DOPAMINE HYDROCHLORIDE

DOPAMINE HYDROCHLORIDE (doe'pa-meen) Classifications: alpha- and beta-adrenergic agonist; Therapeutic: cardiac stimulant; adrenergic agonist Prototype: Epinephrine Pregnancy Category: C

Availability

40 mg/mL, 80 mg/mL, 160 mg/mL injection

Action

Major cardiovascular effects produced by direct action on alpha- and beta-adrenergic receptors and on specific dopaminergic receptors in mesenteric and renal vascular beds. Positive inotropic effect on myocardium increases cardiac output with increase in systolic and pulse pressure and little or no effect on diastolic pressure. Improves circulation to renal vascular bed by decreasing renal vascular resistance with resulting increase in glomerular filtration rate and urinary output.

Therapeutic Effect

Hemodynamic effects of dopamine are dose-dependent. Due to its potential for inotropic, chronotropic, and vasopressor effects, dopamine has several clinical uses, including decreased cardiac output as well as correction of hypotension associated with cardiogenic and septic shock.

Uses

To correct hemodynamic imbalance in shock syndrome due to MI (cardiogenic shock), trauma, endotoxic septicemia (septic shock), open heart surgery, and CHF.

Unlabeled Uses

Acute renal failure; cirrhosis; hepatorenal syndrome; barbiturate intoxication.

Contraindications

Pheochromocytoma; tachyarrhythmias or ventricular fibrillation; pregnancy (category C); children <2 y.

Cautious Use

Patients with history of occlusive vascular disease (e.g., Buerger's or Raynaud's disease); CAD; cold injury; acute MI; diabetic endarteritis, arterial embolism; neonates, lactation.

Route & Dosage

Shock/Surgery Adult: IV 2–5 mcg/kg/min increased gradually up to 20–50 mcg/kg/min if necessary Adolescent/Child: IV 1–5 mcg/kg/min increased gradually up to 20 mcg/kg/min CHF Adult: IV 3–10 mcg/kg/min

Administration

Intravenous PREPARE: Continuous: • Dilute just prior to administration. • Dilute each ampule in one of the following: D5W, D5/NS, D5/LR, D5/0.45% NaCl, NS.• Dilute 200 mg ampule in 250 mL, 500 mL, or 1000 mL IV solution to yield 800 mcg/mL, 400 mcg/mL, or 200 mcg/mL, respectively. Dilute 400 mg ampule in 250 mL, 500 mL, or 1000 mL IV solution to yield 1600 mcg/mL, 800 mcg/mL or 400 mcg/mL, respectively.• Dilute 800 mg ampule in 250 mL, 500 mL, or 1000 mL IV solution to yield 3200 mcg/mL, 1600 mcg/mL or 800 mcg/mL, respectively.• Consult package information for other dilutions.  ADMINISTER: Continuous: •  Infusion rate is based on body weight.• Infusion rate and guidelines for adjusting rate relative changes in blood pressure are prescribed by physician.• Microdrip and other reliable metering device should be used for accuracy of flow rate.  INCOMPATIBILITIES Solution/additive: Acyclovir, alteplase, amphotericin B, ampicillin, metronidazole, penicillin G, sodium bicarbonate. Y-site: Acyclovir, alteplase, amphotericin b cholesteryl complex, cefepime, doxycycline, furosemide, indomethacin, insulin, lansoprazole, sodium bicarbonate, thiopental. Correct hypovolemia, if possible, with either whole blood or plasma before initiation of dopamine therapy. Monitor infusion continuously for free flow, and take care to avoid extravasation, which can result in tissue sloughing and gangrene. Use a large vein of the antecubital fossa. Antidote for extravasation: Stop infusion promptly and remove needle. Immediately infiltrate the ischemic area with 5–10 mg phentolamine mesylate in 10–15 mL of NS, using syringe and fine needle. Protect dopamine from light. Discolored solutions should not be used.

• Store reconstituted solution for 24 h at 2°–15° C (36°–59° F) or 6 h at room temperature 15°–30° C.

Adverse Effects (≥1%)

CV: Hypotension, ectopic beats, tachycardia, anginal pain, palpitation, vasoconstriction (indicated by disproportionate rise in diastolic pressure), cold extremities; less frequent: aberrant conduction, bradycardia, widening of QRS complex, elevated blood pressure. GI: Nausea, vomiting. CNS: Headache. Skin: Necrosis, tissue sloughing with extravasation, gangrene, piloerection. Other: Azotemia, dyspnea, dilated pupils (high doses).

Diagnostic Test Interference

Dopamine may modify test response when histamine is used as a control for intradermal skin tests.

Interactions

Drug: mao inhibitors, ergot alkaloids, increase alpha-adrenergic effects (headache, hyperpyrexia, hypertension); guanethidine, phenytoin may decrease dopamine action; beta blockers antagonize cardiac effects; alpha blockers antagonize peripheral vasoconstriction; halothane, cyclopropane increase risk of hypertension and ventricular arrhythmias.

Pharmacokinetics

Onset: <5 min. Duration: <10 min. Distribution: Widely distributed; does not cross blood–brain barrier. Metabolism: Inactive in the liver, kidney, and plasma by monoamine oxidase and COMT. Elimination: In urine. Half-Life: 2 min.

Nursing Implications

Assessment & Drug Effects

• Monitor blood pressure, pulse, peripheral pulses, and urinary output at intervals prescribed by physician. Precise measurements are essential for accurate titration of dosage.
• Report the following indicators promptly to physician for use in decreasing or temporarily suspending dose: Reduced urine flow rate in absence of hypotension; ascending tachycardia; dysrhythmias; disproportionate rise in diastolic pressure (marked decrease in pulse pressure); signs of peripheral ischemia (pallor, cyanosis, mottling, coldness, complaints of tenderness, pain, numbness, or burning sensation).
• Monitor therapeutic effectiveness. In addition to improvement in vital signs and urine flow, other indices of adequate dosage and perfusion of vital organs include loss of pallor, increase in toe temperature, adequacy of nail bed capillary filling, and reversal of confusion or comatose state.

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Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug