Autonomic NS 4: Dopamine & Dobutamine Flashcards
Receptors stimulated by Dopamine
- Dopaminergic receptors
- Alpha adrenergic receptors
- Beta 1 adrenergic receptors
Theraputic uses of Dopamine
Shock:
* Cardiogenic
* Hemorrhagic
* endotoxic
+
Heart failure (especially with hypertension)
Explain the Pharmacodynamics of Dopamine depending on the rate of IV infusion
at low rate:
* stimulates D1 receptors
* Causes Vasodilatation—> decreasing peripheral resistance
* Increase renal blood flow & urine output
at moderate rate:
* stimulates Beta 1 receptors
* Increases Cardiac properties (CO & systolic BP)
at high rate:
* stimulates Alpha receptors
* Generalized vasoconstriction
Dopamine effect blockers
- Haloperidol (D1 blocker)
- Propranolol (beta blocker)
- Phentolamine (alpha blocker)
Describe how Dopamine treats shock
- Decreases peripheral resistance by causing VD (renal, coronary, mesenteric & renal blood vesssels), which helps tissue perfusion
t1/2 of dopamine
2 minutes
Side effects of dopamine adminstration
- Ventricular arrhythmia
- Nausea
- Vomiting
- interacts with MAO inhibitors (as it is a substrate of MAO), decrease catecholamine breakdown, thus increases blood pressure (so reduce the dose)
other D1 agonist
Fenoldopam
effect of Fendoldopam
Decrease PR by vasodilatation
t1/2 of Fenoldopam
5 minutes
theraputic use for Fenoldopam
emergency hypertension
Compare between Dopamine & Bobutamine
Chemisty:
* Dopamine: precursor of adrenaline found in the body (CNS)
* Dobutamine: synthetic
Receptors affected:
* Dopamine: D1, Beta1, Alpha
* Dobutamine: Beta1 (& weak Alpha)
presence of Dobutamine in the body
not present (synthetic)
receptors stimulated by Dobutamine
Beta1 (& weak alpha)
effect of dobutamine (pharmacodynamics)
(Beta 1)
* increases all cardiac properties
* No effect on peripheral resistance
