Dobutamine

Question 1

What is the trade name of Dobutamine Hydrochloride?

Answer 1

Dobutrex

Question 2

What are the Broad Category and Sub-category drug classifications and the reason for classification for Dobutamine?

Answer 2

Broad Category= Sympathomimetic Drug
-derived from beta-phenylethylamine; its a synthetic analog of isoproterenol, which is made from dopamine

Sub-Category= Synthetic Catecholamine
-Dobutamine is a catecholamine because it has hydroxyl groups on the 3 and 4 carbon posns of the benzene ring of beta-phenylethylamine

Question 3

What is Dobutamine a synthetic analog of?

Answer 3

Isoproterenol

Question 4

What are the Clinical uses for Dobutamine?

Answer 4

• Increases CO (inotropic effect)
• Reduction in Atrial filling pressures
• Moderate increase in RBF due to increases in CO and Vasodilation
• Coronary artery vasodilation
• Decreases pulmonary artery pressures
• Increases LV stroke work index

Question 5

What receptors does Dobutamine work on/ what is Dobutamine??

Answer 5

direct acting selective B1 adrenergic receptor agonist (but at clinical doses some Beta 2 and alpha 1 stimulation may occur)

Question 6

What are the MINIMAL changes produced by Dobutamine?

Answer 6

• minimal effects on Systemic BP
• minimal increases in myocardial oxygen requirements
• minimal increases in HR
• minimal increases in MAP

Question 7

Dobutamine produces NO change in…?

Answer 7

Airway resistance

Question 8

Dobutamine produces no change to minimal change in….?

Answer 8

peripheral vascular resistance (vasodilation)

Question 9

Why is Dobutamine used for patients with organic heart disease? Patients recovering from cardiac surgery? Patients recovering from MI?

Answer 9

it can increase exercise tolerance and improve cardiac output in patients with CHF that present with increased HR and SVR

Question 10

Why is Dobutamine used for patients with RV failure/ cor pulmonale?

Answer 10

Dobutamine causes Pulmonary vasodilation

Question 11

What is Dobutamine used for patients with mitral valve replacement?

Answer 11

These patients have increased pulmonary artery pressures and Dobutamine increases CO and decreases systemic and pulmonary vascular resistance

Question 12

Why is Dobutamine used in Septic Shock?

Answer 12

Does NOT reverse hypotension therefore; its not considered a first line drug for septic shock; after fluid resuscitation, Dobutamine can be used in conjunction with vasopressors to reverse tissue hypo-perfusion by increasing oxygen delivery and consumption though increasing CO

Question 13

How is Dobutamine used to detect CAD?

Answer 13

Dobutamine Echocardiography: useful in patients that are unable to undergo stress testing such as patients with pacemakers, significant bradycardia or those taking high dose Beta-adrenergic blockers. Dobutamine can also be used to help determine the responsive or unresponsive areas of dyskinesia post myocardial infarction

Question 14

Why is Dobutamine often used in combination therapy?

Answer 14

useful in the distribution of cardiac output

Question 15

What are Dobutamine + low dose dopamine used in combo therapy for?

Answer 15

Increase Renal Perfusion

Question 16

What are Dobutamine + vasodilators used in combo therapy for?

Answer 16

Improve CO by decreasing afterload in patients that have increased SVR

Question 17

What is the MOA of Dobutamine?

Answer 17

• direct acting selective B1 adrenergic receptor agonist; these effects are due to the fact that the clinically available formulation of Dobutamine is a racemic mixture of enantiomers that may have differential effects on adrenergic receptor subtypes
• Dobutamine binds to beta-receptors, which are G-protein coupled receptors; these are ligand specific and once activated the G protein diffuses into the cell and through a series of reactions increases cAMP, which stimulates the production of Protein kinase C, which in turn increases the inward flux of calcium; this enhances the muscle contraction

Question 18

Where are the B1 receptors located?

Answer 18

Cardiac Muscle (heart) (also in Kidneys)

Question 19

At what dose is Dobutamine B1 selective?

Answer 19

<5mcg/kg/min

Question 20

What does the B2 action of Dobutamine cause?

Answer 20

leads to peripheral arterial vasodilation and a reduction in afterload.

Question 21

What is the onset of action of Dobutamine?

Answer 21

1-2 minutes; 10 minutes may be required to obtain peak effect

Question 22

What is the E 1/2 life of Dobutamine?

Answer 22

2 minutes

Question 23

How is Dobutamine metabolized?

Answer 23

In tissues and the liver through the breakdown of the catechol and conjugation via MAO (monoamine oxidase) or COMT (catechol-O-methyltransferase

Question 24

What and Where is MAO? COMT?

Answer 24

MAO- is an enzyme present in the liver, kidneys, and GI tract and catalyzes oxidative deamination

COMT- methylates the hydroxyl group on Dobutamine, which inactivates the drug and metabolites that are conjugated with glucuronic acid are passed in the urine

Question 25

How is Dobutamine eliminated?

