Sympathomimetics

They activate adrenergic receptors, copying the norepinephrine and epinephrine of the sympathetic nervous system. Alpha-1 activation constricts blood vessels, beta-1 activation makes the heart beat faster and harder, and beta-2 activation relaxes bronchial and some vascular smooth muscle. Each drug's mix of receptors decides its use, and the catecholamines here are given by injection or infusion and act briefly.

• EpinephrineIts beta-2 action, which norepinephrine largely lacks, opens the airways and makes it the emergency drug for anaphylaxis.
• NorepinephrineMainly a vasoconstrictor: it has little beta-2 action, unlike epinephrine, and reflex slowing means it raises pressure more than cardiac output.
• DobutamineRaises cardiac output mainly through a bigger stroke volume rather than a faster rate, unlike isoproterenol.

• Anaphylaxis
• Shock with low blood pressure, such as septic shock
• Cardiac arrest
• Acute heart failure with low cardiac output
• Asthma (inhaled beta-2 agonists)
• COPD (inhaled beta-2 agonists)

• Fast heart rate and palpitationsKnown for
• Arrhythmias, including ventricular arrhythmiasKnown forSerious
• High blood pressureSerious
• Angina or myocardial ischemiaSerious
• Tremor
• Anxiety and restlessness
• Headache
• Low potassium
• High blood sugar
• Tissue necrosis if an infusion leaksSerious

What the class has in common. Each drug's card has its own, and Known for marks what an exam expects you to know.

• Extravasation of a catecholamine infusion causes local necrosis; phentolamine, an alpha blocker, is infiltrated as the antidote.
• Low blood volume is corrected before vasopressors, or organs stay underperfused despite a normal pressure.
• MAOIs and tricyclic antidepressants can cause severe, prolonged hypertension with catecholamines.
• Heart disease: more arrhythmias and angina; halogenated anesthetics such as halothane sensitize the heart.

Written for biofideX in plain words, after checking these references:

• Epinephrine injection 1 mg/mL: label (DailyMed)
• Norepinephrine bitartrate in dextrose injection: label (DailyMed)
• Dobutamine injection: label (DailyMed)
• Albuterol sulfate HFA inhalation aerosol: label (DailyMed)
• Formoterol fumarate inhalation solution: label (DailyMed)
• Adrenergic agonist (NCI Thesaurus)
• Alpha-adrenergic agonist (NCI Thesaurus)
• Adrenaline 1 mg/10 ml (1:10,000) pre-filled syringe: SmPC (emc)

For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.