Phenylephrine Hydrochloride

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Cat Number

API0231630

CAS Number

61-76-7

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Product Detail Description Scientific Support Customer Q&A

CAS Number

61-76-7

EINECS

200-517-3

Storage

Store at room temperature

Synonyms

Phenylephrine HCl; Mydfrin; Nostril; (R)-Phenylephrine hydrochloride; Neo-Synephrine; L-PHENYLEPHRINE HYDROCHLORIDE; Almefrin

Molecular Formula

C9H14ClNO2

Molecular Weight

203.66

Smiles

CNC[C@@H](C1=CC(=CC=C1)O)O.Cl

Appearance

White to off-white crystalline powder

Melting Point

143-145℃

General Description

Phenylephrine hydrochloride is a direct‑acting synthetic sympathomimetic amine that selectively activates alpha‑1 adrenergic receptors. It is widely available as an oral decongestant, an ophthalmic solution for pupil dilation, and as a parenteral agent for managing hypotension. The drug has no significant beta‑adrenergic activity, making it distinct from ephedrine.

Mechanism of Action

Phenylephrine stimulates alpha‑1 receptors on vascular smooth muscle, causing arteriolar vasoconstriction and increased peripheral vascular resistance. This elevates systolic and diastolic blood pressure without directly increasing heart rate. In the nasal mucosa, vasoconstriction reduces edema and congestion. In the eye, contraction of the radial dilator muscle produces mydriasis without cycloplegia. The effect is rapid and reversible, with a duration of action of 2–4 hours for decongestion.

Application

Oral phenylephrine is used as a nonprescription decongestant for sinus congestion and allergic rhinitis, though its oral bioavailability is low (about 38%), limiting efficacy. Ophthalmic phenylephrine (2.5% or 10%) is indicated for fundoscopic examination and preoperative mydriasis. Intravenous phenylephrine is a first‑line agent for treating hypotension during anesthesia or shock.

In 24 anesthetized patients without surgical stimulation, phenylephrine (2 µg/kg) was given when mean arterial pressure dropped below 80% of awake baseline. Hemodynamic monitoring showed that phenylephrine increased mean arterial pressure, stroke volume, cardiac output, central venous pressure, and end‑tidal CO₂ while decreasing pulse pressure variation and stroke volume variation. The increase in MAP initially aligned with systemic vascular resistance, but after 150 seconds the two curves dissociated. The authors conclude that in anesthesia‑induced hypotension, phenylephrine increases cardiac output primarily by augmenting venous return and preload, not solely by increasing afterload.

Fig. 1 The course of the hemodynamic variables after administration of phenylephrine. (Kalmar AF, et al., 2018)

References

Kalmar AF, et al. Phenylephrine increases cardiac output by raising cardiac preload in patients with anesthesia induced hypotension. J Clin Monit Comput. 2018;32(6):969-976.

Does Phenylephrine Hydrochloride require protection from light and oxygen?

Yes, it is susceptible to photodegradation and oxidation. Light and air can cause discoloration (pink to brown) and formation of quinone-like impurities. Store in airtight, light-resistant containers.

What is the recommended storage temperature for Phenylephrine Hydrochloride?

Store at controlled room temperature (15-25°C). Avoid excessive heat above 30°C, which accelerates oxidative degradation, especially in the presence of moisture.

Is Phenylephrine Hydrochloride stable in solution for parenteral or ophthalmic use?

Solutions require antioxidants (e.g., sodium metabisulfite) and pH control (acidic) for stability. We provide in-use stability data for various formulations.

How is the impurity 4-hydroxyphenylglycol monitored during stability?

This oxidative degradation product is quantified using a stability-indicating HPLC method with electrochemical detection, ensuring it remains below USP limits.