Phenylephrine HCl Injection (2 mL Vial)

Phenylephrine HCl Injection is a sterile, injectable medication primarily used to increase blood pressure in patients experiencing hypotension, especially during anesthesia. It is a selective alpha-1 adrenergic receptor agonist, which works by constricting blood vessels, thereby elevating systemic vascular resistance and improving blood flow to vital organs. This medication is typically used in emergency settings, operating rooms, or intensive care units.

Phenylephrine exerts its effects by directly stimulating alpha-1 adrenergic receptors on vascular smooth muscle. This activation causes vasoconstriction, which results in increased peripheral vascular resistance and a consequent rise in blood pressure. Unlike some other vasopressors, phenylephrine has minimal effect on beta-adrenergic receptors, meaning it typically does not increase heart rate significantly. Its targeted action makes it useful in managing hypotension without excessive cardiac stimulation.

Phenylephrine HCl Injection is contraindicated in individuals with severe hypertension, ventricular tachycardia, or hypersensitivity to phenylephrine or any component of the formulation. Caution is advised in patients with hyperthyroidism, bradycardia, heart block, or advanced arteriosclerosis, as vasoconstriction may exacerbate these conditions. Close monitoring of blood pressure and cardiac function is essential, especially in patients with cardiovascular disease or during prolonged infusions.

Phenylephrine may interact with monoamine oxidase inhibitors (MAOIs), leading to a hypertensive crisis due to exaggerated vasopressor effects. It can also potentiate the effects of other adrenergic drugs and reduce the efficacy of antihypertensive medications, especially alpha-blockers. Concurrent use with certain anesthetics, particularly halogenated hydrocarbons, may increase the risk of arrhythmias. Always review the patient’s full medication profile before administration.

Possible adverse effects include reflex bradycardia, hypertension, headache, and restlessness. Prolonged use or high doses may lead to reduced cardiac output, arrhythmias, or ischemia. At the injection site, local irritation or tissue necrosis may occur if extravasation takes place. In rare cases, patients may experience anxiety, tremors, or dizziness. Continuous monitoring and prompt adjustment of dose can help minimize these risks.

The safety of phenylephrine in pregnancy has not been fully established. It should be used during pregnancy only if the potential benefits justify the potential risk to the fetus. Phenylephrine can reduce uteroplacental blood flow, which may affect fetal oxygenation. Its presence in breast milk is unknown; therefore, caution is advised when administering to breastfeeding mothers. Consultation with a healthcare provider is essential before use in pregnant or lactating women.

Store this medication at 68°F to 77°F (20°C to 25°C) and away from heat, moisture and light. Keep all medicine out of the reach of children. Throw away any unused medicine after the beyond use date. Do not flush unused medications or pour down a sink or drain.

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