Classifications: alpha-adrenergic antagonist; vasodilator; Therapeutic: vasodilator
Pregnancy Category: C
5 mg injection
Alpha-adrenergic blocking agent that competitively blocks alpha-adrenergic receptors, but action is transient and incomplete.
Causes vasodilation and decreases general vascular resistance as well as pulmonary arterial pressure, primarily by direct
action on vascular smooth muscle.
Prevents hypertension resulting from elevated levels of circulating epinephrine or norepinephrine.
Diagnosis of pheochromocytoma and to prevent or control hypertensive episodes prior to or during pheochromocytomectomy.
Prevention of dermal necrosis and sloughing following IV administration or extravasation of norepinephrine.
MI (previous or present), coronary artery disease; peptic ulcer disease; pregnancy (category C), lactation.
Route & Dosage
|To Prevent Hypertensive Episode during Surgery
Adult: IV/IM 5 mg 12 h before surgery, repeat as needed
Child: IV/IM 0.050.1 mg/kg/dose (max: 5 mg/dose)
To Test for Pheochromocytoma
Adult: IV/IM 5 mg
Child: IV/IM 0.050.1 mg/kg (max: 5 mg)
To Treat Extravasation
Adult: Intradermal 510 mg diluted in 10 mL of normal saline injected into affected area within 12 h of extravasation
Child: Intradermal 0.10.2 mg/kg diluted with normal saline injected into affected area within 12 h of extravasation
Note: Place patient in supine position when receiving drug parenterally. Monitor BP and pulse q2min until stabilized. Intramuscular
- Reconstitute 5 mg vial with 1 mL of sterile water for injection.
PREPARE: Direct: Reconstitute as for IM. May be further diluted with up to 10 mL of sterile water. Use immediately.
ADMINISTER: Direct: Give a single dose over 60 sec.
Adverse Effects (≥1%)Body as a Whole:
Weakness, dizziness, flushing, orthostatic hypotension. GI: Abdominal pain, nausea, vomiting, diarrhea, exacerbation of peptic ulcer. CV: Acute and prolonged hypotension, tachycardia, anginal pain,
cardiac arrhythmias, MI,
cerebrovascular spasm, shock-like state. Special Senses:
Nasal stuffiness, conjunctival infection
May antagonize BP raising effects of epinephrine, ephedrine.
2 min IV
; 1520 min IM. Duration:
1015 min IV
; 34 h IM. Elimination:
In urine. Half-Life:
Assessment & Drug Effects
Test for pheochromocytoma:
- IV administration: Keep patient at rest in supine position throughout test, preferably in quiet darkened room. Prior to drug administration,
take BP q10min for at least 30 min to establish that BP has stabilized before IV injection. Record BP immediately after
injection and at 30-sec intervals for first 3 min; then at 1-min intervals for next 7 min.
- IM administration: Post-injection, BP determinations at 5-min intervals for 3045 min.
Patient & Family Education
- Avoid sudden changes in position, particularly from reclining to upright posture and dangle legs and exercise ankles and
toes for a few minutes before standing to walk.
- Lie down or sit down in head-low position immediately if light-headed or dizzy.