Abstract
Background: Melatonin is traditionally administered orally but has a poor and variable bioavailability.
This study aims to present an overview of studies investigating the pharmacokinetics
of alternative administration routes of melatonin.
Methods: A systematic literature search was performed and included experimental or clinical
studies, investigating pharmacokinetics of alternative administration routes of melatonin
in vivo. Alternative administration routes were defined as all administration routes
except oral and intravenous.
Results: 10 studies were included in the review. Intranasal administration exhibited a quick
absorption rate and high bioavailability. Transdermal administration displayed a variable
absorption rate and possible deposition of melatonin in the skin. Oral transmucosal
administration of melatonin exhibited a high plasma concentration compared to oral
administration. Subcutaneous injection of melatonin displayed a rapid absorption rate
compared to oral administration.
Conclusion: Intranasal administration of melatonin has a large potential, and more research in
humans is warranted. Transdermal application of melatonin has a possible use in a
local application, due to slow absorption and deposition in the skin. Oral transmucosal
administration may potentially be a clinically relevant due to avoiding first-pass
metabolism. Subcutaneous injection of melatonin did not document any advantages compared
to other administration routes.
Key words
bioavailability - intranasal - transdermal - transmucosal - subcutaneous