Phenylephrine

Alpha-1 adrenergic agonist for hypotension; ophthalmic mydriasis; reversal of penile prolapse in horses. Selective alpha-1 adrenergic receptor agonist (phenylephrine HCl). Mechanism: stimulates alpha-1 receptors → peripheral vasoconstriction → increased systemic vascular resistance and blood pressure. Ophthalmic: alpha-1 mediated pupillary dilator muscle contraction → mydriasis (15–20 min onset; 3–6 hr duration). IV: vasopressor for hypotension. Key information Alpha-1 adrenergic agonist. Ophthalmic: mydriasis and vasoconstriction. Injectable: vasopressor — monitor blood pressure closely. IV: titrate to effect. Do not administer in IV bag with alkaline solutions.

Ophthalmic: Instill into the conjunctival sac; avoid touching dropper tip to eye or periocular tissue. Instill 1 drop into affected eye(s); wait 5 min before other eye drops. IV (vasopressor, horses): dilute to desired concentration; administer as slow IV bolus or CRI with ECG and blood pressure monitoring. Store at room temperature; protect from light. If a dose is missed This medication is administered by a veterinarian or veterinary staff in a clinical setting. Missed doses are managed by your veterinary team — contact your veterinarian to reschedule.

Ophthalmic: transient stinging, burning. Cardiovascular (systemic absorption): hypertension, reflex bradycardia, arrhythmias. Topical nasal: rhinitis medicamentosa with prolonged use. IV: severe hypertension if overdosed; arrhythmias.

For animals Ophthalmic: mydriasis only — no cycloplegia (use tropicamide for cycloplegia). Systemic use: monitor blood pressure and heart rate closely. Avoid in patients with hyperthyroidism or cardiovascular disease. For people handling this medication Wash hands thoroughly with soap and water after handling. Avoid contact with eyes; if contact occurs, flush with water for 15 minutes and seek medical attention. Keep out of reach of children. If accidental ingestion occurs, contact Poison Control (1-800-222-1222). Alpha-1 agonist — avoid ingestion (causes hypertension). Wash hands thoroughly with soap and water after handling. Ophthalmic: avoid human eye contact. Keep out of reach of children.

Contact your veterinarian. Phenylephrine overdose causes severe hypertension, reflex bradycardia, and reduced cardiac output. Medical emergency.