Sympathomimetics
Direct sympathomimetics
Drug | Site | Hemodynamic changes | Applications |
Albuterol, salmeterol, terbutaline | β₂ > β₁ | ↑ HR (little effect) | Albuterol: acute asthma/COPD; salmeterol: long‑term asthma/COPD control; terbutaline: acute bronchospasm in asthma and tocolysis |
Dobutamine | β₁ > β₂, α | -/↓ BP, ↑ HR, ↑ CO | Cardiac stress testing; acute decompensated heart failure with cardiogenic shock (inotrope) |
Dopamine | D₁ = D₂ > β > α | ↑ BP (high dose), ↑ HR, ↑ CO | Unstable bradycardia, shock; inotropic and chronotropic effects at lower doses via β; vasoconstriction at high doses via α |
Epinephrine | β > α | ↑ BP (high dose), ↑ HR, ↑ CO | Anaphylaxis, asthma, shock, open‑angle glaucoma; α effects predominate at high doses; stronger effect at β₂-receptor than norepinephrine |
Fenoldopam | D₁ | ↓ BP (vasodilation), ↑ HR, ↑ CO | Postoperative hypertension, hypertensive crisis; vasodilates coronary, peripheral, renal and splanchnic beds; promotes natriuresis; may cause hypotension, tachycardia, flushing, headache |
Isoproterenol | β₁ = β₂ | ↓ BP (vasodilation), ↑ HR, ↑ CO | Electrophysiologic evaluation of tachyarrhythmias; can worsen ischemia; minimal α effect |
Midodrine | α₁ | ↑ BP (vasoconstriction), ↓ HR, -/↓ CO | Autonomic insufficiency and postural hypotension; may worsen supine hypertension |
Mirabegron | β₃ | — | Urinary urgency or incontinence, overactive bladder (“mirab3gron”) |
Norepinephrine | α₁ > α₂ > β₁ | ↑ BP, -/↓ HR (may have minor reflexive change in response to ↑ BP due to α₁ agonism outweighing direct β₁ chronotropic effect), -/↑ CO | Hypotension, septic shock |
Phenylephrine | α₁ > α₂ | ↑ BP (vasoconstriction), ↓ HR, -/↓ CO | Hypotension (vasoconstrictor), ocular procedures (mydriatic), rhinitis (decongestant), ischemic priapism |
Indirect sympathomimetics
Drug | Mechanism | Applications |
Amphetamine | Indirect general agonist; reuptake inhibitor; also increases release of stored catecholamines | Narcolepsy, obesity, ADHD |
Cocaine | Indirect general agonist; reuptake inhibitor; causes vasoconstriction and local anesthesia; caution when giving β‑blockers if cocaine intoxication suspected (unopposed α₁ activation → ↑↑↑ BP, coronary vasospasm) | Causes mydriasis in eyes with intact sympathetic innervation → used to confirm Horner syndrome |
Ephedrine | Indirect general agonist; release of stored catecholamines | Nasal decongestion (pseudoephedrine), urinary incontinence, hypotension |
Metaraminol
- Alpha agonist with some beta effect
- Treatment hypotension
- Works like phenylephrine
- Used for short term
- Vs noradrenaline
- Can be given peripherally
- Like noradrenaline causes vasoconstrion
Give steroid when giving high dose of norad to allow good response to norad
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