Adrenaline Metabolism Time
Adrenaline has a very short half-life and is rapidly metabolized within minutes, with effects typically lasting only 5-15 minutes after a single dose, which is why repeated dosing is often necessary during anaphylaxis or cardiac arrest. 1
Pharmacokinetic Profile
The metabolism of adrenaline occurs extremely rapidly through multiple pathways:
- Peak plasma concentrations occur within 2.5-3 minutes after intravenous administration 2
- Subcutaneous administration produces peak plasma levels within 5 minutes (rising from baseline 1.0 nmol/L to 6.5 nmol/L), with effects gradually decreasing over 2 hours 3
- Cardiovascular effects reach maximum intensity approximately 15 minutes after subcutaneous administration and persist for nearly 90 minutes 3
- Complete metabolism occurs rapidly, with plasma concentrations returning to baseline levels within 30 minutes after cessation of infusion, though some physiological effects (particularly heart rate elevation) may persist beyond this timeframe 4
Clinical Implications for Dosing
The rapid metabolism of adrenaline directly impacts clinical management:
- Repeat dosing is frequently required every 5-15 minutes during anaphylaxis because the drug effect is short-lived 1
- 10-20% of patients experiencing anaphylaxis require more than one dose of epinephrine before symptom recovery 1
- Continuous infusion may be necessary for severe reactions, as the short half-life makes single bolus doses insufficient for sustained effect 1
- Metabolic effects persist longer than cardiovascular effects, with metabolic rate remaining elevated 15-30 minutes after termination of high-dose infusions 4
Route-Specific Considerations
Different administration routes affect the duration of action:
- Intravenous route: Most rapid onset (2.5 minutes to peak) but shortest duration of action 2
- Endobronchial route: Longer half-life due to ongoing absorption, with bioavailability of approximately 40% and improved hemodynamic effects during early post-resuscitation period 2
- Subcutaneous route: Slower absorption with effects lasting up to 90 minutes, though this route is not recommended for anaphylaxis due to delayed onset 3, 1
The practical answer: 1 mL of adrenaline (concentration dependent) is substantially metabolized within 5-15 minutes, with complete clearance occurring within 30-90 minutes depending on the route of administration, though clinical effects may persist slightly longer. 3, 2, 4