Name: Epinephrine
Class: Catecholamine
Mech.: Stim. a and b receptors. EPI @ NE at a, but EPI>>NE at b2. At normal doses, b actions predominate. At high doses, a actions predominate. IV bolus ® rapid rise in BP (mainly systolic), strength of ventricular contraction, HR, arteriolar constrict. in skin, mucosa, splanchnic areas. Slower app. or lower dose ® ¯ diastolic pressure due to ¯ periph resistance; increased pulse pressure. Causes CO due to rate and strength of contraction. Dilates bronchi and iris. Increases blood sugar and liver glycogenolysis.
Absorption: Subcutaneous, inhalation, IV, ophthalmic. Oral ineffective.
Metab.: Catab. by COMT and MAO, esp. in liver and kidneys. Glucuron. & sulfconj.
Excretion, t½: Short duration of action.
Toxicity/S.E.s: Cerebral hemorrhage, cardiac arrhythmias. May induce angina pain in angina patients. Also fear, anxiety, tenseness, restlessness, headache, tremor, weakness, dizziness, pallor, resp. difficulty, heart palpitations. Use w/ caution w/old folk, CV disease, hypertension, diabetes, hyperthyroidism, psychoneuroses, bronchial asthma, emphysema w/degenerative heart disease, and tricyclic drugs.
Utility: Reduce resp. distress due to bronchospasm. DOC for anaphylaxis. Prolong actions of local anesthetics. Restore cardiac fxn after cardiac arrest. Treat local hemostasis, open-angle glaucoma. Also inhibits uterine contractions, reduces mucosal congestion of hay fever, rhinitis, and acute sinusitis. ONLY OTC sympathomimetic for asthma.