Population pharmacokinetic and pharmacodynamic modeling of epinephrine administered using a mobile inhaler

• Published in: Drug metabolism and pharmacokinetics 2015-12, Vol.30 (6), p.391-399
• Main Authors: Frechen, Sebastian, Suleiman, Ahmed Abbas, Mohammad Nejad Sigaroudi, Ali, Wachall, Bertil, Fuhr, Uwe
• Format: Article
• Language: English
• Subjects: Administration, Inhalation; Adrenergic Agonists - administration & dosage; Adrenergic Agonists - blood; Adrenergic Agonists - pharmacokinetics; Aerosols; Anaphylaxis; Biological Availability; Cross-Over Studies; Epinephrine; Epinephrine - administration & dosage; Epinephrine - blood; Epinephrine - pharmacokinetics; Equipment Design; Female; Germany; Half-Life; Healthy Volunteers; Heart Rate - drug effects; Humans; Inhalation; Injections, Intramuscular; Linear Models; Male; Metabolic Clearance Rate; Mixed-effects modeling; Models, Biological; Models, Statistical; Nebulizers and Vaporizers; Pharmacokinetics and pharmacodynamics; Pilot Projects
• ISSN: 1347-4367; 1880-0920
• DOI: 10.1016/j.dmpk.2015.08.002

Inhaled epinephrine is a potential alternative to self-administered intramuscular epinephrine in imminent anaphylactic reactions. The objective was to develop a pharmacokinetic-pharmacodynamic model describing exposure and effects on heart rate of inhaled epinephrine. Data from a 4-phase cross-over clinical trial in 9 healthy volunteers including 0.3 mg intramuscular epinephrine, two doses of inhaled epinephrine (4 mg/mL solution administered during [mean] 18 and 25 min, respectively) using a mobile pocket inhaler, and an inhaled placebo were analyzed using mixed-effects modeling. Inhaled epinephrine was available almost immediately and more rapidly than via the intramuscular route (absorption half-live 29 min). Epinephrine plasma concentrations declined rapidly after terminating inhalation (elimination half-life 4.1 min) offering the option to stop exposure in case of adverse events. While the expected maximum concentration was higher for inhaled epinephrine, this was not associated with safety concerns due to only moderate additional hemodynamic effects compared to intramuscular administration. Bioavailability after inhalation (4.7%) was subject to high interindividual and interoccasional variability highlighting that training of inhalation would be essential for patients. The proposed model suggests that the use of a highly concentrated epinephrine solution via inhalation may offer an effective treatment option in anaphylaxis, while efficacy in patients remains to be shown.