Sympathomimetic amines

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  1. Epinephrine – potent alpha and beta adrenergic receptor agonist and is one of the most potent vasopressor drugs known; causes myocardial stimulation, increased heart rate and vasoconstriction and relaxes bronchial muscles
  2. Norepinephrine – both epinephrine and norepinephrine have equal beta-1 stimulation; norepinephrine has relatively little beta-2 activity and is slightly less potent on alpha receptors; causes increase in blood pressure, cardiac output is unchanged or decreased and total peripheral resistance is raised
  3. Dopamine – causes increase in GFR, renal blood flow and Na excretion making it especially useful in the treatment of low cardiac output; usually increases systolic blood pressure and has no effect on diastolic blood pressure; total peripheral resistance is unchanged but at high doses causes vasoconstriction
  4. Isoproterenol – potent nonselective catecholamine beta agonist with low affinity for alpha receptors; lowers peripheral vascular resistance by relaxing smooth muscle causing drop in diastolic pressure, cardiac ouput increases due to positive inotropic and chronotropic effects
  5. Dobutamine – has relatively more inotropic than chronotropic effects; does not change peripheral resistance, heart rate increases modestly
  6. Alpha-1 adrenergic agonists (vascular smooth muscle)
    1. phenylephrine – causes arterial vasoconstriction
    2. NOTE: prazosin is an alpha-1 antagonist that causes a fall in peripheral vascular resistance
  7. alpha-2 agonists (cardiovascular centers of the CNS that suppresses outflow of sympathetic nervous system activity from the brain)
    1. clonidine – causes rise in blood pressure followed by a prolonged hypotensive response due to decreased central outflow of impulses in the sympathetic nervous system
    2. neosynephrine is an agonist of both alpha-1 and alpha-2
  8. amphetamine – powerful CNS stimulant in addition to peripheral alpha and beta actions, raises blood pressure, heart rate is reflexly slowed and arrhythmias may occur at high doses (amphetamines are weak bases)
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