Sympathomimetics

Question 1

Epinephrine (Adrenaline)

Answer 1

MOA: affects both beta (1 & 2) and alpha adrenergic receptors, producing bronchodilation and vasoconstriction, increased chronotropy, inotropy, and dromotropy.

Pharmacokinetics: Onset: Rapid IV; Duration: IV 5-10 min, half-life: 5 minutes

Indications: treatment of cardiac arrest or symptomatic bradycardia; anaphylaxis, reative airway disease; can be used as a pressor

AR/SE: angina, arrhythmias, hypertension, tachycardia, nervousness, restlessness, tremors

Contraindications: known allergy

Dosage: cardiac arrest: 1mg (1:10000) IV/IO EVERY 3-5 MIN bRADYCARDIA or for pressor effect 2-10 mcg/min (drip)

Question 2

Norepinephrine (levophed)

Answer 2

Class: vasopressor, Sympathomimetic

MOA: stimulates alpha-adrenergic receptors located mainly in the blood vessels, causing constriction; has minor beta 1 effects

Pharmacokinetics: onset- immediate, duration- 1-2 min

Indications: Cardiogenic Shock;severe hypotension not related to hypovolemia

AR/SE: dizziness, anxiety, cardiac arrhythmias

Contraindications: known allergy

Dosage: 0.1-0.5 mcg/kg/min (max of 30 mcg/min) titrate to maintain adequate blood pressure

Question 3

Dopamine (Intropin)

Answer 3

Class: Inotropic, vasopressor, adrenergic, Sympathetic agonist

MOA: stimulates both alpha and beta adrenergic receptors in a dose dependent fashion.

Pharmacokinetics: onset 1-2 minutes; duration 10 minutes

Indications: adjunct to improving BP, cardiac output, and urine output in the treatment of shock unresponsive to fluid replacement; symptomatic bradycardia

AR/SE: arrhythmias, hypotension, headache, N/V.

Contraindications: known allergy; pheochromocytoma (adrenal gland tumor)

Dosage: 2-20 mcg/kg/min IV (2-4 will cause vasodilation, 5-15 beta 1 effects, >15 alpha effects

Special Considerations: Use caution in pts with hypovolemia or MI, correct hypovolemia before administering

Question 4

Dobutamine (dobutrex)

Answer 4

Class: inotropic, adrenergic, Sympathetic agonist

MOA: increases inotropy by stimulating beta-1 adrenergic receptors with a minor effect on the rate and peripheral blood vessels

Pharmacokinetics: Onset 2-10 min, duration varies; HL: 2 min

Indications: short term management of heart failure caused by decreased contractility

AR/SE: hypertension, increased HR, pVC’s headache, N/V

Contraindications: known allergy

Dosage: 2-20 mcg/kg/min IV titrated to response

Special Considerations: (P class B) use caution in pts with hx of MI or afib; beta blocker may negate the effects

Question 5

Milrinone (Primacor)

Answer 5

MOA: increases myocardial contractility and decreases preload and afterload by dilating the vascular smooth muscle, does not work through adrenergic receptors.

Pharmacokinetics: onset 5-15 min, duration 3-6 hrs; HL; 2-3 Hours

Indications: short term treatment of CHF unresponsive to conventional therapy

AR/SE: ventricular arrhythmias, Hypotension, N/V

Contraindications: known allergy, severe aortic or pulmonary valvular heart disease

Dosage: 50 mcg/kg Slow IV/IO (over 10 minutes) followed by infusion of 0.375 mcg/kg/min

Question 6

Vasopressin (Pitressin)

Answer 6

Class: Hormone; vasopressor

MOA: Acts as a non-alpha-adrenergic vasoconstrictor via direct stimulation of smooth muscle receptors. Can be used as an alternative to epinephrine during CPR.

Pharmacokinetics: onset: varies, duration 30-60 minutes; HL: 10-20 min

Indications: may replace the 1st or second dose of Epinephrine in cardiac arrest, increases peripheral vascular resistance during CPR.

AR/SE: skin blanching, hypertension, bradycardia, abdominal cramps, nausea, minor arrythmia.

Contraindications: known allergy, None when used during CPR

Dosage: 40 units IV/IO (1 time only) can replace 1st or 2nd dose of EpI during cardiac arrest