Answer 25

Excreted via the renal system; In urine the major excretion products are the conjugates of Dobutamine and the inactive derivative of Dobutamine (3-O- methyl Dobutamine)

Question 26

What are the CNS side effects of Dobutamine?

Answer 26

Fever, Headache, Parasthesia

Question 27

What is the resp. side effect of Dobut?

Answer 27

Dyspnea

Question 28

What are the CV side effects of Dobutamine (excluding Tachycardia, we will cover that separately!)?

Answer 28

``` Cardiac Dysrhythmias Increased Ventricular Ectopy Increased BP Anginal Pain Chest Pain Palpitations ```

Question 29

How does administration of Dobutamine cause tachycardia? What dosage/infusion rate do you see this effect more prominently?

Answer 29

Usually elicited through HIGH infusion rates (>10mcg/kg/min) or infusions lasting over 72hrs. Tachycardias may be more prominent in patients with Afib b/c Dobutamine increases the conduction velocity through the AV node!

Question 30

What are the GI side effects of dobut?

Answer 30

nausea

Question 31

What are the musculoskeletal side effects of Dobutamine?

Answer 31

mild leg cramps

Question 32

What are the hematologic side effects of Dobutamine?

Answer 32

Thrombocytopenia | Platelet Inhibition

Question 33

What are the local side effects of Dobutamine?

Answer 33

Phlebitis Local Inflammation Infiltration pain Cutaneous Necrosis

Question 34

What are 2 other side effects of Dobutamine?

Answer 34

down regulation of beta receptors | toxicity

Question 35

What are signs/symptoms of Dobutamine toxicity?

Answer 35

Due to excessive beta receptor stimulation include anorexia, nausea, vomiting, tremor, anxiety, palpitations, headache, SOB, anginal and non-specific chest pain

Question 36

What is Dobutamine NOT recommended as first line therapy for? why?

Answer 36

not the first line drug of choice for patients that need increased SVR to increase SBP; therefore, hypovolemia should be corrected b4 administration of Dobut. b/c Dobutamine does not have any clinically significant vasoconstrictor activity

Question 37

What can develop with dobutamine for patients with non-chf CAD?

Answer 37

myocardial ischemia

Question 38

What are contraindications to administration of dobutamine?

Answer 38

- Do not use this drug in patients with idiopathic hypertrophic subaortic stenosis or other forms of mechanical obstruction - dont use in ppl with hypersensitivity to Dobutamine or sodium bisulfite(sulfite allergy is more commonly seen in asthma patients) - Use cautiously in patients post MI b/c it may increase myocardial oxygen command

Question 39

Name the drugs that have drug interactions with Dobutamine.

Answer 39

- Beta-blocking drugs - Nitroprusside - Cocaine - Guanethidine - MAOIs - Methyldopa - Reserpine - TCAs - Heparin, Cefazolin, PCN, NaBicarb, Alkaline solutions

Question 40

What is the drug interaction of Dobutamine with beta blocking drugs?

Answer 40

an increase in peripheral vascular resistance may be noted

Question 41

What is the drug interaction of Dobutamine with Nitroprusside?

Answer 41

may cause synergistic effect resulting in higher CO and lower pulmonary wedge pressure

Question 42

What is the drug interaction of Dobutamine with Cocaine?

Answer 42

may cause malignant arrythmia

Question 43

What is the drug interaction of Dobutamine with Guanethidine?

Answer 43

Can increase the pressor response

Question 44

What is the drug interaction of Dobutamine with MAOIs?

Answer 44

potentiates hypertension and hypertensive crisis

Question 45

What is the drug interaction of Dobutamine with Methyldopa?

Answer 45

can increase the pressor response

Question 46

What is the drug interaction of Dobutamine with Reserpine? same as with TCAs?

Answer 46

increases the pressor response

Question 47

What is the drug interaction of Dobutamine with Heparin, Cefazolin, PCN, Sodium Bicarb, Alkaline Solutions?

Answer 47

Precipitates may form if infused in combination

Question 48

What is the Dosage of Dobutamine?

Answer 48

Infusion should be started at 0.5-1 mcg/kg/min and titrated every few minutes according to parameters such as SVR, urine flow, frequency of ectopic activity, HR, CO, CVP, and PCWP Typically infusion rates range from 2-10mcg/kg/min with a max dose of 40mcg/kg/min for adults

Question 49

What can Dobutamine do to potassium levels?

Answer 49

Can decrease K!!!! so check serum potassium

Question 50

What pregnancy category is Dobutamine in?

Answer 50

B

Question 51

How is Dobutamine usually mixed?

Answer 51

-dissolved in solution of 5% dextrose, 5% dextrose and 0.45% sodium chloride, 5% dextrose and 0.9% sodium chloride, 10% dextrose, lactated ringers, 5% dextrose in lactated ringers, 0.9% sodium chloride or sodium lactate for infusion BECAUSE inactivation can occur in ALKALINE solutions such as 5% sodium bicarb

Question 52

What should you NOT mix Dobutamine in? Why?

Answer 52

Alkaline solutions such as 5% sodium bicarbonate