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Dopamine: Class, Trade name, Action, uses and dosages
- Class: sympathomimetic
- Trade name: Intropin
- Actions: naturally occurring neurotransmitter and immediate precursor of norepinephrine. Major cardiovascular effects are produced by direct action on alpha and beta adrenergic receptors and on specific dopaminergic receptors in mesenteric & renal vascular beds. Positive inotrpoic effect on mycardium increases cardiac output w/increase in systolic and pulse pressure and little effect on diastolic. Decreases renal vascular resistance which increases glomerular filtration rate and urinary output.
- Uses: increase end organ perfusion in cardiogenic shock & in hemodynamically significant hypotension
- Dose: Adult/Ped- 2 to 20 mcg/kg/min titrated to effect
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DOPAMINE: Pharmacokinetics, Contraindications, side effects
- Onset: less then 5 min Duration: less then 10 min Half Life: 2 min
- Does not cross blood-brain barrier
- Inactivated in the liver, kidney and plasma by MAO and COMT, excreted in urine
- Contraindicated: in pts w/pheochromocytoma, tachydysrhythmias or VF. Cautious use on pts w/history of occlusive vascular disease, cold injury, diabetic, endarteritis, or arterial embolism. Pt should be normovolemic prior to use for hypovolemic shock. Infusion rates above 20mcg/kg/min will cause profound vasoconstriction because of the drug's predominantly alpha stimulation.
- CV: hypotension, ectopic beats, tachycardia, anginal pain, palpitation, vasoconstriction (indicated by disproportionate rise in diastolic pressure), cold extremities, aberrant conduction, bradycardia, widening of QRS, elevated BP
- GI: nausea, vomiting
- Other: headache, necrosis, tissue sloughing w/extravasation, gangrene, azotemia, piloerection, dyspnea, dilated pupils
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DOPAMINE: interactions and considerations
- Interactions: like all catecholamines, it is deactivated by alkaline solutions like sodium bicarb. MAO inhibitors increase the alpha adrenergic effects of dopamine and cause headache, hyperpyrexia and hypertension. Phenytoin may decrease dopamine action & actually cause hypotensive effects. Beta blockers will antagonize its cardiac effects just as alpha blockers will antagonize peripheral vasoconstriction.
- Considerations: Correct hypovolemia before admiistration of dopamine. Use a large vein. Protect it from light and discolored solutions should be discarded. Monitor BP, pulse, peripheral pulses every 5 min. Precise measurements are essential for accurate titration dosage. Observe the pt closely. Suspend dose if ascending tach, dysrhythmias, disproportionate rise in diastolic pressure, signs of peripheral ischemia (pallor, cyanosis, mottling, coldness, complaints of tenderness, pain, numbness, or burning sensation), presence of peripheral pulses is not always indicative of adequate circulation. In addition to improvement in vital signs if loss of pallor,, increase in toe temp, adaquacy of nail bed cap filling, and reversal of confusion or comatose state indicates adequate dose and perfusion.
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