Category: pharmacological
Aliases: adrenaline, EpiPen
Endogenous catecholamine and emergency drug. Mixed α1/α2/β1/β2/β3 agonist (with higher β-affinity than norepinephrine due to the N-methyl group added by PNMT). Endogenously synthesized in adrenal medulla + brainstem PNMT-expressing neurons under sympathetic activation. Clinical use: IM anaphylaxis (0.3-0.5 mg adult / 0.15 mg pediatric), ACLS cardiac arrest (1 mg IV q3-5 min), septic shock vasopressor, local-anesthetic vasoconstrictor (with lidocaine to extend block + reduce systemic absorption), nebulized for upper-airway croup. Extremely short t½ (~2-3 min IV) due to rapid MAO/COMT degradation — bolus or infusion only. PK (Coté 2009 critical-care popPK PMID:19534820 + EpiPen label): IV anaphylaxis/cardiac-arrest workhorse + IM autoinjector for outpatient anaphylaxis. t½ ~3.5 min — among the shortest of all clinical drugs. Vd 8 L (vascular + minimal tissue). Clearance dominated by hepatic MAO + COMT extraneuronal metabolism (cross-link: monoamine_oxidase_metabolism + catecholamine_synthesis). Oral F essentially zero (massive first-pass MAO/COMT). IM/SC absorption via local vasoconstriction is paradoxically variable; IM thigh (vastus lateralis) preferred over deltoid for autoinjector use (faster + more reliable absorption).
IV: 0.058h