should be selected carefully, usually starting at the low end of the dosage range, since renal, hepatic, and cardiovascular dysfunction and concomitant disease or other drug therapy are more common in this age group.
Clinical studies of phenylephrine hydrochloride did not include sufficient numbers of patients >=65 years of age to determine whether geriatric patients respond differently than younger patients. Clinical experience to date has not identified any differences in response between geriatric and younger patients.
If phenylephrine is used in geriatric patients, dosage should be selected carefully, usually starting at the low end of the dosage range, since renal, hepatic, and cardiovascular dysfunction and concomitant disease or other drug therapy are more common in this age group.
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Last reviewed · Source: First Databank (FDB) drug data
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